package com.test.fn;
import java.security.*;
import java.security.spec.*;
import java.util.Base64;
import java.util.logging.*;
import java.security.MessageDigest;
public class RSASignVerify {
private static final Logger logger =
Logger.getLogger(RSASignVerify.class.getName());
public static class Input {
public String message;
public String signatureBase64;
public String publicKeyBase64;
public String privateKeyBase64;
public String hashType;
public String actionType; //SIGN or VERIFY
public String messageType; // BASE64 or TEXT or MESSAGE_TO_DIGEST
}
public static class Result {
public boolean verifyResult;
public String signatureBase64;
public String executionInfo;
}
/**
* Verifies an RSA signature.
*
* @param Input
* The original data that was signed.
* signatureBase64 The signature in Base64 encoding.
* publicKeyBase64 The RSA public key in Base64 encoding (X.509 format).
* HashType Hashing value to Initialize the Signature object for verification, SHA256withRSA.
*
* @return true if the signature is valid, false otherwise.
* @throws Exception on errors during verification.
*/
public Result verifyMessage(Input input) throws Exception {
Result result = new Result();
try {
// Decode the public key
byte[] publicKeyBytes = Base64.getDecoder().decode(input.publicKeyBase64);
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicKeyBytes);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PublicKey publicKey = keyFactory.generatePublic(keySpec);
// Decode the signature
byte[] signatureBytes = Base64.getDecoder().decode(input.signatureBase64);
// Initialize the Signature object for verification with SHA256withRSA
Signature signature = Signature.getInstance(input.hashType);
signature.initVerify(publicKey);
if("BASE64".equals(input.messageType)){
byte [] messageBytes = Base64.getDecoder().decode(input.message);
signature.update(messageBytes);
}else if ("MESSAGE_TO_DIGEST".equals(input.messageType)){
signature.update(getDigestBytes(input.message));
}else{
signature.update(input.message.getBytes("UTF-8"));
}
// Verify the signature
result.verifyResult = signature.verify(signatureBytes);
result.executionInfo = "SUCCESS";
} catch(Exception e) {
result.verifyResult = false;
result.executionInfo = e.getMessage();
System.out.println("Error Details:" + e.getMessage());
}
return result;
}
public Result signMessage(Input input) throws Exception {
Result result = new Result();
try {
// Decode the private key
byte[] keyBytes = Base64.getDecoder().decode(input.privateKeyBase64);
PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PrivateKey privateKey=keyFactory.generatePrivate(spec);
// Initialize the Signature object for verification with SHA256withRSA
Signature signature = Signature.getInstance(input.hashType);
signature.initSign(privateKey);
//sign message
if("BASE64".equals(input.messageType)){
byte [] messageBytes = Base64.getDecoder().decode(input.message);
signature.update(messageBytes);
}else{
signature.update(input.message.getBytes("UTF-8"));
}
byte[] signedBytes = signature.sign();
//generate signature
result.signatureBase64 = Base64.getEncoder().encodeToString(signedBytes);
result.executionInfo = "SUCCESS";
} catch (Exception e) {
result.executionInfo = e.getMessage();
System.out.println("Error Details:" + e.getMessage());
}
return result;
}
//For FPS
public static byte[] getDigestBytes (String message) throws Exception {
MessageDigest digest = MessageDigest.getInstance("SHA-256");
digest.update (message.getBytes());
byte[] message_digest = digest.digest();
return message_digest;
}
public Result handleRequest (Input input) throws Exception {
logger.log(Level.INFO, "OIC message:", input.message);
logger.log (Level.INFO, "OIC actionType:", input.actionType);
Result result = null;
if ("SIGN".equals(input.actionType)) {
result = signMessage (input);
} else if ("VERIFY".equals(input.actionType)) {
result = verifyMessage(input);
} else {
result = new Result();
result.executionInfo = "ERROR: No proper action found, possible value "
+ "is VERIFY or SIGN recieved value:"
+ input.actionType;
}
return result;
}}
For online testing we can use below code:
public static void main(String[] args) {
Input input = new Input();
input.message = "base64 encrypted message";
input.actionType = "VERIFY";
input.messageType = "BASE64";
input.hashType = "SHA256withRSA";
input.signatureBase64 = "Base64 encoded signature";
input.publicKeyBase64 = "Public key";
try {
RSASignVerify service = new RSASignVerify();
Result result = service.handleRequest(input);
System.out.println(result.executionInfo);
System.out.println("Signature: " + result.signatureBase64);
System.out.println("Verify Result: " + result.verifyResult);
System.out.println("Execution Info: " + result.executionInfo);
} catch (Exception e) {
e.printStackTrace();
}
}
Code screenshots:
