username = base36(tuplehash(31, masterpassword, domain))
password = z85(tuplehash(128, masterpassword, domain, username))
keypair = ed25519(tuplehash(256, masterpassword, "ed25519", identity))
tuplehash(output_bits, t_1, ..., t_n) = shake128(t_1 || length(t_1) || ... || t_n || length(t_n) || n || output_bits)