I'm using openssl like Whity already mentioned. Here is my striped down example. Be aware of any character encoding, line ending, etc. This results in changed binary representation of your text data.
PHP-RSA_SHA256-Sign:
<?php
$data = "For my current project I have to send a signature from PHP to Java application. I am using Crypt/RSA right now for signing my data.";
$private_key = <<<EOD
-----BEGIN RSA PRIVATE KEY-----
MIIBOgIBAAJBANDiE2+Xi/WnO+s120NiiJhNyIButVu6zxqlVzz0wy2j4kQVUC4Z
RZD80IY+4wIiX2YxKBZKGnd2TtPkcJ/ljkUCAwEAAQJAL151ZeMKHEU2c1qdRKS9
sTxCcc2pVwoAGVzRccNX16tfmCf8FjxuM3WmLdsPxYoHrwb1LFNxiNk1MXrxjH3R
6QIhAPB7edmcjH4bhMaJBztcbNE1VRCEi/bisAwiPPMq9/2nAiEA3lyc5+f6DEIJ
h1y6BWkdVULDSM+jpi1XiV/DevxuijMCIQCAEPGqHsF+4v7Jj+3HAgh9PU6otj2n
Y79nJtCYmvhoHwIgNDePaS4inApN7omp7WdXyhPZhBmulnGDYvEoGJN66d0CIHra
I2SvDkQ5CmrzkW5qPaE2oO7BSqAhRZxiYpZFb5CI
-----END RSA PRIVATE KEY-----
EOD;
$binary_signature = "";
$algo = "SHA256";
openssl_sign($data, $binary_signature, $private_key, $algo);
print(base64_encode($binary_signature) ."
");
?>
The output of base64 encoded binary signature is:
OnqiWnFQ2nAjOa1S57Du9jDpVr4Wp2nLdMk2FX+/qX1+SAHpVsW1JvQYqQUDlxvbTOE9vg6dlU6i3omR7KipLw==
JAVA-RSA_SHA256-Verify:
import java.security.GeneralSecurityException;
import java.security.KeyFactory;
import java.security.PublicKey;
import java.security.Signature;
import java.security.spec.X509EncodedKeySpec;
import org.apache.commons.codec.binary.Base64;
public class RsaVerify {
public static void main(String args[]){
String publicKey =
// "-----BEGIN PUBLIC KEY-----"+
"MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBANDiE2+Xi/WnO+s120NiiJhNyIButVu6"+
"zxqlVzz0wy2j4kQVUC4ZRZD80IY+4wIiX2YxKBZKGnd2TtPkcJ/ljkUCAwEAAQ==";
// "-----END PUBLIC KEY-----";
byte[] data = "For my current project I have to send a signature from PHP to Java application. I am using Crypt/RSA right now for signing my data.".getBytes();
byte[] signature = Base64.decodeBase64("OnqiWnFQ2nAjOa1S57Du9jDpVr4Wp2nLdMk2FX+/qX1+SAHpVsW1JvQYqQUDlxvbTOE9vg6dlU6i3omR7KipLw==");
try {
System.out.println(verify(data, signature, publicKey));
} catch (GeneralSecurityException e) {
e.printStackTrace();
}
}
private static boolean verify(byte[] data, byte[] signature, String publicKey) throws GeneralSecurityException{
X509EncodedKeySpec pubKeySpec = new X509EncodedKeySpec(Base64.decodeBase64(publicKey));
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PublicKey pubKey = keyFactory.generatePublic(pubKeySpec);
Signature sig = Signature.getInstance("SHA256withRSA");
sig.initVerify(pubKey);
sig.update(data);
return sig.verify(signature);
}
}