Java

Duplicate openssl dgst -md5 -sign myKey.pem something.txt | openssl enc -base64 -A

See more RSA Examples

Demonstrates how to duplicate the creation of an RSA signature produced by this OpenSSL command:

openssl dgst -md5 -sign myKey.pem something.txt | openssl enc -base64 -A

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 assumes 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 RSA PEM file:
    success = pkey.LoadPemFile("myKey.pem");

    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 BigEndian byte ordering:
    rsa.put_LittleEndian(false);

    // The resulting signature will be a Base64 string:
    rsa.put_EncodingMode("base64");

    // For simplicity, we're not loading
    // the data to be signed from a file.  We are instead simply
    // using a literal string value.  
    String strData = "This is the text to be signed.";

    // Hash the input using MD5, and then sign the hash:
    // Other valid hash algorithm choices are "md2" and "sha-1".
    String base64Sig = rsa.signStringENC(strData,"md5");

    System.out.println(base64Sig);

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