Dart

openssl smime -encrypt -des3 -in <file> <pem file>

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OpenSSL SMIME encrypt file using PEM containing a certificate. 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.

  // Load the cert from a PEM file.

  final pem = CkPem();
  // Our particular PEM was not encrypted, so we pass an empty password.
  // Also, a private key is not needed for encryption.  The PEM used to test this example
  // happens to have a private key, but it's not actually used.
  try {
    pem.loadPemFile('qa_data/openssl/rsaCertAndKey.pem', '');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  if (pem.numCerts == 0) {
    print('PEM does not contain any certificates.');
    return;
  }

  final CkCert cert;
  try {
    cert = pem.getCert(0);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // -------------------------------------------------------------------------------------
  // Duplicate this OpenSSL command:   openssl smime -encrypt -des3 -in <file> <pem file>
  // -------------------------------------------------------------------------------------
  final crypt = CkCrypt2();
  try {
    crypt.setEncryptCert(cert);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);

    return;
  }

  crypt.cryptAlgorithm = 'PKI';
  crypt.pkcs7CryptAlg = '3des';
  crypt.keyLength = 168;

  // Load the file to be encrypted.
  final bd = CkBinData();
  try {
    bd.loadFile('qa_data/openssl/hello.txt');
  } on ChilkatException {
    print('Failed to load the input file.');
    return;
  }

  // Encrypt.
  try {
    crypt.encryptBd(bd);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // The openssl smime -encrypt command produces encrypte MIME such as this:

  // MIME-Version: 1.0
  // Content-Disposition: attachment; filename="smime.p7m"
  // Content-Type: application/x-pkcs7-mime; smime-type=enveloped-data; name="smime.p7m"
  // Content-Transfer-Encoding: base64
  // 
  // MIICzwYJKoZIhvcNAQcDoIICwDCCArwCAQAxggF8MIIBeAIBADBgMEoxCzAJBgNVBAYTAlVTMRYw
  // FAYDVQQKEw1MZXQncyBFbmNyeXB0MSMwIQYDVQQDExpMZXQncyBFbmNyeXB0IEF1dGhvcml0eSBY
  // MwISA9Nqgb1dH/XTDNeKzN1nR85iMA0GCSqGSIb3DQEBAQUABIIBAIQqPexjxWovgxwKV/r3HL/U
  // EP9Yozvz5hBeX5VvRZjKSi4FRw5wapElPK+4FB82hiAR9Mi3c16PvPSVkJv3l78Mv5uaaOs/OmUz
  // mIHFB6Z+l2E52BDmUVWJZTQ09vdWy6+NIRlg2R9Z1NkmZ4BZCJk6mHB/Yx03IaOxK8LnwieDMthM
  // SvxbhJnIOISN7k7ofs+/0vTXUpdQ+tlmwyVySMGQ6VMk+z4sqZJ2stacqCPtt/aiSwJ9p0OKmihf
  // 3KDJceXJtavIQeA97yz1LqPvle35mmd5sBhV9qQYdTV/KJ+YM5uEZ9BHYbvMJbADFHwKzhcEY3qA
  // 7T9acmEsb7NycOIwggE1BgkqhkiG9w0BBwEwFAYIKoZIhvcNAwcECERX/ZoHweSkgIIBEMmCMx49
  // zjVAnGqRaBbvzQT1hg0uQSxIJjxMxC+HSuM+eY9oSOsbrw4uIijHKH9NdOpeDsdRzg2z5EBM7AlP
  // Ht9DyPW5C2deV6RPX4F8gyExz+JUXrd+3Yb3AKTdpDkTWDmNCeO0r/YSqp518+mfU5hG8e336u51
  // HAM44FeknA8oThWsD/wUB1e8vzsatK4UXW/KSu/166V7z+VT86kd+IHa7t60U9Yp0ZXgcM5Pb5Ni
  // 69Qc5MKPzom2801H5UR/WjCgsxOIjOj49sKisjRy79skrJzxY5ZG05T0dKn6KC3TjRpIEEeOyhCd
  // Nm2Y7dcW8GLMepdhWay5vePmQxmvmhbAtBprIem14NcrYeG6D5wP

  // We have the body in bd
  // Construct the header and base64 body...
  final sbEncryptedMime = CkStringBuilder();

  sbEncryptedMime.appendLine('MIME-Version: 1.0', true);
  sbEncryptedMime.appendLine('Content-Disposition: attachment; filename="smime.p7m"', true);
  sbEncryptedMime.appendLine('Content-Type: application/x-pkcs7-mime; smime-type=enveloped-data; name="smime.p7m"', true);
  sbEncryptedMime.appendLine('Content-Transfer-Encoding: base64', true);
  sbEncryptedMime.appendLine('', true);
  sbEncryptedMime.appendLine(bd.getEncoded('base64_mime'), true);

  // Show the result.
  print(sbEncryptedMime.getAsString());

  // or save to a file..
  sbEncryptedMime.writeFile('qa_output/encryptedMime.txt', 'utf-8', false);
}