Dart

Encrypt File to PKCS7 .p7m

See more Encryption Examples

_LANGUAGE_ example to public-key encrypt a file creating a PKCS#7 .p7m file as output. Also demonstrates how to decrypt the .p7m to recover the original file. Dart

import 'package:chilkat/chilkat.dart';

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

  final crypt = CkCrypt2();

  // Indicate the public-key encryption is to be used.
  // Do this by setting the encryption algorithm equal 
  // to "PKI" (an acroynm for public-key infrastructure).
  crypt.cryptAlgorithm = 'PKI';

  // Indicate the inner symmetric encryption algorithm to be used.
  // possible values are "aes", "des", "3des", and "rc2".
  // For this example, we'll use 256-bit AES encryption.
  crypt.pkcs7CryptAlg = 'aes';
  crypt.keyLength = 256;

  // To encrypt, only a certificate w/ public key is needed.
  // (The certificate w/ private key is required for decryption.)

  // The LoadFromFile method can load virtually any certificate format:
  // 1. DER encoded binary X.509 (.CER)
  // 2. Base-64 encoded X.509 (.CER)
  // 3. Cryptographic Message Syntax Standard - PKCS #7 Certificates (.P7B)
  // 4. PEM format
  final encryptCert = CkCert();
  try {
    encryptCert.loadFromFile('/Users/chilkat/testData/cer/acme.cer');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Tell the crypt object to use the certificate for encrypting:
  crypt.addEncryptCert(encryptCert);

  // Encrypt a file, producing a .p7m as output.
  // The input file is unchanged, the output .p7m contains the encrypted
  // contents of the input file.
  var inFile = '/Users/chilkat/testData/pdf/sample.pdf';
  var outFile = '/Users/chilkat/testData/p7m/sample.pdf.p7m';
  try {
    crypt.ckEncryptFile(inFile, outFile);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // For demonstration purposes, a different instance of the object will be used
  // for decryption.
  final decrypt = CkCrypt2();

  // To decrypt, the certificate w/ private key is required.  A PFX (also known
  // as PKCS#12) is a common secure container for certs and private keys.
  final pfxFilename = '/Users/chilkat/testData/pfx/acme.pfx';
  final pfxPassword = 'secret';

  // Tell the component to look in the PFX file for certs and private keys.
  try {
    decrypt.addPfxSourceFile(pfxFilename, pfxPassword);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Tell the decrypt object that PKI (public key encryption) is to be used
  // for decryptiong.
  decrypt.cryptAlgorithm = 'PKI';
  // There is no need to set the Pkcs7Alg or KeyLength because this information
  // is contained within the .p7m

  // Decrypt the .p7m
  inFile = '/Users/chilkat/testData/p7m/sample.pdf.p7m';
  outFile = '/Users/chilkat/testData/pdf/recovered.pdf';
  try {
    decrypt.ckDecryptFile(inFile, outFile);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Success!');
}