使用HMAC-SHA1签名方法详解

/**
* @brief 使用HMAC-SHA1算法生成oauth_signature签名值
*
* @param $key 密钥
* @param $str 源串
*
* @return 签名值
*/
function getSignature($str,$key) {
$signature = "";
if (function_exists('hash_hmac')) {
$signature = base64_encode(hash_hmac("sha1",$str,$key,true));
} else {
$blocksize = 64;
$hashfunc = 'sha1';
if (strlen($key) > $blocksize) {
$key = pack('H*',$hashfunc($key));
}
$key = str_pad($key,$blocksize,chr(0x00));
$ipad = str_repeat(chr(0x36),$blocksize);
$opad = str_repeat(chr(0x5c),$blocksize);
$hmac = pack(
'H*',$hashfunc(
($key ^ $opad) . pack(
'H*',$hashfunc(
($key ^ $ipad) . $str
)
)
)
);
$signature = base64_encode($hmac);
}
return $signature;
}