Dart Requires Chilkat v11.0.0+

RSA Encrypt String to Encoded Result and Reverse

See more RSA Examples

Demonstrates how to RSA encrypt a string to a base64 encoded result, and the reverse. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  var success = false;

  // The RSA public key is used for encryption, and the private key for decryption.

  // The public key's role is to make encryption accessible to anyone while ensuring that
  // only the private key holder can decrypt the messages.
  // The public key is designed to be widely distributed so anyone can use it to encrypt messages
  // intended for the owner of the private key.

  // Load our 2048-bit RSA public key.
  final pubKey = CkPublicKey();
  // In all Chilkat methods expecting a path, you pass either absolute or relative paths.
  success = true;
  try {
    pubKey.loadFromFile('rsaKeys/myTestRsaPublic.pem');
  } on ChilkatException {
    success = false;
  }
  if (!success) {
    print(pubKey.lastErrorText);
    return;
  }

  final rsa = CkRsa();

  // Tell RSA to use the public key.
  rsa.usePublicKey(pubKey);

  // RSA encryption is for small amounts of data, on the order of 200 bytes or less.
  // The maximum number of bytes that can be RSA encrypted depends
  // on the RSA key size and padding scheme (OAEP padding vs PKCS#1 v1.5 padding).
  // For specific limits, see: RSA Encryption Maximum Number of Bytes

  // Encrypt the utf-8 byte representation of the string.
  rsa.charset = 'utf-8';
  rsa.encodingMode = 'base64';

  // Be Careful when Using non-us-ascii String Literals in Source Code
  final encryptedB64 = rsa.encryptStringENC('Élève français dîne à côté d’un café où l’on sert déjà du gâteau au chocolat et des éclairs délicieux', false);

  // ------------------------------------------------------------------------------------------------------------------------
  // Let's decrypt, which requires the matching private key...

  // Load the matching 2048-bit RSA private key.
  final privKey = CkPrivateKey();
  final password = 'secret';
  success = true;
  try {
    privKey.loadAnyFormatFile('rsaKeys/myTestRsaPrivate.pem', password);
  } on ChilkatException {
    success = false;
  }
  if (!success) {
    print(privKey.lastErrorText);
    return;
  }

  // Tell the RSA object to use the private key.
  rsa.usePrivateKey(privKey);

  // Indicate that after decrypting the resultant decrypted bytes contains the utf-8 byte representation of the text.
  rsa.charset = 'utf-8';
  rsa.encodingMode = 'base64';
  final originalText = rsa.decryptStringENC(encryptedB64, true);
  if (!success) {
    print(rsa.lastErrorText);
    return;
  }

  print('Original text = $originalText');
  print('Success.');
}