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v/vlib/crypto/md5/md5.v
2019-07-18 10:50:05 +02:00

149 lines
3.2 KiB
Go

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