Examples: Ed25519-SHA-512 and SHA-512-Ed25519-SHA-512. Ed25519-SHA-512 is
PureEdDSA with the following parameters: q is the prime 2255 − 19; b = 256; the 255-bit encoding
of F2255 −19 is the usual little-endian encoding of {0, 1, . . . , 2255 − 20}; H is SHA-512; c = 3; n = 254;
a = −1; d = −121665/121666; B is the point (. . . 202, 4/5) ∈ E; and is the prime