[crypto] Add SHA-256 algorithm

This implementation has been verified using the NIST SHA-256 test vectors.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/crypto/sha256.c

@@ -0,0 +1,254 @@
+/*
+ * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/** @file
+ *
+ * SHA-256 algorithm
+ *
+ */
+
+#include <stdint.h>
+#include <string.h>
+#include <byteswap.h>
+#include <assert.h>
+#include <ipxe/crypto.h>
+#include <ipxe/sha256.h>
+
+/**
+ * Rotate dword right
+ *
+ * @v dword		Dword
+ * @v rotate		Amount of rotation
+ */
+static inline __attribute__ (( always_inline )) uint32_t
+ror32 ( uint32_t dword, unsigned int rotate ) {
+	return ( ( dword >> rotate ) | ( dword << ( 32 - rotate ) ) );
+}
+
+/** SHA-256 variables */
+struct sha256_variables {
+	/* This layout matches that of struct sha256_digest_data,
+	 * allowing for efficient endianness-conversion,
+	 */
+	uint32_t a;
+	uint32_t b;
+	uint32_t c;
+	uint32_t d;
+	uint32_t e;
+	uint32_t f;
+	uint32_t g;
+	uint32_t h;
+	uint32_t w[64];
+} __attribute__ (( packed ));
+
+/** SHA-256 constants */
+static const uint32_t k[64] = {
+	0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1,
+	0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
+	0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786,
+	0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
+	0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147,
+	0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
+	0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b,
+	0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
+	0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a,
+	0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
+	0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
+};
+
+/**
+ * Initialise SHA-256 algorithm
+ *
+ * @v ctx		SHA-256 context
+ */
+static void sha256_init ( void *ctx ) {
+	struct sha256_context *context = ctx;
+
+	context->ddd.dd.digest.h[0] = cpu_to_be32 ( 0x6a09e667 );
+	context->ddd.dd.digest.h[1] = cpu_to_be32 ( 0xbb67ae85 );
+	context->ddd.dd.digest.h[2] = cpu_to_be32 ( 0x3c6ef372 );
+	context->ddd.dd.digest.h[3] = cpu_to_be32 ( 0xa54ff53a );
+	context->ddd.dd.digest.h[4] = cpu_to_be32 ( 0x510e527f );
+	context->ddd.dd.digest.h[5] = cpu_to_be32 ( 0x9b05688c );
+	context->ddd.dd.digest.h[6] = cpu_to_be32 ( 0x1f83d9ab );
+	context->ddd.dd.digest.h[7] = cpu_to_be32 ( 0x5be0cd19 );
+	context->len = 0;
+}
+
+/**
+ * Calculate SHA-256 digest of accumulated data
+ *
+ * @v context		SHA-256 context
+ */
+static void sha256_digest ( struct sha256_context *context ) {
+        union {
+		union sha256_digest_data_dwords ddd;
+		struct sha256_variables v;
+	} u;
+	uint32_t *a = &u.v.a;
+	uint32_t *b = &u.v.b;
+	uint32_t *c = &u.v.c;
+	uint32_t *d = &u.v.d;
+	uint32_t *e = &u.v.e;
+	uint32_t *f = &u.v.f;
+	uint32_t *g = &u.v.g;
+	uint32_t *h = &u.v.h;
+	uint32_t *w = u.v.w;
+	uint32_t s0;
+	uint32_t s1;
+	uint32_t maj;
+	uint32_t t1;
+	uint32_t t2;
+	uint32_t ch;
+	unsigned int i;
+
+	/* Sanity checks */
+	assert ( ( context->len % sizeof ( context->ddd.dd.data ) ) == 0 );
+	linker_assert ( &u.ddd.dd.digest.h[0] == a, sha256_bad_layout );
+	linker_assert ( &u.ddd.dd.digest.h[1] == b, sha256_bad_layout );
+	linker_assert ( &u.ddd.dd.digest.h[2] == c, sha256_bad_layout );
+	linker_assert ( &u.ddd.dd.digest.h[3] == d, sha256_bad_layout );
+	linker_assert ( &u.ddd.dd.digest.h[4] == e, sha256_bad_layout );
+	linker_assert ( &u.ddd.dd.digest.h[5] == f, sha256_bad_layout );
+	linker_assert ( &u.ddd.dd.digest.h[6] == g, sha256_bad_layout );
+	linker_assert ( &u.ddd.dd.digest.h[7] == h, sha256_bad_layout );
+	linker_assert ( &u.ddd.dd.data.dword[0] == w, sha256_bad_layout );
+
+	DBGC ( context, "SHA256 digesting:\n" );
+	DBGC_HDA ( context, 0, &context->ddd.dd.digest,
+		   sizeof ( context->ddd.dd.digest ) );
+	DBGC_HDA ( context, context->len, &context->ddd.dd.data,
+		   sizeof ( context->ddd.dd.data ) );
+
+	/* Convert h[0..7] to host-endian, and initialise a, b, c, d,
+	 * e, f, g, h, and w[0..15]
+	 */
+	for ( i = 0 ; i < ( sizeof ( u.ddd.dword ) /
+			    sizeof ( u.ddd.dword[0] ) ) ; i++ ) {
+		be32_to_cpus ( &context->ddd.dword[i] );
+		u.ddd.dword[i] = context->ddd.dword[i];
+	}
+
+	/* Initialise w[16..63] */
+	for ( i = 16 ; i < 64 ; i++ ) {
+		s0 = ( ror32 ( w[i-15], 7 ) ^ ror32 ( w[i-15], 18 ) ^
+		       ( w[i-15] >> 3 ) );
+		s1 = ( ror32 ( w[i-2], 17 ) ^ ror32 ( w[i-2], 19 ) ^
+		       ( w[i-2] >> 10 ) );
+		w[i] = ( w[i-16] + s0 + w[i-7] + s1 );
+	}
+
+	/* Main loop */
+	for ( i = 0 ; i < 64 ; i++ ) {
+		s0 = ( ror32 ( *a, 2 ) ^ ror32 ( *a, 13 ) ^ ror32 ( *a, 22 ) );
+		maj = ( ( *a & *b ) ^ ( *a & *c ) ^ ( *b & *c ) );
+		t2 = ( s0 + maj );
+		s1 = ( ror32 ( *e, 6 ) ^ ror32 ( *e, 11 ) ^ ror32 ( *e, 25 ) );
+		ch = ( ( *e & *f ) ^ ( (~*e) & *g ) );
+		t1 = ( *h + s1 + ch + k[i] + w[i] );
+		*h = *g;
+		*g = *f;
+		*f = *e;
+		*e = ( *d + t1 );
+		*d = *c;
+		*c = *b;
+		*b = *a;
+		*a = ( t1 + t2 );
+		DBGC2 ( context, "%2d : %08x %08x %08x %08x %08x %08x %08x "
+			"%08x\n", i, *a, *b, *c, *d, *e, *f, *g, *h );
+	}
+
+	/* Add chunk to hash and convert back to big-endian */
+	for ( i = 0 ; i < 8 ; i++ ) {
+		context->ddd.dd.digest.h[i] =
+			cpu_to_be32 ( context->ddd.dd.digest.h[i] +
+				      u.ddd.dd.digest.h[i] );
+	}
+
+	DBGC ( context, "SHA256 digested:\n" );
+	DBGC_HDA ( context, 0, &context->ddd.dd.digest,
+		   sizeof ( context->ddd.dd.digest ) );
+}
+
+/**
+ * Accumulate data with SHA-256 algorithm
+ *
+ * @v ctx		SHA-256 context
+ * @v data		Data
+ * @v len		Length of data
+ */
+static void sha256_update ( void *ctx, const void *data, size_t len ) {
+	struct sha256_context *context = ctx;
+	const uint8_t *byte = data;
+	size_t offset;
+
+	/* Accumulate data a byte at a time, performing the digest
+	 * whenever we fill the data buffer
+	 */
+	while ( len-- ) {
+		offset = ( context->len % sizeof ( context->ddd.dd.data ) );
+		context->ddd.dd.data.byte[offset] = *(byte++);
+		context->len++;
+		if ( ( context->len % sizeof ( context->ddd.dd.data ) ) == 0 )
+			sha256_digest ( context );
+	}
+}
+
+/**
+ * Generate SHA-256 digest
+ *
+ * @v ctx		SHA-256 context
+ * @v out		Output buffer
+ */
+static void sha256_final ( void *ctx, void *out ) {
+	struct sha256_context *context = ctx;
+	uint64_t len_bits;
+	uint8_t pad;
+
+	/* Record length before pre-processing */
+	len_bits = cpu_to_be64 ( ( ( uint64_t ) context->len ) * 8 );
+
+	/* Pad with a single "1" bit followed by as many "0" bits as required */
+	pad = 0x80;
+	do {
+		sha256_update ( ctx, &pad, sizeof ( pad ) );
+		pad = 0x00;
+	} while ( ( context->len % sizeof ( context->ddd.dd.data ) ) !=
+		  offsetof ( typeof ( context->ddd.dd.data ), final.len ) );
+
+	/* Append length (in bits) */
+	sha256_update ( ctx, &len_bits, sizeof ( len_bits ) );
+	assert ( ( context->len % sizeof ( context->ddd.dd.data ) ) == 0 );
+
+	/* Copy out final digest */
+	memcpy ( out, &context->ddd.dd.digest,
+		 sizeof ( context->ddd.dd.digest ) );
+}
+
+/** SHA-256 algorithm */
+struct digest_algorithm sha256_algorithm = {
+	.name		= "sha256",
+	.ctxsize	= sizeof ( struct sha256_context ),
+	.blocksize	= sizeof ( union sha256_block ),
+	.digestsize	= sizeof ( struct sha256_digest ),
+	.init		= sha256_init,
+	.update		= sha256_update,
+	.final		= sha256_final,
+};

src/include/ipxe/sha256.h

@@ -0,0 +1,73 @@
+#ifndef _IPXE_SHA256_H
+#define _IPXE_SHA256_H
+
+/** @file
+ *
+ * SHA-256 algorithm
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdint.h>
+#include <ipxe/crypto.h>
+
+/** An SHA-256 digest */
+struct sha256_digest {
+	/** Hash output */
+	uint32_t h[8];
+};
+
+/** An SHA-256 data block */
+union sha256_block {
+	/** Raw bytes */
+	uint8_t byte[64];
+	/** Raw dwords */
+	uint32_t dword[16];
+	/** Final block structure */
+	struct {
+		/** Padding */
+		uint8_t pad[56];
+		/** Length in bits */
+		uint64_t len;
+	} final;
+};
+
+/** SHA-256 digest and data block
+ *
+ * The order of fields within this structure is designed to minimise
+ * code size.
+ */
+struct sha256_digest_data {
+	/** Digest of data already processed */
+	struct sha256_digest digest;
+	/** Accumulated data */
+	union sha256_block data;
+} __attribute__ (( packed ));
+
+/** SHA-256 digest and data block */
+union sha256_digest_data_dwords {
+	/** Digest and data block */
+	struct sha256_digest_data dd;
+	/** Raw dwords */
+	uint32_t dword[ sizeof ( struct sha256_digest_data ) /
+			sizeof ( uint32_t ) ];
+};
+
+/** An SHA-256 context */
+struct sha256_context {
+	/** Amount of accumulated data */
+	size_t len;
+	/** Digest and accumulated data */
+	union sha256_digest_data_dwords ddd;
+} __attribute__ (( packed ));
+
+/** SHA-256 context size */
+#define SHA256_CTX_SIZE sizeof ( struct sha256_context )
+
+/** SHA-256 digest size */
+#define SHA256_DIGEST_SIZE sizeof ( struct sha256_digest )
+
+extern struct digest_algorithm sha256_algorithm;
+
+#endif /* _IPXE_SHA256_H */