openssl_verify

Description

int openssl_verify ( string data, string signature, mixed pub_key_id )

Returns 1 if the signature is correct, 0 if it is incorrect, and -1 on error.

openssl_verify() verifies that the signature is correct for the specified data using the public key associated with pub_key_id. This must be the public key corresponding to the private key used for signing.

例子 1. openssl_verify() example
<?php // $data and $signature are assumed to contain the data and the signature // fetch public key from certificate and ready it $fp = fopen("/src/openssl-0.9.6/demos/sign/cert.pem", "r"); $cert = fread($fp, 8192); fclose($fp); $pubkeyid = openssl_get_publickey($cert); // state whether signature is okay or not $ok = openssl_verify($data, $signature, $pubkeyid); if ($ok == 1) { echo "good"; } elseif ($ok == 0) { echo "bad"; } else { echo "ugly, error checking signature"; } // free the key from memory openssl_free_key($pubkeyid); ?>

See also openssl_sign().

add a note User Contributed Notes

Stiv
02-Mar-2006 10:34


I've finally found a way to verify signature. Sample in the documentation doesn't work. Code bellow DOES work :)



<?php

// $data is assumed to contain the data to be signed



// fetch certificate from file and ready it

$fp = fopen("path/file.pem", "r");

$cert = fread($fp, 8192);

fclose($fp);



// state whether signature is okay or not

// use the certificate, not the public key

$ok = openssl_verify($data, $signature, $cert);

if ($ok == 1) {

    echo "good";

} elseif ($ok == 0) {

    echo "bad";

} else {

    echo "ugly, error checking signature";

}

?>

devel@no-spam
15-Jun-2005 09:25


It should be noted that in order to verify a signature successfully, SHA-1 must be used to digest the data before signing. 



If, for example, you are using Java to create a signature and you want to verify it in PHP, you must not use "MD5withRSA" or "SHA512withRSA" as the signature algorithm. Use "SHA1withRSA" or the like...

steve dot venable at lmco dot com
31-May-2002 03:36


A note about the openssl_verify() (and some of the other functions).  The public key comes from a certificate in any of the support formats (as the example shows, use openssl_get_publickey() to get the resource id).  But after some trial and error I found the signature string MUST BE BINARY.  While no error occurs, passing a base64-formatted signature string (PEM format?), you simply get a mismatch.  When I did the base64 decode myself, the verify returned a match (return value 1).  You can simply drop the begin/end lines and take the output of the 'base64_decode()' function.

meint dot post at bigfoot dot com
10-Jun-2001 02:56


Anbybody trying to get a Win32 CryptoAPI based digital signature component to work with the openssl_verify() function should be aware that the CryptoAPI PKCS1 (RSA) method uses bytes in reverse order while the openssl_verify() method expects a correctly formatted PKCS1 digital signature (as should be). I learned this the hard way and it took me some time to dig this out. A simple solution in VBScript to reverse the byte order:





N = Len(Blob.Hex)





' reverse bytes in the signature using Hex format 


For i = 1 To N - 1 Step 2 


    s = Mid(Blob, i, 2) & s 


Next 





s contains the digital signature in reverse order. Blob is an arbitrary binary container.





Send the signature off in Hex format and use a hex2bin method in PHP to convert to the correct format for openssl_verify(), i.e.





function hex2bin($data) {





    $len = strlen($data);


    return pack("H" . $len, $data);





} 





That's it, hope it helps out. BTW I used ASPEncrypt to toy around with on Win32 platform. Works only with Internet Explorer but you could also use a Java applet and have none of the abovementioned problems :-)

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