github.com/rohankumardubey/syslog-redirector-golang@v0.0.0-20140320174030-4859f03d829a/src/pkg/crypto/sha1/sha1block.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  // +build !amd64,!386
     6  
     7  // SHA1 block step.
     8  // In its own file so that a faster assembly or C version
     9  // can be substituted easily.
    10  
    11  package sha1
    12  
    13  const (
    14  	_K0 = 0x5A827999
    15  	_K1 = 0x6ED9EBA1
    16  	_K2 = 0x8F1BBCDC
    17  	_K3 = 0xCA62C1D6
    18  )
    19  
    20  func block(dig *digest, p []byte) {
    21  	var w [16]uint32
    22  
    23  	h0, h1, h2, h3, h4 := dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4]
    24  	for len(p) >= chunk {
    25  		// Can interlace the computation of w with the
    26  		// rounds below if needed for speed.
    27  		for i := 0; i < 16; i++ {
    28  			j := i * 4
    29  			w[i] = uint32(p[j])<<24 | uint32(p[j+1])<<16 | uint32(p[j+2])<<8 | uint32(p[j+3])
    30  		}
    31  
    32  		a, b, c, d, e := h0, h1, h2, h3, h4
    33  
    34  		// Each of the four 20-iteration rounds
    35  		// differs only in the computation of f and
    36  		// the choice of K (_K0, _K1, etc).
    37  		i := 0
    38  		for ; i < 16; i++ {
    39  			f := b&c | (^b)&d
    40  			a5 := a<<5 | a>>(32-5)
    41  			b30 := b<<30 | b>>(32-30)
    42  			t := a5 + f + e + w[i&0xf] + _K0
    43  			a, b, c, d, e = t, a, b30, c, d
    44  		}
    45  		for ; i < 20; i++ {
    46  			tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf]
    47  			w[i&0xf] = tmp<<1 | tmp>>(32-1)
    48  
    49  			f := b&c | (^b)&d
    50  			a5 := a<<5 | a>>(32-5)
    51  			b30 := b<<30 | b>>(32-30)
    52  			t := a5 + f + e + w[i&0xf] + _K0
    53  			a, b, c, d, e = t, a, b30, c, d
    54  		}
    55  		for ; i < 40; i++ {
    56  			tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf]
    57  			w[i&0xf] = tmp<<1 | tmp>>(32-1)
    58  			f := b ^ c ^ d
    59  			a5 := a<<5 | a>>(32-5)
    60  			b30 := b<<30 | b>>(32-30)
    61  			t := a5 + f + e + w[i&0xf] + _K1
    62  			a, b, c, d, e = t, a, b30, c, d
    63  		}
    64  		for ; i < 60; i++ {
    65  			tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf]
    66  			w[i&0xf] = tmp<<1 | tmp>>(32-1)
    67  			f := ((b | c) & d) | (b & c)
    68  
    69  			a5 := a<<5 | a>>(32-5)
    70  			b30 := b<<30 | b>>(32-30)
    71  			t := a5 + f + e + w[i&0xf] + _K2
    72  			a, b, c, d, e = t, a, b30, c, d
    73  		}
    74  		for ; i < 80; i++ {
    75  			tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf]
    76  			w[i&0xf] = tmp<<1 | tmp>>(32-1)
    77  			f := b ^ c ^ d
    78  			a5 := a<<5 | a>>(32-5)
    79  			b30 := b<<30 | b>>(32-30)
    80  			t := a5 + f + e + w[i&0xf] + _K3
    81  			a, b, c, d, e = t, a, b30, c, d
    82  		}
    83  
    84  		h0 += a
    85  		h1 += b
    86  		h2 += c
    87  		h3 += d
    88  		h4 += e
    89  
    90  		p = p[chunk:]
    91  	}
    92  
    93  	dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4] = h0, h1, h2, h3, h4
    94  }