RsaSignatureStringFull.php

<?php
function rsaSignToBase64 ($privateKey, $dataToSign) {
    openssl_sign($dataToSign, $signature, $privateKey, OPENSSL_ALGO_SHA256);
    return base64_encode($signature);
}

function rsaVerifySignatureFromBase64 ($publicKey, $dataToSign, $signatureBase64) {
    $ok = openssl_verify($dataToSign, base64_decode($signatureBase64), $publicKey, OPENSSL_ALGO_SHA256);
    if ($ok == 1) {
        return true;
    } elseif ($ok == 0) {
        return false;
    } else {
        return false;
    }
    return false;
}

function loadRsaPrivateKeyPem() {
    // this is a sample key - don't worry !
    return '
-----BEGIN PRIVATE KEY-----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-----END PRIVATE KEY-----
';
}

function loadRsaPublicKeyPem() {
    // this is a sample key - don't worry !
    return '
-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA8EmWJUZ/Osz4vXtUU2S+
0M4BP9+s423gjMjoX+qP1iCnlcRcFWxthQGN2CWSMZwR/vY9V0un/nsIxhZSWOH9
iKzqUtZD4jt35jqOTeJ3PCSr48JirVDNLet7hRT37Ovfu5iieMN7ZNpkjeIG/CfT
/QQl7R+kO/EnTmL3QjLKQNV/HhEbHS2/44x7PPoHqSqkOvl8GW0qtL39gTLWgAe8
01/w5PmcQ38CKG0oT2gdJmJqIxNmAEHkatYGHcMDtXRBpOhOSdraFj6SmPyHEmLB
ishaq7Jm8NPPNK9QcEQ3q+ERa5M6eM72PpF93g2p5cjKgyzzfoIV09Zb/LJ2aW2g
QwIDAQAB
-----END PUBLIC KEY-----
';
}

echo 'RSA signature string' . PHP_EOL;

$dataToSign = "The quick brown fox jumps over the lazy dog";
echo 'dataToSign: ' . $dataToSign . PHP_EOL;

// usually we would load the private and public key from a file or keystore
// here we use hardcoded keys for demonstration - don't do this in real programs

echo PHP_EOL . '* * * sign the plaintext with the RSA private key * * *' . PHP_EOL;
$privateRsaKeyPem = loadRsaPrivateKeyPem();
$rsaPrivateKey = openssl_pkey_get_private($privateRsaKeyPem);
echo 'used private key:' . $privateRsaKeyPem . PHP_EOL;
$signatureBase64 = rsaSignToBase64($rsaPrivateKey, $dataToSign);
echo 'signature (Base64): ' . $signatureBase64 . PHP_EOL;

echo PHP_EOL . '* * * verify the signature against the plaintext with the RSA public key * * *' . PHP_EOL;
$publicRsaKeyPem = loadRsaPublicKeyPem();
$rsaPublicKey = openssl_pkey_get_public($publicRsaKeyPem);
echo 'used public key:' . $publicRsaKeyPem . PHP_EOL;
$signatureVerified = rsaVerifySignatureFromBase64($rsaPublicKey, $dataToSign, $signatureBase64);
//$signatureVerified = rsaVerifySignatureFromBase64($rsaPublicKey, 'test', $signatureBase64);
if ($signatureVerified == 1) {
    echo 'signature (Base64) verified: ' . 'true'. PHP_EOL;
} else {
    echo 'signature (Base64) verified: ' . 'false'. PHP_EOL;
}
?>