Java

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.

Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.EdDSA;
import com.chilkatsoft.chilkat2.JsonObject;
import com.chilkatsoft.chilkat2.PrivateKey;
import com.chilkatsoft.chilkat2.Prng;
import com.chilkatsoft.chilkat2.StringBuilder;

public class ChilkatExample {

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

        EdDSA eddsa = new EdDSA();
        Prng prng = new Prng();
        PrivateKey privKey = new PrivateKey();

        // Generates a new ed25519 key and stores it in privKey.
        try {
            eddsa.genEd25519Key(prng, privKey);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // ----------------------------------------------------------
        // Ed25519 PKCS1 format
        //
        // This is the format created by:  openssl genpkey -algorithm X25519 -out xkey.pem
        String pkcs1Base64 = privKey.getPkcs1ENC("base64");
        System.out.println(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.
        String pkcs8Base64 = privKey.getPkcs8ENC("base64");
        System.out.println(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.
        String password = "secret";
        String pkcs8EncBase64 = privKey.getPkcs8EncryptedENC("base64", password);
        System.out.println(pkcs8EncBase64);

        // ----------------------------------------------------------
        // Ed25519 in PEM format:
        //
        String ed25519Pem = privKey.getPkcs1Pem();
        System.out.println(ed25519Pem);

        // Sample output:

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

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

        JsonObject json = new JsonObject();
        json.load(jwk);
        json.setEmitCompact(false);
        System.out.println(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
        //
        String ed25519_xml = privKey.getXml();
        System.out.println(ed25519_xml);

        // 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
        //
        StringBuilder sbPubKeyHex = new StringBuilder();
        String privKeyHex = privKey.getRawHex(sbPubKeyHex);

        // We should have a 32-byte private key (a 64 character hex string).
        System.out.println("private key = " + privKeyHex);

        // We should have a 32-byte public key (a 64 character hex string).
        System.out.println("public key = " + sbPubKeyHex.getAsString());

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