Source file src/crypto/sha256/sha256block.go

Documentation: crypto/sha256

     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  // SHA256 block step.
     6  // In its own file so that a faster assembly or C version
     7  // can be substituted easily.
     8  
     9  package sha256
    10  
    11  import "math/bits"
    12  
    13  var _K = []uint32{
    14  	0x428a2f98,
    15  	0x71374491,
    16  	0xb5c0fbcf,
    17  	0xe9b5dba5,
    18  	0x3956c25b,
    19  	0x59f111f1,
    20  	0x923f82a4,
    21  	0xab1c5ed5,
    22  	0xd807aa98,
    23  	0x12835b01,
    24  	0x243185be,
    25  	0x550c7dc3,
    26  	0x72be5d74,
    27  	0x80deb1fe,
    28  	0x9bdc06a7,
    29  	0xc19bf174,
    30  	0xe49b69c1,
    31  	0xefbe4786,
    32  	0x0fc19dc6,
    33  	0x240ca1cc,
    34  	0x2de92c6f,
    35  	0x4a7484aa,
    36  	0x5cb0a9dc,
    37  	0x76f988da,
    38  	0x983e5152,
    39  	0xa831c66d,
    40  	0xb00327c8,
    41  	0xbf597fc7,
    42  	0xc6e00bf3,
    43  	0xd5a79147,
    44  	0x06ca6351,
    45  	0x14292967,
    46  	0x27b70a85,
    47  	0x2e1b2138,
    48  	0x4d2c6dfc,
    49  	0x53380d13,
    50  	0x650a7354,
    51  	0x766a0abb,
    52  	0x81c2c92e,
    53  	0x92722c85,
    54  	0xa2bfe8a1,
    55  	0xa81a664b,
    56  	0xc24b8b70,
    57  	0xc76c51a3,
    58  	0xd192e819,
    59  	0xd6990624,
    60  	0xf40e3585,
    61  	0x106aa070,
    62  	0x19a4c116,
    63  	0x1e376c08,
    64  	0x2748774c,
    65  	0x34b0bcb5,
    66  	0x391c0cb3,
    67  	0x4ed8aa4a,
    68  	0x5b9cca4f,
    69  	0x682e6ff3,
    70  	0x748f82ee,
    71  	0x78a5636f,
    72  	0x84c87814,
    73  	0x8cc70208,
    74  	0x90befffa,
    75  	0xa4506ceb,
    76  	0xbef9a3f7,
    77  	0xc67178f2,
    78  }
    79  
    80  func blockGeneric(dig *digest, p []byte) {
    81  	var w [64]uint32
    82  	h0, h1, h2, h3, h4, h5, h6, h7 := dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4], dig.h[5], dig.h[6], dig.h[7]
    83  	for len(p) >= chunk {
    84  		// Can interlace the computation of w with the
    85  		// rounds below if needed for speed.
    86  		for i := 0; i < 16; i++ {
    87  			j := i * 4
    88  			w[i] = uint32(p[j])<<24 | uint32(p[j+1])<<16 | uint32(p[j+2])<<8 | uint32(p[j+3])
    89  		}
    90  		for i := 16; i < 64; i++ {
    91  			v1 := w[i-2]
    92  			t1 := (bits.RotateLeft32(v1, -17)) ^ (bits.RotateLeft32(v1, -19)) ^ (v1 >> 10)
    93  			v2 := w[i-15]
    94  			t2 := (bits.RotateLeft32(v2, -7)) ^ (bits.RotateLeft32(v2, -18)) ^ (v2 >> 3)
    95  			w[i] = t1 + w[i-7] + t2 + w[i-16]
    96  		}
    97  
    98  		a, b, c, d, e, f, g, h := h0, h1, h2, h3, h4, h5, h6, h7
    99  
   100  		for i := 0; i < 64; i++ {
   101  			t1 := h + ((bits.RotateLeft32(e, -6)) ^ (bits.RotateLeft32(e, -11)) ^ (bits.RotateLeft32(e, -25))) + ((e & f) ^ (^e & g)) + _K[i] + w[i]
   102  
   103  			t2 := ((bits.RotateLeft32(a, -2)) ^ (bits.RotateLeft32(a, -13)) ^ (bits.RotateLeft32(a, -22))) + ((a & b) ^ (a & c) ^ (b & c))
   104  
   105  			h = g
   106  			g = f
   107  			f = e
   108  			e = d + t1
   109  			d = c
   110  			c = b
   111  			b = a
   112  			a = t1 + t2
   113  		}
   114  
   115  		h0 += a
   116  		h1 += b
   117  		h2 += c
   118  		h3 += d
   119  		h4 += e
   120  		h5 += f
   121  		h6 += g
   122  		h7 += h
   123  
   124  		p = p[chunk:]
   125  	}
   126  
   127  	dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4], dig.h[5], dig.h[6], dig.h[7] = h0, h1, h2, h3, h4, h5, h6, h7
   128  }
   129  

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