SHA2_FLAGS
sha1, SHA_CTX, SHA_CBLOCK, SHA_DIGEST_LENGTH, SHA2_FLAGS,
SHA256_CBLOCK, SHA224_DIGEST_LENGTH, SHA2_FLAGS,
SHA256_CBLOCK, SHA256_DIGEST_LENGTH, SHA2_FLAGS,
SHA256_CBLOCK, SHA256_192_DIGEST_LENGTH, SHA2_FLAGS,
SHA512_CBLOCK, SHA384_DIGEST_LENGTH, SHA2_FLAGS,
SHA512_CBLOCK, SHA512_DIGEST_LENGTH, SHA2_FLAGS,
SHA512_CBLOCK, SHA224_DIGEST_LENGTH, SHA2_FLAGS,
SHA512_CBLOCK, SHA256_DIGEST_LENGTH, SHA2_FLAGS,