| // 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 sha1 implements the SHA-1 hash algorithm as defined in RFC 3174. |
| // |
| // SHA-1 is cryptographically broken and should not be used for secure |
| // applications. |
| package sha1 |
| |
| import ( |
| "crypto" |
| "encoding/binary" |
| "errors" |
| "hash" |
| ) |
| |
| func init() { |
| crypto.RegisterHash(crypto.SHA1, New) |
| } |
| |
| // The size of a SHA-1 checksum in bytes. |
| const Size = 20 |
| |
| // The blocksize of SHA-1 in bytes. |
| const BlockSize = 64 |
| |
| const ( |
| chunk = 64 |
| init0 = 0x67452301 |
| init1 = 0xEFCDAB89 |
| init2 = 0x98BADCFE |
| init3 = 0x10325476 |
| init4 = 0xC3D2E1F0 |
| ) |
| |
| // digest represents the partial evaluation of a checksum. |
| type digest struct { |
| h [5]uint32 |
| x [chunk]byte |
| nx int |
| len uint64 |
| } |
| |
| const ( |
| magic = "sha\x01" |
| marshaledSize = len(magic) + 5*4 + chunk + 8 |
| ) |
| |
| func (d *digest) MarshalBinary() ([]byte, error) { |
| b := make([]byte, 0, marshaledSize) |
| b = append(b, 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)-int(d.nx)] // already zero |
| b = appendUint64(b, d.len) |
| return b, nil |
| } |
| |
| func (d *digest) UnmarshalBinary(b []byte) error { |
| if len(b) < len(magic) || string(b[:len(magic)]) != magic { |
| return errors.New("crypto/sha1: invalid hash state identifier") |
| } |
| if len(b) != marshaledSize { |
| return errors.New("crypto/sha1: invalid hash state size") |
| } |
| b = b[len(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 % chunk) |
| return nil |
| } |
| |
| func appendUint64(b []byte, x uint64) []byte { |
| var a [8]byte |
| binary.BigEndian.PutUint64(a[:], x) |
| return append(b, a[:]...) |
| } |
| |
| func appendUint32(b []byte, x uint32) []byte { |
| var a [4]byte |
| binary.BigEndian.PutUint32(a[:], x) |
| return append(b, a[:]...) |
| } |
| |
| func consumeUint64(b []byte) ([]byte, uint64) { |
| _ = b[7] |
| x := uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<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] = init0 |
| d.h[1] = init1 |
| d.h[2] = init2 |
| d.h[3] = init3 |
| d.h[4] = init4 |
| d.nx = 0 |
| d.len = 0 |
| } |
| |
| // 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 { |
| if boringEnabled { |
| return boringNewSHA1() |
| } |
| d := new(digest) |
| 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) { |
| boringUnreachable() |
| 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 (d *digest) Sum(in []byte) []byte { |
| boringUnreachable() |
| // 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 |
| } |
| |
| // ConstantTimeSum computes the same result of Sum() but in constant time |
| func (d *digest) ConstantTimeSum(in []byte) []byte { |
| d0 := *d |
| hash := d0.constSum() |
| return append(in, hash[:]...) |
| } |
| |
| func (d *digest) constSum() [Size]byte { |
| var length [8]byte |
| l := d.len << 3 |
| for i := uint(0); i < 8; i++ { |
| length[i] = byte(l >> (56 - 8*i)) |
| } |
| |
| nx := byte(d.nx) |
| t := nx - 56 // if nx < 56 then the MSB of t is one |
| mask1b := byte(int8(t) >> 7) // mask1b is 0xFF iff one block is enough |
| |
| separator := byte(0x80) // gets reset to 0x00 once used |
| for i := byte(0); i < chunk; i++ { |
| mask := byte(int8(i-nx) >> 7) // 0x00 after the end of data |
| |
| // if we reached the end of the data, replace with 0x80 or 0x00 |
| d.x[i] = (^mask & separator) | (mask & d.x[i]) |
| |
| // zero the separator once used |
| separator &= mask |
| |
| if i >= 56 { |
| // we might have to write the length here if all fit in one block |
| d.x[i] |= mask1b & length[i-56] |
| } |
| } |
| |
| // compress, and only keep the digest if all fit in one block |
| block(d, d.x[:]) |
| |
| var digest [Size]byte |
| for i, s := range d.h { |
| digest[i*4] = mask1b & byte(s>>24) |
| digest[i*4+1] = mask1b & byte(s>>16) |
| digest[i*4+2] = mask1b & byte(s>>8) |
| digest[i*4+3] = mask1b & byte(s) |
| } |
| |
| for i := byte(0); i < chunk; i++ { |
| // second block, it's always past the end of data, might start with 0x80 |
| if i < 56 { |
| d.x[i] = separator |
| separator = 0 |
| } else { |
| d.x[i] = length[i-56] |
| } |
| } |
| |
| // compress, and only keep the digest if we actually needed the second block |
| block(d, d.x[:]) |
| |
| for i, s := range d.h { |
| digest[i*4] |= ^mask1b & byte(s>>24) |
| digest[i*4+1] |= ^mask1b & byte(s>>16) |
| digest[i*4+2] |= ^mask1b & byte(s>>8) |
| digest[i*4+3] |= ^mask1b & byte(s) |
| } |
| |
| return digest |
| } |
| |
| // Sum returns the SHA-1 checksum of the data. |
| func Sum(data []byte) [Size]byte { |
| if boringEnabled { |
| return boringSHA1(data) |
| } |
| var d digest |
| d.Reset() |
| d.Write(data) |
| return d.checkSum() |
| } |