Dart Requires Chilkat v11.0.0+

RSA SHA256 Signature using Private Key from Java Keystore

See more RSA Examples

Signs plaintext using RSA SHA256 using a key from a Java keystore.

Duplicatest this code:

KeyStore keystore; // key repository for keys containing signature certificate
String alias; // alias for the certificate in the key repository
String password; // password for the certificate's private key
String plaintext; // text being signed


Signature signature = Signature.getInstance("SHA256withRSA");
signature.initSign((PrivateKey) keystore.getKey(alias, password.toCharArray()));
signature.update(plaintext.getBytes("UTF-8"));
byte[] rsa_text= signature.sign();

Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  final jks = CkJavaKeyStore();

  final jksPassword = 'secret';

  // Load the Java keystore from a file.  The JKS file password is used
  // to verify the keyed digest that is found at the very end of the keystore.
  // It verifies that the keystore has not been modified.
  try {
    jks.loadFile(jksPassword, 'qa_data/jks/sample_secret.jks');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Get the private key from the JKS.
  // The private key password may be different than the file password.
  final privKeyPassword = 'secret';
  final caseSensitive = false;
  final privKey = CkPrivateKey();
  try {
    jks.privateKeyOf(privKeyPassword, 'some.alias', caseSensitive, privKey);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Establish the RSA object and tell it to use the private key..
  final rsa = CkRsa();

  try {
    rsa.usePrivateKey(privKey);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Indicate we'll be signing the utf-8 byte representation of the string..
  rsa.charset = 'utf-8';

  // Sign some plaintext using RSA-SHA256
  final plaintext = 'this is the text to be signed';
  final binarySignature = rsa.signString(plaintext, 'SHA256');
  if (!rsa.lastMethodSuccess) {
    print(rsa.lastErrorText);
    return;
  }

  // Alternatively, if the signature is desired in some encoded string form,
  // such as base64, base64-url, hex, etc.
  rsa.encodingMode = 'base64-url';
  final signatureStr = rsa.signStringENC(plaintext, 'SHA256');
  print('base64-url RSA signature: $signatureStr');
}