openssl_verify

(PHP 4 >= 4.0.4, PHP 5)

openssl_verifyVerify signature

Description

int openssl_verify ( string $data , string $signature , mixed $pub_key_id [, mixed $signature_alg = OPENSSL_ALGO_SHA1 ] )

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.

Parameters

data

The string of data used to generate the signature previously

signature

A raw binary string, generated by openssl_sign() or similar means

pub_key_id

resource - a key, returned by openssl_get_publickey()

string - a PEM formatted key, example, "-----BEGIN PUBLIC KEY----- MIIBCgK..."

signature_alg

int - one of these Signature Algorithms.

string - a valid string returned by openssl_get_md_methods() example, "sha1WithRSAEncryption" or "sha512".

Return Values

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

Changelog

Version Description
5.2.0 The signature_alg parameter was added.

Examples

Example #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
$pubkeyid openssl_pkey_get_public("file://src/openssl-0.9.6/demos/sign/cert.pem");

// 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);
?>

Example #2 openssl_verify() example

<?php
//data you want to sign
$data 'my data';

//create new private and public key
$private_key_res openssl_pkey_new(array(
    
"private_key_bits" => 2048,
    
"private_key_type" => OPENSSL_KEYTYPE_RSA,
));
$details openssl_pkey_get_details($private_key_res);
$public_key_res openssl_pkey_get_public($details['key']);

//create signature
openssl_sign($data$signature$private_key_res"sha1WithRSAEncryption");

//verify signature
$ok openssl_verify($data$signature$public_key_resOPENSSL_ALGO_SHA1);
if (
$ok == 1) {
    echo 
"valid";
} elseif (
$ok == 0) {
    echo 
"invalid";
} else {
    echo 
"error: ".openssl_error_string();
}
?>

See Also

Коментарии

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 :-)
2001-06-09 14:56:41
http://php5.kiev.ua/manual/ru/function.openssl-verify.html
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.
2002-05-30 15:36:09
http://php5.kiev.ua/manual/ru/function.openssl-verify.html
Автор:
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");
$cert fread($fp8192);
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";
}
?>
2006-03-02 08:34:57
http://php5.kiev.ua/manual/ru/function.openssl-verify.html
I spent days scouring the php openssl documentation trying to figure out how to do what sounds like a simple task - given two PEM encoded certificates, is one the signer of the other?  Nowhere in the openssl_verify() documentation or comments is it explained where to obtain the signature of an existing certificate.  The openssl_x509_parse() function looked promising, but it is an unstable API that may change.

I had to write my own code to determine if one cert signed another, it is located here: http://badpenguins.com/source/misc/isCertSigner.php?viewSource

In a nutshell here is what I learned...

The signature data in a signed X.509 certificate contains DER formatted data about the signature that is encrypted with the signers public key.  The data contains a hash of the original subject certificate and information about what encryption algorithm was used to create the signature.

So you need to get this signature data and a copy of the original certificate with the issuer and signature sequences removed.  Hash a copy of the original certificate (sans issuer/signature sequences) with the same algorithm the issuer used and if the hashes match, you have the issuer cert that signed the certificate.
2010-06-07 00:04:45
http://php5.kiev.ua/manual/ru/function.openssl-verify.html
You can actually use the public key as third parameter and not the certificate.

If you can't make it work, make sure that :

1) Your public key is well formatted. It seems that it must have the ----BEGIN PUBLIC KEY---- and ----END PUBLIC KEY----

2) Your signature is in binary format. You can use the php base64_decode for this.
2011-08-31 14:08:53
http://php5.kiev.ua/manual/ru/function.openssl-verify.html
mikey at badpenguins dot com -- validating an X509 certificate chain in php seems to be possible with openssl_x509_checkpurpose()
2014-08-27 00:37:52
http://php5.kiev.ua/manual/ru/function.openssl-verify.html
openssl_verify() is populating openssl_error_string() even on false. 

When openssl_verify() returns 0, openssl_error_string() is populated with 1.
I spent lot of time to understand, while my next call to openssl was failing with checks for error.

<?php
$c 
file_get_contents($filename);
$publicKey openssl_pkey_get_public($c);
$result openssl_verify('freedom''someirrelevantnosign'$publicKey);

$error "";

while (
$msg openssl_error_string() !== false) {
   
$error .= $msg;
}

if (!empty(
$error)) {
    echo 
$error// 1
}
2018-01-23 16:10:15
http://php5.kiev.ua/manual/ru/function.openssl-verify.html
As stated from the doc: "Returns 1 if the signature is correct, 0 if it is incorrect, and -1 or false on error. "

In the second example as a well as in Stiv's note, following condition will match for both 0 or false, which have different meaning:
elseif ($ok == 0) {
    echo "bad";
}

On should do an identical test here (===) instead of an equal test (==):
elseif ($ok === 0) {
    echo "bad";
}
---
var_dump(0==false); //==> true
var_dump(0===false);//==> false
2021-09-20 16:17:31
http://php5.kiev.ua/manual/ru/function.openssl-verify.html

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