Algorithm encoding: add flag bit PSA_ALG_AEAD_FROM_BLOCK_FLAG
Make it easy to distinguish generic constructions on top of block
ciphers, such as CCM or GCM, from specialized algorithms such as
Chacha20-Poly1305.
diff --git a/include/psa/crypto_values.h b/include/psa/crypto_values.h
index eddf632..d01367d 100644
--- a/include/psa/crypto_values.h
+++ b/include/psa/crypto_values.h
@@ -874,13 +874,34 @@
*/
#define PSA_ALG_CBC_PKCS7 ((psa_algorithm_t)0x04600101)
+#define PSA_ALG_AEAD_FROM_BLOCK_FLAG ((psa_algorithm_t)0x00400000)
+
+/** Whether the specified algorithm is an AEAD mode on a block cipher.
+ *
+ * \param alg An algorithm identifier (value of type #psa_algorithm_t).
+ *
+ * \return 1 if \p alg is an AEAD algorithm which is an AEAD mode based on
+ * a block cipher, 0 otherwise.
+ * This macro may return either 0 or 1 if \p alg is not a supported
+ * algorithm identifier.
+ */
+#define PSA_ALG_IS_AEAD_ON_BLOCK_CIPHER(alg) \
+ (((alg) & (PSA_ALG_CATEGORY_MASK | PSA_ALG_AEAD_FROM_BLOCK_FLAG)) == \
+ (PSA_ALG_CATEGORY_AEAD | PSA_ALG_AEAD_FROM_BLOCK_FLAG))
+
/** The CCM authenticated encryption algorithm.
*/
-#define PSA_ALG_CCM ((psa_algorithm_t)0x06001001)
+#define PSA_ALG_CCM ((psa_algorithm_t)0x06401001)
/** The GCM authenticated encryption algorithm.
*/
-#define PSA_ALG_GCM ((psa_algorithm_t)0x06001002)
+#define PSA_ALG_GCM ((psa_algorithm_t)0x06401002)
+
+/** The Chacha20-Poly1305 AEAD algorithm.
+ *
+ * The ChaCha20_Poly1305 construction is defined in RFC 7539.
+ */
+#define PSA_ALG_CHACHA20_POLY1305 ((psa_algorithm_t)0x06001005)
/* In the encoding of a AEAD algorithm, the bits corresponding to
* PSA_ALG_AEAD_TAG_LENGTH_MASK encode the length of the AEAD tag.