SHA512_DIGEST_STRING_LENGTH
char *SHA512_End(SHA512_CTX* context, char buffer[SHA512_DIGEST_STRING_LENGTH]) {
char* SHA512_Data(const sha2_byte* data, size_t len, char digest[SHA512_DIGEST_STRING_LENGTH]) {
char* SHA512_End(SHA512_CTX*, char[SHA512_DIGEST_STRING_LENGTH]);
char* SHA512_Data(const u_int8_t*, size_t, char[SHA512_DIGEST_STRING_LENGTH]);