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aes: add a define for the size of a block

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In the code, we use the size of the key for the
size of the block. It's true when the key is 128 bits,
but it become false for key of 192 bits and 256 bits.
So to prepare the support of aes192  and 256,
we introduce a constant for the iaes block size.

Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Philippe Reynes 2020-01-06 15:22:34 +01:00 committed by Tom Rini
parent d7bb6aceb2
commit 7012c04ef3
3 changed files with 21 additions and 20 deletions
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2
cmd/aes.c
View File

@ -56,7 +56,7 @@ static int do_aes(cmd_tbl_t *cmdtp, int flag, int argc, char *const argv[])
aes_expand_key(key_ptr, key_exp);
/* Calculate the number of AES blocks to encrypt. */
aes_blocks = DIV_ROUND_UP(len, AES_KEY_LENGTH);
aes_blocks = DIV_ROUND_UP(len, AES_BLOCK_LENGTH);
if (enc)
aes_cbc_encrypt_blocks(key_exp, iv_ptr, src_ptr, dst_ptr,

5
include/uboot_aes.h
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@ -18,7 +18,7 @@ typedef unsigned int u32;
* AES encryption library, with small code size, supporting only 128-bit AES
*
* AES is a stream cipher which works a block at a time, with each block
* in this case being AES_KEY_LENGTH bytes.
* in this case being AES_BLOCK_LENGTH bytes.
*/
enum {
@ -28,6 +28,7 @@ enum {
AES_KEY_LENGTH = 128 / 8,
AES_EXPAND_KEY_LENGTH = 4 * AES_STATECOLS * (AES_ROUNDS + 1),
AES_BLOCK_LENGTH = 128 / 8,
};
/**
@ -62,7 +63,7 @@ void aes_decrypt(u8 *in, u8 *expkey, u8 *out);
/**
* Apply chain data to the destination using EOR
*
* Each array is of length AES_KEY_LENGTH.
* Each array is of length AES_BLOCK_LENGTH.
*
* @cbc_chain_data Chain data
* @src Source data

34
lib/aes.c
View File

@ -596,62 +596,62 @@ void aes_apply_cbc_chain_data(u8 *cbc_chain_data, u8 *src, u8 *dst)
{
int i;
for (i = 0; i < AES_KEY_LENGTH; i++)
for (i = 0; i < AES_BLOCK_LENGTH; i++)
*dst++ = *src++ ^ *cbc_chain_data++;
}
void aes_cbc_encrypt_blocks(u8 *key_exp, u8 *iv, u8 *src, u8 *dst,
u32 num_aes_blocks)
{
u8 tmp_data[AES_KEY_LENGTH];
u8 tmp_data[AES_BLOCK_LENGTH];
u8 *cbc_chain_data = iv;
u32 i;
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);
debug_print_vector("AES Src", AES_BLOCK_LENGTH, src);
/* Apply the chain data */
aes_apply_cbc_chain_data(cbc_chain_data, src, tmp_data);
debug_print_vector("AES Xor", AES_KEY_LENGTH, tmp_data);
debug_print_vector("AES Xor", AES_BLOCK_LENGTH, tmp_data);
/* Encrypt the AES block */
aes_encrypt(tmp_data, key_exp, dst);
debug_print_vector("AES Dst", AES_KEY_LENGTH, dst);
debug_print_vector("AES Dst", AES_BLOCK_LENGTH, dst);
/* Update pointers for next loop. */
cbc_chain_data = dst;
src += AES_KEY_LENGTH;
dst += AES_KEY_LENGTH;
src += AES_BLOCK_LENGTH;
dst += AES_BLOCK_LENGTH;
}
}
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];
u8 tmp_data[AES_BLOCK_LENGTH], tmp_block[AES_BLOCK_LENGTH];
/* Convenient array of 0's for IV */
u8 cbc_chain_data[AES_KEY_LENGTH];
u8 cbc_chain_data[AES_BLOCK_LENGTH];
u32 i;
memcpy(cbc_chain_data, iv, AES_KEY_LENGTH);
memcpy(cbc_chain_data, iv, AES_BLOCK_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);
debug_print_vector("AES Src", AES_BLOCK_LENGTH, src);
memcpy(tmp_block, src, AES_KEY_LENGTH);
memcpy(tmp_block, src, AES_BLOCK_LENGTH);
/* Decrypt the AES block */
aes_decrypt(src, key_exp, tmp_data);
debug_print_vector("AES Xor", AES_KEY_LENGTH, tmp_data);
debug_print_vector("AES Xor", AES_BLOCK_LENGTH, tmp_data);
/* Apply the chain data */
aes_apply_cbc_chain_data(cbc_chain_data, tmp_data, dst);
debug_print_vector("AES Dst", AES_KEY_LENGTH, dst);
debug_print_vector("AES Dst", AES_BLOCK_LENGTH, dst);
/* Update pointers for next loop. */
memcpy(cbc_chain_data, tmp_block, AES_KEY_LENGTH);
src += AES_KEY_LENGTH;
dst += AES_KEY_LENGTH;
memcpy(cbc_chain_data, tmp_block, AES_BLOCK_LENGTH);
src += AES_BLOCK_LENGTH;
dst += AES_BLOCK_LENGTH;
}
}