Java 如何制作弹力城堡公钥

我知道EC公钥的曲线名称（

secp256k1

）和

X

和

Y

坐标

package nl.owlstead.stackoverflow;

import static java.nio.charset.StandardCharsets.US_ASCII;

import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPairGenerator;
import java.security.Security;
import java.security.interfaces.ECPublicKey;
import java.security.spec.ECGenParameterSpec;
import java.security.spec.ECParameterSpec;
import java.security.spec.ECPoint;
import java.security.spec.ECPublicKeySpec;

import javax.crypto.Cipher;

import org.bouncycastle.jce.ECNamedCurveTable;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.jce.spec.ECNamedCurveParameterSpec;
import org.bouncycastle.jce.spec.ECNamedCurveSpec;
import org.bouncycastle.util.encoders.Hex;

public class ECPublicKeyFactory {

    public static void main(String[] args) throws Exception {

        String name = "secp256r1";

        Security.addProvider(new BouncyCastleProvider());

        // === NOT PART OF THE CODE, JUST GETTING TEST VECTOR ===
        KeyPairGenerator kpg = KeyPairGenerator.getInstance("EC", "BC");
        ECGenParameterSpec ecGenParameterSpec = new ECGenParameterSpec(name);
        kpg.initialize(ecGenParameterSpec);
        ECPublicKey key = (ECPublicKey) kpg.generateKeyPair().getPublic();
        byte[] x = key.getW().getAffineX().toByteArray();
        byte[] y = key.getW().getAffineY().toByteArray();

        // === here the magic happens ===
        KeyFactory eckf = KeyFactory.getInstance("EC");
        ECPoint point = new ECPoint(new BigInteger(1, x), new BigInteger(1, y));
        ECNamedCurveParameterSpec parameterSpec = ECNamedCurveTable.getParameterSpec(name);
        ECParameterSpec spec = new ECNamedCurveSpec(name, parameterSpec.getCurve(), parameterSpec.getG(), parameterSpec.getN(), parameterSpec.getH(), parameterSpec.getSeed());
        ECPublicKey ecPublicKey = (ECPublicKey) eckf.generatePublic(new ECPublicKeySpec(point, spec));
        System.out.println(ecPublicKey.getClass().getName());

        // === test 123 ===
        Cipher ecies = Cipher.getInstance("ECIESwithAES", "BC");
        ecies.init(Cipher.ENCRYPT_MODE, ecPublicKey);
        byte[] ct = ecies.doFinal("owlstead".getBytes(US_ASCII));
        System.out.println(Hex.toHexString(ct));
    }
}

如何从它们中生成

org.bouncycastle.jce.interfaces.ECPublicKey

我读过，但是那里的代码使用

java.security…

而不是

org.bouncycastle…

，ECPublicKey是

org.bouncycastle…

中的一个接口，而不是一个可实例化的类。

使用Bouncy Castle生成ECPublicKey 这将生成JCE/JCA中使用的EC公钥。Bouncy Castle提供商可以直接使用这些软件密钥。否则，Bouncy仅用于生成生成公钥所需的参数

package nl.owlstead.stackoverflow;

import static java.nio.charset.StandardCharsets.US_ASCII;

import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPairGenerator;
import java.security.Security;
import java.security.interfaces.ECPublicKey;
import java.security.spec.ECGenParameterSpec;
import java.security.spec.ECParameterSpec;
import java.security.spec.ECPoint;
import java.security.spec.ECPublicKeySpec;

import javax.crypto.Cipher;

import org.bouncycastle.jce.ECNamedCurveTable;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.jce.spec.ECNamedCurveParameterSpec;
import org.bouncycastle.jce.spec.ECNamedCurveSpec;
import org.bouncycastle.util.encoders.Hex;

public class ECPublicKeyFactory {

    public static void main(String[] args) throws Exception {

        String name = "secp256r1";

        Security.addProvider(new BouncyCastleProvider());

        // === NOT PART OF THE CODE, JUST GETTING TEST VECTOR ===
        KeyPairGenerator kpg = KeyPairGenerator.getInstance("EC", "BC");
        ECGenParameterSpec ecGenParameterSpec = new ECGenParameterSpec(name);
        kpg.initialize(ecGenParameterSpec);
        ECPublicKey key = (ECPublicKey) kpg.generateKeyPair().getPublic();
        byte[] x = key.getW().getAffineX().toByteArray();
        byte[] y = key.getW().getAffineY().toByteArray();

        // === here the magic happens ===
        KeyFactory eckf = KeyFactory.getInstance("EC");
        ECPoint point = new ECPoint(new BigInteger(1, x), new BigInteger(1, y));
        ECNamedCurveParameterSpec parameterSpec = ECNamedCurveTable.getParameterSpec(name);
        ECParameterSpec spec = new ECNamedCurveSpec(name, parameterSpec.getCurve(), parameterSpec.getG(), parameterSpec.getN(), parameterSpec.getH(), parameterSpec.getSeed());
        ECPublicKey ecPublicKey = (ECPublicKey) eckf.generatePublic(new ECPublicKeySpec(point, spec));
        System.out.println(ecPublicKey.getClass().getName());

        // === test 123 ===
        Cipher ecies = Cipher.getInstance("ECIESwithAES", "BC");
        ecies.init(Cipher.ENCRYPT_MODE, ecPublicKey);
        byte[] ct = ecies.doFinal("owlstead".getBytes(US_ASCII));
        System.out.println(Hex.toHexString(ct));
    }
}

生成Bouncy Castle和PublicKeyParameters 最初我认为需要一个Bouncy Castle特定的密钥，因此下面的代码生成了Bouncy Castle轻量级API中使用的EC公钥

package nl.owlstead.stackoverflow;

import java.math.BigInteger;
import java.security.KeyPairGenerator;
import java.security.Security;
import java.security.interfaces.ECPublicKey;
import java.security.spec.ECGenParameterSpec;

import org.bouncycastle.asn1.ASN1ObjectIdentifier;
import org.bouncycastle.asn1.x9.ECNamedCurveTable;
import org.bouncycastle.asn1.x9.X9ECParameters;
import org.bouncycastle.crypto.params.ECNamedDomainParameters;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.math.ec.ECCurve;
import org.bouncycastle.math.ec.ECPoint;
import org.bouncycastle.util.encoders.Hex;

public class BC_EC_KeyCreator {

    public static void main(String[] args) throws Exception {

        String name = "secp256r1";

        // === NOT PART OF THE CODE, JUST GETTING TEST VECTOR ===
        Security.addProvider(new BouncyCastleProvider());
        KeyPairGenerator kpg = KeyPairGenerator.getInstance("EC", "BC");
        kpg.initialize(new ECGenParameterSpec(name));
        ECPublicKey key = (ECPublicKey) kpg.generateKeyPair().getPublic();
        byte[] x = key.getW().getAffineX().toByteArray();
        byte[] y = key.getW().getAffineY().toByteArray();

        // assumes that x and y are (unsigned) big endian encoded
        BigInteger xbi = new BigInteger(1, x);
        BigInteger ybi = new BigInteger(1, y);
        X9ECParameters x9 = ECNamedCurveTable.getByName(name);
        ASN1ObjectIdentifier oid = ECNamedCurveTable.getOID(name);
        ECCurve curve = x9.getCurve();
        ECPoint point = curve.createPoint(xbi, ybi);
        ECNamedDomainParameters dParams = new ECNamedDomainParameters(oid,
                x9.getCurve(), x9.getG(), x9.getN(), x9.getH(), x9.getSeed());
        ECPublicKeyParameters pubKey = new ECPublicKeyParameters(point, dParams);
        System.out.println(pubKey);

        // some additional encoding tricks
        byte[] compressed = point.getEncoded(true);
        System.out.println(Hex.toHexString(compressed));
        byte[] uncompressed = point.getEncoded(false);
        System.out.println(Hex.toHexString(uncompressed));
    }
}

---

这很棘手，因为我不想包含任何特定于JCE的代码，

X9ECParameters

不是

ECDomainParameters

的子类。因此，我使用了对从Bouncy Castle代码库中其他地方复制的

ECNamedDomainParameters

的转换。

在下面的代码中，

encoded

包含

0x04

，后面是32字节的X，然后是32字节的Y

或者，它可以包含

0x02

或

0x03

（取决于Y的符号），后跟32个字节的X

public static ECPublicKey decodeKey(byte[] encoded) throws InvalidKeySpecException, NoSuchAlgorithmException, NoSuchProviderException{
    ECNamedCurveParameterSpec params = ECNamedCurveTable.getParameterSpec("secp256k1");
    KeyFactory fact = KeyFactory.getInstance("ECDSA", "BC");
    ECCurve curve = params.getCurve();
    java.security.spec.EllipticCurve ellipticCurve = EC5Util.convertCurve(curve, params.getSeed());
    java.security.spec.ECPoint point = ECPointUtil.decodePoint(ellipticCurve, encoded);
    java.security.spec.ECParameterSpec params2 =EC5Util.convertSpec(ellipticCurve, params);
    java.security.spec.ECPublicKeySpec keySpec = new java.security.spec.ECPublicKeySpec(point,params2);
    return (ECPublicKey) fact.generatePublic(keySpec);
}

---

已提供ECUtil

ECPublicKeyParameters bcecPublicKey =(ECPublicKeyParameters) ECUtil.generatePublicKeyParameter(kp.getPublic());
ECPrivateKeyParameters bcecPrivateKey = (ECPrivateKeyParameters) ECUtil.generatePrivateKeyParameter(kp.getPrivate());

---

Thomas答案的一个较短的变体（不使用

KeyFactory

）是：

公共静态ECPublicKey解码密钥（字节[]编码）{
ECNamedCurveParameterSpec params=ECNamedCurveTable.getParameterSpec（“secp256k1”）；
ECPublicKeySpec keySpec=新的ECPublicKeySpec（params.getCurve（）.decodePoint（encoded），params）；
返回新的BCECPublicKey（“ECDSA”、keySpec、BouncyCastleProvider.CONFIGURATION）；
}

---

我假设

encoded

是通过

BCECPublicKey.getQ（）.getEncoded（bool）

获得的，也就是说，它是一个字节

0x2-0x4

，后跟

secp256k1

上公共点的一个或两个仿射坐标，你真的需要使用org.bouncycastle.*类吗？我希望您能够更好地尝试将JCEAPI与BC一起用作提供者。或者，如果您不介意对BC的直接依赖，那么如果您直接使用轻量级（即非JCE）API，事情可能会更简单。@PeterDettman bouncycastle有一个非JCE API吗？我正在使用BC的ECIES——这是否意味着我应该坚持使用JCE API？请不要忘记指出语言/运行时（Java）以及其他标记，如加密。没有那么多人关注。谢谢你的工作。使用bcpkix-jdk15on-152.jar和bcprov-jdk15on-152.jar

org.bouncycastle.jce.ECNameCurveTable

没有方法

getByName

或

getOID

，因此代码不会编译。

org.bouncycastle.crypto.params.ECPublicKeyParameters

不是

org.bouncycastle.jce.interfaces.ECPublicKey

，这就是我认为我需要在“ECIESwithAES”

javax.crypto.Cipher

上调用的

init

。谢谢你的工作-我还没有足够的代表投票支持你的答案，但我会的。我找到了一种更简单的方法来满足我的需要。@MaartenBodewes我接受了你的答案，因为它更普遍地有用。