PHP 5.4.33 Released

openssl_verify

(PHP 4 >= 4.0.4, PHP 5)

openssl_verifyÜberprüft eine Signatur

Beschreibung

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

Die Funktion openssl_verify() überprüft die Korrektheit der Unterschrift signature für die angegebenen Daten data mit Hilfe des öffentlichen Schlüssels pub_key_id. Das muss der passende öffentliche zum privaten Schlüssel sein, der für die Unterschrift benutzt wurde.

Parameter-Liste

data

signature

pub_key_id

signature_alg

Standard ist OPENSSL_ALGO_SHA1. Für weitere Informationen siehe Signatur-Algorithmen.

Rückgabewerte

Gibt für eine korrekte Signatur 1 zurück, 0 für eine unkorrekte und -1 falls ein Fehler aufgetreten ist.

Changelog

Version Beschreibung
5.0.0 Der Parameter signature_alg wurde hinzugefügt.

Beispiele

Beispiel #1 openssl_verify() example

<?php
// Annahme: $data und $signature enthalten die Daten und die Unterschrift

// holen des öffentlichen Schlüssels aus dem Zertifikat und vorbereiten
$fp fopen("/src/openssl-0.9.6/demos/sign/cert.pem""r");
$cert fread($fp8192);
fclose($fp);
$pubkeyid openssl_get_publickey($cert);

// feststellen, ob die Unterschrift ok ist oder nicht 
$ok openssl_verify($data$signature$pubkeyid);
if (
$ok == 1) {
    echo 
"gut";
} elseif (
$ok == 0) {
    echo 
"schlecht";
} else {
    echo 
"Mist, Fehler beim überprüfen der Signatur";
}

// Löschen des Schlüssels aus dem Speicher
openssl_free_key($pubkeyid);
?>

Siehe auch

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User Contributed Notes 6 notes

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2
mikey at badpenguins dot com
4 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: 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.
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1
meint dot post at bigfoot dot com
13 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
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 :-)
up
0
attila dot m dot magyar at gmail dot com
23 days ago
mikey at badpenguins dot com -- validating an X509 certificate chain in php seems to be possible with openssl_x509_checkpurpose()
up
0
jeremie dot gomez at gmail dot com
3 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.
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0
Stiv
8 years ago
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";
}
?>
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0
steve dot venable at lmco dot com
12 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.
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