Generating signature using self signed certificate

Question

I have the following sample code which I made for generating a signature using self signed certificate

public static String generateSignature(String data) throws Exception {

        System.out.println("@@inside generateSignature: " + data);

        String signature;

        String jksFilepath = "E:\\test.jks";

        try {
            // Adding Security Provider for PKCS 12
            Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
            // Setting password for the e-Token

            // logging into token
            ks = KeyStore.getInstance("jks");


            FileInputStream fileInputStream = new FileInputStream(jksFilepath);

            // Loading Keystore
            // System.out.println("loading keystore");
            ks.load(fileInputStream, JKSPassword);
            Enumeration<String> e = ks.aliases();

            while (e.hasMoreElements()) {
                alias = e.nextElement();
                // System.out.println("Alias of the e-Token : "+ alias);

                UserCert = (X509Certificate) ks.getCertificate(alias);

                UserCertPubKey = (PublicKey) ks.getCertificate(alias).getPublicKey();

                // System.out.println("loading Private key");
                UserCertPrivKey = (PrivateKey) ks.getKey(alias, JKSPassword);
            }

            // Method Call to generate Signature
            signature = MakeSignature(data);

            return signature;

        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("generateSignature" + e.getCause());
            throw new Exception();
        }

    }

    private static String MakeSignature(String data) {

        System.out.println("@@inside MakeSignature...");

        try {
            PrivateKey privateKey = (PrivateKey) ks.getKey(alias, JKSPassword);
            myPubCert = (X509Certificate) ks.getCertificate(alias);
            Store certs = new JcaCertStore(Arrays.asList(myPubCert));

            CMSSignedDataGenerator generator = new CMSSignedDataGenerator();

            generator.addSignerInfoGenerator(new JcaSimpleSignerInfoGeneratorBuilder().setProvider("BC").build("SHA256withRSA", privateKey, myPubCert));

            generator.addCertificates(certs);

            CMSTypedData data1 = new CMSProcessableByteArray(data.getBytes());

            CMSSignedData signed = generator.generate(data1, true);

            BASE64Encoder encoder = new BASE64Encoder();

            String signedContent = encoder.encode((byte[]) signed.getSignedContent().getContent());

            String envelopedData = encoder.encode(signed.getEncoded());

            return envelopedData;
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("MakeSignature ==" + e.getCause());
            return "";
        }
    }

There are some associated functions as well, but for the sake of giving brief I am not adding it.

Now I want to do the exact same things using PHP.

JKS doesnt work on PHP as its keystore for Java.

I tried open_ssl functions with different sets of encryption methods. But I am not getting the expected result which is as same as what I get via this java code ("not same" is about the bit rate and length of generated signature).

Can someone help me to implement the same signature generation in PHP, please?

Answer 1

I think the PHP official document is very clear: http://php.net/manual/en/function.openssl-csr-new.php

Example #1 Creating a self-signed certificate

<?php
$dn = array(
    "countryName" => "GB",
    "stateOrProvinceName" => "Somerset",
    "localityName" => "Glastonbury",
    "organizationName" => "The Brain Room Limited",
    "organizationalUnitName" => "PHP Documentation Team",
    "commonName" => "Wez Furlong",
    "emailAddress" => "wez@example.com"
);

// Generate a new private (and public) key pair
$privkey = openssl_pkey_new(array(
    "private_key_bits" => 2048,
    "private_key_type" => OPENSSL_KEYTYPE_RSA,
));

// Generate a certificate signing request
$csr = openssl_csr_new($dn, $privkey, array('digest_alg' => 'sha256'));

// Generate a self-signed cert, valid for 365 days
$x509 = openssl_csr_sign($csr, null, $privkey, $days=365, array('digest_alg' => 'sha256'));

// Save your private key, CSR and self-signed cert for later use
openssl_csr_export($csr, $csrout) and var_dump($csrout);
openssl_x509_export($x509, $certout) and var_dump($certout);
openssl_pkey_export($privkey, $pkeyout, "mypassword") and var_dump($pkeyout);

// Show any errors that occurred here
while (($e = openssl_error_string()) !== false) {
    echo $e . "\n";
}

Then you can call openssl_sign: http://php.net/manual/en/function.openssl-sign.php , use the generated private key to sign.

If you want to use the Java(JKS)'s key in PHP code, you should export the keys first, and then use PHP function load the keys.