Dart Requires Chilkat v11.0.0+

Demonstrate RSA Encrypt/Decrypt using BinData

See more RSA Examples

Demonstrates how to RSA encrypt and decrypt data contained in a Chilkat BinData object. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // 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.
  try {
    pubKey.loadFromFile('rsaKeys/myTestRsaPublic.pem');
  } on ChilkatException catch (e) {
    print(e.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

  // Create some binary data to encrypt.
  final bd = CkBinData();
  for (var i = 0; i <= 49; i++) {
    bd.appendByte(i);
  }

  // Show the bytes to be encrypted in hex format:
  print('To be encrypted: ${bd.getEncoded('hex')}');

  // To be encrypted: 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F202122232425262728292A2B2C2D2E2F3031

  // RSA encrypt the contents of the bd, replacing the contents with the RSA encrypted data.
  rsa.encryptBd(bd, false);

  // Now it is encrypted.
  print('Encrypted size = ${bd.numBytes}');
  print(bd.getEncoded('hex'));

  // Encrypted size = 256
  // 749ED9D0A8767C06C09AD9697F654F86B145F966722F9714902C4175BDBD02E68984ECF111D4D461
  // EDB4A8E677D399D19CCA60F35C6DE9972F4262880FE9D77DB75915393E8E7DB80AAB5E383013FAEB
  // 60C77D1E6FECC9A7C8426976416C6218FE7DA998EE063CE709E79C240F8625F4A56A0A33AFD63F7A
  // BA26F2A692B42E878C53B78602C725FE63FF961A46A2B9D436E5E3D9D64AE3F1D1F5AD5F5B47FCD69
  // 447306B77F2FD6D766CCAA1A110A3371586B43DF0D7FFE2220D1B305CF9371AC342F849FB0C90CD99E
  // C176928D877FE1C0DE1A7CB6EB824FEC7E1DCF90EF2C6BA9F1DFD3EBFBE89C51AF074DC6AE02E544A78
  // 5018C36D3D48B2EF5202AF61AC

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

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

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

  // Decrypt
  try {
    rsa.decryptBd(bd, true);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Examine the contents of bd to see if it now contains the unencrypted original data.
  print('Decrypted: ${bd.getEncoded('hex')}');

  // Decrypted: 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F202122232425262728292A2B2C2D2E2F3031
}