PSA_ALG_ED448PH macro

Edwards-curve digital signature algorithm with prehashing (HashEdDSA), using SHAKE256 and the Edwards448 curve. See #PSA_ALG_PURE_EDDSA regarding context support and the signature format. This algorithm is Ed448 as specified in RFC 8032. The curve is Edwards448. The prehash is the first 64 bytes of the SHAKE256 output. The hash function used internally is the first 114 bytes of the SHAKE256 output. This is a hash-and-sign algorithm: to calculate a signature, you can either: - call psa_sign_message() on the message; - or calculate the first 64 bytes of the SHAKE256 output of the message with psa_hash_compute() or with a multi-part hash operation started with psa_hash_setup(), using the hash algorithm #PSA_ALG_SHAKE256_512, then sign the calculated hash with psa_sign_hash(). Verifying a signature is similar, using psa_verify_message() or psa_verify_hash() instead of the signature function.