(PHP 5 >= 5.3.0, PHP 7)
openssl_get_md_methods — 获取可用的摘要算法
$aliases = false
] ) : array获取可用的摘要算法列表
含有可用摘要算法的数组
Example #1 openssl_get_md_methods() 范例：
显示了可用的摘要，以及哪些别名可能是可用的。
<?php
$digests = openssl_get_md_methods();
$digests_and_aliases = openssl_get_md_methods(true);
$digest_aliases = array_diff($digests_and_aliases, $digests);
print_r($digests);
print_r($digest_aliases);
?>
以上例程的输出类似于：
Array
(
[0] => DSA
[1] => DSA-SHA
[2] => MD2
[3] => MD4
[4] => MD5
[5] => RIPEMD160
[6] => SHA
[7] => SHA1
[8] => SHA224
[9] => SHA256
[10] => SHA384
[11] => SHA512
[12] => dsaEncryption
[13] => dsaWithSHA
[14] => ecdsa-with-SHA1
[15] => md2
[16] => md4
[17] => md5
[18] => ripemd160
[19] => sha
[20] => sha1
[21] => sha224
[22] => sha256
[23] => sha384
[24] => sha512
)
Array
(
[2] => DSA-SHA1
[3] => DSA-SHA1-old
[4] => DSS1
[9] => RSA-MD2
[10] => RSA-MD4
[11] => RSA-MD5
[12] => RSA-RIPEMD160
[13] => RSA-SHA
[14] => RSA-SHA1
[15] => RSA-SHA1-2
[16] => RSA-SHA224
[17] => RSA-SHA256
[18] => RSA-SHA384
[19] => RSA-SHA512
[28] => dsaWithSHA1
[29] => dss1
[32] => md2WithRSAEncryption
[34] => md4WithRSAEncryption
[36] => md5WithRSAEncryption
[37] => ripemd
[39] => ripemd160WithRSA
[40] => rmd160
[43] => sha1WithRSAEncryption
[45] => sha224WithRSAEncryption
[47] => sha256WithRSAEncryption
[49] => sha384WithRSAEncryption
[51] => sha512WithRSAEncryption
[52] => shaWithRSAEncryption
[53] => ssl2-md5
[54] => ssl3-md5
[55] => ssl3-sha1
)