PSA_ALG_PURE_EDDSA macro

Edwards-curve digital signature algorithm without prehashing (PureEdDSA), using standard parameters. Contexts are not supported in the current version of this specification because there is no suitable signature interface that can take the context as a parameter. A future version of this specification may add suitable functions and extend this algorithm to support contexts. PureEdDSA requires an elliptic curve key on a twisted Edwards curve. In this specification, the following curves are supported: - #PSA_ECC_FAMILY_TWISTED_EDWARDS, 255-bit: Ed25519 as specified in RFC 8032. The curve is Edwards25519. The hash function used internally is SHA-512. - #PSA_ECC_FAMILY_TWISTED_EDWARDS, 448-bit: Ed448 as specified in RFC 8032. The curve is Edwards448. The hash function used internally is the first 114 bytes of the SHAKE256 output. This algorithm can be used with psa_sign_message() and psa_verify_message(). Since there is no prehashing, it cannot be used with psa_sign_hash() or psa_verify_hash(). The signature format is the concatenation of R and S as defined by RFC 8032 §5.1.6 and §5.2.6 (a 64-byte string for Ed25519, a 114-byte string for Ed448).