lib/crypto: add aes_cmac_128* (rfc 4493)

Thanks to Jeremy, Michael and Volker for the debugging!

metze

lib/crypto/aes_cmac_128.c

@@ -0,0 +1,184 @@
+/*
+   AES-CMAC-128 (rfc 4493)
+   Copyright (C) Stefan Metzmacher 2012
+   Copyright (C) Jeremy Allison 2012
+   Copyright (C) Michael Adam 2012
+
+   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 3 of the License, or
+   (at your option) 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, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "replace.h"
+#include "../lib/crypto/crypto.h"
+
+static const uint8_t const_Zero[] = {
+	0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00
+};
+
+static const uint8_t const_Rb[] = {
+	0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x87
+};
+
+#define _MSB(x) (((x)[0] & 0x80)?1:0)
+
+static inline void aes_cmac_128_left_shift_1(const uint8_t in[AES_BLOCK_SIZE],
+					     uint8_t out[AES_BLOCK_SIZE])
+{
+	uint8_t overflow = 0;
+	int8_t i;
+
+	for (i = AES_BLOCK_SIZE - 1; i >= 0; i--) {
+		out[i] = in[i] << 1;
+
+		out[i] |= overflow;
+
+		overflow = _MSB(&in[i]);
+	}
+}
+
+static inline void aes_cmac_128_xor(const uint8_t in1[AES_BLOCK_SIZE],
+				    const uint8_t in2[AES_BLOCK_SIZE],
+				    uint8_t out[AES_BLOCK_SIZE])
+{
+	uint8_t i;
+
+	for (i = 0; i < AES_BLOCK_SIZE; i++) {
+		out[i] = in1[i] ^ in2[i];
+	}
+}
+
+void aes_cmac_128_init(struct aes_cmac_128_context *ctx,
+		       const uint8_t K[AES_BLOCK_SIZE])
+{
+	uint8_t L[AES_BLOCK_SIZE];
+
+	ZERO_STRUCTP(ctx);
+
+	AES_set_encrypt_key(K, 128, &ctx->aes_key);
+
+	/* step 1 - generate subkeys k1 and k2 */
+
+	AES_encrypt(const_Zero, L, &ctx->aes_key);
+
+	if (_MSB(L) == 0) {
+		aes_cmac_128_left_shift_1(L, ctx->K1);
+	} else {
+		uint8_t tmp_block[AES_BLOCK_SIZE];
+
+		aes_cmac_128_left_shift_1(L, tmp_block);
+		aes_cmac_128_xor(tmp_block, const_Rb, ctx->K1);
+		ZERO_STRUCT(tmp_block);
+	}
+
+	if (_MSB(ctx->K1) == 0) {
+		aes_cmac_128_left_shift_1(ctx->K1, ctx->K2);
+	} else {
+		uint8_t tmp_block[AES_BLOCK_SIZE];
+
+		aes_cmac_128_left_shift_1(ctx->K1, tmp_block);
+		aes_cmac_128_xor(tmp_block, const_Rb, ctx->K2);
+		ZERO_STRUCT(tmp_block);
+	}
+
+	ZERO_STRUCT(L);
+}
+
+void aes_cmac_128_update(struct aes_cmac_128_context *ctx,
+			 const uint8_t *_msg, size_t _msg_len)
+{
+	uint8_t tmp_block[AES_BLOCK_SIZE];
+	uint8_t Y[AES_BLOCK_SIZE];
+	const uint8_t *msg = _msg;
+	size_t msg_len = _msg_len;
+
+	/*
+	 * copy the remembered last block
+	 */
+	ZERO_STRUCT(tmp_block);
+	if (ctx->last_len) {
+		memcpy(tmp_block, ctx->last, ctx->last_len);
+	}
+
+	/*
+	 * check if we expand the block
+	 */
+	if (ctx->last_len < AES_BLOCK_SIZE) {
+		size_t len = MIN(AES_BLOCK_SIZE - ctx->last_len, msg_len);
+
+		memcpy(&tmp_block[ctx->last_len], msg, len);
+		memcpy(ctx->last, tmp_block, AES_BLOCK_SIZE);
+		msg += len;
+		msg_len -= len;
+		ctx->last_len += len;
+	}
+
+	if (msg_len == 0) {
+		/* if it is still the last block, we are done */
+		ZERO_STRUCT(tmp_block);
+		return;
+	}
+
+	/*
+	 * It is not the last block anymore
+	 */
+	ZERO_STRUCT(ctx->last);
+	ctx->last_len = 0;
+
+	/*
+	 * now checksum everything but the last block
+	 */
+	aes_cmac_128_xor(ctx->X, tmp_block, Y);
+	AES_encrypt(Y, ctx->X, &ctx->aes_key);
+
+	while (msg_len > AES_BLOCK_SIZE) {
+		memcpy(tmp_block, msg, AES_BLOCK_SIZE);
+		msg += AES_BLOCK_SIZE;
+		msg_len -= AES_BLOCK_SIZE;
+
+		aes_cmac_128_xor(ctx->X, tmp_block, Y);
+		AES_encrypt(Y, ctx->X, &ctx->aes_key);
+	}
+
+	/*
+	 * copy the last block, it will be processed in
+	 * aes_cmac_128_final().
+	 */
+	memcpy(ctx->last, msg, msg_len);
+	ctx->last_len = msg_len;
+
+	ZERO_STRUCT(tmp_block);
+	ZERO_STRUCT(Y);
+}
+
+void aes_cmac_128_final(struct aes_cmac_128_context *ctx,
+			uint8_t T[AES_BLOCK_SIZE])
+{
+	uint8_t tmp_block[AES_BLOCK_SIZE];
+	uint8_t Y[AES_BLOCK_SIZE];
+
+	if (ctx->last_len < AES_BLOCK_SIZE) {
+		ctx->last[ctx->last_len] = 0x80;
+		aes_cmac_128_xor(ctx->last, ctx->K2, tmp_block);
+	} else {
+		aes_cmac_128_xor(ctx->last, ctx->K1, tmp_block);
+	}
+
+	aes_cmac_128_xor(tmp_block, ctx->X, Y);
+	AES_encrypt(Y, T, &ctx->aes_key);
+
+	ZERO_STRUCT(tmp_block);
+	ZERO_STRUCT(Y);
+	ZERO_STRUCTP(ctx);
+}

lib/crypto/aes_cmac_128.h

@@ -0,0 +1,41 @@
+/*
+   AES-CMAC-128 (rfc 4493)
+   Copyright (C) Stefan Metzmacher 2012
+
+   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 3 of the License, or
+   (at your option) 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, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef LIB_CRYPTO_AES_CMAC_128_H
+#define LIB_CRYPTO_AES_CMAC_128_H
+
+struct aes_cmac_128_context {
+	AES_KEY aes_key;
+
+	uint8_t K1[AES_BLOCK_SIZE];
+	uint8_t K2[AES_BLOCK_SIZE];
+
+	uint8_t X[AES_BLOCK_SIZE];
+
+	uint8_t last[AES_BLOCK_SIZE];
+	size_t last_len;
+};
+
+void aes_cmac_128_init(struct aes_cmac_128_context *ctx,
+		       const uint8_t K[AES_BLOCK_SIZE]);
+void aes_cmac_128_update(struct aes_cmac_128_context *ctx,
+			 const uint8_t *_msg, size_t _msg_len);
+void aes_cmac_128_final(struct aes_cmac_128_context *ctx,
+			uint8_t T[AES_BLOCK_SIZE]);
+
+#endif /* LIB_CRYPTO_AES_CMAC_128_H */

lib/crypto/crypto.h

@@ -25,4 +25,5 @@
 #include "../lib/crypto/hmacsha256.h"
 #include "../lib/crypto/arcfour.h"
 #include "../lib/crypto/aes.h"
+#include "../lib/crypto/aes_cmac_128.h"
 

lib/crypto/wscript_build

@@ -8,10 +8,11 @@ else:
 	extra_source += ' md5.c'
 
 bld.SAMBA_SUBSYSTEM('LIBCRYPTO',
-	source='crc32.c hmacmd5.c md4.c arcfour.c sha256.c hmacsha256.c aes.c rijndael-alg-fst.c' + extra_source,
-	deps='talloc' + extra_deps
-	)
-
+        source='''crc32.c hmacmd5.c md4.c arcfour.c sha256.c hmacsha256.c
+        aes.c rijndael-alg-fst.c aes_cmac_128.c
+        ''' + extra_source,
+        deps='talloc' + extra_deps
+        )
 
 bld.SAMBA_SUBSYSTEM('TORTURE_LIBCRYPTO',
 	source='md4test.c md5test.c hmacmd5test.c',

source3/Makefile.in

@@ -426,7 +426,8 @@ CRYPTO_OBJ = ../lib/crypto/crc32.o ../lib/crypto/md5.o \
 			 ../lib/crypto/hmacmd5.o ../lib/crypto/arcfour.o \
 			 ../lib/crypto/md4.o \
 			 ../lib/crypto/sha256.o ../lib/crypto/hmacsha256.o \
-			 ../lib/crypto/aes.o ../lib/crypto/rijndael-alg-fst.o
+			 ../lib/crypto/aes.o ../lib/crypto/rijndael-alg-fst.o \
+			 ../lib/crypto/aes_cmac_128.o
 
 LIB_OBJ = $(LIBSAMBAUTIL_OBJ) $(UTIL_OBJ) $(CRYPTO_OBJ) $(LIBTSOCKET_OBJ) \
 	  lib/messages.o librpc/gen_ndr/ndr_messaging.o lib/messages_local.o \