Move remaining text about DSA out of the specification
diff --git a/include/psa/crypto_extra.h b/include/psa/crypto_extra.h
index 5a06614..732149d 100644
--- a/include/psa/crypto_extra.h
+++ b/include/psa/crypto_extra.h
@@ -449,10 +449,33 @@
* @{
*/
-/** DSA public key. */
+/** DSA public key.
+ *
+ * The import and export format is the
+ * representation of the public key `y = g^x mod p` as a big-endian byte
+ * string. The length of the byte string is the length of the base prime `p`
+ * in bytes.
+ */
#define PSA_KEY_TYPE_DSA_PUBLIC_KEY ((psa_key_type_t)0x60020000)
-/** DSA key pair (private and public key). */
+
+/** DSA key pair (private and public key).
+ *
+ * The import and export format is the
+ * representation of the private key `x` as a big-endian byte string. The
+ * length of the byte string is the private key size in bytes (leading zeroes
+ * are not stripped).
+ *
+ * Determinstic DSA key derivation with psa_generate_derived_key follows
+ * FIPS 186-4 §B.1.2: interpret the byte string as integer
+ * in big-endian order. Discard it if it is not in the range
+ * [0, *N* - 2] where *N* is the boundary of the private key domain
+ * (the prime *p* for Diffie-Hellman, the subprime *q* for DSA,
+ * or the order of the curve's base point for ECC).
+ * Add 1 to the resulting integer and use this as the private key *x*.
+ *
+ */
#define PSA_KEY_TYPE_DSA_KEYPAIR ((psa_key_type_t)0x70020000)
+
/** Whether a key type is an DSA key (pair or public-only). */
#define PSA_KEY_TYPE_IS_DSA(type) \
(PSA_KEY_TYPE_PUBLIC_KEY_OF_KEYPAIR(type) == PSA_KEY_TYPE_DSA_PUBLIC_KEY)