diff --git a/src/pkg/crypto/sha256/sha256.go b/src/pkg/crypto/sha256/sha256.go
index d69ed24a3b425a0b489497bda448c8b48059fd92..89628a1b75b78c0ced7454abbcba7a0f4eed5f9f 100644
--- a/src/pkg/crypto/sha256/sha256.go
+++ b/src/pkg/crypto/sha256/sha256.go
@@ -3,7 +3,7 @@
// license that can be found in the LICENSE file.
// Package sha256 implements the SHA224 and SHA256 hash algorithms as defined
-// in FIPS 180-2.
+// in FIPS 180-4.
package sha256
import (
diff --git a/src/pkg/crypto/sha256/sha256block.go b/src/pkg/crypto/sha256/sha256block.go
index 2ac49100ac65264ceb74b9363a9638ec1780e14e..98cf2f31a6e29da469b3a6ec8184275e9898c1e1 100644
--- a/src/pkg/crypto/sha256/sha256block.go
+++ b/src/pkg/crypto/sha256/sha256block.go
@@ -2,6 +2,8 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
+// +build !amd64
+
// SHA256 block step.
// In its own file so that a faster assembly or C version
// can be substituted easily.
diff --git a/src/pkg/crypto/sha256/sha256block_amd64.s b/src/pkg/crypto/sha256/sha256block_amd64.s
new file mode 100644
index 0000000000000000000000000000000000000000..b83897c7caf43011876952dc37d030671fec4618
--- /dev/null
+++ b/src/pkg/crypto/sha256/sha256block_amd64.s
@@ -0,0 +1,256 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "../../../cmd/ld/textflag.h"
+
+// SHA256 block routine. See sha256block.go for Go equivalent.
+//
+// The algorithm is detailed in FIPS 180-4:
+//
+// http://csrc.nist.gov/publications/fips/fips180-4/fips-180-4.pdf
+//
+// Wt = Mt; for 0 <= t <= 15
+// Wt = SIGMA1(Wt-2) + SIGMA0(Wt-15) + Wt-16; for 16 <= t <= 63
+//
+// a = H0
+// b = H1
+// c = H2
+// d = H3
+// e = H4
+// f = H5
+// g = H6
+// h = H7
+//
+// for t = 0 to 63 {
+// T1 = h + BIGSIGMA1(e) + Ch(e,f,g) + Kt + Wt
+// T2 = BIGSIGMA0(a) + Maj(a,b,c)
+// h = g
+// g = f
+// f = e
+// e = d + T1
+// d = c
+// c = b
+// b = a
+// a = T1 + T2
+// }
+//
+// H0 = a + H0
+// H1 = b + H1
+// H2 = c + H2
+// H3 = d + H3
+// H4 = e + H4
+// H5 = f + H5
+// H6 = g + H6
+// H7 = h + H7
+
+// Wt = Mt; for 0 <= t <= 15
+#define MSGSCHEDULE0(index) \
+ MOVL (index*4)(SI), AX; \
+ BSWAPL AX; \
+ MOVL AX, (index*4)(BP)
+
+// Wt = SIGMA1(Wt-2) + Wt-7 + SIGMA0(Wt-15) + Wt-16; for 16 <= t <= 63
+// SIGMA0(x) = ROTR(7,x) XOR ROTR(18,x) XOR SHR(3,x)
+// SIGMA1(x) = ROTR(17,x) XOR ROTR(19,x) XOR SHR(10,x)
+#define MSGSCHEDULE1(index) \
+ MOVL ((index-2)*4)(BP), AX; \
+ MOVL AX, CX; \
+ RORL $17, AX; \
+ MOVL CX, DX; \
+ RORL $19, CX; \
+ SHRL $10, DX; \
+ MOVL ((index-15)*4)(BP), BX; \
+ XORL CX, AX; \
+ MOVL BX, CX; \
+ XORL DX, AX; \
+ RORL $7, BX; \
+ MOVL CX, DX; \
+ SHRL $3, DX; \
+ RORL $18, CX; \
+ ADDL ((index-7)*4)(BP), AX; \
+ XORL CX, BX; \
+ XORL DX, BX; \
+ ADDL ((index-16)*4)(BP), BX; \
+ ADDL BX, AX; \
+ MOVL AX, ((index)*4)(BP)
+
+// Calculate T1 in AX - uses AX, CX and DX registers.
+// h is also used as an accumulator. Wt is passed in AX.
+// T1 = h + BIGSIGMA1(e) + Ch(e, f, g) + Kt + Wt
+// BIGSIGMA1(x) = ROTR(6,x) XOR ROTR(11,x) XOR ROTR(25,x)
+// Ch(x, y, z) = (x AND y) XOR (NOT x AND z)
+#define SHA256T1(const, e, f, g, h) \
+ ADDL AX, h; \
+ MOVL e, AX; \
+ ADDL $const, h; \
+ MOVL e, CX; \
+ RORL $6, AX; \
+ MOVL e, DX; \
+ RORL $11, CX; \
+ XORL CX, AX; \
+ MOVL e, CX; \
+ RORL $25, DX; \
+ ANDL f, CX; \
+ XORL AX, DX; \
+ MOVL e, AX; \
+ NOTL AX; \
+ ADDL DX, h; \
+ ANDL g, AX; \
+ XORL CX, AX; \
+ ADDL h, AX
+
+// Calculate T2 in BX - uses BX, CX, DX and DI registers.
+// T2 = BIGSIGMA0(a) + Maj(a, b, c)
+// BIGSIGMA0(x) = ROTR(2,x) XOR ROTR(13,x) XOR ROTR(22,x)
+// Maj(x, y, z) = (x AND y) XOR (x AND z) XOR (y AND z)
+#define SHA256T2(a, b, c) \
+ MOVL a, DI; \
+ MOVL c, BX; \
+ RORL $2, DI; \
+ MOVL a, DX; \
+ ANDL b, BX; \
+ RORL $13, DX; \
+ MOVL a, CX; \
+ ANDL c, CX; \
+ XORL DX, DI; \
+ XORL CX, BX; \
+ MOVL a, DX; \
+ MOVL b, CX; \
+ RORL $22, DX; \
+ ANDL a, CX; \
+ XORL CX, BX; \
+ XORL DX, DI; \
+ ADDL DI, BX
+
+// Calculate T1 and T2, then e = d + T1 and a = T1 + T2.
+// The values for e and a are stored in d and h, ready for rotation.
+#define SHA256ROUND(index, const, a, b, c, d, e, f, g, h) \
+ SHA256T1(const, e, f, g, h); \
+ SHA256T2(a, b, c); \
+ MOVL BX, h; \
+ ADDL AX, d; \
+ ADDL AX, h
+
+#define SHA256ROUND0(index, const, a, b, c, d, e, f, g, h) \
+ MSGSCHEDULE0(index); \
+ SHA256ROUND(index, const, a, b, c, d, e, f, g, h)
+
+#define SHA256ROUND1(index, const, a, b, c, d, e, f, g, h) \
+ MSGSCHEDULE1(index); \
+ SHA256ROUND(index, const, a, b, c, d, e, f, g, h)
+
+TEXT ·block(SB),0,$264-24
+ MOVQ p_base+8(FP), SI
+ MOVQ p_len+16(FP), DX
+ SHRQ $6, DX
+ SHLQ $6, DX
+
+ LEAQ (SI)(DX*1), DI
+ MOVQ DI, 256(SP)
+ CMPQ SI, DI
+ JEQ end
+
+ MOVQ dig+0(FP), BP
+ MOVL (0*4)(BP), R8 // a = H0
+ MOVL (1*4)(BP), R9 // b = H1
+ MOVL (2*4)(BP), R10 // c = H2
+ MOVL (3*4)(BP), R11 // d = H3
+ MOVL (4*4)(BP), R12 // e = H4
+ MOVL (5*4)(BP), R13 // f = H5
+ MOVL (6*4)(BP), R14 // g = H6
+ MOVL (7*4)(BP), R15 // h = H7
+
+loop:
+ MOVQ SP, BP // message schedule
+
+ SHA256ROUND0(0, 0x428a2f98, R8, R9, R10, R11, R12, R13, R14, R15)
+ SHA256ROUND0(1, 0x71374491, R15, R8, R9, R10, R11, R12, R13, R14)
+ SHA256ROUND0(2, 0xb5c0fbcf, R14, R15, R8, R9, R10, R11, R12, R13)
+ SHA256ROUND0(3, 0xe9b5dba5, R13, R14, R15, R8, R9, R10, R11, R12)
+ SHA256ROUND0(4, 0x3956c25b, R12, R13, R14, R15, R8, R9, R10, R11)
+ SHA256ROUND0(5, 0x59f111f1, R11, R12, R13, R14, R15, R8, R9, R10)
+ SHA256ROUND0(6, 0x923f82a4, R10, R11, R12, R13, R14, R15, R8, R9)
+ SHA256ROUND0(7, 0xab1c5ed5, R9, R10, R11, R12, R13, R14, R15, R8)
+ SHA256ROUND0(8, 0xd807aa98, R8, R9, R10, R11, R12, R13, R14, R15)
+ SHA256ROUND0(9, 0x12835b01, R15, R8, R9, R10, R11, R12, R13, R14)
+ SHA256ROUND0(10, 0x243185be, R14, R15, R8, R9, R10, R11, R12, R13)
+ SHA256ROUND0(11, 0x550c7dc3, R13, R14, R15, R8, R9, R10, R11, R12)
+ SHA256ROUND0(12, 0x72be5d74, R12, R13, R14, R15, R8, R9, R10, R11)
+ SHA256ROUND0(13, 0x80deb1fe, R11, R12, R13, R14, R15, R8, R9, R10)
+ SHA256ROUND0(14, 0x9bdc06a7, R10, R11, R12, R13, R14, R15, R8, R9)
+ SHA256ROUND0(15, 0xc19bf174, R9, R10, R11, R12, R13, R14, R15, R8)
+
+ SHA256ROUND1(16, 0xe49b69c1, R8, R9, R10, R11, R12, R13, R14, R15)
+ SHA256ROUND1(17, 0xefbe4786, R15, R8, R9, R10, R11, R12, R13, R14)
+ SHA256ROUND1(18, 0x0fc19dc6, R14, R15, R8, R9, R10, R11, R12, R13)
+ SHA256ROUND1(19, 0x240ca1cc, R13, R14, R15, R8, R9, R10, R11, R12)
+ SHA256ROUND1(20, 0x2de92c6f, R12, R13, R14, R15, R8, R9, R10, R11)
+ SHA256ROUND1(21, 0x4a7484aa, R11, R12, R13, R14, R15, R8, R9, R10)
+ SHA256ROUND1(22, 0x5cb0a9dc, R10, R11, R12, R13, R14, R15, R8, R9)
+ SHA256ROUND1(23, 0x76f988da, R9, R10, R11, R12, R13, R14, R15, R8)
+ SHA256ROUND1(24, 0x983e5152, R8, R9, R10, R11, R12, R13, R14, R15)
+ SHA256ROUND1(25, 0xa831c66d, R15, R8, R9, R10, R11, R12, R13, R14)
+ SHA256ROUND1(26, 0xb00327c8, R14, R15, R8, R9, R10, R11, R12, R13)
+ SHA256ROUND1(27, 0xbf597fc7, R13, R14, R15, R8, R9, R10, R11, R12)
+ SHA256ROUND1(28, 0xc6e00bf3, R12, R13, R14, R15, R8, R9, R10, R11)
+ SHA256ROUND1(29, 0xd5a79147, R11, R12, R13, R14, R15, R8, R9, R10)
+ SHA256ROUND1(30, 0x06ca6351, R10, R11, R12, R13, R14, R15, R8, R9)
+ SHA256ROUND1(31, 0x14292967, R9, R10, R11, R12, R13, R14, R15, R8)
+ SHA256ROUND1(32, 0x27b70a85, R8, R9, R10, R11, R12, R13, R14, R15)
+ SHA256ROUND1(33, 0x2e1b2138, R15, R8, R9, R10, R11, R12, R13, R14)
+ SHA256ROUND1(34, 0x4d2c6dfc, R14, R15, R8, R9, R10, R11, R12, R13)
+ SHA256ROUND1(35, 0x53380d13, R13, R14, R15, R8, R9, R10, R11, R12)
+ SHA256ROUND1(36, 0x650a7354, R12, R13, R14, R15, R8, R9, R10, R11)
+ SHA256ROUND1(37, 0x766a0abb, R11, R12, R13, R14, R15, R8, R9, R10)
+ SHA256ROUND1(38, 0x81c2c92e, R10, R11, R12, R13, R14, R15, R8, R9)
+ SHA256ROUND1(39, 0x92722c85, R9, R10, R11, R12, R13, R14, R15, R8)
+ SHA256ROUND1(40, 0xa2bfe8a1, R8, R9, R10, R11, R12, R13, R14, R15)
+ SHA256ROUND1(41, 0xa81a664b, R15, R8, R9, R10, R11, R12, R13, R14)
+ SHA256ROUND1(42, 0xc24b8b70, R14, R15, R8, R9, R10, R11, R12, R13)
+ SHA256ROUND1(43, 0xc76c51a3, R13, R14, R15, R8, R9, R10, R11, R12)
+ SHA256ROUND1(44, 0xd192e819, R12, R13, R14, R15, R8, R9, R10, R11)
+ SHA256ROUND1(45, 0xd6990624, R11, R12, R13, R14, R15, R8, R9, R10)
+ SHA256ROUND1(46, 0xf40e3585, R10, R11, R12, R13, R14, R15, R8, R9)
+ SHA256ROUND1(47, 0x106aa070, R9, R10, R11, R12, R13, R14, R15, R8)
+ SHA256ROUND1(48, 0x19a4c116, R8, R9, R10, R11, R12, R13, R14, R15)
+ SHA256ROUND1(49, 0x1e376c08, R15, R8, R9, R10, R11, R12, R13, R14)
+ SHA256ROUND1(50, 0x2748774c, R14, R15, R8, R9, R10, R11, R12, R13)
+ SHA256ROUND1(51, 0x34b0bcb5, R13, R14, R15, R8, R9, R10, R11, R12)
+ SHA256ROUND1(52, 0x391c0cb3, R12, R13, R14, R15, R8, R9, R10, R11)
+ SHA256ROUND1(53, 0x4ed8aa4a, R11, R12, R13, R14, R15, R8, R9, R10)
+ SHA256ROUND1(54, 0x5b9cca4f, R10, R11, R12, R13, R14, R15, R8, R9)
+ SHA256ROUND1(55, 0x682e6ff3, R9, R10, R11, R12, R13, R14, R15, R8)
+ SHA256ROUND1(56, 0x748f82ee, R8, R9, R10, R11, R12, R13, R14, R15)
+ SHA256ROUND1(57, 0x78a5636f, R15, R8, R9, R10, R11, R12, R13, R14)
+ SHA256ROUND1(58, 0x84c87814, R14, R15, R8, R9, R10, R11, R12, R13)
+ SHA256ROUND1(59, 0x8cc70208, R13, R14, R15, R8, R9, R10, R11, R12)
+ SHA256ROUND1(60, 0x90befffa, R12, R13, R14, R15, R8, R9, R10, R11)
+ SHA256ROUND1(61, 0xa4506ceb, R11, R12, R13, R14, R15, R8, R9, R10)
+ SHA256ROUND1(62, 0xbef9a3f7, R10, R11, R12, R13, R14, R15, R8, R9)
+ SHA256ROUND1(63, 0xc67178f2, R9, R10, R11, R12, R13, R14, R15, R8)
+
+ MOVQ dig+0(FP), BP
+ ADDL (0*4)(BP), R8 // H0 = a + H0
+ MOVL R8, (0*4)(BP)
+ ADDL (1*4)(BP), R9 // H1 = b + H1
+ MOVL R9, (1*4)(BP)
+ ADDL (2*4)(BP), R10 // H2 = c + H2
+ MOVL R10, (2*4)(BP)
+ ADDL (3*4)(BP), R11 // H3 = d + H3
+ MOVL R11, (3*4)(BP)
+ ADDL (4*4)(BP), R12 // H4 = e + H4
+ MOVL R12, (4*4)(BP)
+ ADDL (5*4)(BP), R13 // H5 = f + H5
+ MOVL R13, (5*4)(BP)
+ ADDL (6*4)(BP), R14 // H6 = g + H6
+ MOVL R14, (6*4)(BP)
+ ADDL (7*4)(BP), R15 // H7 = h + H7
+ MOVL R15, (7*4)(BP)
+
+ ADDQ $64, SI
+ CMPQ SI, 256(SP)
+ JB loop
+
+end:
+ RET
diff --git a/src/pkg/crypto/sha256/sha256block_decl.go b/src/pkg/crypto/sha256/sha256block_decl.go
new file mode 100644
index 0000000000000000000000000000000000000000..d923ce2944b8762cf38b6d13f7341eb8eab326ae
--- /dev/null
+++ b/src/pkg/crypto/sha256/sha256block_decl.go
@@ -0,0 +1,11 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build amd64
+
+package sha256
+
+//go:noescape
+
+func block(dig *digest, p []byte)