mirror of https://github.com/ethereum/go-ethereum
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// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package sha3 |
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// This file implements the core Keccak permutation function necessary for computing SHA3.
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// This is implemented in a separate file to allow for replacement by an optimized implementation.
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// Nothing in this package is exported.
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// For the detailed specification, refer to the Keccak web site (http://keccak.noekeon.org/).
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// rc stores the round constants for use in the ι step.
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var rc = [...]uint64{ |
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0x0000000000000001, |
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0x0000000000008082, |
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0x800000000000808A, |
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0x8000000080008000, |
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0x000000000000808B, |
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0x0000000080000001, |
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0x8000000080008081, |
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0x8000000000008009, |
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0x000000000000008A, |
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0x0000000000000088, |
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0x0000000080008009, |
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0x000000008000000A, |
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0x000000008000808B, |
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0x800000000000008B, |
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0x8000000000008089, |
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0x8000000000008003, |
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0x8000000000008002, |
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0x8000000000000080, |
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0x000000000000800A, |
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0x800000008000000A, |
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0x8000000080008081, |
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0x8000000000008080, |
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0x0000000080000001, |
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0x8000000080008008, |
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} |
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// ro_xx represent the rotation offsets for use in the χ step.
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// Defining them as const instead of in an array allows the compiler to insert constant shifts.
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const ( |
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ro_00 = 0 |
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ro_01 = 36 |
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ro_02 = 3 |
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ro_03 = 41 |
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ro_04 = 18 |
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ro_05 = 1 |
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ro_06 = 44 |
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ro_07 = 10 |
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ro_08 = 45 |
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ro_09 = 2 |
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ro_10 = 62 |
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ro_11 = 6 |
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ro_12 = 43 |
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ro_13 = 15 |
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ro_14 = 61 |
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ro_15 = 28 |
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ro_16 = 55 |
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ro_17 = 25 |
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ro_18 = 21 |
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ro_19 = 56 |
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ro_20 = 27 |
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ro_21 = 20 |
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ro_22 = 39 |
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ro_23 = 8 |
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ro_24 = 14 |
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) |
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// keccakF computes the complete Keccak-f function consisting of 24 rounds with a different
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// constant (rc) in each round. This implementation fully unrolls the round function to avoid
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// inner loops, as well as pre-calculating shift offsets.
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func (d *digest) keccakF() { |
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for _, roundConstant := range rc { |
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// θ step
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d.c[0] = d.a[0] ^ d.a[5] ^ d.a[10] ^ d.a[15] ^ d.a[20] |
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d.c[1] = d.a[1] ^ d.a[6] ^ d.a[11] ^ d.a[16] ^ d.a[21] |
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d.c[2] = d.a[2] ^ d.a[7] ^ d.a[12] ^ d.a[17] ^ d.a[22] |
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d.c[3] = d.a[3] ^ d.a[8] ^ d.a[13] ^ d.a[18] ^ d.a[23] |
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d.c[4] = d.a[4] ^ d.a[9] ^ d.a[14] ^ d.a[19] ^ d.a[24] |
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d.d[0] = d.c[4] ^ (d.c[1]<<1 ^ d.c[1]>>63) |
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d.d[1] = d.c[0] ^ (d.c[2]<<1 ^ d.c[2]>>63) |
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d.d[2] = d.c[1] ^ (d.c[3]<<1 ^ d.c[3]>>63) |
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d.d[3] = d.c[2] ^ (d.c[4]<<1 ^ d.c[4]>>63) |
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d.d[4] = d.c[3] ^ (d.c[0]<<1 ^ d.c[0]>>63) |
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d.a[0] ^= d.d[0] |
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d.a[1] ^= d.d[1] |
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d.a[2] ^= d.d[2] |
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d.a[3] ^= d.d[3] |
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d.a[4] ^= d.d[4] |
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d.a[5] ^= d.d[0] |
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d.a[6] ^= d.d[1] |
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d.a[7] ^= d.d[2] |
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d.a[8] ^= d.d[3] |
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d.a[9] ^= d.d[4] |
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d.a[10] ^= d.d[0] |
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d.a[11] ^= d.d[1] |
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d.a[12] ^= d.d[2] |
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d.a[13] ^= d.d[3] |
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d.a[14] ^= d.d[4] |
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d.a[15] ^= d.d[0] |
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d.a[16] ^= d.d[1] |
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d.a[17] ^= d.d[2] |
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d.a[18] ^= d.d[3] |
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d.a[19] ^= d.d[4] |
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d.a[20] ^= d.d[0] |
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d.a[21] ^= d.d[1] |
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d.a[22] ^= d.d[2] |
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d.a[23] ^= d.d[3] |
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d.a[24] ^= d.d[4] |
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// ρ and π steps
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d.b[0] = d.a[0] |
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d.b[1] = d.a[6]<<ro_06 ^ d.a[6]>>(64-ro_06) |
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d.b[2] = d.a[12]<<ro_12 ^ d.a[12]>>(64-ro_12) |
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d.b[3] = d.a[18]<<ro_18 ^ d.a[18]>>(64-ro_18) |
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d.b[4] = d.a[24]<<ro_24 ^ d.a[24]>>(64-ro_24) |
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d.b[5] = d.a[3]<<ro_15 ^ d.a[3]>>(64-ro_15) |
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d.b[6] = d.a[9]<<ro_21 ^ d.a[9]>>(64-ro_21) |
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d.b[7] = d.a[10]<<ro_02 ^ d.a[10]>>(64-ro_02) |
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d.b[8] = d.a[16]<<ro_08 ^ d.a[16]>>(64-ro_08) |
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d.b[9] = d.a[22]<<ro_14 ^ d.a[22]>>(64-ro_14) |
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d.b[10] = d.a[1]<<ro_05 ^ d.a[1]>>(64-ro_05) |
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d.b[11] = d.a[7]<<ro_11 ^ d.a[7]>>(64-ro_11) |
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d.b[12] = d.a[13]<<ro_17 ^ d.a[13]>>(64-ro_17) |
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d.b[13] = d.a[19]<<ro_23 ^ d.a[19]>>(64-ro_23) |
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d.b[14] = d.a[20]<<ro_04 ^ d.a[20]>>(64-ro_04) |
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d.b[15] = d.a[4]<<ro_20 ^ d.a[4]>>(64-ro_20) |
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d.b[16] = d.a[5]<<ro_01 ^ d.a[5]>>(64-ro_01) |
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d.b[17] = d.a[11]<<ro_07 ^ d.a[11]>>(64-ro_07) |
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d.b[18] = d.a[17]<<ro_13 ^ d.a[17]>>(64-ro_13) |
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d.b[19] = d.a[23]<<ro_19 ^ d.a[23]>>(64-ro_19) |
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d.b[20] = d.a[2]<<ro_10 ^ d.a[2]>>(64-ro_10) |
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d.b[21] = d.a[8]<<ro_16 ^ d.a[8]>>(64-ro_16) |
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d.b[22] = d.a[14]<<ro_22 ^ d.a[14]>>(64-ro_22) |
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d.b[23] = d.a[15]<<ro_03 ^ d.a[15]>>(64-ro_03) |
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d.b[24] = d.a[21]<<ro_09 ^ d.a[21]>>(64-ro_09) |
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// χ step
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d.a[0] = d.b[0] ^ (^d.b[1] & d.b[2]) |
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d.a[1] = d.b[1] ^ (^d.b[2] & d.b[3]) |
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d.a[2] = d.b[2] ^ (^d.b[3] & d.b[4]) |
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d.a[3] = d.b[3] ^ (^d.b[4] & d.b[0]) |
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d.a[4] = d.b[4] ^ (^d.b[0] & d.b[1]) |
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d.a[5] = d.b[5] ^ (^d.b[6] & d.b[7]) |
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d.a[6] = d.b[6] ^ (^d.b[7] & d.b[8]) |
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d.a[7] = d.b[7] ^ (^d.b[8] & d.b[9]) |
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d.a[8] = d.b[8] ^ (^d.b[9] & d.b[5]) |
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d.a[9] = d.b[9] ^ (^d.b[5] & d.b[6]) |
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d.a[10] = d.b[10] ^ (^d.b[11] & d.b[12]) |
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d.a[11] = d.b[11] ^ (^d.b[12] & d.b[13]) |
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d.a[12] = d.b[12] ^ (^d.b[13] & d.b[14]) |
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d.a[13] = d.b[13] ^ (^d.b[14] & d.b[10]) |
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d.a[14] = d.b[14] ^ (^d.b[10] & d.b[11]) |
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d.a[15] = d.b[15] ^ (^d.b[16] & d.b[17]) |
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d.a[16] = d.b[16] ^ (^d.b[17] & d.b[18]) |
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d.a[17] = d.b[17] ^ (^d.b[18] & d.b[19]) |
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d.a[18] = d.b[18] ^ (^d.b[19] & d.b[15]) |
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d.a[19] = d.b[19] ^ (^d.b[15] & d.b[16]) |
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d.a[20] = d.b[20] ^ (^d.b[21] & d.b[22]) |
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d.a[21] = d.b[21] ^ (^d.b[22] & d.b[23]) |
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d.a[22] = d.b[22] ^ (^d.b[23] & d.b[24]) |
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d.a[23] = d.b[23] ^ (^d.b[24] & d.b[20]) |
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d.a[24] = d.b[24] ^ (^d.b[20] & d.b[21]) |
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// ι step
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d.a[0] ^= roundConstant |
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} |
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} |
@ -0,0 +1,216 @@ |
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// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package sha3 implements the SHA3 hash algorithm (formerly called Keccak) chosen by NIST in 2012.
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// This file provides a SHA3 implementation which implements the standard hash.Hash interface.
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// Writing input data, including padding, and reading output data are computed in this file.
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// Note that the current implementation can compute the hash of an integral number of bytes only.
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// This is a consequence of the hash interface in which a buffer of bytes is passed in.
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// The internals of the Keccak-f function are computed in keccakf.go.
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// For the detailed specification, refer to the Keccak web site (http://keccak.noekeon.org/).
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package sha3 |
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import ( |
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"encoding/binary" |
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"hash" |
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) |
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// laneSize is the size in bytes of each "lane" of the internal state of SHA3 (5 * 5 * 8).
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// Note that changing this size would requires using a type other than uint64 to store each lane.
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const laneSize = 8 |
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// sliceSize represents the dimensions of the internal state, a square matrix of
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// sliceSize ** 2 lanes. This is the size of both the "rows" and "columns" dimensions in the
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// terminology of the SHA3 specification.
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const sliceSize = 5 |
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// numLanes represents the total number of lanes in the state.
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const numLanes = sliceSize * sliceSize |
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// stateSize is the size in bytes of the internal state of SHA3 (5 * 5 * WSize).
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const stateSize = laneSize * numLanes |
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// digest represents the partial evaluation of a checksum.
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// Note that capacity, and not outputSize, is the critical security parameter, as SHA3 can output
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// an arbitrary number of bytes for any given capacity. The Keccak proposal recommends that
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// capacity = 2*outputSize to ensure that finding a collision of size outputSize requires
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// O(2^{outputSize/2}) computations (the birthday lower bound). Future standards may modify the
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// capacity/outputSize ratio to allow for more output with lower cryptographic security.
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type digest struct { |
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a [numLanes]uint64 // main state of the hash
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b [numLanes]uint64 // intermediate states
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c [sliceSize]uint64 // intermediate states
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d [sliceSize]uint64 // intermediate states
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outputSize int // desired output size in bytes
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capacity int // number of bytes to leave untouched during squeeze/absorb
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absorbed int // number of bytes absorbed thus far
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} |
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// minInt returns the lesser of two integer arguments, to simplify the absorption routine.
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func minInt(v1, v2 int) int { |
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if v1 <= v2 { |
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return v1 |
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} |
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return v2 |
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} |
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// rate returns the number of bytes of the internal state which can be absorbed or squeezed
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// in between calls to the permutation function.
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func (d *digest) rate() int { |
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return stateSize - d.capacity |
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} |
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// Reset clears the internal state by zeroing bytes in the state buffer.
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// This can be skipped for a newly-created hash state; the default zero-allocated state is correct.
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func (d *digest) Reset() { |
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d.absorbed = 0 |
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for i := range d.a { |
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d.a[i] = 0 |
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} |
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} |
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// BlockSize, required by the hash.Hash interface, does not have a standard intepretation
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// for a sponge-based construction like SHA3. We return the data rate: the number of bytes which
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// can be absorbed per invocation of the permutation function. For Merkle-Damgård based hashes
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// (ie SHA1, SHA2, MD5) the output size of the internal compression function is returned.
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// We consider this to be roughly equivalent because it represents the number of bytes of output
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// produced per cryptographic operation.
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func (d *digest) BlockSize() int { return d.rate() } |
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// Size returns the output size of the hash function in bytes.
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func (d *digest) Size() int { |
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return d.outputSize |
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} |
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// unalignedAbsorb is a helper function for Write, which absorbs data that isn't aligned with an
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// 8-byte lane. This requires shifting the individual bytes into position in a uint64.
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func (d *digest) unalignedAbsorb(p []byte) { |
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var t uint64 |
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for i := len(p) - 1; i >= 0; i-- { |
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t <<= 8 |
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t |= uint64(p[i]) |
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} |
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offset := (d.absorbed) % d.rate() |
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t <<= 8 * uint(offset%laneSize) |
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d.a[offset/laneSize] ^= t |
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d.absorbed += len(p) |
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} |
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// Write "absorbs" bytes into the state of the SHA3 hash, updating as needed when the sponge
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// "fills up" with rate() bytes. Since lanes are stored internally as type uint64, this requires
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// converting the incoming bytes into uint64s using a little endian interpretation. This
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// implementation is optimized for large, aligned writes of multiples of 8 bytes (laneSize).
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// Non-aligned or uneven numbers of bytes require shifting and are slower.
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func (d *digest) Write(p []byte) (int, error) { |
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// An initial offset is needed if the we aren't absorbing to the first lane initially.
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offset := d.absorbed % d.rate() |
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toWrite := len(p) |
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// The first lane may need to absorb unaligned and/or incomplete data.
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if (offset%laneSize != 0 || len(p) < 8) && len(p) > 0 { |
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toAbsorb := minInt(laneSize-(offset%laneSize), len(p)) |
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d.unalignedAbsorb(p[:toAbsorb]) |
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p = p[toAbsorb:] |
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offset = (d.absorbed) % d.rate() |
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// For every rate() bytes absorbed, the state must be permuted via the F Function.
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if (d.absorbed)%d.rate() == 0 { |
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d.keccakF() |
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} |
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} |
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// This loop should absorb the bulk of the data into full, aligned lanes.
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// It will call the update function as necessary.
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for len(p) > 7 { |
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firstLane := offset / laneSize |
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lastLane := minInt(d.rate()/laneSize, firstLane+len(p)/laneSize) |
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// This inner loop absorbs input bytes into the state in groups of 8, converted to uint64s.
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for lane := firstLane; lane < lastLane; lane++ { |
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d.a[lane] ^= binary.LittleEndian.Uint64(p[:laneSize]) |
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p = p[laneSize:] |
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} |
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d.absorbed += (lastLane - firstLane) * laneSize |
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// For every rate() bytes absorbed, the state must be permuted via the F Function.
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if (d.absorbed)%d.rate() == 0 { |
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d.keccakF() |
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} |
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offset = 0 |
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} |
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// If there are insufficient bytes to fill the final lane, an unaligned absorption.
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// This should always start at a correct lane boundary though, or else it would be caught
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// by the uneven opening lane case above.
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if len(p) > 0 { |
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d.unalignedAbsorb(p) |
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} |
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return toWrite, nil |
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} |
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// pad computes the SHA3 padding scheme based on the number of bytes absorbed.
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// The padding is a 1 bit, followed by an arbitrary number of 0s and then a final 1 bit, such that
|
||||||
|
// the input bits plus padding bits are a multiple of rate(). Adding the padding simply requires
|
||||||
|
// xoring an opening and closing bit into the appropriate lanes.
|
||||||
|
func (d *digest) pad() { |
||||||
|
offset := d.absorbed % d.rate() |
||||||
|
// The opening pad bit must be shifted into position based on the number of bytes absorbed
|
||||||
|
padOpenLane := offset / laneSize |
||||||
|
d.a[padOpenLane] ^= 0x0000000000000001 << uint(8*(offset%laneSize)) |
||||||
|
// The closing padding bit is always in the last position
|
||||||
|
padCloseLane := (d.rate() / laneSize) - 1 |
||||||
|
d.a[padCloseLane] ^= 0x8000000000000000 |
||||||
|
} |
||||||
|
|
||||||
|
// finalize prepares the hash to output data by padding and one final permutation of the state.
|
||||||
|
func (d *digest) finalize() { |
||||||
|
d.pad() |
||||||
|
d.keccakF() |
||||||
|
} |
||||||
|
|
||||||
|
// squeeze outputs an arbitrary number of bytes from the hash state.
|
||||||
|
// Squeezing can require multiple calls to the F function (one per rate() bytes squeezed),
|
||||||
|
// although this is not the case for standard SHA3 parameters. This implementation only supports
|
||||||
|
// squeezing a single time, subsequent squeezes may lose alignment. Future implementations
|
||||||
|
// may wish to support multiple squeeze calls, for example to support use as a PRNG.
|
||||||
|
func (d *digest) squeeze(in []byte, toSqueeze int) []byte { |
||||||
|
// Because we read in blocks of laneSize, we need enough room to read
|
||||||
|
// an integral number of lanes
|
||||||
|
needed := toSqueeze + (laneSize-toSqueeze%laneSize)%laneSize |
||||||
|
if cap(in)-len(in) < needed { |
||||||
|
newIn := make([]byte, len(in), len(in)+needed) |
||||||
|
copy(newIn, in) |
||||||
|
in = newIn |
||||||
|
} |
||||||
|
out := in[len(in) : len(in)+needed] |
||||||
|
|
||||||
|
for len(out) > 0 { |
||||||
|
for i := 0; i < d.rate() && len(out) > 0; i += laneSize { |
||||||
|
binary.LittleEndian.PutUint64(out[:], d.a[i/laneSize]) |
||||||
|
out = out[laneSize:] |
||||||
|
} |
||||||
|
if len(out) > 0 { |
||||||
|
d.keccakF() |
||||||
|
} |
||||||
|
} |
||||||
|
return in[:len(in)+toSqueeze] // Re-slice in case we wrote extra data.
|
||||||
|
} |
||||||
|
|
||||||
|
// Sum applies padding to the hash state and then squeezes out the desired nubmer of output bytes.
|
||||||
|
func (d *digest) Sum(in []byte) []byte { |
||||||
|
// Make a copy of the original hash so that caller can keep writing and summing.
|
||||||
|
dup := *d |
||||||
|
dup.finalize() |
||||||
|
return dup.squeeze(in, dup.outputSize) |
||||||
|
} |
||||||
|
|
||||||
|
// The NewKeccakX constructors enable initializing a hash in any of the four recommend sizes
|
||||||
|
// from the Keccak specification, all of which set capacity=2*outputSize. Note that the final
|
||||||
|
// NIST standard for SHA3 may specify different input/output lengths.
|
||||||
|
// The output size is indicated in bits but converted into bytes internally.
|
||||||
|
func NewKeccak224() hash.Hash { return &digest{outputSize: 224 / 8, capacity: 2 * 224 / 8} } |
||||||
|
func NewKeccak256() hash.Hash { return &digest{outputSize: 256 / 8, capacity: 2 * 256 / 8} } |
||||||
|
func NewKeccak384() hash.Hash { return &digest{outputSize: 384 / 8, capacity: 2 * 384 / 8} } |
||||||
|
func NewKeccak512() hash.Hash { return &digest{outputSize: 512 / 8, capacity: 2 * 512 / 8} } |
Loading…
Reference in new issue