149 lines
3.2 KiB
Go
149 lines
3.2 KiB
Go
// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
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// that can be found in the LICENSE file.
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// Package md5 implements the MD5 hash algorithm as defined in RFC 1321.
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// MD5 is cryptographically broken and should not be used for secure
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// applications.
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// Adapted from: https://github.com/golang/go/blob/master/src/crypto/md5
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module md5
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import math
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import encoding.binary
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const (
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// The size of an MD5 checksum in bytes.
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Size = 16
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// The blocksize of MD5 in bytes.
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BlockSize = 64
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)
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const (
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Init0 = 0x67452301
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Init1 = 0xEFCDAB89
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Init2 = 0x98BADCFE
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Init3 = 0x10325476
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)
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// Digest represents the partial evaluation of a checksum.
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struct Digest {
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mut:
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s []u32
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x []byte
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nx int
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len u64
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}
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fn (d mut Digest) reset() {
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d.s = [u32(0); 4]
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d.x = [byte(0); BlockSize]
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d.s[0] = u32(Init0)
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d.s[1] = u32(Init1)
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d.s[2] = u32(Init2)
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d.s[3] = u32(Init3)
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d.nx = 0
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d.len = u64(0)
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}
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// new returns a new Digest (implementing hash.Hash) computing the MD5 checksum.
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pub fn new() *Digest {
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mut d := &Digest{}
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d.reset()
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return d
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}
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pub fn (d mut Digest) write(p []byte) ?int {
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nn := p.len
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d.len += u64(nn)
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if d.nx > 0 {
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n := int(math.min(f64(d.x.len), f64(p.len)))
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for i:=0; i<n; i++ {
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d.x.set(i+d.nx, p[i])
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}
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d.nx += n
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if d.nx == BlockSize {
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block(d, d.x)
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d.nx = 0
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}
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if n >= p.len {
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p = []byte
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} else {
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p = p.right(n)
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}
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}
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if p.len >= BlockSize {
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n := p.len &~ (BlockSize - 1)
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block(d, p.left(n))
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if n >= p.len {
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p = []byte
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} else {
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p = p.right(n)
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}
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}
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if p.len > 0 {
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d.nx = int(math.min(f64(d.x.len), f64(p.len)))
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for i:=0; i<d.nx; i++ {
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d.x.set(i, p[i])
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}
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}
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return nn
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}
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pub fn (d &Digest) sum(b_in mut []byte) []byte {
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// Make a copy of d so that caller can keep writing and summing.
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mut d0 := *d
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hash := d0.checksum()
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for b in hash {
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b_in << b
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}
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return *b_in
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}
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pub fn (d mut Digest) checksum() []byte {
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// Append 0x80 to the end of the message and then append zeros
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// until the length is a multiple of 56 bytes. Finally append
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// 8 bytes representing the message length in bits.
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//
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// 1 byte end marker :: 0-63 padding bytes :: 8 byte length
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// tmp := [1 + 63 + 8]byte{0x80}
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mut tmp := [byte(0); 1 + 63 + 8]
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tmp[0] = 0x80
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pad := (55 - int(d.len)) % 64 // calculate number of padding bytes
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binary.little_endian_put_u64(tmp.right(1+pad), u64(d.len<<u64(3))) // append length in bits
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d.write(tmp.left(1+pad+8))
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// The previous write ensures that a whole number of
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// blocks (i.e. a multiple of 64 bytes) have been hashed.
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if d.nx != 0 {
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panic('d.nx != 0')
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}
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digest := [byte(0); Size]
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binary.little_endian_put_u32(digest, d.s[0])
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binary.little_endian_put_u32(digest.right(4), d.s[1])
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binary.little_endian_put_u32(digest.right(8), d.s[2])
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binary.little_endian_put_u32(digest.right(12), d.s[3])
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return digest
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}
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// sum returns the MD5 checksum of the data.
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pub fn sum(data []byte) []byte {
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mut d := new()
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d.write(data)
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return d.checksum()
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}
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fn block(dig &Digest, p []byte) {
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// For now just use block_generic until we have specific
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// architecture optimized versions
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block_generic(dig, p)
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}
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pub fn (d &Digest) size() int { return Size }
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pub fn (d &Digest) block_size() int { return BlockSize }
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