crypto: move reader and writer to its own file
This commit is contained in:
Alexander Neumann
parent
64f7d4d611
commit
7e6acfe44d
3 changed files with 207 additions and 195 deletions
195
crypto/crypto.go
195
crypto/crypto.go
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@ -1,16 +1,12 @@
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package crypto
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import (
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"bytes"
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"crypto/aes"
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"crypto/cipher"
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"crypto/rand"
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"encoding/json"
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"errors"
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"fmt"
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"io"
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"io/ioutil"
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"sync"
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"github.com/restic/restic/chunker"
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"golang.org/x/crypto/poly1305"
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@ -300,194 +296,3 @@ func KDF(N, R, P int, salt []byte, password string) (*Key, error) {
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return derKeys, nil
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}
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type encryptWriter struct {
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iv iv
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wroteIV bool
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data *bytes.Buffer
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key *Key
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s cipher.Stream
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w io.Writer
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origWr io.Writer
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err error // remember error writing iv
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}
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func (e *encryptWriter) Close() error {
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// write mac
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mac := poly1305_sign(e.data.Bytes()[ivSize:], e.data.Bytes()[:ivSize], &e.key.Sign)
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_, err := e.origWr.Write(mac)
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if err != nil {
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return err
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}
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// return buffer
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bufPool.Put(e.data.Bytes())
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return nil
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}
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const encryptWriterChunkSize = 512 * 1024 // 512 KiB
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var encryptWriterBufPool = sync.Pool{
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New: func() interface{} {
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return make([]byte, encryptWriterChunkSize)
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},
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}
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func (e *encryptWriter) Write(p []byte) (int, error) {
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// write iv first
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if !e.wroteIV {
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_, e.err = e.origWr.Write(e.iv[:])
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e.wroteIV = true
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}
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if e.err != nil {
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return 0, e.err
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}
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buf := encryptWriterBufPool.Get().([]byte)
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defer encryptWriterBufPool.Put(buf)
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written := 0
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for len(p) > 0 {
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max := len(p)
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if max > encryptWriterChunkSize {
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max = encryptWriterChunkSize
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}
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e.s.XORKeyStream(buf, p[:max])
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n, err := e.w.Write(buf[:max])
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if n != max {
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if err == nil { // should never happen
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err = io.ErrShortWrite
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}
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}
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written += n
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p = p[n:]
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if err != nil {
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e.err = err
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return written, err
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}
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}
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return written, nil
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}
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// EncryptTo buffers data written to the returned io.WriteCloser. When Close()
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// is called, the data is encrypted an written to the underlying writer.
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func EncryptTo(ks *Key, wr io.Writer) io.WriteCloser {
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ew := &encryptWriter{
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iv: newIV(),
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data: bytes.NewBuffer(getBuffer()[:0]),
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key: ks,
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origWr: wr,
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}
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// buffer iv for mac
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_, err := ew.data.Write(ew.iv[:])
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if err != nil {
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panic(err)
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}
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c, err := aes.NewCipher(ks.Encrypt[:])
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if err != nil {
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panic(fmt.Sprintf("unable to create cipher: %v", err))
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}
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ew.s = cipher.NewCTR(c, ew.iv[:])
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ew.w = io.MultiWriter(ew.data, wr)
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return ew
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}
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type decryptReader struct {
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buf []byte
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pos int
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}
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func (d *decryptReader) Read(dst []byte) (int, error) {
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if d.buf == nil {
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return 0, io.EOF
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}
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if len(dst) == 0 {
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return 0, nil
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}
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remaining := len(d.buf) - d.pos
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if len(dst) >= remaining {
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n := copy(dst, d.buf[d.pos:])
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d.Close()
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return n, io.EOF
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}
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n := copy(dst, d.buf[d.pos:d.pos+len(dst)])
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d.pos += n
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return n, nil
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}
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func (d *decryptReader) ReadByte() (c byte, err error) {
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if d.buf == nil {
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return 0, io.EOF
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}
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remaining := len(d.buf) - d.pos
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if remaining == 1 {
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c = d.buf[d.pos]
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d.Close()
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return c, io.EOF
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}
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c = d.buf[d.pos]
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d.pos++
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return
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}
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func (d *decryptReader) Close() error {
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if d.buf == nil {
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return nil
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}
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freeBuffer(d.buf)
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d.buf = nil
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return nil
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}
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// DecryptFrom verifies and decrypts the ciphertext read from rd with ks and
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// makes it available on the returned Reader. Ciphertext must be in the form IV
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// || Ciphertext || MAC. In order to correctly verify the ciphertext, rd is
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// drained, locally buffered and made available on the returned Reader
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// afterwards. If a MAC verification failure is observed, it is returned
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// immediately.
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func DecryptFrom(ks *Key, rd io.Reader) (io.ReadCloser, error) {
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ciphertext := getBuffer()
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ciphertext = ciphertext[0:cap(ciphertext)]
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n, err := io.ReadFull(rd, ciphertext)
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if err != io.ErrUnexpectedEOF {
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// read remaining data
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buf, e := ioutil.ReadAll(rd)
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ciphertext = append(ciphertext, buf...)
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n += len(buf)
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err = e
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} else {
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err = nil
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}
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if err != nil {
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return nil, err
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}
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ciphertext = ciphertext[:n]
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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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}
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return &decryptReader{buf: ciphertext}, nil
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}
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97
crypto/reader.go
Normal file
97
crypto/reader.go
Normal file
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@ -0,0 +1,97 @@
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package crypto
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import (
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"io"
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"io/ioutil"
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)
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type decryptReader struct {
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buf []byte
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pos int
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}
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func (d *decryptReader) Read(dst []byte) (int, error) {
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if d.buf == nil {
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return 0, io.EOF
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}
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if len(dst) == 0 {
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return 0, nil
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}
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remaining := len(d.buf) - d.pos
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if len(dst) >= remaining {
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n := copy(dst, d.buf[d.pos:])
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d.Close()
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return n, io.EOF
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}
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n := copy(dst, d.buf[d.pos:d.pos+len(dst)])
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d.pos += n
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return n, nil
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}
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func (d *decryptReader) ReadByte() (c byte, err error) {
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if d.buf == nil {
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return 0, io.EOF
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}
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remaining := len(d.buf) - d.pos
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if remaining == 1 {
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c = d.buf[d.pos]
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d.Close()
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return c, io.EOF
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}
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c = d.buf[d.pos]
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d.pos++
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return
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}
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func (d *decryptReader) Close() error {
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if d.buf == nil {
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return nil
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}
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freeBuffer(d.buf)
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d.buf = nil
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return nil
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}
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// DecryptFrom verifies and decrypts the ciphertext read from rd with ks and
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// makes it available on the returned Reader. Ciphertext must be in the form IV
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// || Ciphertext || MAC. In order to correctly verify the ciphertext, rd is
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// drained, locally buffered and made available on the returned Reader
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// afterwards. If a MAC verification failure is observed, it is returned
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// immediately.
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func DecryptFrom(ks *Key, rd io.Reader) (io.ReadCloser, error) {
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ciphertext := getBuffer()
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ciphertext = ciphertext[0:cap(ciphertext)]
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n, err := io.ReadFull(rd, ciphertext)
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if err != io.ErrUnexpectedEOF {
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// read remaining data
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buf, e := ioutil.ReadAll(rd)
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ciphertext = append(ciphertext, buf...)
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n += len(buf)
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err = e
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} else {
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err = nil
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}
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if err != nil {
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return nil, err
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}
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ciphertext = ciphertext[:n]
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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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}
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return &decryptReader{buf: ciphertext}, nil
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}
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110
crypto/writer.go
Normal file
110
crypto/writer.go
Normal file
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@ -0,0 +1,110 @@
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package crypto
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import (
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"bytes"
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"crypto/aes"
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"crypto/cipher"
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"fmt"
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"io"
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"sync"
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)
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type encryptWriter struct {
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iv iv
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wroteIV bool
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data *bytes.Buffer
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key *Key
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s cipher.Stream
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w io.Writer
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origWr io.Writer
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err error // remember error writing iv
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}
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func (e *encryptWriter) Close() error {
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// write mac
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mac := poly1305_sign(e.data.Bytes()[ivSize:], e.data.Bytes()[:ivSize], &e.key.Sign)
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_, err := e.origWr.Write(mac)
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if err != nil {
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return err
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}
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// return buffer
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bufPool.Put(e.data.Bytes())
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return nil
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}
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const encryptWriterChunkSize = 512 * 1024 // 512 KiB
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var encryptWriterBufPool = sync.Pool{
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New: func() interface{} {
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return make([]byte, encryptWriterChunkSize)
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},
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}
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func (e *encryptWriter) Write(p []byte) (int, error) {
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// write iv first
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if !e.wroteIV {
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_, e.err = e.origWr.Write(e.iv[:])
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e.wroteIV = true
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}
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if e.err != nil {
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return 0, e.err
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}
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buf := encryptWriterBufPool.Get().([]byte)
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defer encryptWriterBufPool.Put(buf)
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written := 0
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for len(p) > 0 {
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max := len(p)
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if max > encryptWriterChunkSize {
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max = encryptWriterChunkSize
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}
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e.s.XORKeyStream(buf, p[:max])
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n, err := e.w.Write(buf[:max])
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if n != max {
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if err == nil { // should never happen
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err = io.ErrShortWrite
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}
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}
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written += n
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p = p[n:]
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if err != nil {
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e.err = err
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return written, err
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}
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}
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return written, nil
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}
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// EncryptTo buffers data written to the returned io.WriteCloser. When Close()
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// is called, the data is encrypted an written to the underlying writer.
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func EncryptTo(ks *Key, wr io.Writer) io.WriteCloser {
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ew := &encryptWriter{
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iv: newIV(),
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data: bytes.NewBuffer(getBuffer()[:0]),
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key: ks,
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origWr: wr,
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}
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// buffer iv for mac
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_, err := ew.data.Write(ew.iv[:])
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if err != nil {
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panic(err)
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}
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c, err := aes.NewCipher(ks.Encrypt[:])
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if err != nil {
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panic(fmt.Sprintf("unable to create cipher: %v", err))
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}
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ew.s = cipher.NewCTR(c, ew.iv[:])
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ew.w = io.MultiWriter(ew.data, wr)
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return ew
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}
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