Use resumable hash in digest package

Vendored resumable sha256/sha512 library. Digest package new exports a
resumable variant of the Digester.

Docker-DCO-1.1-Signed-off-by: Josh Hawn <josh.hawn@docker.com> (github: jlhawn)

Godeps/Godeps.json

@@ -76,6 +76,10 @@
 			"ImportPath": "github.com/gorilla/mux",
 			"Rev": "e444e69cbd2e2e3e0749a2f3c717cec491552bbf"
 		},
+		{
+			"ImportPath": "github.com/jlhawn/go-crypto",
+			"Rev": "cd738dde20f0b3782516181b0866c9bb9db47401"
+		},
 		{
 			"ImportPath": "github.com/yvasiyarov/go-metrics",
 			"Rev": "57bccd1ccd43f94bb17fdd8bf3007059b802f85e"

Godeps/_workspace/src/github.com/AdRoll/goamz/cloudfront/testdata/key.pem

@@ -1,15 +0,0 @@
------BEGIN RSA PRIVATE KEY-----
-MIICXAIBAAKBgQC0yMzp9DkPAE99DhsEaGkqougLvtmDKri4bZj0fFjmGmjyyjz9
-hlrsr87LHVWzH/7igK7040HG1UqypX3ijtJa9+6BKHwBBctboU3y4GfwFwVAOumY
-9UytFpyPlgUFrffZLQAywKkT24OgcfEj0G5kiQn760wFnmSUtOuITo708QIDAQAB
-AoGAJUA6+PoZx72Io3wElSPuh5qJteHdb+mdpmLu4XG936wRc/W4G4VTtvGC6tdg
-kUhGfOWHJ26sXwwUGDuBdO146m0DkBTuIooy97afpL6hXgL5v4ELHbbuFJcf4Geg
-/UAuexvRT1HenYFQ/iXM0LlqI33i8cFRc1A+j0Gseo07gAECQQDYFCn7OUokX+Q8
-M2Cwhu7JT1obmP2HwsBtXl0CDDxtOQkuYJP/UqvtdYPz/kRn3yQjoynaCTHYrFz/
-H8oN1nNhAkEA1i9TEpo7RbanIyT4vbc1/5xfjE7Pj0lnGku0QXFp/S+8YxbqhjrQ
-4Qp7TTXIPPqvQhhEpAGGspM460K3F6h7kQJBANJCbMeFa9wRY2ohJIkiA+HoUWph
-aPNeUxkZpa+EcJhn08NJPzpIG/ypSYl3duEMhYIYF3WPVO3ea2/mYxsr/oECQFj5
-td/fdEoEk7AU1sQxDNyPwF2QC8dxbcRNuKcLD0Wfg/oB9hEm88jYytoLQpCabx3c
-6P7cp3EdmaKZx2erlRECQDYTSK2tS0+VoXSV9JbU08Pbu53j3Zhmp4l0csP+l7EU
-U+rRQzKho4X9vpR/VpRGXbw8tTIhojNpHh5ofryVfgk=
------END RSA PRIVATE KEY-----

Godeps/_workspace/src/github.com/jlhawn/go-crypto/.gitignore

@@ -0,0 +1,24 @@
+# Compiled Object files, Static and Dynamic libs (Shared Objects)
+*.o
+*.a
+*.so
+
+# Folders
+_obj
+_test
+
+# Architecture specific extensions/prefixes
+*.[568vq]
+[568vq].out
+
+*.cgo1.go
+*.cgo2.c
+_cgo_defun.c
+_cgo_gotypes.go
+_cgo_export.*
+
+_testmain.go
+
+*.exe
+*.test
+*.prof

Godeps/_workspace/src/github.com/jlhawn/go-crypto/LICENSE

@@ -0,0 +1,28 @@
+Copyright (c) 2012 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+

Godeps/_workspace/src/github.com/jlhawn/go-crypto/README.md

@@ -0,0 +1,6 @@
+# go-crypto
+A Subset of the Go `crypto` Package with a Resumable Hash Interface
+
+### Documentation
+
+GoDocs: http://godoc.org/github.com/jlhawn/go-crypto

Godeps/_workspace/src/github.com/jlhawn/go-crypto/crypto.go

@@ -0,0 +1,87 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package crypto is a Subset of the Go `crypto` Package with a Resumable Hash
+package crypto
+
+import (
+	"hash"
+	"strconv"
+)
+
+// Hash identifies a cryptographic hash function that is implemented in another
+// package.
+type Hash uint
+
+// HashFunc simply returns the value of h so that Hash implements SignerOpts.
+func (h Hash) HashFunc() Hash {
+	return h
+}
+
+const (
+	SHA224 Hash = 1 + iota // import crypto/sha256
+	SHA256                 // import crypto/sha256
+	SHA384                 // import crypto/sha512
+	SHA512                 // import crypto/sha512
+	maxHash
+)
+
+var digestSizes = []uint8{
+	SHA224: 28,
+	SHA256: 32,
+	SHA384: 48,
+	SHA512: 64,
+}
+
+// Size returns the length, in bytes, of a digest resulting from the given hash
+// function. It doesn't require that the hash function in question be linked
+// into the program.
+func (h Hash) Size() int {
+	if h > 0 && h < maxHash {
+		return int(digestSizes[h])
+	}
+	panic("crypto: Size of unknown hash function")
+}
+
+// ResumableHash is the common interface implemented by all resumable hash
+// functions.
+type ResumableHash interface {
+	// ResumableHash is a superset of hash.Hash
+	hash.Hash
+	// Len returns the number of bytes written to the Hash so far.
+	Len() uint64
+	// State returns a snapshot of the state of the Hash.
+	State() ([]byte, error)
+	// Restore resets the Hash to the given state.
+	Restore(state []byte) error
+}
+
+var hashes = make([]func() ResumableHash, maxHash)
+
+// New returns a new ResumableHash calculating the given hash function. New panics
+// if the hash function is not linked into the binary.
+func (h Hash) New() ResumableHash {
+	if h > 0 && h < maxHash {
+		f := hashes[h]
+		if f != nil {
+			return f()
+		}
+	}
+	panic("crypto: requested hash function #" + strconv.Itoa(int(h)) + " is unavailable")
+}
+
+// Available reports whether the given hash function is linked into the binary.
+func (h Hash) Available() bool {
+	return h < maxHash && hashes[h] != nil
+}
+
+// RegisterHash registers a function that returns a new instance of the given
+// hash function. This is intended to be called from the init function in
+// packages that implement hash functions.
+func RegisterHash(h Hash, f func() ResumableHash) {
+	if h >= maxHash {
+		panic("crypto: RegisterHash of unknown hash function")
+	}
+	hashes[h] = f
+}

Godeps/_workspace/src/github.com/jlhawn/go-crypto/sha256/resume.go

@@ -0,0 +1,50 @@
+package sha256
+
+import (
+	"bytes"
+	"encoding/gob"
+)
+
+// Len returns the number of bytes which have been written to the digest.
+func (d *digest) Len() uint64 {
+	return d.len
+}
+
+// State returns a snapshot of the state of the digest.
+func (d *digest) State() ([]byte, error) {
+	var buf bytes.Buffer
+	encoder := gob.NewEncoder(&buf)
+
+	// We encode this way so that we do not have
+	// to export these fields of the digest struct.
+	vals := []interface{}{
+		d.h, d.x, d.nx, d.len, d.is224,
+	}
+
+	for _, val := range vals {
+		if err := encoder.Encode(val); err != nil {
+			return nil, err
+		}
+	}
+
+	return buf.Bytes(), nil
+}
+
+// Restore resets the digest to the given state.
+func (d *digest) Restore(state []byte) error {
+	decoder := gob.NewDecoder(bytes.NewReader(state))
+
+	// We decode this way so that we do not have
+	// to export these fields of the digest struct.
+	vals := []interface{}{
+		&d.h, &d.x, &d.nx, &d.len, &d.is224,
+	}
+
+	for _, val := range vals {
+		if err := decoder.Decode(val); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

Godeps/_workspace/src/github.com/jlhawn/go-crypto/sha256/sha256.go

@@ -0,0 +1,192 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package sha256 implements the SHA224 and SHA256 hash algorithms as defined
+// in FIPS 180-4.
+package sha256
+
+import (
+	"github.com/jlhawn/go-crypto"
+)
+
+func init() {
+	crypto.RegisterHash(crypto.SHA224, New224)
+	crypto.RegisterHash(crypto.SHA256, New)
+}
+
+// The size of a SHA256 checksum in bytes.
+const Size = 32
+
+// The size of a SHA224 checksum in bytes.
+const Size224 = 28
+
+// The blocksize of SHA256 and SHA224 in bytes.
+const BlockSize = 64
+
+const (
+	chunk     = 64
+	init0     = 0x6A09E667
+	init1     = 0xBB67AE85
+	init2     = 0x3C6EF372
+	init3     = 0xA54FF53A
+	init4     = 0x510E527F
+	init5     = 0x9B05688C
+	init6     = 0x1F83D9AB
+	init7     = 0x5BE0CD19
+	init0_224 = 0xC1059ED8
+	init1_224 = 0x367CD507
+	init2_224 = 0x3070DD17
+	init3_224 = 0xF70E5939
+	init4_224 = 0xFFC00B31
+	init5_224 = 0x68581511
+	init6_224 = 0x64F98FA7
+	init7_224 = 0xBEFA4FA4
+)
+
+// digest represents the partial evaluation of a checksum.
+type digest struct {
+	h     [8]uint32
+	x     [chunk]byte
+	nx    int
+	len   uint64
+	is224 bool // mark if this digest is SHA-224
+}
+
+func (d *digest) Reset() {
+	if !d.is224 {
+		d.h[0] = init0
+		d.h[1] = init1
+		d.h[2] = init2
+		d.h[3] = init3
+		d.h[4] = init4
+		d.h[5] = init5
+		d.h[6] = init6
+		d.h[7] = init7
+	} else {
+		d.h[0] = init0_224
+		d.h[1] = init1_224
+		d.h[2] = init2_224
+		d.h[3] = init3_224
+		d.h[4] = init4_224
+		d.h[5] = init5_224
+		d.h[6] = init6_224
+		d.h[7] = init7_224
+	}
+	d.nx = 0
+	d.len = 0
+}
+
+// New returns a new crypto.ResumableHash computing the SHA256 checksum.
+func New() crypto.ResumableHash {
+	d := new(digest)
+	d.Reset()
+	return d
+}
+
+// New224 returns a new crypto.ResumableHash computing the SHA224 checksum.
+func New224() crypto.ResumableHash {
+	d := new(digest)
+	d.is224 = true
+	d.Reset()
+	return d
+}
+
+func (d *digest) Size() int {
+	if !d.is224 {
+		return Size
+	}
+	return Size224
+}
+
+func (d *digest) BlockSize() int { return BlockSize }
+
+func (d *digest) Write(p []byte) (nn int, err error) {
+	nn = len(p)
+	d.len += uint64(nn)
+	if d.nx > 0 {
+		n := copy(d.x[d.nx:], p)
+		d.nx += n
+		if d.nx == chunk {
+			block(d, d.x[:])
+			d.nx = 0
+		}
+		p = p[n:]
+	}
+	if len(p) >= chunk {
+		n := len(p) &^ (chunk - 1)
+		block(d, p[:n])
+		p = p[n:]
+	}
+	if len(p) > 0 {
+		d.nx = copy(d.x[:], p)
+	}
+	return
+}
+
+func (d0 *digest) Sum(in []byte) []byte {
+	// Make a copy of d0 so that caller can keep writing and summing.
+	d := *d0
+	hash := d.checkSum()
+	if d.is224 {
+		return append(in, hash[:Size224]...)
+	}
+	return append(in, hash[:]...)
+}
+
+func (d *digest) checkSum() [Size]byte {
+	len := d.len
+	// Padding.  Add a 1 bit and 0 bits until 56 bytes mod 64.
+	var tmp [64]byte
+	tmp[0] = 0x80
+	if len%64 < 56 {
+		d.Write(tmp[0 : 56-len%64])
+	} else {
+		d.Write(tmp[0 : 64+56-len%64])
+	}
+
+	// Length in bits.
+	len <<= 3
+	for i := uint(0); i < 8; i++ {
+		tmp[i] = byte(len >> (56 - 8*i))
+	}
+	d.Write(tmp[0:8])
+
+	if d.nx != 0 {
+		panic("d.nx != 0")
+	}
+
+	h := d.h[:]
+	if d.is224 {
+		h = d.h[:7]
+	}
+
+	var digest [Size]byte
+	for i, s := range h {
+		digest[i*4] = byte(s >> 24)
+		digest[i*4+1] = byte(s >> 16)
+		digest[i*4+2] = byte(s >> 8)
+		digest[i*4+3] = byte(s)
+	}
+
+	return digest
+}
+
+// Sum256 returns the SHA256 checksum of the data.
+func Sum256(data []byte) [Size]byte {
+	var d digest
+	d.Reset()
+	d.Write(data)
+	return d.checkSum()
+}
+
+// Sum224 returns the SHA224 checksum of the data.
+func Sum224(data []byte) (sum224 [Size224]byte) {
+	var d digest
+	d.is224 = true
+	d.Reset()
+	d.Write(data)
+	sum := d.checkSum()
+	copy(sum224[:], sum[:Size224])
+	return
+}

Godeps/_workspace/src/github.com/jlhawn/go-crypto/sha256/sha256_test.go

@@ -0,0 +1,176 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// SHA256 hash algorithm.  See FIPS 180-2.
+
+package sha256
+
+import (
+	"fmt"
+	"io"
+	"testing"
+)
+
+type sha256Test struct {
+	out string
+	in  string
+}
+
+var golden = []sha256Test{
+	{"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855", ""},
+	{"ca978112ca1bbdcafac231b39a23dc4da786eff8147c4e72b9807785afee48bb", "a"},
+	{"fb8e20fc2e4c3f248c60c39bd652f3c1347298bb977b8b4d5903b85055620603", "ab"},
+	{"ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad", "abc"},
+	{"88d4266fd4e6338d13b845fcf289579d209c897823b9217da3e161936f031589", "abcd"},
+	{"36bbe50ed96841d10443bcb670d6554f0a34b761be67ec9c4a8ad2c0c44ca42c", "abcde"},
+	{"bef57ec7f53a6d40beb640a780a639c83bc29ac8a9816f1fc6c5c6dcd93c4721", "abcdef"},
+	{"7d1a54127b222502f5b79b5fb0803061152a44f92b37e23c6527baf665d4da9a", "abcdefg"},
+	{"9c56cc51b374c3ba189210d5b6d4bf57790d351c96c47c02190ecf1e430635ab", "abcdefgh"},
+	{"19cc02f26df43cc571bc9ed7b0c4d29224a3ec229529221725ef76d021c8326f", "abcdefghi"},
+	{"72399361da6a7754fec986dca5b7cbaf1c810a28ded4abaf56b2106d06cb78b0", "abcdefghij"},
+	{"a144061c271f152da4d151034508fed1c138b8c976339de229c3bb6d4bbb4fce", "Discard medicine more than two years old."},
+	{"6dae5caa713a10ad04b46028bf6dad68837c581616a1589a265a11288d4bb5c4", "He who has a shady past knows that nice guys finish last."},
+	{"ae7a702a9509039ddbf29f0765e70d0001177914b86459284dab8b348c2dce3f", "I wouldn't marry him with a ten foot pole."},
+	{"6748450b01c568586715291dfa3ee018da07d36bb7ea6f180c1af6270215c64f", "Free! Free!/A trip/to Mars/for 900/empty jars/Burma Shave"},
+	{"14b82014ad2b11f661b5ae6a99b75105c2ffac278cd071cd6c05832793635774", "The days of the digital watch are numbered.  -Tom Stoppard"},
+	{"7102cfd76e2e324889eece5d6c41921b1e142a4ac5a2692be78803097f6a48d8", "Nepal premier won't resign."},
+	{"23b1018cd81db1d67983c5f7417c44da9deb582459e378d7a068552ea649dc9f", "For every action there is an equal and opposite government program."},
+	{"8001f190dfb527261c4cfcab70c98e8097a7a1922129bc4096950e57c7999a5a", "His money is twice tainted: 'taint yours and 'taint mine."},
+	{"8c87deb65505c3993eb24b7a150c4155e82eee6960cf0c3a8114ff736d69cad5", "There is no reason for any individual to have a computer in their home. -Ken Olsen, 1977"},
+	{"bfb0a67a19cdec3646498b2e0f751bddc41bba4b7f30081b0b932aad214d16d7", "It's a tiny change to the code and not completely disgusting. - Bob Manchek"},
+	{"7f9a0b9bf56332e19f5a0ec1ad9c1425a153da1c624868fda44561d6b74daf36", "size:  a.out:  bad magic"},
+	{"b13f81b8aad9e3666879af19886140904f7f429ef083286195982a7588858cfc", "The major problem is with sendmail.  -Mark Horton"},
+	{"b26c38d61519e894480c70c8374ea35aa0ad05b2ae3d6674eec5f52a69305ed4", "Give me a rock, paper and scissors and I will move the world.  CCFestoon"},
+	{"049d5e26d4f10222cd841a119e38bd8d2e0d1129728688449575d4ff42b842c1", "If the enemy is within range, then so are you."},
+	{"0e116838e3cc1c1a14cd045397e29b4d087aa11b0853fc69ec82e90330d60949", "It's well we cannot hear the screams/That we create in others' dreams."},
+	{"4f7d8eb5bcf11de2a56b971021a444aa4eafd6ecd0f307b5109e4e776cd0fe46", "You remind me of a TV show, but that's all right: I watch it anyway."},
+	{"61c0cc4c4bd8406d5120b3fb4ebc31ce87667c162f29468b3c779675a85aebce", "C is as portable as Stonehedge!!"},
+	{"1fb2eb3688093c4a3f80cd87a5547e2ce940a4f923243a79a2a1e242220693ac", "Even if I could be Shakespeare, I think I should still choose to be Faraday. - A. Huxley"},
+	{"395585ce30617b62c80b93e8208ce866d4edc811a177fdb4b82d3911d8696423", "The fugacity of a constituent in a mixture of gases at a given temperature is proportional to its mole fraction.  Lewis-Randall Rule"},
+	{"4f9b189a13d030838269dce846b16a1ce9ce81fe63e65de2f636863336a98fe6", "How can you write a big system without C++?  -Paul Glick"},
+}
+
+var golden224 = []sha256Test{
+	{"d14a028c2a3a2bc9476102bb288234c415a2b01f828ea62ac5b3e42f", ""},
+	{"abd37534c7d9a2efb9465de931cd7055ffdb8879563ae98078d6d6d5", "a"},
+	{"db3cda86d4429a1d39c148989566b38f7bda0156296bd364ba2f878b", "ab"},
+	{"23097d223405d8228642a477bda255b32aadbce4bda0b3f7e36c9da7", "abc"},
+	{"a76654d8e3550e9a2d67a0eeb6c67b220e5885eddd3fde135806e601", "abcd"},
+	{"bdd03d560993e675516ba5a50638b6531ac2ac3d5847c61916cfced6", "abcde"},
+	{"7043631cb415556a275a4ebecb802c74ee9f6153908e1792a90b6a98", "abcdef"},
+	{"d1884e711701ad81abe0c77a3b0ea12e19ba9af64077286c72fc602d", "abcdefg"},
+	{"17eb7d40f0356f8598e89eafad5f6c759b1f822975d9c9b737c8a517", "abcdefgh"},
+	{"aeb35915346c584db820d2de7af3929ffafef9222a9bcb26516c7334", "abcdefghi"},
+	{"d35e1e5af29ddb0d7e154357df4ad9842afee527c689ee547f753188", "abcdefghij"},
+	{"19297f1cef7ddc8a7e947f5c5a341e10f7245045e425db67043988d7", "Discard medicine more than two years old."},
+	{"0f10c2eb436251f777fbbd125e260d36aecf180411726c7c885f599a", "He who has a shady past knows that nice guys finish last."},
+	{"4d1842104919f314cad8a3cd20b3cba7e8ed3e7abed62b57441358f6", "I wouldn't marry him with a ten foot pole."},
+	{"a8ba85c6fe0c48fbffc72bbb2f03fcdbc87ae2dc7a56804d1590fb3b", "Free! Free!/A trip/to Mars/for 900/empty jars/Burma Shave"},
+	{"5543fbab26e67e8885b1a852d567d1cb8b9bfe42e0899584c50449a9", "The days of the digital watch are numbered.  -Tom Stoppard"},
+	{"65ca107390f5da9efa05d28e57b221657edc7e43a9a18fb15b053ddb", "Nepal premier won't resign."},
+	{"84953962be366305a9cc9b5cd16ed019edc37ac96c0deb3e12cca116", "For every action there is an equal and opposite government program."},
+	{"35a189ce987151dfd00b3577583cc6a74b9869eecf894459cb52038d", "His money is twice tainted: 'taint yours and 'taint mine."},
+	{"2fc333713983edfd4ef2c0da6fb6d6415afb94987c91e4069eb063e6", "There is no reason for any individual to have a computer in their home. -Ken Olsen, 1977"},
+	{"cbe32d38d577a1b355960a4bc3c659c2dc4670859a19777a875842c4", "It's a tiny change to the code and not completely disgusting. - Bob Manchek"},
+	{"a2dc118ce959e027576413a7b440c875cdc8d40df9141d6ef78a57e1", "size:  a.out:  bad magic"},
+	{"d10787e24052bcff26dc484787a54ed819e4e4511c54890ee977bf81", "The major problem is with sendmail.  -Mark Horton"},
+	{"62efcf16ab8a893acdf2f348aaf06b63039ff1bf55508c830532c9fb", "Give me a rock, paper and scissors and I will move the world.  CCFestoon"},
+	{"3e9b7e4613c59f58665104c5fa86c272db5d3a2ff30df5bb194a5c99", "If the enemy is within range, then so are you."},
+	{"5999c208b8bdf6d471bb7c359ac5b829e73a8211dff686143a4e7f18", "It's well we cannot hear the screams/That we create in others' dreams."},
+	{"3b2d67ff54eabc4ef737b14edf87c64280ef582bcdf2a6d56908b405", "You remind me of a TV show, but that's all right: I watch it anyway."},
+	{"d0733595d20e4d3d6b5c565a445814d1bbb2fd08b9a3b8ffb97930c6", "C is as portable as Stonehedge!!"},
+	{"43fb8aeed8a833175c9295c1165415f98c866ef08a4922959d673507", "Even if I could be Shakespeare, I think I should still choose to be Faraday. - A. Huxley"},
+	{"ec18e66e93afc4fb1604bc2baedbfd20b44c43d76e65c0996d7851c6", "The fugacity of a constituent in a mixture of gases at a given temperature is proportional to its mole fraction.  Lewis-Randall Rule"},
+	{"86ed2eaa9c75ba98396e5c9fb2f679ecf0ea2ed1e0ee9ceecb4a9332", "How can you write a big system without C++?  -Paul Glick"},
+}
+
+func TestGolden(t *testing.T) {
+	for i := 0; i < len(golden); i++ {
+		g := golden[i]
+		s := fmt.Sprintf("%x", Sum256([]byte(g.in)))
+		if s != g.out {
+			t.Fatalf("Sum256 function: sha256(%s) = %s want %s", g.in, s, g.out)
+		}
+		c := New()
+		for j := 0; j < 3; j++ {
+			if j < 2 {
+				io.WriteString(c, g.in)
+			} else {
+				io.WriteString(c, g.in[0:len(g.in)/2])
+				c.Sum(nil)
+				io.WriteString(c, g.in[len(g.in)/2:])
+			}
+			s := fmt.Sprintf("%x", c.Sum(nil))
+			if s != g.out {
+				t.Fatalf("sha256[%d](%s) = %s want %s", j, g.in, s, g.out)
+			}
+			c.Reset()
+		}
+	}
+	for i := 0; i < len(golden224); i++ {
+		g := golden224[i]
+		s := fmt.Sprintf("%x", Sum224([]byte(g.in)))
+		if s != g.out {
+			t.Fatalf("Sum224 function: sha224(%s) = %s want %s", g.in, s, g.out)
+		}
+		c := New224()
+		for j := 0; j < 3; j++ {
+			if j < 2 {
+				io.WriteString(c, g.in)
+			} else {
+				io.WriteString(c, g.in[0:len(g.in)/2])
+				c.Sum(nil)
+				io.WriteString(c, g.in[len(g.in)/2:])
+			}
+			s := fmt.Sprintf("%x", c.Sum(nil))
+			if s != g.out {
+				t.Fatalf("sha224[%d](%s) = %s want %s", j, g.in, s, g.out)
+			}
+			c.Reset()
+		}
+	}
+}
+
+func TestSize(t *testing.T) {
+	c := New()
+	if got := c.Size(); got != Size {
+		t.Errorf("Size = %d; want %d", got, Size)
+	}
+	c = New224()
+	if got := c.Size(); got != Size224 {
+		t.Errorf("New224.Size = %d; want %d", got, Size224)
+	}
+}
+
+func TestBlockSize(t *testing.T) {
+	c := New()
+	if got := c.BlockSize(); got != BlockSize {
+		t.Errorf("BlockSize = %d want %d", got, BlockSize)
+	}
+}
+
+var bench = New()
+var buf = make([]byte, 8192)
+
+func benchmarkSize(b *testing.B, size int) {
+	b.SetBytes(int64(size))
+	sum := make([]byte, bench.Size())
+	for i := 0; i < b.N; i++ {
+		bench.Reset()
+		bench.Write(buf[:size])
+		bench.Sum(sum[:0])
+	}
+}
+
+func BenchmarkHash8Bytes(b *testing.B) {
+	benchmarkSize(b, 8)
+}
+
+func BenchmarkHash1K(b *testing.B) {
+	benchmarkSize(b, 1024)
+}
+
+func BenchmarkHash8K(b *testing.B) {
+	benchmarkSize(b, 8192)
+}

Godeps/_workspace/src/github.com/jlhawn/go-crypto/sha256/sha256block.go

@@ -0,0 +1,128 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !386,!amd64
+
+// SHA256 block step.
+// In its own file so that a faster assembly or C version
+// can be substituted easily.
+
+package sha256
+
+var _K = []uint32{
+	0x428a2f98,
+	0x71374491,
+	0xb5c0fbcf,
+	0xe9b5dba5,
+	0x3956c25b,
+	0x59f111f1,
+	0x923f82a4,
+	0xab1c5ed5,
+	0xd807aa98,
+	0x12835b01,
+	0x243185be,
+	0x550c7dc3,
+	0x72be5d74,
+	0x80deb1fe,
+	0x9bdc06a7,
+	0xc19bf174,
+	0xe49b69c1,
+	0xefbe4786,
+	0x0fc19dc6,
+	0x240ca1cc,
+	0x2de92c6f,
+	0x4a7484aa,
+	0x5cb0a9dc,
+	0x76f988da,
+	0x983e5152,
+	0xa831c66d,
+	0xb00327c8,
+	0xbf597fc7,
+	0xc6e00bf3,
+	0xd5a79147,
+	0x06ca6351,
+	0x14292967,
+	0x27b70a85,
+	0x2e1b2138,
+	0x4d2c6dfc,
+	0x53380d13,
+	0x650a7354,
+	0x766a0abb,
+	0x81c2c92e,
+	0x92722c85,
+	0xa2bfe8a1,
+	0xa81a664b,
+	0xc24b8b70,
+	0xc76c51a3,
+	0xd192e819,
+	0xd6990624,
+	0xf40e3585,
+	0x106aa070,
+	0x19a4c116,
+	0x1e376c08,
+	0x2748774c,
+	0x34b0bcb5,
+	0x391c0cb3,
+	0x4ed8aa4a,
+	0x5b9cca4f,
+	0x682e6ff3,
+	0x748f82ee,
+	0x78a5636f,
+	0x84c87814,
+	0x8cc70208,
+	0x90befffa,
+	0xa4506ceb,
+	0xbef9a3f7,
+	0xc67178f2,
+}
+
+func block(dig *digest, p []byte) {
+	var w [64]uint32
+	h0, h1, h2, h3, h4, h5, h6, h7 := dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4], dig.h[5], dig.h[6], dig.h[7]
+	for len(p) >= chunk {
+		// Can interlace the computation of w with the
+		// rounds below if needed for speed.
+		for i := 0; i < 16; i++ {
+			j := i * 4
+			w[i] = uint32(p[j])<<24 | uint32(p[j+1])<<16 | uint32(p[j+2])<<8 | uint32(p[j+3])
+		}
+		for i := 16; i < 64; i++ {
+			v1 := w[i-2]
+			t1 := (v1>>17 | v1<<(32-17)) ^ (v1>>19 | v1<<(32-19)) ^ (v1 >> 10)
+			v2 := w[i-15]
+			t2 := (v2>>7 | v2<<(32-7)) ^ (v2>>18 | v2<<(32-18)) ^ (v2 >> 3)
+			w[i] = t1 + w[i-7] + t2 + w[i-16]
+		}
+
+		a, b, c, d, e, f, g, h := h0, h1, h2, h3, h4, h5, h6, h7
+
+		for i := 0; i < 64; i++ {
+			t1 := h + ((e>>6 | e<<(32-6)) ^ (e>>11 | e<<(32-11)) ^ (e>>25 | e<<(32-25))) + ((e & f) ^ (^e & g)) + _K[i] + w[i]
+
+			t2 := ((a>>2 | a<<(32-2)) ^ (a>>13 | a<<(32-13)) ^ (a>>22 | a<<(32-22))) + ((a & b) ^ (a & c) ^ (b & c))
+
+			h = g
+			g = f
+			f = e
+			e = d + t1
+			d = c
+			c = b
+			b = a
+			a = t1 + t2
+		}
+
+		h0 += a
+		h1 += b
+		h2 += c
+		h3 += d
+		h4 += e
+		h5 += f
+		h6 += g
+		h7 += h
+
+		p = p[chunk:]
+	}
+
+	dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4], dig.h[5], dig.h[6], dig.h[7] = h0, h1, h2, h3, h4, h5, h6, h7
+}

Godeps/_workspace/src/github.com/jlhawn/go-crypto/sha256/sha256block_386.s

@@ -0,0 +1,283 @@
+// Copyright 2013 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// SHA256 block routine. See sha256block.go for Go equivalent.
+//
+// The algorithm is detailed in FIPS 180-4:
+//
+//  http://csrc.nist.gov/publications/fips/fips180-4/fips-180-4.pdf
+//
+// Wt = Mt; for 0 <= t <= 15
+// Wt = SIGMA1(Wt-2) + SIGMA0(Wt-15) + Wt-16; for 16 <= t <= 63
+//
+// a = H0
+// b = H1
+// c = H2
+// d = H3
+// e = H4
+// f = H5
+// g = H6
+// h = H7
+//
+// for t = 0 to 63 {
+//    T1 = h + BIGSIGMA1(e) + Ch(e,f,g) + Kt + Wt
+//    T2 = BIGSIGMA0(a) + Maj(a,b,c)
+//    h = g
+//    g = f
+//    f = e
+//    e = d + T1
+//    d = c
+//    c = b
+//    b = a
+//    a = T1 + T2
+// }
+//
+// H0 = a + H0
+// H1 = b + H1
+// H2 = c + H2
+// H3 = d + H3
+// H4 = e + H4
+// H5 = f + H5
+// H6 = g + H6
+// H7 = h + H7
+
+// Wt = Mt; for 0 <= t <= 15
+#define MSGSCHEDULE0(index) \
+	MOVL	(index*4)(SI), AX; \
+	BSWAPL	AX; \
+	MOVL	AX, (index*4)(BP)
+
+// Wt = SIGMA1(Wt-2) + Wt-7 + SIGMA0(Wt-15) + Wt-16; for 16 <= t <= 63
+//   SIGMA0(x) = ROTR(7,x) XOR ROTR(18,x) XOR SHR(3,x)
+//   SIGMA1(x) = ROTR(17,x) XOR ROTR(19,x) XOR SHR(10,x)
+#define MSGSCHEDULE1(index) \
+	MOVL	((index-2)*4)(BP), AX; \
+	MOVL	AX, CX; \
+	RORL	$17, AX; \
+	MOVL	CX, DX; \
+	RORL	$19, CX; \
+	SHRL	$10, DX; \
+	MOVL	((index-15)*4)(BP), BX; \
+	XORL	CX, AX; \
+	MOVL	BX, CX; \
+	XORL	DX, AX; \
+	RORL	$7, BX; \
+	MOVL	CX, DX; \
+	SHRL	$3, DX; \
+	RORL	$18, CX; \
+	ADDL	((index-7)*4)(BP), AX; \
+	XORL	CX, BX; \
+	XORL	DX, BX; \
+	ADDL	((index-16)*4)(BP), BX; \
+	ADDL	BX, AX; \
+	MOVL	AX, ((index)*4)(BP)
+
+// Calculate T1 in AX - uses AX, BX, CX and DX registers.
+// Wt is passed in AX.
+//   T1 = h + BIGSIGMA1(e) + Ch(e, f, g) + Kt + Wt
+//     BIGSIGMA1(x) = ROTR(6,x) XOR ROTR(11,x) XOR ROTR(25,x)
+//     Ch(x, y, z) = (x AND y) XOR (NOT x AND z)
+#define SHA256T1(const, e, f, g, h) \
+	MOVL	(h*4)(DI), BX; \
+	ADDL	AX, BX; \
+	MOVL	(e*4)(DI), AX; \
+	ADDL	$const, BX; \
+	MOVL	(e*4)(DI), CX; \
+	RORL	$6, AX; \
+	MOVL	(e*4)(DI), DX; \
+	RORL	$11, CX; \
+	XORL	CX, AX; \
+	MOVL	(e*4)(DI), CX; \
+	RORL	$25, DX; \
+	ANDL	(f*4)(DI), CX; \
+	XORL	AX, DX; \
+	MOVL	(e*4)(DI), AX; \
+	NOTL	AX; \
+	ADDL	DX, BX; \
+	ANDL	(g*4)(DI), AX; \
+	XORL	CX, AX; \
+	ADDL	BX, AX
+
+// Calculate T2 in BX - uses AX, BX, CX and DX registers.
+//   T2 = BIGSIGMA0(a) + Maj(a, b, c)
+//     BIGSIGMA0(x) = ROTR(2,x) XOR ROTR(13,x) XOR ROTR(22,x)
+//     Maj(x, y, z) = (x AND y) XOR (x AND z) XOR (y AND z)
+#define SHA256T2(a, b, c) \
+	MOVL	(a*4)(DI), AX; \
+	MOVL	(c*4)(DI), BX; \
+	RORL	$2, AX; \
+	MOVL	(a*4)(DI), DX; \
+	ANDL	(b*4)(DI), BX; \
+	RORL	$13, DX; \
+	MOVL	(a*4)(DI), CX; \
+	ANDL	(c*4)(DI), CX; \
+	XORL	DX, AX; \
+	XORL	CX, BX; \
+	MOVL	(a*4)(DI), DX; \
+	MOVL	(b*4)(DI), CX; \
+	RORL	$22, DX; \
+	ANDL	(a*4)(DI), CX; \
+	XORL	CX, BX; \
+	XORL	DX, AX; \
+	ADDL	AX, BX
+
+// Calculate T1 and T2, then e = d + T1 and a = T1 + T2.
+// The values for e and a are stored in d and h, ready for rotation.
+#define SHA256ROUND(index, const, a, b, c, d, e, f, g, h) \
+	SHA256T1(const, e, f, g, h); \
+	MOVL	AX, 292(SP); \
+	SHA256T2(a, b, c); \
+	MOVL	292(SP), AX; \
+	ADDL	AX, BX; \
+	ADDL	AX, (d*4)(DI); \
+	MOVL	BX, (h*4)(DI)
+
+#define SHA256ROUND0(index, const, a, b, c, d, e, f, g, h) \
+	MSGSCHEDULE0(index); \
+	SHA256ROUND(index, const, a, b, c, d, e, f, g, h)
+
+#define SHA256ROUND1(index, const, a, b, c, d, e, f, g, h) \
+	MSGSCHEDULE1(index); \
+	SHA256ROUND(index, const, a, b, c, d, e, f, g, h)
+
+TEXT ·block(SB),0,$296-12
+	MOVL	p_base+4(FP), SI
+	MOVL	p_len+8(FP), DX
+	SHRL	$6, DX
+	SHLL	$6, DX
+
+	LEAL	(SI)(DX*1), DI
+	MOVL	DI, 288(SP)
+	CMPL	SI, DI
+	JEQ	end
+
+	LEAL	256(SP), DI		// variables
+
+	MOVL	dig+0(FP), BP
+	MOVL	(0*4)(BP), AX		// a = H0
+	MOVL	AX, (0*4)(DI)
+	MOVL	(1*4)(BP), BX		// b = H1
+	MOVL	BX, (1*4)(DI)
+	MOVL	(2*4)(BP), CX		// c = H2
+	MOVL	CX, (2*4)(DI)
+	MOVL	(3*4)(BP), DX		// d = H3
+	MOVL	DX, (3*4)(DI)
+	MOVL	(4*4)(BP), AX		// e = H4
+	MOVL	AX, (4*4)(DI)
+	MOVL	(5*4)(BP), BX		// f = H5
+	MOVL	BX, (5*4)(DI)
+	MOVL	(6*4)(BP), CX		// g = H6
+	MOVL	CX, (6*4)(DI)
+	MOVL	(7*4)(BP), DX		// h = H7
+	MOVL	DX, (7*4)(DI)
+
+loop:
+	MOVL	SP, BP			// message schedule
+
+	SHA256ROUND0(0, 0x428a2f98, 0, 1, 2, 3, 4, 5, 6, 7)
+	SHA256ROUND0(1, 0x71374491, 7, 0, 1, 2, 3, 4, 5, 6)
+	SHA256ROUND0(2, 0xb5c0fbcf, 6, 7, 0, 1, 2, 3, 4, 5)
+	SHA256ROUND0(3, 0xe9b5dba5, 5, 6, 7, 0, 1, 2, 3, 4)
+	SHA256ROUND0(4, 0x3956c25b, 4, 5, 6, 7, 0, 1, 2, 3)
+	SHA256ROUND0(5, 0x59f111f1, 3, 4, 5, 6, 7, 0, 1, 2)
+	SHA256ROUND0(6, 0x923f82a4, 2, 3, 4, 5, 6, 7, 0, 1)
+	SHA256ROUND0(7, 0xab1c5ed5, 1, 2, 3, 4, 5, 6, 7, 0)
+	SHA256ROUND0(8, 0xd807aa98, 0, 1, 2, 3, 4, 5, 6, 7)
+	SHA256ROUND0(9, 0x12835b01, 7, 0, 1, 2, 3, 4, 5, 6)
+	SHA256ROUND0(10, 0x243185be, 6, 7, 0, 1, 2, 3, 4, 5)
+	SHA256ROUND0(11, 0x550c7dc3, 5, 6, 7, 0, 1, 2, 3, 4)
+	SHA256ROUND0(12, 0x72be5d74, 4, 5, 6, 7, 0, 1, 2, 3)
+	SHA256ROUND0(13, 0x80deb1fe, 3, 4, 5, 6, 7, 0, 1, 2)
+	SHA256ROUND0(14, 0x9bdc06a7, 2, 3, 4, 5, 6, 7, 0, 1)
+	SHA256ROUND0(15, 0xc19bf174, 1, 2, 3, 4, 5, 6, 7, 0)
+
+	SHA256ROUND1(16, 0xe49b69c1, 0, 1, 2, 3, 4, 5, 6, 7)
+	SHA256ROUND1(17, 0xefbe4786, 7, 0, 1, 2, 3, 4, 5, 6)
+	SHA256ROUND1(18, 0x0fc19dc6, 6, 7, 0, 1, 2, 3, 4, 5)
+	SHA256ROUND1(19, 0x240ca1cc, 5, 6, 7, 0, 1, 2, 3, 4)
+	SHA256ROUND1(20, 0x2de92c6f, 4, 5, 6, 7, 0, 1, 2, 3)
+	SHA256ROUND1(21, 0x4a7484aa, 3, 4, 5, 6, 7, 0, 1, 2)
+	SHA256ROUND1(22, 0x5cb0a9dc, 2, 3, 4, 5, 6, 7, 0, 1)
+	SHA256ROUND1(23, 0x76f988da, 1, 2, 3, 4, 5, 6, 7, 0)
+	SHA256ROUND1(24, 0x983e5152, 0, 1, 2, 3, 4, 5, 6, 7)
+	SHA256ROUND1(25, 0xa831c66d, 7, 0, 1, 2, 3, 4, 5, 6)
+	SHA256ROUND1(26, 0xb00327c8, 6, 7, 0, 1, 2, 3, 4, 5)
+	SHA256ROUND1(27, 0xbf597fc7, 5, 6, 7, 0, 1, 2, 3, 4)
+	SHA256ROUND1(28, 0xc6e00bf3, 4, 5, 6, 7, 0, 1, 2, 3)
+	SHA256ROUND1(29, 0xd5a79147, 3, 4, 5, 6, 7, 0, 1, 2)
+	SHA256ROUND1(30, 0x06ca6351, 2, 3, 4, 5, 6, 7, 0, 1)
+	SHA256ROUND1(31, 0x14292967, 1, 2, 3, 4, 5, 6, 7, 0)
+	SHA256ROUND1(32, 0x27b70a85, 0, 1, 2, 3, 4, 5, 6, 7)
+	SHA256ROUND1(33, 0x2e1b2138, 7, 0, 1, 2, 3, 4, 5, 6)
+	SHA256ROUND1(34, 0x4d2c6dfc, 6, 7, 0, 1, 2, 3, 4, 5)
+	SHA256ROUND1(35, 0x53380d13, 5, 6, 7, 0, 1, 2, 3, 4)
+	SHA256ROUND1(36, 0x650a7354, 4, 5, 6, 7, 0, 1, 2, 3)
+	SHA256ROUND1(37, 0x766a0abb, 3, 4, 5, 6, 7, 0, 1, 2)
+	SHA256ROUND1(38, 0x81c2c92e, 2, 3, 4, 5, 6, 7, 0, 1)
+	SHA256ROUND1(39, 0x92722c85, 1, 2, 3, 4, 5, 6, 7, 0)
+	SHA256ROUND1(40, 0xa2bfe8a1, 0, 1, 2, 3, 4, 5, 6, 7)
+	SHA256ROUND1(41, 0xa81a664b, 7, 0, 1, 2, 3, 4, 5, 6)
+	SHA256ROUND1(42, 0xc24b8b70, 6, 7, 0, 1, 2, 3, 4, 5)
+	SHA256ROUND1(43, 0xc76c51a3, 5, 6, 7, 0, 1, 2, 3, 4)
+	SHA256ROUND1(44, 0xd192e819, 4, 5, 6, 7, 0, 1, 2, 3)
+	SHA256ROUND1(45, 0xd6990624, 3, 4, 5, 6, 7, 0, 1, 2)
+	SHA256ROUND1(46, 0xf40e3585, 2, 3, 4, 5, 6, 7, 0, 1)
+	SHA256ROUND1(47, 0x106aa070, 1, 2, 3, 4, 5, 6, 7, 0)
+	SHA256ROUND1(48, 0x19a4c116, 0, 1, 2, 3, 4, 5, 6, 7)
+	SHA256ROUND1(49, 0x1e376c08, 7, 0, 1, 2, 3, 4, 5, 6)
+	SHA256ROUND1(50, 0x2748774c, 6, 7, 0, 1, 2, 3, 4, 5)
+	SHA256ROUND1(51, 0x34b0bcb5, 5, 6, 7, 0, 1, 2, 3, 4)
+	SHA256ROUND1(52, 0x391c0cb3, 4, 5, 6, 7, 0, 1, 2, 3)
+	SHA256ROUND1(53, 0x4ed8aa4a, 3, 4, 5, 6, 7, 0, 1, 2)
+	SHA256ROUND1(54, 0x5b9cca4f, 2, 3, 4, 5, 6, 7, 0, 1)
+	SHA256ROUND1(55, 0x682e6ff3, 1, 2, 3, 4, 5, 6, 7, 0)
+	SHA256ROUND1(56, 0x748f82ee, 0, 1, 2, 3, 4, 5, 6, 7)
+	SHA256ROUND1(57, 0x78a5636f, 7, 0, 1, 2, 3, 4, 5, 6)
+	SHA256ROUND1(58, 0x84c87814, 6, 7, 0, 1, 2, 3, 4, 5)
+	SHA256ROUND1(59, 0x8cc70208, 5, 6, 7, 0, 1, 2, 3, 4)
+	SHA256ROUND1(60, 0x90befffa, 4, 5, 6, 7, 0, 1, 2, 3)
+	SHA256ROUND1(61, 0xa4506ceb, 3, 4, 5, 6, 7, 0, 1, 2)
+	SHA256ROUND1(62, 0xbef9a3f7, 2, 3, 4, 5, 6, 7, 0, 1)
+	SHA256ROUND1(63, 0xc67178f2, 1, 2, 3, 4, 5, 6, 7, 0)
+
+	MOVL	dig+0(FP), BP
+	MOVL	(0*4)(BP), AX		// H0 = a + H0
+	ADDL	(0*4)(DI), AX
+	MOVL	AX, (0*4)(DI)
+	MOVL	AX, (0*4)(BP)
+	MOVL	(1*4)(BP), BX		// H1 = b + H1
+	ADDL	(1*4)(DI), BX
+	MOVL	BX, (1*4)(DI)
+	MOVL	BX, (1*4)(BP)
+	MOVL	(2*4)(BP), CX		// H2 = c + H2
+	ADDL	(2*4)(DI), CX
+	MOVL	CX, (2*4)(DI)
+	MOVL	CX, (2*4)(BP)
+	MOVL	(3*4)(BP), DX		// H3 = d + H3
+	ADDL	(3*4)(DI), DX
+	MOVL	DX, (3*4)(DI)
+	MOVL	DX, (3*4)(BP)
+	MOVL	(4*4)(BP), AX		// H4 = e + H4
+	ADDL	(4*4)(DI), AX
+	MOVL	AX, (4*4)(DI)
+	MOVL	AX, (4*4)(BP)
+	MOVL	(5*4)(BP), BX		// H5 = f + H5
+	ADDL	(5*4)(DI), BX
+	MOVL	BX, (5*4)(DI)
+	MOVL	BX, (5*4)(BP)
+	MOVL	(6*4)(BP), CX		// H6 = g + H6
+	ADDL	(6*4)(DI), CX
+	MOVL	CX, (6*4)(DI)
+	MOVL	CX, (6*4)(BP)
+	MOVL	(7*4)(BP), DX		// H7 = h + H7
+	ADDL	(7*4)(DI), DX
+	MOVL	DX, (7*4)(DI)
+	MOVL	DX, (7*4)(BP)
+
+	ADDL	$64, SI
+	CMPL	SI, 288(SP)
+	JB	loop
+
+end:
+	RET

Godeps/_workspace/src/github.com/jlhawn/go-crypto/sha256/sha256block_amd64.s

@@ -0,0 +1,256 @@
+// Copyright 2013 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "../textflag.h"
+
+// SHA256 block routine. See sha256block.go for Go equivalent.
+//
+// The algorithm is detailed in FIPS 180-4:
+//
+//  http://csrc.nist.gov/publications/fips/fips180-4/fips-180-4.pdf
+//
+// Wt = Mt; for 0 <= t <= 15
+// Wt = SIGMA1(Wt-2) + SIGMA0(Wt-15) + Wt-16; for 16 <= t <= 63
+//
+// a = H0
+// b = H1
+// c = H2
+// d = H3
+// e = H4
+// f = H5
+// g = H6
+// h = H7
+//
+// for t = 0 to 63 {
+//    T1 = h + BIGSIGMA1(e) + Ch(e,f,g) + Kt + Wt
+//    T2 = BIGSIGMA0(a) + Maj(a,b,c)
+//    h = g
+//    g = f
+//    f = e
+//    e = d + T1
+//    d = c
+//    c = b
+//    b = a
+//    a = T1 + T2
+// }
+//
+// H0 = a + H0
+// H1 = b + H1
+// H2 = c + H2
+// H3 = d + H3
+// H4 = e + H4
+// H5 = f + H5
+// H6 = g + H6
+// H7 = h + H7
+
+// Wt = Mt; for 0 <= t <= 15
+#define MSGSCHEDULE0(index) \
+	MOVL	(index*4)(SI), AX; \
+	BSWAPL	AX; \
+	MOVL	AX, (index*4)(BP)
+
+// Wt = SIGMA1(Wt-2) + Wt-7 + SIGMA0(Wt-15) + Wt-16; for 16 <= t <= 63
+//   SIGMA0(x) = ROTR(7,x) XOR ROTR(18,x) XOR SHR(3,x)
+//   SIGMA1(x) = ROTR(17,x) XOR ROTR(19,x) XOR SHR(10,x)
+#define MSGSCHEDULE1(index) \
+	MOVL	((index-2)*4)(BP), AX; \
+	MOVL	AX, CX; \
+	RORL	$17, AX; \
+	MOVL	CX, DX; \
+	RORL	$19, CX; \
+	SHRL	$10, DX; \
+	MOVL	((index-15)*4)(BP), BX; \
+	XORL	CX, AX; \
+	MOVL	BX, CX; \
+	XORL	DX, AX; \
+	RORL	$7, BX; \
+	MOVL	CX, DX; \
+	SHRL	$3, DX; \
+	RORL	$18, CX; \
+	ADDL	((index-7)*4)(BP), AX; \
+	XORL	CX, BX; \
+	XORL	DX, BX; \
+	ADDL	((index-16)*4)(BP), BX; \
+	ADDL	BX, AX; \
+	MOVL	AX, ((index)*4)(BP)
+
+// Calculate T1 in AX - uses AX, CX and DX registers.
+// h is also used as an accumulator. Wt is passed in AX.
+//   T1 = h + BIGSIGMA1(e) + Ch(e, f, g) + Kt + Wt
+//     BIGSIGMA1(x) = ROTR(6,x) XOR ROTR(11,x) XOR ROTR(25,x)
+//     Ch(x, y, z) = (x AND y) XOR (NOT x AND z)
+#define SHA256T1(const, e, f, g, h) \
+	ADDL	AX, h; \
+	MOVL	e, AX; \
+	ADDL	$const, h; \
+	MOVL	e, CX; \
+	RORL	$6, AX; \
+	MOVL	e, DX; \
+	RORL	$11, CX; \
+	XORL	CX, AX; \
+	MOVL	e, CX; \
+	RORL	$25, DX; \
+	ANDL	f, CX; \
+	XORL	AX, DX; \
+	MOVL	e, AX; \
+	NOTL	AX; \
+	ADDL	DX, h; \
+	ANDL	g, AX; \
+	XORL	CX, AX; \
+	ADDL	h, AX
+
+// Calculate T2 in BX - uses BX, CX, DX and DI registers.
+//   T2 = BIGSIGMA0(a) + Maj(a, b, c)
+//     BIGSIGMA0(x) = ROTR(2,x) XOR ROTR(13,x) XOR ROTR(22,x)
+//     Maj(x, y, z) = (x AND y) XOR (x AND z) XOR (y AND z)
+#define SHA256T2(a, b, c) \
+	MOVL	a, DI; \
+	MOVL	c, BX; \
+	RORL	$2, DI; \
+	MOVL	a, DX; \
+	ANDL	b, BX; \
+	RORL	$13, DX; \
+	MOVL	a, CX; \
+	ANDL	c, CX; \
+	XORL	DX, DI; \
+	XORL	CX, BX; \
+	MOVL	a, DX; \
+	MOVL	b, CX; \
+	RORL	$22, DX; \
+	ANDL	a, CX; \
+	XORL	CX, BX; \
+	XORL	DX, DI; \
+	ADDL	DI, BX
+
+// Calculate T1 and T2, then e = d + T1 and a = T1 + T2.
+// The values for e and a are stored in d and h, ready for rotation.
+#define SHA256ROUND(index, const, a, b, c, d, e, f, g, h) \
+	SHA256T1(const, e, f, g, h); \
+	SHA256T2(a, b, c); \
+	MOVL	BX, h; \
+	ADDL	AX, d; \
+	ADDL	AX, h
+
+#define SHA256ROUND0(index, const, a, b, c, d, e, f, g, h) \
+	MSGSCHEDULE0(index); \
+	SHA256ROUND(index, const, a, b, c, d, e, f, g, h)
+
+#define SHA256ROUND1(index, const, a, b, c, d, e, f, g, h) \
+	MSGSCHEDULE1(index); \
+	SHA256ROUND(index, const, a, b, c, d, e, f, g, h)
+
+TEXT ·block(SB),0,$264-32
+	MOVQ	p_base+8(FP), SI
+	MOVQ	p_len+16(FP), DX
+	SHRQ	$6, DX
+	SHLQ	$6, DX
+
+	LEAQ	(SI)(DX*1), DI
+	MOVQ	DI, 256(SP)
+	CMPQ	SI, DI
+	JEQ	end
+
+	MOVQ	dig+0(FP), BP
+	MOVL	(0*4)(BP), R8		// a = H0
+	MOVL	(1*4)(BP), R9		// b = H1
+	MOVL	(2*4)(BP), R10		// c = H2
+	MOVL	(3*4)(BP), R11		// d = H3
+	MOVL	(4*4)(BP), R12		// e = H4
+	MOVL	(5*4)(BP), R13		// f = H5
+	MOVL	(6*4)(BP), R14		// g = H6
+	MOVL	(7*4)(BP), R15		// h = H7
+
+loop:
+	MOVQ	SP, BP			// message schedule
+
+	SHA256ROUND0(0, 0x428a2f98, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA256ROUND0(1, 0x71374491, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA256ROUND0(2, 0xb5c0fbcf, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA256ROUND0(3, 0xe9b5dba5, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA256ROUND0(4, 0x3956c25b, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA256ROUND0(5, 0x59f111f1, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA256ROUND0(6, 0x923f82a4, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA256ROUND0(7, 0xab1c5ed5, R9, R10, R11, R12, R13, R14, R15, R8)
+	SHA256ROUND0(8, 0xd807aa98, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA256ROUND0(9, 0x12835b01, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA256ROUND0(10, 0x243185be, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA256ROUND0(11, 0x550c7dc3, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA256ROUND0(12, 0x72be5d74, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA256ROUND0(13, 0x80deb1fe, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA256ROUND0(14, 0x9bdc06a7, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA256ROUND0(15, 0xc19bf174, R9, R10, R11, R12, R13, R14, R15, R8)
+
+	SHA256ROUND1(16, 0xe49b69c1, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA256ROUND1(17, 0xefbe4786, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA256ROUND1(18, 0x0fc19dc6, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA256ROUND1(19, 0x240ca1cc, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA256ROUND1(20, 0x2de92c6f, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA256ROUND1(21, 0x4a7484aa, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA256ROUND1(22, 0x5cb0a9dc, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA256ROUND1(23, 0x76f988da, R9, R10, R11, R12, R13, R14, R15, R8)
+	SHA256ROUND1(24, 0x983e5152, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA256ROUND1(25, 0xa831c66d, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA256ROUND1(26, 0xb00327c8, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA256ROUND1(27, 0xbf597fc7, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA256ROUND1(28, 0xc6e00bf3, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA256ROUND1(29, 0xd5a79147, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA256ROUND1(30, 0x06ca6351, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA256ROUND1(31, 0x14292967, R9, R10, R11, R12, R13, R14, R15, R8)
+	SHA256ROUND1(32, 0x27b70a85, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA256ROUND1(33, 0x2e1b2138, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA256ROUND1(34, 0x4d2c6dfc, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA256ROUND1(35, 0x53380d13, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA256ROUND1(36, 0x650a7354, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA256ROUND1(37, 0x766a0abb, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA256ROUND1(38, 0x81c2c92e, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA256ROUND1(39, 0x92722c85, R9, R10, R11, R12, R13, R14, R15, R8)
+	SHA256ROUND1(40, 0xa2bfe8a1, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA256ROUND1(41, 0xa81a664b, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA256ROUND1(42, 0xc24b8b70, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA256ROUND1(43, 0xc76c51a3, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA256ROUND1(44, 0xd192e819, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA256ROUND1(45, 0xd6990624, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA256ROUND1(46, 0xf40e3585, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA256ROUND1(47, 0x106aa070, R9, R10, R11, R12, R13, R14, R15, R8)
+	SHA256ROUND1(48, 0x19a4c116, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA256ROUND1(49, 0x1e376c08, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA256ROUND1(50, 0x2748774c, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA256ROUND1(51, 0x34b0bcb5, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA256ROUND1(52, 0x391c0cb3, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA256ROUND1(53, 0x4ed8aa4a, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA256ROUND1(54, 0x5b9cca4f, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA256ROUND1(55, 0x682e6ff3, R9, R10, R11, R12, R13, R14, R15, R8)
+	SHA256ROUND1(56, 0x748f82ee, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA256ROUND1(57, 0x78a5636f, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA256ROUND1(58, 0x84c87814, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA256ROUND1(59, 0x8cc70208, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA256ROUND1(60, 0x90befffa, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA256ROUND1(61, 0xa4506ceb, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA256ROUND1(62, 0xbef9a3f7, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA256ROUND1(63, 0xc67178f2, R9, R10, R11, R12, R13, R14, R15, R8)
+
+	MOVQ	dig+0(FP), BP
+	ADDL	(0*4)(BP), R8	// H0 = a + H0
+	MOVL	R8, (0*4)(BP)
+	ADDL	(1*4)(BP), R9	// H1 = b + H1
+	MOVL	R9, (1*4)(BP)
+	ADDL	(2*4)(BP), R10	// H2 = c + H2
+	MOVL	R10, (2*4)(BP)
+	ADDL	(3*4)(BP), R11	// H3 = d + H3
+	MOVL	R11, (3*4)(BP)
+	ADDL	(4*4)(BP), R12	// H4 = e + H4
+	MOVL	R12, (4*4)(BP)
+	ADDL	(5*4)(BP), R13	// H5 = f + H5
+	MOVL	R13, (5*4)(BP)
+	ADDL	(6*4)(BP), R14	// H6 = g + H6
+	MOVL	R14, (6*4)(BP)
+	ADDL	(7*4)(BP), R15	// H7 = h + H7
+	MOVL	R15, (7*4)(BP)
+
+	ADDQ	$64, SI
+	CMPQ	SI, 256(SP)
+	JB	loop
+
+end:
+	RET

Godeps/_workspace/src/github.com/jlhawn/go-crypto/sha256/sha256block_decl.go

@@ -0,0 +1,11 @@
+// Copyright 2013 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build 386 amd64
+
+package sha256
+
+//go:noescape
+
+func block(dig *digest, p []byte)

Godeps/_workspace/src/github.com/jlhawn/go-crypto/sha256/sha256resume_test.go

@@ -0,0 +1,57 @@
+package sha256
+
+import (
+	"bytes"
+	stdlib "crypto"
+	"crypto/rand"
+	_ "crypto/sha256" // To register the stdlib sha224 and sha256 algs.
+	resumable "github.com/jlhawn/go-crypto"
+	"io"
+	"testing"
+)
+
+func compareResumableHash(t *testing.T, r resumable.Hash, h stdlib.Hash) {
+	// Read 3 Kilobytes of random data into a buffer.
+	buf := make([]byte, 3*1024)
+	if _, err := io.ReadFull(rand.Reader, buf); err != nil {
+		t.Fatalf("unable to load random data: %s", err)
+	}
+
+	// Use two Hash objects to consume prefixes of the data. One will be
+	// snapshotted and resumed with each additional byte, then both will write
+	// that byte. The digests should be equal after each byte is digested.
+	resumableHasher := r.New()
+	stdlibHasher := h.New()
+
+	// First, assert that the initial distest is the same.
+	if !bytes.Equal(resumableHasher.Sum(nil), stdlibHasher.Sum(nil)) {
+		t.Fatalf("initial digests do not match: got %x, expected %x", resumableHasher.Sum(nil), stdlibHasher.Sum(nil))
+	}
+
+	multiWriter := io.MultiWriter(resumableHasher, stdlibHasher)
+
+	for i := 1; i <= len(buf); i++ {
+
+		// Write the next byte.
+		multiWriter.Write(buf[i-1 : i])
+
+		if !bytes.Equal(resumableHasher.Sum(nil), stdlibHasher.Sum(nil)) {
+			t.Fatalf("digests do not match: got %x, expected %x", resumableHasher.Sum(nil), stdlibHasher.Sum(nil))
+		}
+
+		// Snapshot, reset, and restore the chunk hasher.
+		hashState, err := resumableHasher.State()
+		if err != nil {
+			t.Fatalf("unable to get state of hash function: %s", err)
+		}
+		resumableHasher.Reset()
+		if err := resumableHasher.Restore(hashState); err != nil {
+			t.Fatalf("unable to restorte state of hash function: %s", err)
+		}
+	}
+}
+
+func TestResumable(t *testing.T) {
+	compareResumableHash(t, resumable.SHA224, stdlib.SHA224)
+	compareResumableHash(t, resumable.SHA256, stdlib.SHA256)
+}

Godeps/_workspace/src/github.com/jlhawn/go-crypto/sha512/resume.go

@@ -0,0 +1,50 @@
+package sha512
+
+import (
+	"bytes"
+	"encoding/gob"
+)
+
+// Len returns the number of bytes which have been written to the digest.
+func (d *digest) Len() uint64 {
+	return d.len
+}
+
+// State returns a snapshot of the state of the digest.
+func (d *digest) State() ([]byte, error) {
+	var buf bytes.Buffer
+	encoder := gob.NewEncoder(&buf)
+
+	// We encode this way so that we do not have
+	// to export these fields of the digest struct.
+	vals := []interface{}{
+		d.h, d.x, d.nx, d.len, d.is384,
+	}
+
+	for _, val := range vals {
+		if err := encoder.Encode(val); err != nil {
+			return nil, err
+		}
+	}
+
+	return buf.Bytes(), nil
+}
+
+// Restore resets the digest to the given state.
+func (d *digest) Restore(state []byte) error {
+	decoder := gob.NewDecoder(bytes.NewReader(state))
+
+	// We decode this way so that we do not have
+	// to export these fields of the digest struct.
+	vals := []interface{}{
+		&d.h, &d.x, &d.nx, &d.len, &d.is384,
+	}
+
+	for _, val := range vals {
+		if err := decoder.Decode(val); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

Godeps/_workspace/src/github.com/jlhawn/go-crypto/sha512/sha512.go

@@ -0,0 +1,197 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package sha512 implements the SHA384 and SHA512 hash algorithms as defined
+// in FIPS 180-2.
+package sha512
+
+import (
+	"github.com/jlhawn/go-crypto"
+)
+
+func init() {
+	crypto.RegisterHash(crypto.SHA384, New384)
+	crypto.RegisterHash(crypto.SHA512, New)
+}
+
+// The size of a SHA512 checksum in bytes.
+const Size = 64
+
+// The size of a SHA384 checksum in bytes.
+const Size384 = 48
+
+// The blocksize of SHA512 and SHA384 in bytes.
+const BlockSize = 128
+
+const (
+	chunk     = 128
+	init0     = 0x6a09e667f3bcc908
+	init1     = 0xbb67ae8584caa73b
+	init2     = 0x3c6ef372fe94f82b
+	init3     = 0xa54ff53a5f1d36f1
+	init4     = 0x510e527fade682d1
+	init5     = 0x9b05688c2b3e6c1f
+	init6     = 0x1f83d9abfb41bd6b
+	init7     = 0x5be0cd19137e2179
+	init0_384 = 0xcbbb9d5dc1059ed8
+	init1_384 = 0x629a292a367cd507
+	init2_384 = 0x9159015a3070dd17
+	init3_384 = 0x152fecd8f70e5939
+	init4_384 = 0x67332667ffc00b31
+	init5_384 = 0x8eb44a8768581511
+	init6_384 = 0xdb0c2e0d64f98fa7
+	init7_384 = 0x47b5481dbefa4fa4
+)
+
+// digest represents the partial evaluation of a checksum.
+type digest struct {
+	h     [8]uint64
+	x     [chunk]byte
+	nx    int
+	len   uint64
+	is384 bool // mark if this digest is SHA-384
+}
+
+func (d *digest) Reset() {
+	if !d.is384 {
+		d.h[0] = init0
+		d.h[1] = init1
+		d.h[2] = init2
+		d.h[3] = init3
+		d.h[4] = init4
+		d.h[5] = init5
+		d.h[6] = init6
+		d.h[7] = init7
+	} else {
+		d.h[0] = init0_384
+		d.h[1] = init1_384
+		d.h[2] = init2_384
+		d.h[3] = init3_384
+		d.h[4] = init4_384
+		d.h[5] = init5_384
+		d.h[6] = init6_384
+		d.h[7] = init7_384
+	}
+	d.nx = 0
+	d.len = 0
+}
+
+// New returns a new crypto.ResumableHash computing the SHA512 checksum.
+func New() crypto.ResumableHash {
+	d := new(digest)
+	d.Reset()
+	return d
+}
+
+// New384 returns a new crypto.ResumableHash computing the SHA384 checksum.
+func New384() crypto.ResumableHash {
+	d := new(digest)
+	d.is384 = true
+	d.Reset()
+	return d
+}
+
+func (d *digest) Size() int {
+	if !d.is384 {
+		return Size
+	}
+	return Size384
+}
+
+func (d *digest) BlockSize() int { return BlockSize }
+
+func (d *digest) Write(p []byte) (nn int, err error) {
+	nn = len(p)
+	d.len += uint64(nn)
+	if d.nx > 0 {
+		n := copy(d.x[d.nx:], p)
+		d.nx += n
+		if d.nx == chunk {
+			block(d, d.x[:])
+			d.nx = 0
+		}
+		p = p[n:]
+	}
+	if len(p) >= chunk {
+		n := len(p) &^ (chunk - 1)
+		block(d, p[:n])
+		p = p[n:]
+	}
+	if len(p) > 0 {
+		d.nx = copy(d.x[:], p)
+	}
+	return
+}
+
+func (d0 *digest) Sum(in []byte) []byte {
+	// Make a copy of d0 so that caller can keep writing and summing.
+	d := new(digest)
+	*d = *d0
+	hash := d.checkSum()
+	if d.is384 {
+		return append(in, hash[:Size384]...)
+	}
+	return append(in, hash[:]...)
+}
+
+func (d *digest) checkSum() [Size]byte {
+	// Padding.  Add a 1 bit and 0 bits until 112 bytes mod 128.
+	len := d.len
+	var tmp [128]byte
+	tmp[0] = 0x80
+	if len%128 < 112 {
+		d.Write(tmp[0 : 112-len%128])
+	} else {
+		d.Write(tmp[0 : 128+112-len%128])
+	}
+
+	// Length in bits.
+	len <<= 3
+	for i := uint(0); i < 16; i++ {
+		tmp[i] = byte(len >> (120 - 8*i))
+	}
+	d.Write(tmp[0:16])
+
+	if d.nx != 0 {
+		panic("d.nx != 0")
+	}
+
+	h := d.h[:]
+	if d.is384 {
+		h = d.h[:6]
+	}
+
+	var digest [Size]byte
+	for i, s := range h {
+		digest[i*8] = byte(s >> 56)
+		digest[i*8+1] = byte(s >> 48)
+		digest[i*8+2] = byte(s >> 40)
+		digest[i*8+3] = byte(s >> 32)
+		digest[i*8+4] = byte(s >> 24)
+		digest[i*8+5] = byte(s >> 16)
+		digest[i*8+6] = byte(s >> 8)
+		digest[i*8+7] = byte(s)
+	}
+
+	return digest
+}
+
+// Sum512 returns the SHA512 checksum of the data.
+func Sum512(data []byte) [Size]byte {
+	var d digest
+	d.Reset()
+	d.Write(data)
+	return d.checkSum()
+}
+
+// Sum384 returns the SHA384 checksum of the data.
+func Sum384(data []byte) (sum384 [Size384]byte) {
+	var d digest
+	d.is384 = true
+	d.Reset()
+	d.Write(data)
+	sum := d.checkSum()
+	copy(sum384[:], sum[:Size384])
+	return
+}

Godeps/_workspace/src/github.com/jlhawn/go-crypto/sha512/sha512_test.go

@@ -0,0 +1,176 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// SHA512 hash algorithm.  See FIPS 180-2.
+
+package sha512
+
+import (
+	"fmt"
+	"io"
+	"testing"
+)
+
+type sha512Test struct {
+	out string
+	in  string
+}
+
+var golden = []sha512Test{
+	{"cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e", ""},
+	{"1f40fc92da241694750979ee6cf582f2d5d7d28e18335de05abc54d0560e0f5302860c652bf08d560252aa5e74210546f369fbbbce8c12cfc7957b2652fe9a75", "a"},
+	{"2d408a0717ec188158278a796c689044361dc6fdde28d6f04973b80896e1823975cdbf12eb63f9e0591328ee235d80e9b5bf1aa6a44f4617ff3caf6400eb172d", "ab"},
+	{"ddaf35a193617abacc417349ae20413112e6fa4e89a97ea20a9eeee64b55d39a2192992a274fc1a836ba3c23a3feebbd454d4423643ce80e2a9ac94fa54ca49f", "abc"},
+	{"d8022f2060ad6efd297ab73dcc5355c9b214054b0d1776a136a669d26a7d3b14f73aa0d0ebff19ee333368f0164b6419a96da49e3e481753e7e96b716bdccb6f", "abcd"},
+	{"878ae65a92e86cac011a570d4c30a7eaec442b85ce8eca0c2952b5e3cc0628c2e79d889ad4d5c7c626986d452dd86374b6ffaa7cd8b67665bef2289a5c70b0a1", "abcde"},
+	{"e32ef19623e8ed9d267f657a81944b3d07adbb768518068e88435745564e8d4150a0a703be2a7d88b61e3d390c2bb97e2d4c311fdc69d6b1267f05f59aa920e7", "abcdef"},
+	{"d716a4188569b68ab1b6dfac178e570114cdf0ea3a1cc0e31486c3e41241bc6a76424e8c37ab26f096fc85ef9886c8cb634187f4fddff645fb099f1ff54c6b8c", "abcdefg"},
+	{"a3a8c81bc97c2560010d7389bc88aac974a104e0e2381220c6e084c4dccd1d2d17d4f86db31c2a851dc80e6681d74733c55dcd03dd96f6062cdda12a291ae6ce", "abcdefgh"},
+	{"f22d51d25292ca1d0f68f69aedc7897019308cc9db46efb75a03dd494fc7f126c010e8ade6a00a0c1a5f1b75d81e0ed5a93ce98dc9b833db7839247b1d9c24fe", "abcdefghi"},
+	{"ef6b97321f34b1fea2169a7db9e1960b471aa13302a988087357c520be957ca119c3ba68e6b4982c019ec89de3865ccf6a3cda1fe11e59f98d99f1502c8b9745", "abcdefghij"},
+	{"2210d99af9c8bdecda1b4beff822136753d8342505ddce37f1314e2cdbb488c6016bdaa9bd2ffa513dd5de2e4b50f031393d8ab61f773b0e0130d7381e0f8a1d", "Discard medicine more than two years old."},
+	{"a687a8985b4d8d0a24f115fe272255c6afaf3909225838546159c1ed685c211a203796ae8ecc4c81a5b6315919b3a64f10713da07e341fcdbb08541bf03066ce", "He who has a shady past knows that nice guys finish last."},
+	{"8ddb0392e818b7d585ab22769a50df660d9f6d559cca3afc5691b8ca91b8451374e42bcdabd64589ed7c91d85f626596228a5c8572677eb98bc6b624befb7af8", "I wouldn't marry him with a ten foot pole."},
+	{"26ed8f6ca7f8d44b6a8a54ae39640fa8ad5c673f70ee9ce074ba4ef0d483eea00bab2f61d8695d6b34df9c6c48ae36246362200ed820448bdc03a720366a87c6", "Free! Free!/A trip/to Mars/for 900/empty jars/Burma Shave"},
+	{"e5a14bf044be69615aade89afcf1ab0389d5fc302a884d403579d1386a2400c089b0dbb387ed0f463f9ee342f8244d5a38cfbc0e819da9529fbff78368c9a982", "The days of the digital watch are numbered.  -Tom Stoppard"},
+	{"420a1faa48919e14651bed45725abe0f7a58e0f099424c4e5a49194946e38b46c1f8034b18ef169b2e31050d1648e0b982386595f7df47da4b6fd18e55333015", "Nepal premier won't resign."},
+	{"d926a863beadb20134db07683535c72007b0e695045876254f341ddcccde132a908c5af57baa6a6a9c63e6649bba0c213dc05fadcf9abccea09f23dcfb637fbe", "For every action there is an equal and opposite government program."},
+	{"9a98dd9bb67d0da7bf83da5313dff4fd60a4bac0094f1b05633690ffa7f6d61de9a1d4f8617937d560833a9aaa9ccafe3fd24db418d0e728833545cadd3ad92d", "His money is twice tainted: 'taint yours and 'taint mine."},
+	{"d7fde2d2351efade52f4211d3746a0780a26eec3df9b2ed575368a8a1c09ec452402293a8ea4eceb5a4f60064ea29b13cdd86918cd7a4faf366160b009804107", "There is no reason for any individual to have a computer in their home. -Ken Olsen, 1977"},
+	{"b0f35ffa2697359c33a56f5c0cf715c7aeed96da9905ca2698acadb08fbc9e669bf566b6bd5d61a3e86dc22999bcc9f2224e33d1d4f32a228cf9d0349e2db518", "It's a tiny change to the code and not completely disgusting. - Bob Manchek"},
+	{"3d2e5f91778c9e66f7e061293aaa8a8fc742dd3b2e4f483772464b1144189b49273e610e5cccd7a81a19ca1fa70f16b10f1a100a4d8c1372336be8484c64b311", "size:  a.out:  bad magic"},
+	{"b2f68ff58ac015efb1c94c908b0d8c2bf06f491e4de8e6302c49016f7f8a33eac3e959856c7fddbc464de618701338a4b46f76dbfaf9a1e5262b5f40639771c7", "The major problem is with sendmail.  -Mark Horton"},
+	{"d8c92db5fdf52cf8215e4df3b4909d29203ff4d00e9ad0b64a6a4e04dec5e74f62e7c35c7fb881bd5de95442123df8f57a489b0ae616bd326f84d10021121c57", "Give me a rock, paper and scissors and I will move the world.  CCFestoon"},
+	{"19a9f8dc0a233e464e8566ad3ca9b91e459a7b8c4780985b015776e1bf239a19bc233d0556343e2b0a9bc220900b4ebf4f8bdf89ff8efeaf79602d6849e6f72e", "If the enemy is within range, then so are you."},
+	{"00b4c41f307bde87301cdc5b5ab1ae9a592e8ecbb2021dd7bc4b34e2ace60741cc362560bec566ba35178595a91932b8d5357e2c9cec92d393b0fa7831852476", "It's well we cannot hear the screams/That we create in others' dreams."},
+	{"91eccc3d5375fd026e4d6787874b1dce201cecd8a27dbded5065728cb2d09c58a3d467bb1faf353bf7ba567e005245d5321b55bc344f7c07b91cb6f26c959be7", "You remind me of a TV show, but that's all right: I watch it anyway."},
+	{"fabbbe22180f1f137cfdc9556d2570e775d1ae02a597ded43a72a40f9b485d500043b7be128fb9fcd982b83159a0d99aa855a9e7cc4240c00dc01a9bdf8218d7", "C is as portable as Stonehedge!!"},
+	{"2ecdec235c1fa4fc2a154d8fba1dddb8a72a1ad73838b51d792331d143f8b96a9f6fcb0f34d7caa351fe6d88771c4f105040e0392f06e0621689d33b2f3ba92e", "Even if I could be Shakespeare, I think I should still choose to be Faraday. - A. Huxley"},
+	{"7ad681f6f96f82f7abfa7ecc0334e8fa16d3dc1cdc45b60b7af43fe4075d2357c0c1d60e98350f1afb1f2fe7a4d7cd2ad55b88e458e06b73c40b437331f5dab4", "The fugacity of a constituent in a mixture of gases at a given temperature is proportional to its mole fraction.  Lewis-Randall Rule"},
+	{"833f9248ab4a3b9e5131f745fda1ffd2dd435b30e965957e78291c7ab73605fd1912b0794e5c233ab0a12d205a39778d19b83515d6a47003f19cdee51d98c7e0", "How can you write a big system without C++?  -Paul Glick"},
+}
+
+var golden384 = []sha512Test{
+	{"38b060a751ac96384cd9327eb1b1e36a21fdb71114be07434c0cc7bf63f6e1da274edebfe76f65fbd51ad2f14898b95b", ""},
+	{"54a59b9f22b0b80880d8427e548b7c23abd873486e1f035dce9cd697e85175033caa88e6d57bc35efae0b5afd3145f31", "a"},
+	{"c7be03ba5bcaa384727076db0018e99248e1a6e8bd1b9ef58a9ec9dd4eeebb3f48b836201221175befa74ddc3d35afdd", "ab"},
+	{"cb00753f45a35e8bb5a03d699ac65007272c32ab0eded1631a8b605a43ff5bed8086072ba1e7cc2358baeca134c825a7", "abc"},
+	{"1165b3406ff0b52a3d24721f785462ca2276c9f454a116c2b2ba20171a7905ea5a026682eb659c4d5f115c363aa3c79b", "abcd"},
+	{"4c525cbeac729eaf4b4665815bc5db0c84fe6300068a727cf74e2813521565abc0ec57a37ee4d8be89d097c0d2ad52f0", "abcde"},
+	{"c6a4c65b227e7387b9c3e839d44869c4cfca3ef583dea64117859b808c1e3d8ae689e1e314eeef52a6ffe22681aa11f5", "abcdef"},
+	{"9f11fc131123f844c1226f429b6a0a6af0525d9f40f056c7fc16cdf1b06bda08e302554417a59fa7dcf6247421959d22", "abcdefg"},
+	{"9000cd7cada59d1d2eb82912f7f24e5e69cc5517f68283b005fa27c285b61e05edf1ad1a8a9bded6fd29eb87d75ad806", "abcdefgh"},
+	{"ef54915b60cf062b8dd0c29ae3cad69abe6310de63ac081f46ef019c5c90897caefd79b796cfa81139788a260ded52df", "abcdefghi"},
+	{"a12070030a02d86b0ddacd0d3a5b598344513d0a051e7355053e556a0055489c1555399b03342845c4adde2dc44ff66c", "abcdefghij"},
+	{"86f58ec2d74d1b7f8eb0c2ff0967316699639e8d4eb129de54bdf34c96cdbabe200d052149f2dd787f43571ba74670d4", "Discard medicine more than two years old."},
+	{"ae4a2b639ca9bfa04b1855d5a05fe7f230994f790891c6979103e2605f660c4c1262a48142dcbeb57a1914ba5f7c3fa7", "He who has a shady past knows that nice guys finish last."},
+	{"40ae213df6436eca952aa6841886fcdb82908ef1576a99c8f49bb9dd5023169f7c53035abdda0b54c302f4974e2105e7", "I wouldn't marry him with a ten foot pole."},
+	{"e7cf8b873c9bc950f06259aa54309f349cefa72c00d597aebf903e6519a50011dfe355afff064a10701c705693848df9", "Free! Free!/A trip/to Mars/for 900/empty jars/Burma Shave"},
+	{"c3d4f0f4047181c7d39d34703365f7bf70207183caf2c2f6145f04da895ef69124d9cdeb635da636c3a474e61024e29b", "The days of the digital watch are numbered.  -Tom Stoppard"},
+	{"a097aab567e167d5cf93676ed73252a69f9687cb3179bb2d27c9878119e94bf7b7c4b58dc90582edfaf66e11388ed714", "Nepal premier won't resign."},
+	{"5026ca45c41fc64712eb65065da92f6467541c78f8966d3fe2c8e3fb769a3ec14215f819654b47bd64f7f0eac17184f3", "For every action there is an equal and opposite government program."},
+	{"ac1cc0f5ac8d5f5514a7b738ac322b7fb52a161b449c3672e9b6a6ad1a5e4b26b001cf3bad24c56598676ca17d4b445a", "His money is twice tainted: 'taint yours and 'taint mine."},
+	{"722d10c5de371ec0c8c4b5247ac8a5f1d240d68c73f8da13d8b25f0166d6f309bf9561979a111a0049405771d201941a", "There is no reason for any individual to have a computer in their home. -Ken Olsen, 1977"},
+	{"dc2d3ea18bfa10549c63bf2b75b39b5167a80c12aff0e05443168ea87ff149fb0eda5e0bd234eb5d48c7d02ffc5807f1", "It's a tiny change to the code and not completely disgusting. - Bob Manchek"},
+	{"1d67c969e2a945ae5346d2139760261504d4ba164c522443afe19ef3e29b152a4c52445489cfc9d7215e5a450e8e1e4e", "size:  a.out:  bad magic"},
+	{"5ff8e075e465646e7b73ef36d812c6e9f7d60fa6ea0e533e5569b4f73cde53cdd2cc787f33540af57cca3fe467d32fe0", "The major problem is with sendmail.  -Mark Horton"},
+	{"5bd0a997a67c9ae1979a894eb0cde403dde003c9b6f2c03cf21925c42ff4e1176e6df1ca005381612ef18457b9b7ec3b", "Give me a rock, paper and scissors and I will move the world.  CCFestoon"},
+	{"1eee6da33e7e54fc5be52ae23b94b16ba4d2a947ae4505c6a3edfc7401151ea5205ac01b669b56f27d8ef7f175ed7762", "If the enemy is within range, then so are you."},
+	{"76b06e9dea66bfbb1a96029426dc0dfd7830bd297eb447ff5358d94a87cd00c88b59df2493fef56ecbb5231073892ea9", "It's well we cannot hear the screams/That we create in others' dreams."},
+	{"12acaf21452cff586143e3f5db0bfdf7802c057e1adf2a619031c4e1b0ccc4208cf6cef8fe722bbaa2fb46a30d9135d8", "You remind me of a TV show, but that's all right: I watch it anyway."},
+	{"0fc23d7f4183efd186f0bc4fc5db867e026e2146b06cb3d52f4bdbd57d1740122caa853b41868b197b2ac759db39df88", "C is as portable as Stonehedge!!"},
+	{"bc805578a7f85d34a86a32976e1c34fe65cf815186fbef76f46ef99cda10723f971f3f1464d488243f5e29db7488598d", "Even if I could be Shakespeare, I think I should still choose to be Faraday. - A. Huxley"},
+	{"b23918399a12ebf4431559eec3813eaf7412e875fd7464f16d581e473330842d2e96c6be49a7ce3f9bb0b8bc0fcbe0fe", "The fugacity of a constituent in a mixture of gases at a given temperature is proportional to its mole fraction.  Lewis-Randall Rule"},
+	{"1764b700eb1ead52a2fc33cc28975c2180f1b8faa5038d94cffa8d78154aab16e91dd787e7b0303948ebed62561542c8", "How can you write a big system without C++?  -Paul Glick"},
+}
+
+func TestGolden(t *testing.T) {
+	for i := 0; i < len(golden); i++ {
+		g := golden[i]
+		s := fmt.Sprintf("%x", Sum512([]byte(g.in)))
+		if s != g.out {
+			t.Fatalf("Sum512 function: sha512(%s) = %s want %s", g.in, s, g.out)
+		}
+		c := New()
+		for j := 0; j < 3; j++ {
+			if j < 2 {
+				io.WriteString(c, g.in)
+			} else {
+				io.WriteString(c, g.in[0:len(g.in)/2])
+				c.Sum(nil)
+				io.WriteString(c, g.in[len(g.in)/2:])
+			}
+			s := fmt.Sprintf("%x", c.Sum(nil))
+			if s != g.out {
+				t.Fatalf("sha512[%d](%s) = %s want %s", j, g.in, s, g.out)
+			}
+			c.Reset()
+		}
+	}
+	for i := 0; i < len(golden384); i++ {
+		g := golden384[i]
+		s := fmt.Sprintf("%x", Sum384([]byte(g.in)))
+		if s != g.out {
+			t.Fatalf("Sum384 function: sha384(%s) = %s want %s", g.in, s, g.out)
+		}
+		c := New384()
+		for j := 0; j < 3; j++ {
+			if j < 2 {
+				io.WriteString(c, g.in)
+			} else {
+				io.WriteString(c, g.in[0:len(g.in)/2])
+				c.Sum(nil)
+				io.WriteString(c, g.in[len(g.in)/2:])
+			}
+			s := fmt.Sprintf("%x", c.Sum(nil))
+			if s != g.out {
+				t.Fatalf("sha384[%d](%s) = %s want %s", j, g.in, s, g.out)
+			}
+			c.Reset()
+		}
+	}
+}
+
+func TestSize(t *testing.T) {
+	c := New()
+	if got := c.Size(); got != Size {
+		t.Errorf("Size = %d; want %d", got, Size)
+	}
+	c = New384()
+	if got := c.Size(); got != Size384 {
+		t.Errorf("New384.Size = %d; want %d", got, Size384)
+	}
+}
+
+func TestBlockSize(t *testing.T) {
+	c := New()
+	if got := c.BlockSize(); got != BlockSize {
+		t.Errorf("BlockSize = %d; want %d", got, BlockSize)
+	}
+}
+
+var bench = New()
+var buf = make([]byte, 8192)
+
+func benchmarkSize(b *testing.B, size int) {
+	b.SetBytes(int64(size))
+	sum := make([]byte, bench.Size())
+	for i := 0; i < b.N; i++ {
+		bench.Reset()
+		bench.Write(buf[:size])
+		bench.Sum(sum[:0])
+	}
+}
+
+func BenchmarkHash8Bytes(b *testing.B) {
+	benchmarkSize(b, 8)
+}
+
+func BenchmarkHash1K(b *testing.B) {
+	benchmarkSize(b, 1024)
+}
+
+func BenchmarkHash8K(b *testing.B) {
+	benchmarkSize(b, 8192)
+}

Godeps/_workspace/src/github.com/jlhawn/go-crypto/sha512/sha512block.go

@@ -0,0 +1,144 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !amd64
+
+// SHA512 block step.
+// In its own file so that a faster assembly or C version
+// can be substituted easily.
+
+package sha512
+
+var _K = []uint64{
+	0x428a2f98d728ae22,
+	0x7137449123ef65cd,
+	0xb5c0fbcfec4d3b2f,
+	0xe9b5dba58189dbbc,
+	0x3956c25bf348b538,
+	0x59f111f1b605d019,
+	0x923f82a4af194f9b,
+	0xab1c5ed5da6d8118,
+	0xd807aa98a3030242,
+	0x12835b0145706fbe,
+	0x243185be4ee4b28c,
+	0x550c7dc3d5ffb4e2,
+	0x72be5d74f27b896f,
+	0x80deb1fe3b1696b1,
+	0x9bdc06a725c71235,
+	0xc19bf174cf692694,
+	0xe49b69c19ef14ad2,
+	0xefbe4786384f25e3,
+	0x0fc19dc68b8cd5b5,
+	0x240ca1cc77ac9c65,
+	0x2de92c6f592b0275,
+	0x4a7484aa6ea6e483,
+	0x5cb0a9dcbd41fbd4,
+	0x76f988da831153b5,
+	0x983e5152ee66dfab,
+	0xa831c66d2db43210,
+	0xb00327c898fb213f,
+	0xbf597fc7beef0ee4,
+	0xc6e00bf33da88fc2,
+	0xd5a79147930aa725,
+	0x06ca6351e003826f,
+	0x142929670a0e6e70,
+	0x27b70a8546d22ffc,
+	0x2e1b21385c26c926,
+	0x4d2c6dfc5ac42aed,
+	0x53380d139d95b3df,
+	0x650a73548baf63de,
+	0x766a0abb3c77b2a8,
+	0x81c2c92e47edaee6,
+	0x92722c851482353b,
+	0xa2bfe8a14cf10364,
+	0xa81a664bbc423001,
+	0xc24b8b70d0f89791,
+	0xc76c51a30654be30,
+	0xd192e819d6ef5218,
+	0xd69906245565a910,
+	0xf40e35855771202a,
+	0x106aa07032bbd1b8,
+	0x19a4c116b8d2d0c8,
+	0x1e376c085141ab53,
+	0x2748774cdf8eeb99,
+	0x34b0bcb5e19b48a8,
+	0x391c0cb3c5c95a63,
+	0x4ed8aa4ae3418acb,
+	0x5b9cca4f7763e373,
+	0x682e6ff3d6b2b8a3,
+	0x748f82ee5defb2fc,
+	0x78a5636f43172f60,
+	0x84c87814a1f0ab72,
+	0x8cc702081a6439ec,
+	0x90befffa23631e28,
+	0xa4506cebde82bde9,
+	0xbef9a3f7b2c67915,
+	0xc67178f2e372532b,
+	0xca273eceea26619c,
+	0xd186b8c721c0c207,
+	0xeada7dd6cde0eb1e,
+	0xf57d4f7fee6ed178,
+	0x06f067aa72176fba,
+	0x0a637dc5a2c898a6,
+	0x113f9804bef90dae,
+	0x1b710b35131c471b,
+	0x28db77f523047d84,
+	0x32caab7b40c72493,
+	0x3c9ebe0a15c9bebc,
+	0x431d67c49c100d4c,
+	0x4cc5d4becb3e42b6,
+	0x597f299cfc657e2a,
+	0x5fcb6fab3ad6faec,
+	0x6c44198c4a475817,
+}
+
+func block(dig *digest, p []byte) {
+	var w [80]uint64
+	h0, h1, h2, h3, h4, h5, h6, h7 := dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4], dig.h[5], dig.h[6], dig.h[7]
+	for len(p) >= chunk {
+		for i := 0; i < 16; i++ {
+			j := i * 8
+			w[i] = uint64(p[j])<<56 | uint64(p[j+1])<<48 | uint64(p[j+2])<<40 | uint64(p[j+3])<<32 |
+				uint64(p[j+4])<<24 | uint64(p[j+5])<<16 | uint64(p[j+6])<<8 | uint64(p[j+7])
+		}
+		for i := 16; i < 80; i++ {
+			v1 := w[i-2]
+			t1 := (v1>>19 | v1<<(64-19)) ^ (v1>>61 | v1<<(64-61)) ^ (v1 >> 6)
+			v2 := w[i-15]
+			t2 := (v2>>1 | v2<<(64-1)) ^ (v2>>8 | v2<<(64-8)) ^ (v2 >> 7)
+
+			w[i] = t1 + w[i-7] + t2 + w[i-16]
+		}
+
+		a, b, c, d, e, f, g, h := h0, h1, h2, h3, h4, h5, h6, h7
+
+		for i := 0; i < 80; i++ {
+			t1 := h + ((e>>14 | e<<(64-14)) ^ (e>>18 | e<<(64-18)) ^ (e>>41 | e<<(64-41))) + ((e & f) ^ (^e & g)) + _K[i] + w[i]
+
+			t2 := ((a>>28 | a<<(64-28)) ^ (a>>34 | a<<(64-34)) ^ (a>>39 | a<<(64-39))) + ((a & b) ^ (a & c) ^ (b & c))
+
+			h = g
+			g = f
+			f = e
+			e = d + t1
+			d = c
+			c = b
+			b = a
+			a = t1 + t2
+		}
+
+		h0 += a
+		h1 += b
+		h2 += c
+		h3 += d
+		h4 += e
+		h5 += f
+		h6 += g
+		h7 += h
+
+		p = p[chunk:]
+	}
+
+	dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4], dig.h[5], dig.h[6], dig.h[7] = h0, h1, h2, h3, h4, h5, h6, h7
+}

Godeps/_workspace/src/github.com/jlhawn/go-crypto/sha512/sha512block_amd64.s

@@ -0,0 +1,273 @@
+// Copyright 2013 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "../textflag.h"
+
+// SHA512 block routine. See sha512block.go for Go equivalent.
+//
+// The algorithm is detailed in FIPS 180-4:
+//
+//  http://csrc.nist.gov/publications/fips/fips180-4/fips-180-4.pdf
+//
+// Wt = Mt; for 0 <= t <= 15
+// Wt = SIGMA1(Wt-2) + SIGMA0(Wt-15) + Wt-16; for 16 <= t <= 79
+//
+// a = H0
+// b = H1
+// c = H2
+// d = H3
+// e = H4
+// f = H5
+// g = H6
+// h = H7
+//
+// for t = 0 to 79 {
+//    T1 = h + BIGSIGMA1(e) + Ch(e,f,g) + Kt + Wt
+//    T2 = BIGSIGMA0(a) + Maj(a,b,c)
+//    h = g
+//    g = f
+//    f = e
+//    e = d + T1
+//    d = c
+//    c = b
+//    b = a
+//    a = T1 + T2
+// }
+//
+// H0 = a + H0
+// H1 = b + H1
+// H2 = c + H2
+// H3 = d + H3
+// H4 = e + H4
+// H5 = f + H5
+// H6 = g + H6
+// H7 = h + H7
+
+// Wt = Mt; for 0 <= t <= 15
+#define MSGSCHEDULE0(index) \
+	MOVQ	(index*8)(SI), AX; \
+	BSWAPQ	AX; \
+	MOVQ	AX, (index*8)(BP)
+
+// Wt = SIGMA1(Wt-2) + Wt-7 + SIGMA0(Wt-15) + Wt-16; for 16 <= t <= 79
+//   SIGMA0(x) = ROTR(1,x) XOR ROTR(8,x) XOR SHR(7,x)
+//   SIGMA1(x) = ROTR(19,x) XOR ROTR(61,x) XOR SHR(6,x)
+#define MSGSCHEDULE1(index) \
+	MOVQ	((index-2)*8)(BP), AX; \
+	MOVQ	AX, CX; \
+	RORQ	$19, AX; \
+	MOVQ	CX, DX; \
+	RORQ	$61, CX; \
+	SHRQ	$6, DX; \
+	MOVQ	((index-15)*8)(BP), BX; \
+	XORQ	CX, AX; \
+	MOVQ	BX, CX; \
+	XORQ	DX, AX; \
+	RORQ	$1, BX; \
+	MOVQ	CX, DX; \
+	SHRQ	$7, DX; \
+	RORQ	$8, CX; \
+	ADDQ	((index-7)*8)(BP), AX; \
+	XORQ	CX, BX; \
+	XORQ	DX, BX; \
+	ADDQ	((index-16)*8)(BP), BX; \
+	ADDQ	BX, AX; \
+	MOVQ	AX, ((index)*8)(BP)
+
+// Calculate T1 in AX - uses AX, CX and DX registers.
+// h is also used as an accumulator. Wt is passed in AX.
+//   T1 = h + BIGSIGMA1(e) + Ch(e, f, g) + Kt + Wt
+//     BIGSIGMA1(x) = ROTR(14,x) XOR ROTR(18,x) XOR ROTR(41,x)
+//     Ch(x, y, z) = (x AND y) XOR (NOT x AND z)
+#define SHA512T1(const, e, f, g, h) \
+	MOVQ	$const, DX; \
+	ADDQ	AX, h; \
+	MOVQ	e, AX; \
+	ADDQ	DX, h; \
+	MOVQ	e, CX; \
+	RORQ	$14, AX; \
+	MOVQ	e, DX; \
+	RORQ	$18, CX; \
+	XORQ	CX, AX; \
+	MOVQ	e, CX; \
+	RORQ	$41, DX; \
+	ANDQ	f, CX; \
+	XORQ	AX, DX; \
+	MOVQ	e, AX; \
+	NOTQ	AX; \
+	ADDQ	DX, h; \
+	ANDQ	g, AX; \
+	XORQ	CX, AX; \
+	ADDQ	h, AX
+
+// Calculate T2 in BX - uses BX, CX, DX and DI registers.
+//   T2 = BIGSIGMA0(a) + Maj(a, b, c)
+//     BIGSIGMA0(x) = ROTR(28,x) XOR ROTR(34,x) XOR ROTR(39,x)
+//     Maj(x, y, z) = (x AND y) XOR (x AND z) XOR (y AND z)
+#define SHA512T2(a, b, c) \
+	MOVQ	a, DI; \
+	MOVQ	c, BX; \
+	RORQ	$28, DI; \
+	MOVQ	a, DX; \
+	ANDQ	b, BX; \
+	RORQ	$34, DX; \
+	MOVQ	a, CX; \
+	ANDQ	c, CX; \
+	XORQ	DX, DI; \
+	XORQ	CX, BX; \
+	MOVQ	a, DX; \
+	MOVQ	b, CX; \
+	RORQ	$39, DX; \
+	ANDQ	a, CX; \
+	XORQ	CX, BX; \
+	XORQ	DX, DI; \
+	ADDQ	DI, BX
+
+// Calculate T1 and T2, then e = d + T1 and a = T1 + T2.
+// The values for e and a are stored in d and h, ready for rotation.
+#define SHA512ROUND(index, const, a, b, c, d, e, f, g, h) \
+	SHA512T1(const, e, f, g, h); \
+	SHA512T2(a, b, c); \
+	MOVQ	BX, h; \
+	ADDQ	AX, d; \
+	ADDQ	AX, h
+
+#define SHA512ROUND0(index, const, a, b, c, d, e, f, g, h) \
+	MSGSCHEDULE0(index); \
+	SHA512ROUND(index, const, a, b, c, d, e, f, g, h)
+
+#define SHA512ROUND1(index, const, a, b, c, d, e, f, g, h) \
+	MSGSCHEDULE1(index); \
+	SHA512ROUND(index, const, a, b, c, d, e, f, g, h)
+
+TEXT ·block(SB),0,$648-32
+	MOVQ	p_base+8(FP), SI
+	MOVQ	p_len+16(FP), DX
+	SHRQ	$7, DX
+	SHLQ	$7, DX
+
+	LEAQ	(SI)(DX*1), DI
+	MOVQ	DI, 640(SP)
+	CMPQ	SI, DI
+	JEQ	end
+
+	MOVQ	dig+0(FP), BP
+	MOVQ	(0*8)(BP), R8		// a = H0
+	MOVQ	(1*8)(BP), R9		// b = H1
+	MOVQ	(2*8)(BP), R10		// c = H2
+	MOVQ	(3*8)(BP), R11		// d = H3
+	MOVQ	(4*8)(BP), R12		// e = H4
+	MOVQ	(5*8)(BP), R13		// f = H5
+	MOVQ	(6*8)(BP), R14		// g = H6
+	MOVQ	(7*8)(BP), R15		// h = H7
+
+loop:
+	MOVQ	SP, BP			// message schedule
+
+	SHA512ROUND0(0, 0x428a2f98d728ae22, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA512ROUND0(1, 0x7137449123ef65cd, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA512ROUND0(2, 0xb5c0fbcfec4d3b2f, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA512ROUND0(3, 0xe9b5dba58189dbbc, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA512ROUND0(4, 0x3956c25bf348b538, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA512ROUND0(5, 0x59f111f1b605d019, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA512ROUND0(6, 0x923f82a4af194f9b, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA512ROUND0(7, 0xab1c5ed5da6d8118, R9, R10, R11, R12, R13, R14, R15, R8)
+	SHA512ROUND0(8, 0xd807aa98a3030242, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA512ROUND0(9, 0x12835b0145706fbe, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA512ROUND0(10, 0x243185be4ee4b28c, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA512ROUND0(11, 0x550c7dc3d5ffb4e2, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA512ROUND0(12, 0x72be5d74f27b896f, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA512ROUND0(13, 0x80deb1fe3b1696b1, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA512ROUND0(14, 0x9bdc06a725c71235, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA512ROUND0(15, 0xc19bf174cf692694, R9, R10, R11, R12, R13, R14, R15, R8)
+
+	SHA512ROUND1(16, 0xe49b69c19ef14ad2, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA512ROUND1(17, 0xefbe4786384f25e3, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA512ROUND1(18, 0x0fc19dc68b8cd5b5, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA512ROUND1(19, 0x240ca1cc77ac9c65, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA512ROUND1(20, 0x2de92c6f592b0275, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA512ROUND1(21, 0x4a7484aa6ea6e483, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA512ROUND1(22, 0x5cb0a9dcbd41fbd4, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA512ROUND1(23, 0x76f988da831153b5, R9, R10, R11, R12, R13, R14, R15, R8)
+	SHA512ROUND1(24, 0x983e5152ee66dfab, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA512ROUND1(25, 0xa831c66d2db43210, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA512ROUND1(26, 0xb00327c898fb213f, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA512ROUND1(27, 0xbf597fc7beef0ee4, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA512ROUND1(28, 0xc6e00bf33da88fc2, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA512ROUND1(29, 0xd5a79147930aa725, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA512ROUND1(30, 0x06ca6351e003826f, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA512ROUND1(31, 0x142929670a0e6e70, R9, R10, R11, R12, R13, R14, R15, R8)
+	SHA512ROUND1(32, 0x27b70a8546d22ffc, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA512ROUND1(33, 0x2e1b21385c26c926, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA512ROUND1(34, 0x4d2c6dfc5ac42aed, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA512ROUND1(35, 0x53380d139d95b3df, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA512ROUND1(36, 0x650a73548baf63de, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA512ROUND1(37, 0x766a0abb3c77b2a8, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA512ROUND1(38, 0x81c2c92e47edaee6, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA512ROUND1(39, 0x92722c851482353b, R9, R10, R11, R12, R13, R14, R15, R8)
+	SHA512ROUND1(40, 0xa2bfe8a14cf10364, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA512ROUND1(41, 0xa81a664bbc423001, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA512ROUND1(42, 0xc24b8b70d0f89791, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA512ROUND1(43, 0xc76c51a30654be30, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA512ROUND1(44, 0xd192e819d6ef5218, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA512ROUND1(45, 0xd69906245565a910, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA512ROUND1(46, 0xf40e35855771202a, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA512ROUND1(47, 0x106aa07032bbd1b8, R9, R10, R11, R12, R13, R14, R15, R8)
+	SHA512ROUND1(48, 0x19a4c116b8d2d0c8, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA512ROUND1(49, 0x1e376c085141ab53, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA512ROUND1(50, 0x2748774cdf8eeb99, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA512ROUND1(51, 0x34b0bcb5e19b48a8, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA512ROUND1(52, 0x391c0cb3c5c95a63, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA512ROUND1(53, 0x4ed8aa4ae3418acb, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA512ROUND1(54, 0x5b9cca4f7763e373, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA512ROUND1(55, 0x682e6ff3d6b2b8a3, R9, R10, R11, R12, R13, R14, R15, R8)
+	SHA512ROUND1(56, 0x748f82ee5defb2fc, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA512ROUND1(57, 0x78a5636f43172f60, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA512ROUND1(58, 0x84c87814a1f0ab72, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA512ROUND1(59, 0x8cc702081a6439ec, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA512ROUND1(60, 0x90befffa23631e28, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA512ROUND1(61, 0xa4506cebde82bde9, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA512ROUND1(62, 0xbef9a3f7b2c67915, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA512ROUND1(63, 0xc67178f2e372532b, R9, R10, R11, R12, R13, R14, R15, R8)
+	SHA512ROUND1(64, 0xca273eceea26619c, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA512ROUND1(65, 0xd186b8c721c0c207, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA512ROUND1(66, 0xeada7dd6cde0eb1e, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA512ROUND1(67, 0xf57d4f7fee6ed178, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA512ROUND1(68, 0x06f067aa72176fba, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA512ROUND1(69, 0x0a637dc5a2c898a6, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA512ROUND1(70, 0x113f9804bef90dae, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA512ROUND1(71, 0x1b710b35131c471b, R9, R10, R11, R12, R13, R14, R15, R8)
+	SHA512ROUND1(72, 0x28db77f523047d84, R8, R9, R10, R11, R12, R13, R14, R15)
+	SHA512ROUND1(73, 0x32caab7b40c72493, R15, R8, R9, R10, R11, R12, R13, R14)
+	SHA512ROUND1(74, 0x3c9ebe0a15c9bebc, R14, R15, R8, R9, R10, R11, R12, R13)
+	SHA512ROUND1(75, 0x431d67c49c100d4c, R13, R14, R15, R8, R9, R10, R11, R12)
+	SHA512ROUND1(76, 0x4cc5d4becb3e42b6, R12, R13, R14, R15, R8, R9, R10, R11)
+	SHA512ROUND1(77, 0x597f299cfc657e2a, R11, R12, R13, R14, R15, R8, R9, R10)
+	SHA512ROUND1(78, 0x5fcb6fab3ad6faec, R10, R11, R12, R13, R14, R15, R8, R9)
+	SHA512ROUND1(79, 0x6c44198c4a475817, R9, R10, R11, R12, R13, R14, R15, R8)
+
+	MOVQ	dig+0(FP), BP
+	ADDQ	(0*8)(BP), R8	// H0 = a + H0
+	MOVQ	R8, (0*8)(BP)
+	ADDQ	(1*8)(BP), R9	// H1 = b + H1
+	MOVQ	R9, (1*8)(BP)
+	ADDQ	(2*8)(BP), R10	// H2 = c + H2
+	MOVQ	R10, (2*8)(BP)
+	ADDQ	(3*8)(BP), R11	// H3 = d + H3
+	MOVQ	R11, (3*8)(BP)
+	ADDQ	(4*8)(BP), R12	// H4 = e + H4
+	MOVQ	R12, (4*8)(BP)
+	ADDQ	(5*8)(BP), R13	// H5 = f + H5
+	MOVQ	R13, (5*8)(BP)
+	ADDQ	(6*8)(BP), R14	// H6 = g + H6
+	MOVQ	R14, (6*8)(BP)
+	ADDQ	(7*8)(BP), R15	// H7 = h + H7
+	MOVQ	R15, (7*8)(BP)
+
+	ADDQ	$128, SI
+	CMPQ	SI, 640(SP)
+	JB	loop
+
+end:
+	RET

Godeps/_workspace/src/github.com/jlhawn/go-crypto/sha512/sha512block_decl.go

@@ -0,0 +1,11 @@
+// Copyright 2013 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build amd64
+
+package sha512
+
+//go:noescape
+
+func block(dig *digest, p []byte)

Godeps/_workspace/src/github.com/jlhawn/go-crypto/sha512/sha512resume_test.go

@@ -0,0 +1,57 @@
+package sha512
+
+import (
+	"bytes"
+	stdlib "crypto"
+	"crypto/rand"
+	_ "crypto/sha512" // To register the stdlib sha224 and sha256 algs.
+	resumable "github.com/jlhawn/go-crypto"
+	"io"
+	"testing"
+)
+
+func compareResumableHash(t *testing.T, r resumable.Hash, h stdlib.Hash) {
+	// Read 3 Kilobytes of random data into a buffer.
+	buf := make([]byte, 3*1024)
+	if _, err := io.ReadFull(rand.Reader, buf); err != nil {
+		t.Fatalf("unable to load random data: %s", err)
+	}
+
+	// Use two Hash objects to consume prefixes of the data. One will be
+	// snapshotted and resumed with each additional byte, then both will write
+	// that byte. The digests should be equal after each byte is digested.
+	resumableHasher := r.New()
+	stdlibHasher := h.New()
+
+	// First, assert that the initial distest is the same.
+	if !bytes.Equal(resumableHasher.Sum(nil), stdlibHasher.Sum(nil)) {
+		t.Fatalf("initial digests do not match: got %x, expected %x", resumableHasher.Sum(nil), stdlibHasher.Sum(nil))
+	}
+
+	multiWriter := io.MultiWriter(resumableHasher, stdlibHasher)
+
+	for i := 1; i <= len(buf); i++ {
+
+		// Write the next byte.
+		multiWriter.Write(buf[i-1 : i])
+
+		if !bytes.Equal(resumableHasher.Sum(nil), stdlibHasher.Sum(nil)) {
+			t.Fatalf("digests do not match: got %x, expected %x", resumableHasher.Sum(nil), stdlibHasher.Sum(nil))
+		}
+
+		// Snapshot, reset, and restore the chunk hasher.
+		hashState, err := resumableHasher.State()
+		if err != nil {
+			t.Fatalf("unable to get state of hash function: %s", err)
+		}
+		resumableHasher.Reset()
+		if err := resumableHasher.Restore(hashState); err != nil {
+			t.Fatalf("unable to restorte state of hash function: %s", err)
+		}
+	}
+}
+
+func TestResumable(t *testing.T) {
+	compareResumableHash(t, resumable.SHA384, stdlib.SHA384)
+	compareResumableHash(t, resumable.SHA512, stdlib.SHA512)
+}

Godeps/_workspace/src/github.com/jlhawn/go-crypto/textflag.h

@@ -0,0 +1,23 @@
+// Copyright 2013 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file defines flags attached to various functions
+// and data objects.  The compilers, assemblers, and linker must
+// all agree on these values.
+
+// Don't profile the marked routine.  This flag is deprecated.
+#define NOPROF	1
+// It is ok for the linker to get multiple of these symbols.  It will
+// pick one of the duplicates to use.
+#define DUPOK	2
+// Don't insert stack check preamble.
+#define NOSPLIT	4
+// Put this data in a read-only section.
+#define RODATA	8
+// This data contains no pointers.
+#define NOPTR	16
+// This is a wrapper function and should not count as disabling 'recover'.
+#define WRAPPER 32
+// This function uses its incoming context register.
+#define NEEDCTXT 64

digest/digest.go

@@ -2,7 +2,6 @@ package digest
 
 import (
 	"bytes"
-	"crypto/sha256"
 	"fmt"
 	"hash"
 	"io"
@@ -72,13 +71,13 @@ func ParseDigest(s string) (Digest, error) {
 
 // FromReader returns the most valid digest for the underlying content.
 func FromReader(rd io.Reader) (Digest, error) {
-	h := sha256.New()
+	digester := NewCanonicalDigester()
 
-	if _, err := io.Copy(h, rd); err != nil {
+	if _, err := io.Copy(digester, rd); err != nil {
 		return "", err
 	}
 
-	return NewDigest("sha256", h), nil
+	return digester.Digest(), nil
 }
 
 // FromTarArchive produces a tarsum digest from reader rd.

digest/digester.go

@@ -2,7 +2,12 @@ package digest
 
 import (
 	"crypto/sha256"
+	"fmt"
 	"hash"
+
+	"github.com/jlhawn/go-crypto"          // For ResumableHash
+	_ "github.com/jlhawn/go-crypto/sha256" // For Resumable SHA256
+	_ "github.com/jlhawn/go-crypto/sha512" // For Resumable SHA384, SHA512
 )
 
 // Digester calculates the digest of written data. It is functionally
@@ -10,7 +15,7 @@ import (
 // rather than raw bytes.
 type Digester struct {
 	alg string
-	hash hash.Hash
+	hash.Hash
 }
 
 // NewDigester create a new Digester with the given hashing algorithm and instance
@@ -18,27 +23,58 @@ type Digester struct {
 func NewDigester(alg string, h hash.Hash) Digester {
 	return Digester{
 		alg:  alg,
-		hash: h,
+		Hash: h,
 	}
 }
 
 // NewCanonicalDigester is a convenience function to create a new Digester with
-// out default settings.
+// our default settings.
 func NewCanonicalDigester() Digester {
 	return NewDigester("sha256", sha256.New())
 }
 
-// Write data to the digester. These writes cannot fail.
-func (d *Digester) Write(p []byte) (n int, err error) {
-	return d.hash.Write(p)
-}
-
 // Digest returns the current digest for this digester.
 func (d *Digester) Digest() Digest {
-	return NewDigest(d.alg, d.hash)
+	return NewDigest(d.alg, d.Hash)
 }
 
-// Reset the state of the digester.
+// ResumableDigester is a digester that can export its internal state and be
-func (d *Digester) Reset() {
+// restored from saved state.
-	d.hash.Reset()
+type ResumableDigester struct {
+	alg string
+	crypto.ResumableHash
+}
+
+var resumableHashAlgs = map[string]crypto.Hash{
+	"sha256": crypto.SHA256,
+	"sha384": crypto.SHA384,
+	"sha512": crypto.SHA512,
+}
+
+// NewResumableDigester creates a new ResumableDigester with the given hashing
+// algorithm.
+func NewResumableDigester(alg string) (ResumableDigester, error) {
+	hash, supported := resumableHashAlgs[alg]
+	if !supported {
+		return ResumableDigester{}, fmt.Errorf("unsupported resumable hash algorithm: %s", alg)
+	}
+
+	return ResumableDigester{
+		alg:           alg,
+		ResumableHash: hash.New(),
+	}, nil
+}
+
+// NewCanonicalResumableDigester creates a ResumableDigester using the default
+// digest algorithm.
+func NewCanonicalResumableDigester() ResumableDigester {
+	return ResumableDigester{
+		alg:           "sha256",
+		ResumableHash: crypto.SHA256.New(),
+	}
+}
+
+// Digest returns the current digest for this resumable digester.
+func (d ResumableDigester) Digest() Digest {
+	return NewDigest(d.alg, d.ResumableHash)
 }