Correct and simplify block-based cipher modes
OFB and CFB are streaming modes. XTS is a not a cipher mode but it
doesn't use a separate padding step. This leaves only CBC as a block
cipher mode that needs a padding step.
Since CBC is the only mode that uses a separate padding step, and is
likely to remain the only mode in the future, encode the padding mode
directly in the algorithm constant, rather than building up an
algorithm value from a chaining mode and a padding mode. This greatly
simplifies the interface as well as some parts of the implementation.
diff --git a/programs/psa/crypto_examples.c b/programs/psa/crypto_examples.c
index e8b64f1..72c41fa 100644
--- a/programs/psa/crypto_examples.c
+++ b/programs/psa/crypto_examples.c
@@ -167,8 +167,7 @@
key_bits = 256,
part_size = block_size,
};
- const psa_algorithm_t alg = PSA_ALG_CBC_BASE |
- PSA_ALG_BLOCK_CIPHER_PAD_NONE;
+ const psa_algorithm_t alg = PSA_ALG_CBC_NO_PADDING;
psa_status_t status;
size_t output_len = 0;
@@ -216,8 +215,7 @@
part_size = 10,
};
- const psa_algorithm_t alg = PSA_ALG_CBC_BASE |
- PSA_ALG_BLOCK_CIPHER_PAD_PKCS7;
+ const psa_algorithm_t alg = PSA_ALG_CBC_PKCS7;
psa_status_t status;
size_t output_len = 0;