EncTest.java

import java.security.Key;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.KeyPair;
import java.security.Security;
import java.security.Signature;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import javax.crypto.spec.IvParameterSpec;

import org.apache.commons.codec.binary.Base64;

import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.openssl.PEMKeyPair;
import org.bouncycastle.openssl.PEMParser;
import org.bouncycastle.openssl.jcajce.JcaPEMKeyConverter;
import org.bouncycastle.openssl.PEMException;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileNotFoundException;
import java.io.IOException;
/*
Content of tsys.pem - Private key used to decrypt the symmetric key.

-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----
*/

/*
Content of rogers.pem - Generates public key used to verify the signature.

-----BEGIN RSA PRIVATE KEY-----
MIICXQIBAAKBgQDGKLN1YdxSmR1z1u2iE+8+iaTUu/gjk6wwP86Cd8LQOSkNXxxS
zTefY/RQonD6Xyvfxm1WBjbcO0Sx1DdL2bZicVhfuQcx/GO6uYNj8ELVu0f1vsov
6j0oPsZtvf1VJpJvnjndkXUOS9BHggA+A3ahfKA9tFWNIEPjyto/0MTu+QIDAQAB
AoGAGAv+YyNCCl/8W/9cDQwgP1WSxCIfZanY/m3v0JNZ98zH95BwLngq5NPLZTGh
RjDgcSJySDsu0yD6IB5hq3m7ERZoQlpwcmCfOjaLPuJk7pDbOdA6r8qIDbne44qc
sZ3CglxgP1zeNnY4mYVfw20N9HnIuCcJCzQY9dpTguqQiAECQQDw5+wM60PJrY7N
pSKUTCY13L1NvaHiOS8za9gXmdhWfiX7kxAv7XktY0wYZtKYoQPwg3uHm2T5BSVS
gqtS3d8BAkEA0pMgkdlmxrrYI/WDpfCq5ItbGDki1aUBtKYWQvLqNYDLEkvHpcjB
PHTHt7aOo1ij5Z+874/Bj+L5dqgTw94H+QJAS73PRHyPkpAjzto1lgSfGt4tEo0l
oZezFGq6xSjUkNUWohMpyrfSGogWu7FQUzaEo5DjPM6Jn5WTl26H6QTjAQJBAL68
vBzAYsMSDaQMyHGv3Ovlet8nKfGBZFkgtDtyU0mhXtA0yiPWA4ricOFswCkfql3d
YkNQ4NCXlMWxGy4o2OkCQQDCRqlyifxEVCTi2wty5d0cq1hWy0ZxSni+dz6+sUp5
qpBaIqAp7HTHsFeJGfXDzeUpYBppiRuKECEHmDAmcKoI
-----END RSA PRIVATE KEY-----

*/

public class EncTest {
  // Open up a PEM file, and extract the keypair
  public static KeyPair getKeyPairFromPEM(String pemFilename) throws Exception {
    // Open the file
      BufferedReader br = new BufferedReader(new FileReader(pemFilename));
      Security.addProvider(new BouncyCastleProvider());

      // Open the key
      PEMParser pp = new PEMParser(br);
      PEMKeyPair pemKeyPair = (PEMKeyPair) pp.readObject();
      KeyPair kp = new JcaPEMKeyConverter().getKeyPair(pemKeyPair);
      pp.close();

      return kp;
  }

  // Decodes a byte array using the private key from a key pair
  // returns a byte array containing the symmetric key
  public static byte[] decodeUsingPrivateKey(KeyPair kp, byte[] raw_data) throws Exception {
    // Extract the private key
    PrivateKey privateKey = kp.getPrivate();

    // Get the cipher
    Cipher cipher = Cipher.getInstance("RSA");
    cipher.init(Cipher.DECRYPT_MODE, privateKey);

    // Decode the key
    return cipher.doFinal(raw_data);
  }

  // Decodes a byte array using a symmetric key, and a initialization vector of 0
  // Returns a byte array containing the request data
  public static byte[] decodeWithSymmetricKey(byte[] symmetric_key, byte[] raw_data) throws Exception {
    // Get the cipher
    Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
    SecretKeySpec key = new SecretKeySpec(symmetric_key, "AES");

    byte[] iv = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
    IvParameterSpec ivspec = new IvParameterSpec(iv);

    System.out.println("Key Length: " + symmetric_key.length);
    cipher.init(Cipher.DECRYPT_MODE, key, ivspec);

    // Decode the data
    System.out.println("To Decode: " + Base64.encodeBase64String(raw_data));
    return cipher.doFinal(raw_data);
  }

  // Verifies the validity of a byte array using the public key from a key pair, and a pre-calculates signature
  // returns true if the signature matches, false otherwise
  public static boolean verifySignatureUsingPublicKey(KeyPair kp, byte[] signed_data, byte[] signature) throws Exception {
    // Extract the public key
    PublicKey publicKey = kp.getPublic();

    // Initialize the signature algorithm
    Signature signature_algorithm = Signature.getInstance("SHA384withRSA");
    signature_algorithm.initVerify(publicKey);
    signature_algorithm.update(signed_data);

    // Verify the result
    return signature_algorithm.verify(signature);

  }

  public static void main (String[] args) {
    try {
      // Data to be processed
      String signature64 = "G1Qem9wxbpZiWIW8cgAExCzFzdhXSmVGYVBnBvYEt1t9HH/Q3rchSMi/m5Iv Eg6ZvVaGGIdm4YuL/7/D8qv63EYEAOEjbE2k4B8yAe54g9xCFVYJCG2j8qtL /nPZNk4hYQLaAq9l7jXiyrwEcjcxr/J+tnvD/ZVJLG4tfGRInQo=";
      String encData64 = "PL/ac9Nt3kMhk/2GYHGgbr7ML1MkTN9b3A5BhcJ+vgGR45zurFGZvShY2Oyt jzQlNG0K24bG+CDFp4qr3AC4nHhzWcVSWjU35k4mtQosUWRnht563DYmbD71 ArxJRF388ZBpoJpqul+zrQOiEbXKv9f/J60kyKvwPsRFZlSNlQLWGab3OI/5 aEfo2t7JKcjU7HHk5io4BVJO6ubqpASK6tRmBdIAVTI5l3cE1lkcX8ZCg1+F jIF38sxgM/8bVAiCi9o+ZrBYlsrhGCXHBSlVLu6y1U8RDvr8NWMsC6fDV/4Q eEC4DJFKR9li/HmPZvDr673uicgi+4P75dIAPsF41g==";
      String encKey64 = "rKxlHQdbgyDoM0tG4Jwh5zZ9KGaw2/+Iq078jLnrdKYloKnVOncoeW8MY9xy jNJE8vIPvjNdI0ZSCe1PnDsi9ByPz3m8yAY/BQGM7YzBEMlPUuf2yu25dw08 4iXatrJ/rxCwqHVE7BwrOCXDht+/ApuRGc3sd2CxqNv9rD/esQU=";
      
      byte[] rawSig = Base64.decodeBase64(signature64);
      byte[] rawData = Base64.decodeBase64(encData64);
      byte[] rawKey = Base64.decodeBase64(encKey64);

      // Get both of the keypairs
      KeyPair keyPairTSYS = getKeyPairFromPEM("tsys.pem");
      KeyPair keyPairRogers = getKeyPairFromPEM("rogers.pem");

      // Get the symmetric key using the TSYS private key
      byte[] rawDecodedKey = decodeUsingPrivateKey(keyPairTSYS, rawKey);

      // Get the raw data using the decoded symmetric key
      byte[] rawDecodedData = decodeWithSymmetricKey(rawDecodedKey, rawData);

      // Verify the signature using the public key
      boolean signature_result = verifySignatureUsingPublicKey(keyPairRogers, rawDecodedData, rawSig);

      // Print some statistics out to the console
      System.out.println("Base64 Key: " + Base64.encodeBase64String(rawDecodedKey));
      System.out.println("Decrypted Data: " + new String(rawDecodedData));
      System.out.println("Signature: " + signature_result);
      System.out.println("done");
    } catch (Exception e) {
      e.printStackTrace(System.err);
    }
  }
}