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