aes: Allow non-zero initialization vector

AES encryption in CBC mode, in most cases, must be used with random
initialization vector. Using the same key and initialization vector several
times is weak and must be avoided.

Added iv parameter to the aes_cbc_encrypt_blocks and aes_cbc_decrypt_blocks
functions for passing initialization vector.

Command 'aes' now also require the initialization vector parameter.

Signed-off-by: Andrey Mozzhuhin <amozzhuhin@yandex.ru>

arch/arm/mach-tegra/tegra20/crypto.c

@@ -50,6 +50,7 @@ static void sign_object(u8 *key, u8 *key_schedule, u8 *src, u8 *dst,
 			u32 num_aes_blocks)
 {
 	u8 tmp_data[AES_KEY_LENGTH];
+	u8 iv[AES_KEY_LENGTH] = {0};
 	u8 left[AES_KEY_LENGTH];
 	u8 k1[AES_KEY_LENGTH];
 	u8 *cbc_chain_data;
@@ -61,7 +62,7 @@ static void sign_object(u8 *key, u8 *key_schedule, u8 *src, u8 *dst,
 	for (i = 0; i < AES_KEY_LENGTH; i++)
 		tmp_data[i] = 0;
 
-	aes_cbc_encrypt_blocks(key_schedule, tmp_data, left, 1);
+	aes_cbc_encrypt_blocks(key_schedule, iv, tmp_data, left, 1);
 
 	left_shift_vector(left, k1, sizeof(left));
 
@@ -102,6 +103,7 @@ static int encrypt_and_sign(u8 *key, enum security_op oper, u8 *src,
 {
 	u32 num_aes_blocks;
 	u8 key_schedule[AES_EXPAND_KEY_LENGTH];
+	u8 iv[AES_KEY_LENGTH] = {0};
 
 	debug("encrypt_and_sign: length = %d\n", length);
 
@@ -116,7 +118,8 @@ static int encrypt_and_sign(u8 *key, enum security_op oper, u8 *src,
 	if (oper & SECURITY_ENCRYPT) {
 		/* Perform this in place, resulting in src being encrypted. */
 		debug("encrypt_and_sign: begin encryption\n");
-		aes_cbc_encrypt_blocks(key_schedule, src, src, num_aes_blocks);
+		aes_cbc_encrypt_blocks(key_schedule, iv, src, src,
+				       num_aes_blocks);
 		debug("encrypt_and_sign: end encryption\n");
 	}
 

cmd/aes.c

@@ -28,13 +28,13 @@ DECLARE_GLOBAL_DATA_PTR;
  */
 static int do_aes(cmd_tbl_t *cmdtp, int flag, int argc, char *const argv[])
 {
-	uint32_t key_addr, src_addr, dst_addr, len;
-	uint8_t *key_ptr, *src_ptr, *dst_ptr;
+	uint32_t key_addr, iv_addr, src_addr, dst_addr, len;
+	uint8_t *key_ptr, *iv_ptr, *src_ptr, *dst_ptr;
 	uint8_t key_exp[AES_EXPAND_KEY_LENGTH];
 	uint32_t aes_blocks;
 	int enc;
 
-	if (argc != 6)
+	if (argc != 7)
 		return CMD_RET_USAGE;
 
 	if (!strncmp(argv[1], "enc", 3))
@@ -45,11 +45,13 @@ static int do_aes(cmd_tbl_t *cmdtp, int flag, int argc, char *const argv[])
 		return CMD_RET_USAGE;
 
 	key_addr = simple_strtoul(argv[2], NULL, 16);
-	src_addr = simple_strtoul(argv[3], NULL, 16);
-	dst_addr = simple_strtoul(argv[4], NULL, 16);
-	len = simple_strtoul(argv[5], NULL, 16);
+	iv_addr = simple_strtoul(argv[3], NULL, 16);
+	src_addr = simple_strtoul(argv[4], NULL, 16);
+	dst_addr = simple_strtoul(argv[5], NULL, 16);
+	len = simple_strtoul(argv[6], NULL, 16);
 
 	key_ptr = (uint8_t *)key_addr;
+	iv_ptr = (uint8_t *)iv_addr;
 	src_ptr = (uint8_t *)src_addr;
 	dst_ptr = (uint8_t *)dst_addr;
 
@@ -60,9 +62,11 @@ static int do_aes(cmd_tbl_t *cmdtp, int flag, int argc, char *const argv[])
 	aes_blocks = DIV_ROUND_UP(len, AES_KEY_LENGTH);
 
 	if (enc)
-		aes_cbc_encrypt_blocks(key_exp, src_ptr, dst_ptr, aes_blocks);
+		aes_cbc_encrypt_blocks(key_exp, iv_ptr, src_ptr, dst_ptr,
+				       aes_blocks);
 	else
-		aes_cbc_decrypt_blocks(key_exp, src_ptr, dst_ptr, aes_blocks);
+		aes_cbc_decrypt_blocks(key_exp, iv_ptr, src_ptr, dst_ptr,
+				       aes_blocks);
 
 	return 0;
 }
@@ -70,20 +74,22 @@ static int do_aes(cmd_tbl_t *cmdtp, int flag, int argc, char *const argv[])
 /***************************************************/
 #ifdef CONFIG_SYS_LONGHELP
 static char aes_help_text[] =
-	"enc key src dst len - Encrypt block of data $len bytes long\n"
-	"                          at address $src using a key at address\n"
-	"                          $key and store the result at address\n"
-	"                          $dst. The $len size must be multiple of\n"
-	"                          16 bytes and $key must be 16 bytes long.\n"
-	"aes dec key src dst len - Decrypt block of data $len bytes long\n"
-	"                          at address $src using a key at address\n"
-	"                          $key and store the result at address\n"
-	"                          $dst. The $len size must be multiple of\n"
-	"                          16 bytes and $key must be 16 bytes long.";
+	"enc key iv src dst len - Encrypt block of data $len bytes long\n"
+	"                             at address $src using a key at address\n"
+	"                             $key with initialization vector at address\n"
+	"                             $iv. Store the result at address $dst.\n"
+	"                             The $len size must be multiple of 16 bytes.\n"
+	"                             The $key and $iv must be 16 bytes long.\n"
+	"aes dec key iv src dst len - Decrypt block of data $len bytes long\n"
+	"                             at address $src using a key at address\n"
+	"                             $key with initialization vector at address\n"
+	"                             $iv. Store the result at address $dst.\n"
+	"                             The $len size must be multiple of 16 bytes.\n"
+	"                             The $key and $iv must be 16 bytes long.";
 #endif
 
 U_BOOT_CMD(
-	aes, 6, 1, do_aes,
+	aes, 7, 1, do_aes,
 	"AES 128 CBC encryption",
 	aes_help_text
 );

include/uboot_aes.h

@@ -75,20 +75,24 @@ void aes_apply_cbc_chain_data(u8 *cbc_chain_data, u8 *src, u8 *dst);
  * aes_cbc_encrypt_blocks() - Encrypt multiple blocks of data with AES CBC.
  *
  * @key_exp		Expanded key to use
+ * @iv			Initialization vector
  * @src			Source data to encrypt
  * @dst			Destination buffer
  * @num_aes_blocks	Number of AES blocks to encrypt
  */
-void aes_cbc_encrypt_blocks(u8 *key_exp, u8 *src, u8 *dst, u32 num_aes_blocks);
+void aes_cbc_encrypt_blocks(u8 *key_exp, u8 *iv, u8 *src, u8 *dst,
+			    u32 num_aes_blocks);
 
 /**
  * Decrypt multiple blocks of data with AES CBC.
  *
  * @key_exp		Expanded key to use
+ * @iv			Initialization vector
  * @src			Source data to decrypt
  * @dst			Destination buffer
  * @num_aes_blocks	Number of AES blocks to decrypt
  */
-void aes_cbc_decrypt_blocks(u8 *key_exp, u8 *src, u8 *dst, u32 num_aes_blocks);
+void aes_cbc_decrypt_blocks(u8 *key_exp, u8 *iv, u8 *src, u8 *dst,
+			    u32 num_aes_blocks);
 
 #endif /* _AES_REF_H_ */

lib/aes.c

@@ -601,12 +601,11 @@ void aes_apply_cbc_chain_data(u8 *cbc_chain_data, u8 *src, u8 *dst)
 		*dst++ = *src++ ^ *cbc_chain_data++;
 }
 
-void aes_cbc_encrypt_blocks(u8 *key_exp, u8 *src, u8 *dst, u32 num_aes_blocks)
+void aes_cbc_encrypt_blocks(u8 *key_exp, u8 *iv, u8 *src, u8 *dst,
+			    u32 num_aes_blocks)
 {
-	u8 zero_key[AES_KEY_LENGTH] = { 0 };
 	u8 tmp_data[AES_KEY_LENGTH];
-	/* Convenient array of 0's for IV */
-	u8 *cbc_chain_data = zero_key;
+	u8 *cbc_chain_data = iv;
 	u32 i;
 
 	for (i = 0; i < num_aes_blocks; i++) {
@@ -628,13 +627,15 @@ void aes_cbc_encrypt_blocks(u8 *key_exp, u8 *src, u8 *dst, u32 num_aes_blocks)
 	}
 }
 
-void aes_cbc_decrypt_blocks(u8 *key_exp, u8 *src, u8 *dst, u32 num_aes_blocks)
+void aes_cbc_decrypt_blocks(u8 *key_exp, u8 *iv, u8 *src, u8 *dst,
+			    u32 num_aes_blocks)
 {
 	u8 tmp_data[AES_KEY_LENGTH], tmp_block[AES_KEY_LENGTH];
 	/* Convenient array of 0's for IV */
-	u8 cbc_chain_data[AES_KEY_LENGTH] = { 0 };
+	u8 cbc_chain_data[AES_KEY_LENGTH];
 	u32 i;
 
+	memcpy(cbc_chain_data, iv, AES_KEY_LENGTH);
 	for (i = 0; i < num_aes_blocks; i++) {
 		debug("encrypt_object: block %d of %d\n", i, num_aes_blocks);
 		debug_print_vector("AES Src", AES_KEY_LENGTH, src);