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openssl_x509_check_private_key openssl_sign

Last updated: Sat, 27 Jan 2007

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# openssl_verify

(PHP 4 >= 4.0.4, PHP 5)

openssl_verify -- Verify signature

## Description

int openssl_verify ( string data, string signature, mixed pub_key_id [, int signature_alg] )

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.

> Замечание: Optional 4th parameter `signature_alg` was added in version 5.2.0. Its default value is `OPENSSL_ALGO_SHA1`. For more information see the list of Signature Algorithms.

Пример 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
openssl_verify
Stiv
02-Mar-2006 06:34
`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 ($ok == 0) {
echo "bad";
} else {
echo "ugly, error checking signature";
}
?>`
devel@no-spam
14-Jun-2005 06:25
`It should be noted that in order to verify a signature successfully, SHA-1 must be used to digest the data before signing.
If, for example, you are using Java to create a signature and you want to verify it in PHP, you must not use "MD5withRSA" or "SHA512withRSA" as the signature algorithm. Use "SHA1withRSA" or the like...`
steve dot venable at lmco dot com
30-May-2002 12:36
`A note about the openssl_verify() (and some of the other functions). The public key comes from a certificate in any of the support formats (as the example shows, use openssl_get_publickey() to get the resource id). But after some trial and error I found the signature string MUST BE BINARY. While no error occurs, passing a base64-formatted signature string (PEM format?), you simply get a mismatch. When I did the base64 decode myself, the verify returned a match (return value 1). You can simply drop the begin/end lines and take the output of the 'base64_decode()' function.`
meint dot post at bigfoot dot com
09-Jun-2001 11:56
`Anbybody trying to get a Win32 CryptoAPI based digital signature component to work with the openssl_verify() function should be aware that the CryptoAPI PKCS1 (RSA) method uses bytes in reverse order while the openssl_verify() method expects a correctly formatted PKCS1 digital signature (as should be). I learned this the hard way and it took me some time to dig this out. A simple solution in VBScript to reverse the byte order:
N = Len(Blob.Hex)
' reverse bytes in the signature using Hex format
For i = 1 To N - 1 Step 2
s = Mid(Blob, i, 2) & s
Next
s contains the digital signature in reverse order. Blob is an arbitrary binary container.
Send the signature off in Hex format and use a hex2bin method in PHP to convert to the correct format for openssl_verify(), i.e.
function hex2bin($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 :-)`
add a note
openssl_x509_check_private_key openssl_sign

Last updated: Sat, 27 Jan 2007
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