mirror of
https://github.com/restic/restic.git
synced 2024-08-02 10:33:25 +02:00
This commit adds a command called `self-update` which downloads the latest released version of restic from GitHub and replacing the current binary with it. It does not rely on any external program (so it'll work everywhere), but still verifies the GPG signature using the embedded GPG public key. By default, the `self-update` command is hidden behind the `selfupdate` built tag, which is only set when restic is built using `build.go`. The reason for this is that downstream distributions will then not include the command by default, so users are encouraged to use the platform-specific distribution mechanism.
291 lines
7.1 KiB
Go
291 lines
7.1 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package packet
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import (
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"crypto/cipher"
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"crypto/sha1"
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"crypto/subtle"
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"golang.org/x/crypto/openpgp/errors"
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"hash"
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"io"
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"strconv"
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)
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// SymmetricallyEncrypted represents a symmetrically encrypted byte string. The
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// encrypted contents will consist of more OpenPGP packets. See RFC 4880,
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// sections 5.7 and 5.13.
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type SymmetricallyEncrypted struct {
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MDC bool // true iff this is a type 18 packet and thus has an embedded MAC.
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contents io.Reader
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prefix []byte
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}
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const symmetricallyEncryptedVersion = 1
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func (se *SymmetricallyEncrypted) parse(r io.Reader) error {
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if se.MDC {
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// See RFC 4880, section 5.13.
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var buf [1]byte
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_, err := readFull(r, buf[:])
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if err != nil {
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return err
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}
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if buf[0] != symmetricallyEncryptedVersion {
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return errors.UnsupportedError("unknown SymmetricallyEncrypted version")
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}
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}
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se.contents = r
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return nil
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}
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// Decrypt returns a ReadCloser, from which the decrypted contents of the
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// packet can be read. An incorrect key can, with high probability, be detected
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// immediately and this will result in a KeyIncorrect error being returned.
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func (se *SymmetricallyEncrypted) Decrypt(c CipherFunction, key []byte) (io.ReadCloser, error) {
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keySize := c.KeySize()
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if keySize == 0 {
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return nil, errors.UnsupportedError("unknown cipher: " + strconv.Itoa(int(c)))
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}
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if len(key) != keySize {
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return nil, errors.InvalidArgumentError("SymmetricallyEncrypted: incorrect key length")
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}
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if se.prefix == nil {
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se.prefix = make([]byte, c.blockSize()+2)
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_, err := readFull(se.contents, se.prefix)
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if err != nil {
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return nil, err
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}
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} else if len(se.prefix) != c.blockSize()+2 {
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return nil, errors.InvalidArgumentError("can't try ciphers with different block lengths")
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}
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ocfbResync := OCFBResync
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if se.MDC {
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// MDC packets use a different form of OCFB mode.
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ocfbResync = OCFBNoResync
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}
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s := NewOCFBDecrypter(c.new(key), se.prefix, ocfbResync)
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if s == nil {
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return nil, errors.ErrKeyIncorrect
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}
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plaintext := cipher.StreamReader{S: s, R: se.contents}
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if se.MDC {
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// MDC packets have an embedded hash that we need to check.
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h := sha1.New()
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h.Write(se.prefix)
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return &seMDCReader{in: plaintext, h: h}, nil
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}
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// Otherwise, we just need to wrap plaintext so that it's a valid ReadCloser.
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return seReader{plaintext}, nil
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}
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// seReader wraps an io.Reader with a no-op Close method.
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type seReader struct {
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in io.Reader
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}
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func (ser seReader) Read(buf []byte) (int, error) {
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return ser.in.Read(buf)
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}
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func (ser seReader) Close() error {
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return nil
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}
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const mdcTrailerSize = 1 /* tag byte */ + 1 /* length byte */ + sha1.Size
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// An seMDCReader wraps an io.Reader, maintains a running hash and keeps hold
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// of the most recent 22 bytes (mdcTrailerSize). Upon EOF, those bytes form an
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// MDC packet containing a hash of the previous contents which is checked
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// against the running hash. See RFC 4880, section 5.13.
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type seMDCReader struct {
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in io.Reader
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h hash.Hash
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trailer [mdcTrailerSize]byte
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scratch [mdcTrailerSize]byte
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trailerUsed int
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error bool
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eof bool
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}
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func (ser *seMDCReader) Read(buf []byte) (n int, err error) {
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if ser.error {
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err = io.ErrUnexpectedEOF
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return
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}
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if ser.eof {
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err = io.EOF
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return
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}
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// If we haven't yet filled the trailer buffer then we must do that
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// first.
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for ser.trailerUsed < mdcTrailerSize {
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n, err = ser.in.Read(ser.trailer[ser.trailerUsed:])
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ser.trailerUsed += n
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if err == io.EOF {
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if ser.trailerUsed != mdcTrailerSize {
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n = 0
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err = io.ErrUnexpectedEOF
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ser.error = true
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return
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}
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ser.eof = true
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n = 0
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return
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}
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if err != nil {
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n = 0
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return
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}
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}
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// If it's a short read then we read into a temporary buffer and shift
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// the data into the caller's buffer.
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if len(buf) <= mdcTrailerSize {
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n, err = readFull(ser.in, ser.scratch[:len(buf)])
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copy(buf, ser.trailer[:n])
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ser.h.Write(buf[:n])
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copy(ser.trailer[:], ser.trailer[n:])
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copy(ser.trailer[mdcTrailerSize-n:], ser.scratch[:])
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if n < len(buf) {
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ser.eof = true
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err = io.EOF
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}
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return
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}
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n, err = ser.in.Read(buf[mdcTrailerSize:])
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copy(buf, ser.trailer[:])
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ser.h.Write(buf[:n])
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copy(ser.trailer[:], buf[n:])
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if err == io.EOF {
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ser.eof = true
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}
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return
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}
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// This is a new-format packet tag byte for a type 19 (MDC) packet.
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const mdcPacketTagByte = byte(0x80) | 0x40 | 19
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func (ser *seMDCReader) Close() error {
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if ser.error {
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return errors.SignatureError("error during reading")
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}
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for !ser.eof {
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// We haven't seen EOF so we need to read to the end
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var buf [1024]byte
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_, err := ser.Read(buf[:])
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if err == io.EOF {
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break
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}
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if err != nil {
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return errors.SignatureError("error during reading")
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}
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}
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if ser.trailer[0] != mdcPacketTagByte || ser.trailer[1] != sha1.Size {
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return errors.SignatureError("MDC packet not found")
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}
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ser.h.Write(ser.trailer[:2])
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final := ser.h.Sum(nil)
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if subtle.ConstantTimeCompare(final, ser.trailer[2:]) != 1 {
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return errors.SignatureError("hash mismatch")
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}
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return nil
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}
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// An seMDCWriter writes through to an io.WriteCloser while maintains a running
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// hash of the data written. On close, it emits an MDC packet containing the
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// running hash.
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type seMDCWriter struct {
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w io.WriteCloser
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h hash.Hash
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}
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func (w *seMDCWriter) Write(buf []byte) (n int, err error) {
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w.h.Write(buf)
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return w.w.Write(buf)
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}
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func (w *seMDCWriter) Close() (err error) {
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var buf [mdcTrailerSize]byte
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buf[0] = mdcPacketTagByte
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buf[1] = sha1.Size
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w.h.Write(buf[:2])
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digest := w.h.Sum(nil)
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copy(buf[2:], digest)
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_, err = w.w.Write(buf[:])
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if err != nil {
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return
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}
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return w.w.Close()
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}
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// noOpCloser is like an ioutil.NopCloser, but for an io.Writer.
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type noOpCloser struct {
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w io.Writer
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}
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func (c noOpCloser) Write(data []byte) (n int, err error) {
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return c.w.Write(data)
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}
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func (c noOpCloser) Close() error {
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return nil
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}
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// SerializeSymmetricallyEncrypted serializes a symmetrically encrypted packet
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// to w and returns a WriteCloser to which the to-be-encrypted packets can be
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// written.
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// If config is nil, sensible defaults will be used.
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func SerializeSymmetricallyEncrypted(w io.Writer, c CipherFunction, key []byte, config *Config) (contents io.WriteCloser, err error) {
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if c.KeySize() != len(key) {
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return nil, errors.InvalidArgumentError("SymmetricallyEncrypted.Serialize: bad key length")
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}
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writeCloser := noOpCloser{w}
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ciphertext, err := serializeStreamHeader(writeCloser, packetTypeSymmetricallyEncryptedMDC)
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if err != nil {
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return
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}
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_, err = ciphertext.Write([]byte{symmetricallyEncryptedVersion})
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if err != nil {
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return
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}
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block := c.new(key)
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blockSize := block.BlockSize()
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iv := make([]byte, blockSize)
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_, err = config.Random().Read(iv)
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if err != nil {
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return
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}
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s, prefix := NewOCFBEncrypter(block, iv, OCFBNoResync)
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_, err = ciphertext.Write(prefix)
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if err != nil {
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return
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}
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plaintext := cipher.StreamWriter{S: s, W: ciphertext}
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h := sha1.New()
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h.Write(iv)
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h.Write(iv[blockSize-2:])
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contents = &seMDCWriter{w: plaintext, h: h}
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return
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}
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