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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