aes: Implement AES-128-CBC decryption function
Implement a compatible AES-128-CBC decryption function as a counterpart
of the encryption function pulled from tegra20-common/crypto.c .
Signed-off-by: Marek Vasut <marex@denx.de>
diff --git a/lib/aes.c b/lib/aes.c
index a6648f9..9dadb22 100644
--- a/lib/aes.c
+++ b/lib/aes.c
@@ -632,3 +632,31 @@
dst += AES_KEY_LENGTH;
}
}
+
+void aes_cbc_decrypt_blocks(u8 *key_exp, 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 };
+ 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);
+
+ memcpy(tmp_block, src, AES_KEY_LENGTH);
+
+ /* Decrypt the AES block */
+ aes_decrypt(src, key_exp, tmp_data);
+ debug_print_vector("AES Xor", AES_KEY_LENGTH, tmp_data);
+
+ /* Apply the chain data */
+ apply_cbc_chain_data(cbc_chain_data, tmp_data, dst);
+ debug_print_vector("AES Dst", AES_KEY_LENGTH, dst);
+
+ /* Update pointers for next loop. */
+ memcpy(cbc_chain_data, tmp_block, AES_KEY_LENGTH);
+ src += AES_KEY_LENGTH;
+ dst += AES_KEY_LENGTH;
+ }
+}