forked from TrueCloudLab/restic
crypto.go nitpicks
This commit is contained in:
Florian Weingarten
parent
a906b9febe
commit
c500b94216
6 changed files with 55 additions and 86 deletions
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@ -14,13 +14,13 @@ import (
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)
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const (
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aesKeySize = 32 // for AES256
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aesKeySize = 32 // for AES-256
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macKeySizeK = 16 // for AES-128
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macKeySizeR = 16 // for Poly1305
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macKeySize = macKeySizeK + macKeySizeR // for Poly1305-AES128
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ivSize = aes.BlockSize
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macSize = poly1305.TagSize // Poly1305 size is 16 byte
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macSize = poly1305.TagSize
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Extension = ivSize + macSize
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)
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@ -45,8 +45,8 @@ type Key struct {
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type EncryptionKey [32]byte
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type SigningKey struct {
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K [16]byte `json:"k"` // for AES128
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R [16]byte `json:"r"` // for Poly1305
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K [16]byte // for AES-128
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R [16]byte // for Poly1305
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masked bool // remember if the signing key has already been masked
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}
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@ -71,27 +71,9 @@ var poly1305KeyMask = [16]byte{
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0x0f, // 15: top four bits zero
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}
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// key is a [32]byte, in the form k||r
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func poly1305Sign(msg []byte, nonce []byte, key *SigningKey) []byte {
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// prepare key for low-level poly1305.Sum(): r||n
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var k [32]byte
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k := poly1305PrepareKey(nonce, key)
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// make sure key is masked
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if !key.masked {
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maskKey(key)
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}
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// fill in nonce, encrypted with AES and key[:16]
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cipher, err := aes.NewCipher(key.K[:])
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if err != nil {
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panic(err)
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}
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cipher.Encrypt(k[16:], nonce[:])
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// copy r
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copy(k[:16], key.R[:])
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// save mac in out
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var out [16]byte
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poly1305.Sum(&out, msg, &k)
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@ -100,9 +82,10 @@ func poly1305Sign(msg []byte, nonce []byte, key *SigningKey) []byte {
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// mask poly1305 key
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func maskKey(k *SigningKey) {
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if k == nil {
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if k == nil || k.masked {
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return
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}
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for i := 0; i < poly1305.TagSize; i++ {
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k.R[i] = k.R[i] & poly1305KeyMask[i]
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}
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@ -117,36 +100,36 @@ func macKeyFromSlice(mk *SigningKey, data []byte) {
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maskKey(mk)
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}
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// key: k||r
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func poly1305Verify(msg []byte, nonce []byte, key *SigningKey, mac []byte) bool {
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// prepare key for low-level poly1305.Sum(): r||n
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func poly1305PrepareKey(nonce []byte, key *SigningKey) [32]byte {
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var k [32]byte
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// make sure key is masked
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if !key.masked {
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maskKey(key)
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}
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// fill in nonce, encrypted with AES and key[:16]
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cipher, err := aes.NewCipher(key.K[:])
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if err != nil {
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panic(err)
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}
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cipher.Encrypt(k[16:], nonce[:])
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// copy r
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copy(k[:16], key.R[:])
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// copy mac to array
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return k
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}
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func poly1305Verify(msg []byte, nonce []byte, key *SigningKey, mac []byte) bool {
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k := poly1305PrepareKey(nonce, key)
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var m [16]byte
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copy(m[:], mac)
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return poly1305.Verify(&m, msg, &k)
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}
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// NewKey returns new encryption and signing keys.
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func NewKey() (k *Key) {
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k = &Key{}
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// NewRandomKey returns new encryption and signing keys.
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func NewRandomKey() *Key {
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k := &Key{}
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n, err := rand.Read(k.Encrypt[:])
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if n != aesKeySize || err != nil {
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panic("unable to read enough random bytes for encryption key")
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@ -161,9 +144,8 @@ func NewKey() (k *Key) {
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if n != macKeySizeR || err != nil {
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panic("unable to read enough random bytes for mac signing key")
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}
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// mask r
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maskKey(&k.Sign)
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maskKey(&k.Sign)
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return k
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}
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@ -220,7 +202,7 @@ var ErrInvalidCiphertext = errors.New("invalid ciphertext, same slice used for p
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// MAC. Encrypt returns the new ciphertext slice, which is extended when
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// necessary. ciphertext and plaintext may not point to (exactly) the same
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// slice or non-intersecting slices.
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func Encrypt(ks *Key, ciphertext, plaintext []byte) ([]byte, error) {
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func Encrypt(ks *Key, ciphertext []byte, plaintext []byte) ([]byte, error) {
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ciphertext = ciphertext[:cap(ciphertext)]
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// test for same slice, if possible
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@ -245,11 +227,11 @@ func Encrypt(ks *Key, ciphertext, plaintext []byte) ([]byte, error) {
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e.XORKeyStream(ciphertext[ivSize:], plaintext)
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copy(ciphertext, iv[:])
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// truncate to only conver iv and actual ciphertext
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// truncate to only cover iv and actual ciphertext
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ciphertext = ciphertext[:ivSize+len(plaintext)]
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mac := poly1305Sign(ciphertext[ivSize:], ciphertext[:ivSize], &ks.Sign)
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// append the mac tag
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ciphertext = append(ciphertext, mac...)
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return ciphertext, nil
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@ -258,28 +240,28 @@ func Encrypt(ks *Key, ciphertext, plaintext []byte) ([]byte, error) {
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// Decrypt verifies and decrypts the ciphertext. Ciphertext must be in the form
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// IV || Ciphertext || MAC. plaintext and ciphertext may point to (exactly) the
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// same slice.
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func Decrypt(ks *Key, plaintext, ciphertext []byte) ([]byte, error) {
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func Decrypt(ks *Key, plaintext []byte, ciphertextWithMac []byte) ([]byte, error) {
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// check for plausible length
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if len(ciphertext) < ivSize+macSize {
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if len(ciphertextWithMac) < ivSize+macSize {
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panic("trying to decrypt invalid data: ciphertext too small")
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}
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if cap(plaintext) < len(ciphertext) {
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if cap(plaintext) < len(ciphertextWithMac) {
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// extend plaintext
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plaintext = append(plaintext, make([]byte, len(ciphertext)-cap(plaintext))...)
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plaintext = append(plaintext, make([]byte, len(ciphertextWithMac)-cap(plaintext))...)
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}
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// extract mac
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l := len(ciphertext) - macSize
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ciphertext, mac := ciphertext[:l], ciphertext[l:]
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l := len(ciphertextWithMac) - macSize
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ciphertextWithIV, mac := ciphertextWithMac[:l], ciphertextWithMac[l:]
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// verify mac
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if !poly1305Verify(ciphertext[ivSize:], ciphertext[:ivSize], &ks.Sign, mac) {
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if !poly1305Verify(ciphertextWithIV[ivSize:], ciphertextWithIV[:ivSize], &ks.Sign, mac) {
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return nil, ErrUnauthenticated
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}
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// extract iv
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iv, ciphertext := ciphertext[:ivSize], ciphertext[ivSize:]
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iv, ciphertext := ciphertextWithIV[:ivSize], ciphertextWithIV[ivSize:]
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// decrypt data
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c, err := aes.NewCipher(ks.Encrypt[:])
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@ -65,11 +65,12 @@ var testValues = []struct {
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skey SigningKey
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ciphertext []byte
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plaintext []byte
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shouldPanic bool
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}{
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{
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ekey: EncryptionKey([...]byte{0x30, 0x3e, 0x86, 0x87, 0xb1, 0xd7, 0xdb, 0x18, 0x42, 0x1b, 0xdc, 0x6b, 0xb8, 0x58, 0x8c, 0xca,
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0xda, 0xc4, 0xd5, 0x9e, 0xe8, 0x7b, 0x8f, 0xf7, 0x0c, 0x44, 0xe6, 0x35, 0x79, 0x0c, 0xaf, 0xef}),
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ekey: EncryptionKey([...]byte{
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0x30, 0x3e, 0x86, 0x87, 0xb1, 0xd7, 0xdb, 0x18, 0x42, 0x1b, 0xdc, 0x6b, 0xb8, 0x58, 0x8c, 0xca,
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0xda, 0xc4, 0xd5, 0x9e, 0xe8, 0x7b, 0x8f, 0xf7, 0x0c, 0x44, 0xe6, 0x35, 0x79, 0x0c, 0xaf, 0xef,
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}),
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skey: SigningKey{
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K: [...]byte{0xef, 0x4d, 0x88, 0x24, 0xcb, 0x80, 0xb2, 0xbc, 0xc5, 0xfb, 0xff, 0x8a, 0x9b, 0x12, 0xa4, 0x2c},
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R: [...]byte{0xcc, 0x8d, 0x4b, 0x94, 0x8e, 0xe0, 0xeb, 0xfe, 0x1d, 0x41, 0x5d, 0xe9, 0x21, 0xd1, 0x03, 0x53},
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@ -84,19 +85,6 @@ func decodeHex(s string) []byte {
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return d
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}
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// returns true if function called panic
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func shouldPanic(f func()) (didPanic bool) {
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defer func() {
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if r := recover(); r != nil {
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didPanic = true
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}
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}()
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f()
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return false
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}
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func TestCrypto(t *testing.T) {
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msg := make([]byte, 0, 8*1024*1024) // use 8MiB for now
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for _, tv := range testValues {
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@ -17,7 +17,7 @@ import (
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var testLargeCrypto = flag.Bool("test.largecrypto", false, "also test crypto functions with large payloads")
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func TestEncryptDecrypt(t *testing.T) {
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k := crypto.NewKey()
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k := crypto.NewRandomKey()
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tests := []int{5, 23, 2<<18 + 23, 1 << 20}
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if *testLargeCrypto {
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@ -48,7 +48,7 @@ func TestEncryptDecrypt(t *testing.T) {
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}
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func TestSmallBuffer(t *testing.T) {
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k := crypto.NewKey()
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k := crypto.NewRandomKey()
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size := 600
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data := make([]byte, size)
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@ -73,7 +73,7 @@ func TestSmallBuffer(t *testing.T) {
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}
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func TestSameBuffer(t *testing.T) {
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k := crypto.NewKey()
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k := crypto.NewRandomKey()
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size := 600
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data := make([]byte, size)
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@ -96,7 +96,7 @@ func TestSameBuffer(t *testing.T) {
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}
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func TestCornerCases(t *testing.T) {
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k := crypto.NewKey()
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k := crypto.NewRandomKey()
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// nil plaintext should encrypt to the empty string
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// nil ciphertext should allocate a new slice for the ciphertext
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@ -122,7 +122,7 @@ func TestLargeEncrypt(t *testing.T) {
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t.SkipNow()
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}
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k := crypto.NewKey()
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k := crypto.NewRandomKey()
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for _, size := range []int{chunker.MaxSize, chunker.MaxSize + 1, chunker.MaxSize + 1<<20} {
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data := make([]byte, size)
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@ -146,7 +146,7 @@ func BenchmarkEncryptWriter(b *testing.B) {
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size := 8 << 20 // 8MiB
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rd := RandomReader(23, size)
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k := crypto.NewKey()
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k := crypto.NewRandomKey()
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b.ResetTimer()
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b.SetBytes(int64(size))
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@ -166,7 +166,7 @@ func BenchmarkEncrypt(b *testing.B) {
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size := 8 << 20 // 8MiB
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data := make([]byte, size)
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k := crypto.NewKey()
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k := crypto.NewRandomKey()
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buf := make([]byte, len(data)+crypto.Extension)
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b.ResetTimer()
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@ -181,7 +181,7 @@ func BenchmarkEncrypt(b *testing.B) {
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func BenchmarkDecryptReader(b *testing.B) {
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size := 8 << 20 // 8MiB
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buf := Random(23, size)
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k := crypto.NewKey()
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k := crypto.NewRandomKey()
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ciphertext := make([]byte, len(buf)+crypto.Extension)
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_, err := crypto.Encrypt(k, ciphertext, buf)
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@ -203,7 +203,7 @@ func BenchmarkDecryptReader(b *testing.B) {
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}
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func BenchmarkEncryptDecryptReader(b *testing.B) {
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k := crypto.NewKey()
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k := crypto.NewRandomKey()
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size := 8 << 20 // 8MiB
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rd := RandomReader(23, size)
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@ -234,7 +234,7 @@ func BenchmarkDecrypt(b *testing.B) {
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size := 8 << 20 // 8MiB
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data := make([]byte, size)
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k := crypto.NewKey()
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k := crypto.NewRandomKey()
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ciphertext := restic.GetChunkBuf("BenchmarkDecrypt")
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defer restic.FreeChunkBuf("BenchmarkDecrypt", ciphertext)
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@ -254,7 +254,7 @@ func BenchmarkDecrypt(b *testing.B) {
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}
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func TestEncryptStreamWriter(t *testing.T) {
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k := crypto.NewKey()
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k := crypto.NewRandomKey()
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tests := []int{5, 23, 2<<18 + 23, 1 << 20}
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if *testLargeCrypto {
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@ -288,7 +288,7 @@ func TestEncryptStreamWriter(t *testing.T) {
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}
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func TestDecryptStreamReader(t *testing.T) {
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k := crypto.NewKey()
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k := crypto.NewRandomKey()
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tests := []int{5, 23, 2<<18 + 23, 1 << 20}
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if *testLargeCrypto {
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@ -322,7 +322,7 @@ func TestDecryptStreamReader(t *testing.T) {
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}
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func TestEncryptWriter(t *testing.T) {
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k := crypto.NewKey()
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k := crypto.NewRandomKey()
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tests := []int{5, 23, 2<<18 + 23, 1 << 20}
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if *testLargeCrypto {
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@ -77,7 +77,6 @@ func DecryptFrom(ks *Key, rd io.Reader) (io.ReadCloser, error) {
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ciphertext := buf.Bytes()
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// decrypt
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ciphertext, err = Decrypt(ks, ciphertext, ciphertext)
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if err != nil {
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return nil, err
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@ -37,7 +37,7 @@ func TestCreatePack(t *testing.T) {
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file := bytes.NewBuffer(nil)
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// create random keys
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k := crypto.NewKey()
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k := crypto.NewRandomKey()
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// pack blobs
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p := pack.NewPacker(k, file)
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@ -176,7 +176,7 @@ func AddKey(s *Server, password string, template *Key) (*Key, error) {
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if template == nil {
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// generate new random master keys
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newkey.master = crypto.NewKey()
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newkey.master = crypto.NewRandomKey()
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// generate random polynomial for cdc
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p, err := chunker.RandomPolynomial()
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if err != nil {
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