(PHP 4 >= 4.0.4, PHP 5, PHP 7)

openssl_verifyVerify signature


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.



The string of data used to generate the signature previously


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


resource - a key, returned by openssl_get_publickey()

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


int - one of these Signature Algorithms.

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

Valorile întoarse

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

Istoricul schimbărilor

Versiune Descriere
5.2.0 The signature_alg parameter was added.


Example #1 openssl_verify() example

// $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) {
} elseif (
$ok == 0) {
} else {
"ugly, error checking signature";
// free the key from memory

Example #2 openssl_verify() example

//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

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

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User Contributed Notes 6 notes

mikey at badpenguins dot com
6 years ago
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:

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.
steve dot venable at lmco dot com
14 years ago
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.
10 years ago
I've finally found a way to verify signature. Sample in the documentation doesn't work. Code bellow DOES work :)

// $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);

// state whether signature is okay or not
// use the certificate, not the public key
$ok = openssl_verify($data, $signature, $cert);
if (
$ok == 1) {
} elseif (
$ok == 0) {
} else {
"ugly, error checking signature";
attila dot m dot magyar at gmail dot com
2 years ago
mikey at badpenguins dot com -- validating an X509 certificate chain in php seems to be possible with openssl_x509_checkpurpose()
jeremie dot gomez at gmail dot com
5 years ago
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.
meint dot post at bigfoot dot com
15 years ago
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

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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