New elliptic curve family: twisted Edwards
Add an elliptic curve family for the twisted Edwards curves
Edwards25519 and Edwards448 ("Goldilocks"). As with Montgomery curves,
since these are the only two curves in common use, the family has a
generic name.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/psa/crypto.h b/include/psa/crypto.h
index 7ee3293..d1609f8 100644
--- a/include/psa/crypto.h
+++ b/include/psa/crypto.h
@@ -709,6 +709,8 @@
* For Weierstrass curves, this is the content of the `privateKey` field of
* the `ECPrivateKey` format defined by RFC 5915. For Montgomery curves,
* the format is defined by RFC 7748, and output is masked according to §5.
+ * For twisted Edwards curves, the private key is as defined by RFC 8032
+ * (a 32-byte string for Edwards25519, a 57-byte string for Edwards448).
* - For Diffie-Hellman key exchange key pairs (key types for which
* #PSA_KEY_TYPE_IS_DH_KEY_PAIR is true), the
* format is the representation of the private key `x` as a big-endian byte
@@ -774,7 +776,12 @@
* modulus INTEGER, -- n
* publicExponent INTEGER } -- e
* ```
- * - For elliptic curve public keys (key types for which
+ * - For elliptic curve keys on a twisted Edwards curve (key types for which
+ * #PSA_KEY_TYPE_IS_ECC_PUBLIC_KEY is true and #PSA_KEY_TYPE_GET_CURVE
+ * returns #PSA_ECC_FAMILY_TWISTED_EDWARDS), the public key is as defined
+ * by RFC 8032
+ * (a 32-byte string for Edwards25519, a 57-byte string for Edwards448).
+ * - For other elliptic curve public keys (key types for which
* #PSA_KEY_TYPE_IS_ECC_PUBLIC_KEY is true), the format is the uncompressed
* representation defined by SEC1 §2.3.3 as the content of an ECPoint.
* Let `m` be the bit size associated with the curve, i.e. the bit size of