React Native

Create PEM-encoded PKCS#7 Detached Signature

See more Digital Signatures Examples

Demonstrates how to create a PKCS7 PEM-encoded object containing a detached signature. React Native

import { Cert, Crypt2, StringBuilder } from '@chilkat/react-native'

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

  const cert = new Cert();

  // Load the cert and private key.
  try {
    cert.loadPfxFile('qa_data/pfx/myCertAndKey.p12', 'password');
  } catch {
    console.log(cert.lastErrorText);
    return;
  }

  const crypt = new Crypt2();

  try {
    crypt.setSigningCert(cert);
  } catch {
    console.log(crypt.lastErrorText);
    return;
  }

  // Use SHA-256
  crypt.hashAlgorithm = 'sha256';

  // Hash the utf-8 byte representation of the string
  crypt.charset = 'utf-8';

  // Return the result in base64
  crypt.encodingMode = 'base64Mime';

  // Sign some text to create a detached signature (i.e. a signature that does not include the signed data)
  const textToSign = 'This is the text to be hashed and signed.';
  let sigBase64: string;
  try {
    sigBase64 = await crypt.signStringENCAsync(textToSign);
  } catch {
    console.log(crypt.lastErrorText);
    return;
  }

  console.log(sigBase64);

  // The result:

  // MIIWbgYJKoZIhvcNAQcCoIIWXzCCFlsCAQExDzANBglghkgBZQMEAgEFADALBgkqhkiG9w0BBwGg
  // ghMXMIIFuzCCA6OgAwIBAgIIVwoRl0LE48wwDQYJKoZIhvcNAQELBQAwazELMAkGA1UEBhMCSVQx
  // ...
  // ...

  // If we want it in PEM format with just LF line-endings:
  const sb = new StringBuilder();
  // Just LF line endings, not CRLF.
  const crlf = false;
  sb.appendLine('-----BEGIN PKCS7-----', crlf);
  sb.append(sigBase64);
  sb.appendLine('-----END PKCS7-----', crlf);
  sb.toLF();

  // Save to a file.
  sb.writeFile('c:/temp/qa_output/sig.pem', 'utf-8', false);

  // Examine..
  console.log(sb.getAsString());

  // Result is:

  // -----BEGIN PKCS7-----
  // MIIWbgYJKoZIhvcNAQcCoIIWXzCCFlsCAQExDzANBglghkgBZQMEAgEFADALBgkqhkiG9w0BBwGg
  // ghMXMIIFuzCCA6OgAwIBAgIIVwoRl0LE48wwDQYJKoZIhvcNAQELBQAwazELMAkGA1UEBhMCSVQx
  // DjAMBgNVBAcMBU1pbGFuMSMwIQYDVQQKDBpBY3RhbGlzIFMucC5BLi8wMzM1ODUyMDk2NzEnMCUG
  // A1UEAwweQWN0YWxpcyBBdXRoZW50aWNhdGlvbiBSb290IENBMB4XDTExMDkyMjExMjIwMloXDTMw
  // MDkyMjExMjIwMlowazELMAkGA1UEBhMCSVQxDjAMBgNVBAcMBU1pbGFuMSMwIQYDVQQKDBpBY3Rh
  // bGlzIFMucC5BLi8wMzM1ODUyMDk2NzEnMCUGA1UEAwweQWN0YWxpcyBBdXRoZW50aWNhdGlvbiBS
  // b290IENBMIICIjANBgkqhkiG9w0BAQEFAAOCAg8AMIICCgKCAgEAp8bEpSmkLO/lGMWwUKNvUTuf
  // ClrJwkg4CsIcoBh/kbWHuUA/3R1oHwiD1S0eiKD4j1aPbZkCkpAW1V8IbInX4ay8IMKx4INRimlN
  // AJZaby/ARH6jDuSRzVju3PvHHkVH3Se5CAGfpiEd9UEtL0z9KK3giq0itFZljoZUj5NDKd45Rnij
  // MCO6zfB9E1fAXdKDa0hMxKufgFpbOr3JpyI/gCczWw63igxdBzcIy2zSekciRDXFzMwujt0q7bd9
  // ...
  // ...
  // -----END PKCS7-----
}