Java

RSA Hash Binary Data and Sign (and Verify)

See more RSA Examples

Demonstrates how to sign the hash of binary data. Also demonstrates how to verify the RSA signature. Java

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    boolean success = false;

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // Load an RSA private key for signing.
    CkPrivateKey privKey = new CkPrivateKey();
    success = privKey.LoadEncryptedPemFile("qa_data/pem/rsa_passwd.pem","passwd");
    if (success == false) {
        System.out.println(privKey.lastErrorText());
        return;
        }

    CkRsa rsa = new CkRsa();
    rsa.UsePrivateKey(privKey);

    // We have some binary data (in hex) to sign
    String originalData = "0102030405060708090A";
    CkBinData bdData = new CkBinData();
    bdData.AppendEncoded(originalData,"hex");

    // Hash (SHA-256) and sign the hash:
    CkBinData bdSignature = new CkBinData();
    success = rsa.SignBd(bdData,"sha256",bdSignature);
    if (success == false) {
        System.out.println(rsa.lastErrorText());
        return;
        }

    // Show the RSA signature in base64
    System.out.println(bdSignature.getEncoded("base64"));

    // ------------------------------------------
    // Get the public key from the private key
    CkPublicKey pubKey = new CkPublicKey();
    privKey.ToPublicKey(pubKey);

    // Verify the signature..
    CkRsa rsa2 = new CkRsa();
    rsa2.UsePublicKey(pubKey);

    boolean bVerified = rsa2.VerifyBd(bdData,"sha256",bdSignature);
    System.out.println("signature verified: " + bVerified);
  }
}