Java

Duplicate openssl dgst -sha256 -sign private.pem -out sha256.sig in.dat

See more OpenSSL Examples

Demonstrates how to duplicate this OpenSSL command:

openssl dgst -sha256 -sign private.pem -out sha256.sig in.dat

The in.dat file can contain text or binary data of any type. The OpenSSL command does the following:

1. Creates a SHA256 digest of the contents of the input file
2. Signs the SHA256 digest using the private key.

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.

    CkPrivateKey pkey = new CkPrivateKey();

    // Load the private key from an PEM file:
    success = pkey.LoadPemFile("private.pem");
    if (success == false) {
        System.out.println(pkey.lastErrorText());
        return;
        }

    CkRsa rsa = new CkRsa();

    // Import the private key into the RSA component:
    success = rsa.UsePrivateKey(pkey);
    if (success == false) {
        System.out.println(rsa.lastErrorText());
        return;
        }

    // OpenSSL uses big-endian.
    rsa.put_LittleEndian(false);

    // Load the file to be signed.
    CkBinData bdFileData = new CkBinData();
    success = bdFileData.LoadFile("in.dat");

    CkBinData bdSig = new CkBinData();
    success = rsa.SignBd(bdFileData,"sha256",bdSig);
    if (success == false) {
        System.out.println(rsa.lastErrorText());
        return;
        }

    // Save the binary signature to a file.
    success = bdSig.WriteFile("signature.sig");
    if (success != true) {
        System.out.println("Failed to write signature.sig.");
        return;
        }

    System.out.println("Success.");
  }
}