Dart

Get Ed25519 Key in Different Formats

See more Ed25519 Examples

Demonstrates how to get/save an Ed25519 private key to different formats.

Converting a private key from one format to another is done by loading in one format and saving/getting in another.

Note: This example requires Chilkat v9.5.0.83 or greater.

Dart

import 'package:chilkat/chilkat.dart';

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

  final eddsa = CkEdDSA();
  final prng = CkPrng();
  final privKey = CkPrivateKey();

  // Generates a new ed25519 key and stores it in privKey.
  try {
    eddsa.genEd25519Key(prng, privKey);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // ----------------------------------------------------------
  // Ed25519 PKCS1 format
  // 
  // This is the format created by:  openssl genpkey -algorithm X25519 -out xkey.pem
  final pkcs1Base64 = privKey.getPkcs1ENC('base64');
  print(pkcs1Base64);

  // Sample output:  MC4CAQAwBQYDK2VuBCIEIB1mwirs+eC6XGbkjPIiZyBwQ7768uSd9v5PHOLFbIXo

  // PKCS1 is a binary ASN.1 DER format.  You can examine the contents with two online tools:
  // 1) Go to ASN.1 Decoder  and paste the base64 into the online form.
  // 2) Or Decode Base64 ASN.1 to XML 

  // The PKCS1 ASN.1 format for an Ed25519 key look like this:
  //   SEQUENCE
  //     INTEGER 0
  //     SEQUENCE
  //       OBJECT IDENTIFIER 1.3.101.110 curveX25519 (ECDH 25519 key agreement algorithm)
  //     OCTET STRING 
  //       OCTET STRING (32 byte) 1D66C...

  // Save it directly to a file.
  privKey.savePkcs1File('qa_output/ed25519.key');

  // ----------------------------------------------------------
  // Ed25519 Unencrypted PKCS8 format
  // 
  // For ed25519, the ASN.1 output is the same as for PKCS1.
  final pkcs8Base64 = privKey.getPkcs8ENC('base64');
  print(pkcs8Base64);

  // PKCS8 is a binary ASN.1 DER format.  You can examine the contents with two online tools:
  // 1) Go to ASN.1 Decoder  and paste the base64 into the online form.
  // 2) Or Decode Base64 ASN.1 to XML 

  // ----------------------------------------------------------
  // Ed25519 Encrypted PKCS8 format
  // 
  // Note: The encrypted output cannot be examined using the above online tools because the ASN.1 is encrypted.
  final password = 'secret';
  final pkcs8EncBase64 = privKey.getPkcs8EncryptedENC('base64', password);
  print(pkcs8EncBase64);

  // ----------------------------------------------------------
  // Ed25519 in PEM format:
  // 
  final ed25519Pem = privKey.getPkcs1Pem();
  print(ed25519Pem);

  // Sample output:

  // -----BEGIN PRIVATE KEY-----
  // MC4CAQAwBQYDK2VuBCIEIOKPhbULJagBAi7hbRdn1f4AAzh1RqqCHqCAvau7N6yO
  // -----END PRIVATE KEY-----

  // ----------------------------------------------------------
  // Ed25519 in JWK Format
  // 
  final jwk = privKey.getJwk();

  final json = CkJsonObject();
  json.load(jwk);
  json.emitCompact = false;
  print(json.emit());

  // Sample output:
  // {
  //   "kty": "OKP",
  //   "crv": "Ed25519",
  //   "x": "SE2Kne5xt51z1eciMH2T2ftDQp96Gl6FhY6zSQujiP0",
  //   "d": "O-eRXewadF0sNyB0U9omcnt8Qg2ZmeK3WSXPYgqe570",
  //   "use": "sig"
  // }

  // In the above JWK, x is the public key, y is the private key.
  // Both are 32 bytes and are base64-url encoded.

  // ----------------------------------------------------------
  // Ed25519 in XML Format
  // 
  final ed25519Xml = privKey.getXml();
  print(ed25519Xml);

  // Sample output:  <Ed25519KeyValue>w4b/gI0zgYKgjtfWLjNfc4issmP7Qap84uesYNgEefP/WoY3jNOhOzgTYsMtOnuyGn3MdA4NZtsUXVNI1NiTlA==</Ed25519KeyValue>

  // The base64 content is composed of the concatenation of the 32-byte private key with the 32-byte public key and then base64 encoded.
  // In other words:  Base64(privKey || pubKey)

  // ----------------------------------------------------------
  // Ed25519 in Raw Hex Format
  // 
  final sbPubKeyHex = CkStringBuilder();
  final privKeyHex = privKey.getRawHex(sbPubKeyHex);

  // We should have a 32-byte private key (a 64 character hex string).
  print('private key = $privKeyHex');

  // We should have a 32-byte public key (a 64 character hex string).
  print('public key = ${sbPubKeyHex.getAsString()}');

  // Sample output:
  // key type = ed25519
  // size in bits = 256
  // private key = d4ee72dbf913584ad5b6d8f1f769f8ad3afe7c28cbf1d4fbe097a88f44755842
  // public key = 19bf44096984cdfe8541bac167dc3b96c85086aa30b6b6cb0c5c38ad703166e1
}