0

So let's assume you want to verify a signature using a public key that uses ECDSA algorithm with brainpoolP256r1 elliptic curve.

For running the code below, follows these steps:

  1. generate a keypair of brainpool using these commands:
openssl ecparam -name brainpoolP256r1 -genkey -noout -out ec-brainpoolP256r1-priv-key.pem
openssl ec -in ec-brainpoolP256r1-priv-key.pem -pubout > ec-brainpoolP256r1-pub-key.pem
openssl pkcs8 -topk8 -nocrypt -in ec-brainpoolP256r1-priv-key.pem -out ec-brainpoolP256r1-priv-key-pkcs8.pem (to read it with tomitribe PEM utility, we need the PKCS8 format)
  1. Run the following code after using your generated keys:
package com.test.ecdsa;

import org.tomitribe.auth.signatures.PEM;

import java.io.ByteArrayInputStream;
import java.nio.charset.StandardCharsets;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;

public class Main {
    public static void main(String[] args) throws Exception {
        String privateKeyPem = "[use here the content from ec-brainpoolP256r1-priv-key-pkcs8.pem]";

        Signature signer = Signature.getInstance("SHA256withECDSA");
        PrivateKey privateKey = PEM.readPrivateKey(new ByteArrayInputStream(privateKeyPem.getBytes(StandardCharsets.UTF_8)));

        signer.initSign(privateKey);
        signer.update("testMessage".getBytes(StandardCharsets.UTF_8));
        byte[] signature = signer.sign();

        String publicKeyPem = "[use here the content from ec-brainpoolP256r1-pub-key.pem]";

        PublicKey publicKey = PEM.readPublicKey(new ByteArrayInputStream(publicKeyPem.getBytes(StandardCharsets.UTF_8)));
        Signature signatureVerifier = Signature.getInstance("SHA256withECDSA");
        signatureVerifier.initVerify(publicKey);
        signatureVerifier.update("testMessage".getBytes(StandardCharsets.UTF_8));

        boolean result = signatureVerifier.verify(signature);

        System.out.println(result);
    }
}

Running this code on java 8 will lead to:

Exception in thread "main" java.security.SignatureException: Could not sign data
    at sun.security.ec.ECDSASignature.signDigestNative(ECDSASignature.java:367)
    at sun.security.ec.ECDSASignature.engineSign(ECDSASignature.java:386)
    at java.security.Signature$Delegate.engineSign(Signature.java:1382)
    at java.security.Signature.sign(Signature.java:698)
    at com.ing.obp.jws.lib.Main.main(Main.java:29)
Caused by: java.security.InvalidAlgorithmParameterException
    at sun.security.ec.ECDSASignature.signDigest(Native Method)
    at sun.security.ec.ECDSASignature.signDigestNative(ECDSASignature.java:364)
    ... 4 more

Using java 11 the console will print "true".

Why is that?

Florin
  • 55
  • 8

1 Answers1

3

Well, Brainpool and other ECC support was added in java 11 (was not available since java 7, I found this link quite interesting: https://bugs.openjdk.java.net/browse/JDK-7007966)

If you want still to use java 8 for reading keys, signing, verifying signatures, then you will need BouncyCastleProvider.

Maven dependency:

<dependency>
    <groupId>org.bouncycastle</groupId>
    <artifactId>bcpkix-jdk15on</artifactId>
    <version>1.70</version>
</dependency>

To use it, you could register the provider to java's Security layer, and then refer to it in the Signature.getInstance using BouncyCastleProvider.PROVIDER_NAME.

Like this:

...
import org.bouncycastle.jce.provider.BouncyCastleProvider;
...
public class Main {
    static {
        Security.addProvider(new BouncyCastleProvider());
    }
...
        Signature signer = Signature.getInstance("SHA256withECDSA", BouncyCastleProvider.PROVIDER_NAME);
...
        Signature signatureVerifier = Signature.getInstance("SHA256withECDSA", BouncyCastleProvider.PROVIDER_NAME);
...
}
Florin
  • 55
  • 8