Dart Requires Chilkat v11.0.0+

RSA Signature/Verify with .key and .cer

See more RSA Examples

Demonstrates how to use a .key file (private key) and digital certificate (.cer, public key) to create and verify an RSA signature. Dart

import 'package:chilkat/chilkat.dart';

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

  final privKey = CkPrivateKey();

  // Load the private key from an RSA .key file:
  try {
    privKey.loadPemFile('privateKey.key');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final rsa = CkRsa();

  // Import the private key into the RSA component:
  try {
    rsa.usePrivateKey(privKey);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Create the signature as a hex string:
  rsa.encodingMode = 'hex';

  final strData = 'This is the string to be signed.';

  // Sign the string using the sha256 hash algorithm.
  // Other valid choices are "md2", "sha1", "sha384",
  // "sha512", and "md5".
  final hexSig = rsa.signStringENC(strData, 'sha256');

  print(hexSig);

  // Load a digital certificate from a .cer file:
  final cert = CkCert();

  try {
    cert.loadFromFile('myCert.cer');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final pubKey = CkPublicKey();
  cert.getPublicKey(pubKey);

  // Now verify using a new instance of the RSA object:
  final rsa2 = CkRsa();

  // Import the public key into the RSA object:
  try {
    rsa2.usePublicKey(pubKey);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // The signature is a hex string, so make sure the EncodingMode is correct:
  rsa2.encodingMode = 'hex';

  // Verify the signature:
  try {
    rsa2.verifyStringENC(strData, 'sha256', hexSig);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Success.');
}