Generate RSA Key and Sign a String

Demonstrates how to generate a new RSA public/private key pair and use it to generate a signature for a string. The (binary) digital signature is returned as a hexidecimalized string.

Download 32-bit Chilkat RSA ActiveX (.msi)

Download All 32-bit Chilkat ActiveX Components (.zip)

Download All 64-bit Chilkat ActiveX Components (.zip)

<?php

$rsa = new COM("Chilkat.Rsa");

//  Any string argument automatically begins the 30-day trial.
$success = $rsa->UnlockComponent('30-day trial');
if ($success != true) {
    print 'RSA component unlock failed' . "\n";
    exit;
}

//  Generate a 1024-bit RSA key pair.
$rsa->GenerateKey(1024);

//  This example will sign a string, and receive the signature
//  in a hex-encoded string.  Therefore, set the encoding mode
//  to "hex":
$rsa->EncodingMode = 'hex';

//  If some other non-Chilkat application or web service is going to be verifying
//  the signature, it is important to match the byte-ordering.
//  The LittleEndian property may be set to 1
//  for little-endian byte ordering,
//  or 0  for big-endian byte ordering.
//  Microsoft apps typically use little-endian, while
//  OpenSSL and other services (such as Amazon CloudFront)
//  use big-endian.
$rsa->LittleEndian = false;

$strData = 'This is the string to be signed.';

//  Sign the string using the  md5 hash algorithm.
//  Other valid choices are "md2", "sha256", "sha384",
//  "sha512", and "sha-1".
$hexSig = $rsa->signStringENC($strData,'md5');

print $hexSig . "\n";
print $rsa->lastErrorText() . "\n";

//  Now verify the signature:
$success = $rsa->VerifyStringENC($strData,'md5',$hexSig);
if ($success == true) {
    print 'Signature verified!' . "\n";
}
else {
    print $rsa->lastErrorText() . "\n";
}

//  Try it with an invalid signature:
$success = $rsa->VerifyStringENC($strData,'md5','not a valid sig');
if ($success == true) {
    print 'Signature verified!' . "\n";
}
else {
    print $rsa->lastErrorText() . "\n";
}

//  Try it with invalid data:
$success = $rsa->VerifyStringENC('Not the original data','md5',$hexSig);
if ($success == true) {
    print 'Signature verified!' . "\n";
}
else {
    print $rsa->lastErrorText() . "\n";
}

//  Try it with the wrong hash algorithm:
$success = $rsa->VerifyStringENC($strData,'sha-1',$hexSig);
if ($success == true) {
    print 'Signature verified!' . "\n";
}
else {
    print $rsa->lastErrorText() . "\n";
}

?>