Php/docs/openssl.signature-algos
From Get docs
Signature Algorithms
OPENSSL_ALGO_DSS1(int)OPENSSL_ALGO_SHA1(int)- Used as default algorithm by openssl_sign() and openssl_verify().
OPENSSL_ALGO_SHA224(int)- Added in PHP 5.4.8.
OPENSSL_ALGO_SHA256(int)- Added in PHP 5.4.8.
OPENSSL_ALGO_SHA384(int)- Added in PHP 5.4.8.
OPENSSL_ALGO_SHA512(int)- Added in PHP 5.4.8.
OPENSSL_ALGO_RMD160(int)- Added in PHP 5.4.8.
OPENSSL_ALGO_MD5(int)OPENSSL_ALGO_MD4(int)OPENSSL_ALGO_MD2(int)- As of PHP 5.2.13 and PHP 5.3.2, this constant is only available if PHP is compiled with MD2 support. This requires passing in the -DHAVE_OPENSSL_MD2_H CFLAG when compiling PHP, and enable-md2 when compiling OpenSSL 1.0.0+.