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Tutoriel de l'algorithme ECDSA pour signer une chaîne

Pouvez-vous m'aider à trouver un tutoriel simple sur la façon de signer une chaîne à l'aide de l'algorithme ECDSA en Java. Mais sans utiliser de bibliothèques tierces comme Bouncycastle. Just JDK 7. J'ai trouvé difficile de chercher un exemple simple, je suis novice en cryptographie.

import Java.io.*;
import Java.security.*;

public class GenSig {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        /*
         * Generate a DSA signature
         */

        try {

            /*
             * Generate a key pair
             */

            KeyPairGenerator keyGen = KeyPairGenerator.getInstance("DSA", "Sun");
            SecureRandom random = SecureRandom.getInstance("SHA1PRNG", "Sun");

            keyGen.initialize(1024, random);

            KeyPair pair = keyGen.generateKeyPair();
            PrivateKey priv = pair.getPrivate();
            PublicKey pub = pair.getPublic();

            /*
             * Create a Signature object and initialize it with the private key
             */

            Signature dsa = Signature.getInstance("SHA1withDSA", "Sun");

            dsa.initSign(priv);

            String str = "This is string to sign";
            byte[] strByte = str.getBytes();
            dsa.update(strByte);

            /*
             * Now that all the data to be signed has been read in, generate a
             * signature for it
             */

            byte[] realSig = dsa.sign();
            System.out.println("Signature: " + new String(realSig));


        } catch (Exception e) {
            System.err.println("Caught exception " + e.toString());
        }
    }
}

Comment le modifier pour ECDSA?

javacryptographydigital-signaturebouncycastle
14
user1379574

Voici un petit exemple basé sur votre exemple.

import Java.math.BigInteger;
import Java.security.KeyPair;
import Java.security.KeyPairGenerator;
import Java.security.PrivateKey;
import Java.security.PublicKey;
import Java.security.SecureRandom;
import Java.security.Signature;

public class ECDSAExample {

    public static void main(String[] args) throws Exception {
        /*
         * Generate an ECDSA signature
         */

        /*
         * Generate a key pair
         */

        KeyPairGenerator keyGen = KeyPairGenerator.getInstance("EC");
        SecureRandom random = SecureRandom.getInstance("SHA1PRNG");

        keyGen.initialize(256, random);

        KeyPair pair = keyGen.generateKeyPair();
        PrivateKey priv = pair.getPrivate();
        PublicKey pub = pair.getPublic();

        /*
         * Create a Signature object and initialize it with the private key
         */

        Signature dsa = Signature.getInstance("SHA1withECDSA");

        dsa.initSign(priv);

        String str = "This is string to sign";
        byte[] strByte = str.getBytes("UTF-8");
        dsa.update(strByte);

        /*
         * Now that all the data to be signed has been read in, generate a
         * signature for it
         */

        byte[] realSig = dsa.sign();
        System.out.println("Signature: " + new BigInteger(1, realSig).toString(16));

    }
}
19
James K Polk
class ECCCipher {
    @Override
    public byte[] sign(PrivateKey privateKey, String message) throws Exception {
        Signature signature = Signature.getInstance("SHA1withECDSA");
        signature.initSign(privateKey);

        signature.update(message.getBytes());

        return signature.sign();
    }

    @Override
    public boolean verify(PublicKey publicKey, byte[] signed, String message) throws Exception {
        Signature signature = Signature.getInstance("SHA1withECDSA");
        signature.initVerify(publicKey);

        signature.update(message.getBytes());

        return signature.verify(signed);
    }
}

=========================

public class ECCCipherTest {

private final KeyPairGenerator keygen;

public ECCCipherTest() throws NoSuchProviderException, NoSuchAlgorithmException, InvalidAlgorithmParameterException {
    Security.addProvider(new BouncyCastleProvider());
    this.keygen = KeyPairGenerator.getInstance("ECDSA", "BC");
    keygen.initialize(new ECGenParameterSpec("brainpoolP384r1"));
}

@Test
public void ECC_CipherTest_1() throws Exception {
    String message = "hello world";

    ICipher<PrivateKey, PublicKey> cipher = new ECCCipher();
    KeyPair keyPair = keygen.generateKeyPair();

    byte[] encrypted = cipher.sign(keyPair.getPrivate(), message);

    Assert.assertTrue(cipher.verify(keyPair.getPublic(), encrypted, message));
}

}

ceci est un petit extrait de code de mon projet. ça marche pour moi. J'ai également inclus un test Junit; j'espère que cela aide.

juste au cas où quelqu'un se demanderait comment on charge la clé privée et la clé publique: (note: privKey est le tableau d'octets représentant le BigInteger en Java, et pubKey est le point de la courbe au format binaire)

    @Override
public PrivateKey generatePrivateKey(byte[] keyBin) throws InvalidKeySpecException, NoSuchAlgorithmException {
    ECNamedCurveParameterSpec spec = ECNamedCurveTable.getParameterSpec("secp256k1");
    KeyFactory kf = KeyFactory.getInstance("ECDSA", new BouncyCastleProvider());
    ECNamedCurveSpec params = new ECNamedCurveSpec("secp256k1", spec.getCurve(), spec.getG(), spec.getN());
    ECPrivateKeySpec privKeySpec = new ECPrivateKeySpec(new BigInteger(keyBin), params);
    return kf.generatePrivate(privKeySpec);
}

@Override
public PublicKey generatePublicKey(byte[] keyBin) throws InvalidKeySpecException, NoSuchAlgorithmException {
    ECNamedCurveParameterSpec spec = ECNamedCurveTable.getParameterSpec("secp256k1");
    KeyFactory kf = KeyFactory.getInstance("ECDSA", new BouncyCastleProvider());
    ECNamedCurveSpec params = new ECNamedCurveSpec("secp256k1", spec.getCurve(), spec.getG(), spec.getN());
    ECPoint point =  ECPointUtil.decodePoint(params.getCurve(), keyBin);
    ECPublicKeySpec pubKeySpec = new ECPublicKeySpec(point, params);
    return kf.generatePublic(pubKeySpec);
}
0
linehrr