github.com/psiphon-labs/psiphon-tunnel-core@v2.0.28+incompatible/psiphon/upstreamproxy/go-ntlm/ntlm/md4/md4.go (about)

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package md4 implements the MD4 hash algorithm as defined in RFC 1320.
     6  package md4
     7  
     8  import (
     9  	"crypto"
    10  	"hash"
    11  )
    12  
    13  func init() {
    14  	crypto.RegisterHash(crypto.MD4, New)
    15  }
    16  
    17  // The size of an MD4 checksum in bytes.
    18  const Size = 16
    19  
    20  // The blocksize of MD4 in bytes.
    21  const BlockSize = 64
    22  
    23  const (
    24  	_Chunk = 64
    25  	_Init0 = 0x67452301
    26  	_Init1 = 0xEFCDAB89
    27  	_Init2 = 0x98BADCFE
    28  	_Init3 = 0x10325476
    29  )
    30  
    31  // digest represents the partial evaluation of a checksum.
    32  type digest struct {
    33  	s   [4]uint32
    34  	x   [_Chunk]byte
    35  	nx  int
    36  	len uint64
    37  }
    38  
    39  func (d *digest) Reset() {
    40  	d.s[0] = _Init0
    41  	d.s[1] = _Init1
    42  	d.s[2] = _Init2
    43  	d.s[3] = _Init3
    44  	d.nx = 0
    45  	d.len = 0
    46  }
    47  
    48  // New returns a new hash.Hash computing the MD4 checksum.
    49  func New() hash.Hash {
    50  	d := new(digest)
    51  	d.Reset()
    52  	return d
    53  }
    54  
    55  func (d *digest) Size() int { return Size }
    56  
    57  func (d *digest) BlockSize() int { return BlockSize }
    58  
    59  func (d *digest) Write(p []byte) (nn int, err error) {
    60  	nn = len(p)
    61  	d.len += uint64(nn)
    62  	if d.nx > 0 {
    63  		n := len(p)
    64  		if n > _Chunk-d.nx {
    65  			n = _Chunk - d.nx
    66  		}
    67  		for i := 0; i < n; i++ {
    68  			d.x[d.nx+i] = p[i]
    69  		}
    70  		d.nx += n
    71  		if d.nx == _Chunk {
    72  			_Block(d, d.x[0:])
    73  			d.nx = 0
    74  		}
    75  		p = p[n:]
    76  	}
    77  	n := _Block(d, p)
    78  	p = p[n:]
    79  	if len(p) > 0 {
    80  		d.nx = copy(d.x[:], p)
    81  	}
    82  	return
    83  }
    84  
    85  func (d0 *digest) Sum(in []byte) []byte {
    86  	// Make a copy of d0, so that caller can keep writing and summing.
    87  	d := new(digest)
    88  	*d = *d0
    89  
    90  	// Padding.  Add a 1 bit and 0 bits until 56 bytes mod 64.
    91  	len := d.len
    92  	var tmp [64]byte
    93  	tmp[0] = 0x80
    94  	if len%64 < 56 {
    95  		d.Write(tmp[0 : 56-len%64])
    96  	} else {
    97  		d.Write(tmp[0 : 64+56-len%64])
    98  	}
    99  
   100  	// Length in bits.
   101  	len <<= 3
   102  	for i := uint(0); i < 8; i++ {
   103  		tmp[i] = byte(len >> (8 * i))
   104  	}
   105  	d.Write(tmp[0:8])
   106  
   107  	if d.nx != 0 {
   108  		panic("d.nx != 0")
   109  	}
   110  
   111  	for _, s := range d.s {
   112  		in = append(in, byte(s>>0))
   113  		in = append(in, byte(s>>8))
   114  		in = append(in, byte(s>>16))
   115  		in = append(in, byte(s>>24))
   116  	}
   117  	return in
   118  }