1 files changed, 121 insertions, 0 deletions
diff --git a/lib/crypto/aes_cmac_128.c b/lib/crypto/aes_cmac_128.c
new file mode 100644
index 0000000..e7bf030
--- /dev/null
+++ b/lib/crypto/aes_cmac_128.c
@@ -0,0 +1,121 @@
+/*
+   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/aes.h"
+#include "lib/crypto/aes_cmac_128.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)
+
+void aes_cmac_128_init(struct aes_cmac_128_context *ctx,
+		       const uint8_t K[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, ctx->L, &ctx->aes_key);
+
+	if (_MSB(ctx->L) == 0) {
+		aes_block_lshift(ctx->L, ctx->K1);
+	} else {
+		aes_block_lshift(ctx->L, ctx->tmp);
+		aes_block_xor(ctx->tmp, const_Rb, ctx->K1);
+	}
+
+	if (_MSB(ctx->K1) == 0) {
+		aes_block_lshift(ctx->K1, ctx->K2);
+	} else {
+		aes_block_lshift(ctx->K1, ctx->tmp);
+		aes_block_xor(ctx->tmp, const_Rb, ctx->K2);
+	}
+}
+
+void aes_cmac_128_update(struct aes_cmac_128_context *ctx,
+			 const uint8_t *msg, size_t msg_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);
+
+		if (len > 0) {
+			memcpy(&ctx->last[ctx->last_len], msg, len);
+			msg += len;
+			msg_len -= len;
+			ctx->last_len += len;
+		}
+	}
+
+	if (msg_len == 0) {
+		/* if it is still the last block, we are done */
+		return;
+	}
+
+	/*
+	 * now checksum everything but the last block
+	 */
+	aes_block_xor(ctx->X, ctx->last, ctx->Y);
+	AES_encrypt(ctx->Y, ctx->X, &ctx->aes_key);
+
+	while (msg_len > AES_BLOCK_SIZE) {
+		aes_block_xor(ctx->X, msg, ctx->Y);
+		AES_encrypt(ctx->Y, ctx->X, &ctx->aes_key);
+		msg += AES_BLOCK_SIZE;
+		msg_len -= AES_BLOCK_SIZE;
+	}
+
+	/*
+	 * copy the last block, it will be processed in
+	 * aes_cmac_128_final().
+	 */
+	ZERO_STRUCT(ctx->last);
+	memcpy(ctx->last, msg, msg_len);
+	ctx->last_len = msg_len;
+}
+
+void aes_cmac_128_final(struct aes_cmac_128_context *ctx,
+			uint8_t T[AES_BLOCK_SIZE])
+{
+	if (ctx->last_len < AES_BLOCK_SIZE) {
+		ctx->last[ctx->last_len] = 0x80;
+		aes_block_xor(ctx->last, ctx->K2, ctx->tmp);
+	} else {
+		aes_block_xor(ctx->last, ctx->K1, ctx->tmp);
+	}
+
+	aes_block_xor(ctx->tmp, ctx->X, ctx->Y);
+	AES_encrypt(ctx->Y, T, &ctx->aes_key);
+
+	ZERO_STRUCTP(ctx);
+}