peridot/vendor/github.com/pjbgf/sha1cd/sha1cd.go

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// 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 sha1cd implements collision detection based on the whitepaper
// Counter-cryptanalysis from Marc Stevens. The original ubc implementation
// was done by Marc Stevens and Dan Shumow, and can be found at:
// https://github.com/cr-marcstevens/sha1collisiondetection
package sha1cd
// This SHA1 implementation is based on Go's generic SHA1.
// Original: https://github.com/golang/go/blob/master/src/crypto/sha1/sha1.go
import (
"crypto"
"encoding/binary"
"errors"
"hash"
shared "github.com/pjbgf/sha1cd/internal"
)
func init() {
crypto.RegisterHash(crypto.SHA1, New)
}
// The size of a SHA-1 checksum in bytes.
const Size = shared.Size
// The blocksize of SHA-1 in bytes.
const BlockSize = shared.Chunk
// digest represents the partial evaluation of a checksum.
type digest struct {
h [shared.WordBuffers]uint32
x [shared.Chunk]byte
nx int
len uint64
// col defines whether a collision has been found.
col bool
blockFunc func(dig *digest, p []byte)
}
func (d *digest) MarshalBinary() ([]byte, error) {
b := make([]byte, 0, shared.MarshaledSize)
b = append(b, shared.Magic...)
b = appendUint32(b, d.h[0])
b = appendUint32(b, d.h[1])
b = appendUint32(b, d.h[2])
b = appendUint32(b, d.h[3])
b = appendUint32(b, d.h[4])
b = append(b, d.x[:d.nx]...)
b = b[:len(b)+len(d.x)-d.nx] // already zero
b = appendUint64(b, d.len)
return b, nil
}
func appendUint32(b []byte, v uint32) []byte {
return append(b,
byte(v>>24),
byte(v>>16),
byte(v>>8),
byte(v),
)
}
func appendUint64(b []byte, v uint64) []byte {
return append(b,
byte(v>>56),
byte(v>>48),
byte(v>>40),
byte(v>>32),
byte(v>>24),
byte(v>>16),
byte(v>>8),
byte(v),
)
}
func (d *digest) UnmarshalBinary(b []byte) error {
if len(b) < len(shared.Magic) || string(b[:len(shared.Magic)]) != shared.Magic {
return errors.New("crypto/sha1: invalid hash state identifier")
}
if len(b) != shared.MarshaledSize {
return errors.New("crypto/sha1: invalid hash state size")
}
b = b[len(shared.Magic):]
b, d.h[0] = consumeUint32(b)
b, d.h[1] = consumeUint32(b)
b, d.h[2] = consumeUint32(b)
b, d.h[3] = consumeUint32(b)
b, d.h[4] = consumeUint32(b)
b = b[copy(d.x[:], b):]
b, d.len = consumeUint64(b)
d.nx = int(d.len % shared.Chunk)
return nil
}
func consumeUint64(b []byte) ([]byte, uint64) {
_ = b[7]
x := uint64(b[7]) | uint64(b[6])<<8 | uint64(b[shared.WordBuffers])<<16 | uint64(b[4])<<24 |
uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
return b[8:], x
}
func consumeUint32(b []byte) ([]byte, uint32) {
_ = b[3]
x := uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
return b[4:], x
}
func (d *digest) Reset() {
d.h[0] = shared.Init0
d.h[1] = shared.Init1
d.h[2] = shared.Init2
d.h[3] = shared.Init3
d.h[4] = shared.Init4
d.nx = 0
d.len = 0
d.col = false
}
// New returns a new hash.Hash computing the SHA1 checksum. The Hash also
// implements encoding.BinaryMarshaler and encoding.BinaryUnmarshaler to
// marshal and unmarshal the internal state of the hash.
func New() hash.Hash {
d := new(digest)
d.blockFunc = block
d.Reset()
return d
}
// NewGeneric is equivalent to New but uses the Go generic implementation,
// avoiding any processor-specific optimizations.
func NewGeneric() hash.Hash {
d := new(digest)
d.blockFunc = blockGeneric
d.Reset()
return d
}
func (d *digest) Size() int { return Size }
func (d *digest) BlockSize() int { return BlockSize }
func (d *digest) Write(p []byte) (nn int, err error) {
if len(p) == 0 {
return
}
nn = len(p)
d.len += uint64(nn)
if d.nx > 0 {
n := copy(d.x[d.nx:], p)
d.nx += n
if d.nx == shared.Chunk {
d.blockFunc(d, d.x[:])
d.nx = 0
}
p = p[n:]
}
if len(p) >= shared.Chunk {
n := len(p) &^ (shared.Chunk - 1)
d.blockFunc(d, p[:n])
p = p[n:]
}
if len(p) > 0 {
d.nx = copy(d.x[:], p)
}
return
}
func (d *digest) Sum(in []byte) []byte {
// Make a copy of d so that caller can keep writing and summing.
d0 := *d
hash := d0.checkSum()
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
binary.BigEndian.PutUint64(tmp[:], len)
d.Write(tmp[0:8])
if d.nx != 0 {
panic("d.nx != 0")
}
var digest [Size]byte
binary.BigEndian.PutUint32(digest[0:], d.h[0])
binary.BigEndian.PutUint32(digest[4:], d.h[1])
binary.BigEndian.PutUint32(digest[8:], d.h[2])
binary.BigEndian.PutUint32(digest[12:], d.h[3])
binary.BigEndian.PutUint32(digest[16:], d.h[4])
return digest
}
// Sum returns the SHA-1 checksum of the data.
func Sum(data []byte) ([Size]byte, bool) {
d := New().(*digest)
d.Write(data)
return d.checkSum(), d.col
}
func (d *digest) CollisionResistantSum(in []byte) ([]byte, bool) {
// Make a copy of d so that caller can keep writing and summing.
d0 := *d
hash := d0.checkSum()
return append(in, hash[:]...), d0.col
}