使用给定私钥在椭圆曲线算法中生成公钥的代码 [英] Codes to generate a public key in an elliptic curve algorithm using a given private key

问题描述

我需要使用jdk 1.7实现ECC（Elliptic Curve Cryptography）算法。我尝试使用充气城堡，sunEC，但他们都给出了错误和错误。我的目标是使用私钥生成椭圆曲线，我将被提供给系统。

I need to implement ECC (Elliptic Curve Cryptography) algorithm using jdk 1.7. I tried using bouncy castle, sunEC, but all of them gave errors and errors. My target is to generate an elliptic curve using the private key, I will be given to the system.

因此，我需要获得准确的代码来生成公钥使用jdk1.7使用给定的私钥。我使用的IDE是ecllipse。我需要知道，除私钥外，我应该给出的其他参数是什么？是否足以提供一个曲线点和私钥？

Thus, I need to get a accurate code to generate a public key using a given private key using jdk1.7. The IDE I use is ecllipse. And I need to know, what are the other parameters I should be given other than a private key? Is it enough to provide just a curve point and the private key?

有人可以帮助我从私钥生成公钥吗？我可以管理其余的实现。

Can someone help me to generate public key from private key?? I can manage the rest of my implementation.

任何知道使用java实现Elliptic Curve Cryptography密钥的人，请告诉我这段代码是否正确？

Anyone who knows to implement keys of Elliptic Curve Cryptography using java, please tell me whether this code is correct?

public class ECCrypt {

    private ECPoint curve_point;

      public ECCrypt(ECPoint curve_point) {
        this.curve_point = curve_point;
      }

public BigInteger makePublicKey(BigInteger privateKey) {
        ECPoint ecPublicKey = new ECPoint(curve_point);
        ecPublicKey.mult(privateKey);
        return ecPublicKey.pack();
}


public static void main(String[] argv) throws Exception {
        java.util.Random rnd = new java.util.Random();
        ECPoint cp = new ECPoint();
        cp.random(rnd);
        ECCrypt ec = new ECCrypt(cp);
        BigInteger priv = new BigInteger(255,rnd);
        BigInteger pub = ec.makePublicKey(priv);

}

谢谢！

推荐答案

我写了一个输出以下内容的示例程序：

I wrote a sample program that outputs the following:

FL261:java jvah$ javac -cp bcprov-ext-jdk15on-149.jar ECTest.java
FL261:java jvah$ java -cp bcprov-ext-jdk15on-149.jar:. ECTest
Private key: 7ba78909571fbc336b2b94054dfb745a6b0776ff36a8fa98a598dc32cb83cc8e
Public key: 035b9e4a6148c9f9b08b573871ac66a832e6e9f63cf117545523a45b8017b7c43f
Calculated public key: 035b9e4a6148c9f9b08b573871ac66a832e6e9f63cf117545523a45b8017b7c43f
Congratulations, public keys match!
FL261:java jvah$

代码应该足够清晰，以便你能够理解在这里完成。请注意，您必须知道为您的私钥生成哪条曲线，否则无法生成匹配的公钥。示例代码使用 secp256r1 曲线，这是很常用的。

The code should be clear enough so that you can understand what is done here. Please note that you really have to know which curve your private key is generated for, otherwise it is impossible to generate the matching public key. The sample code uses secp256r1 curve, which is quite commonly used.

import java.math.BigInteger;
import java.security.SecureRandom;

import org.bouncycastle.asn1.x9.X9ECParameters;
import org.bouncycastle.asn1.sec.SECNamedCurves;
import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.params.ECDomainParameters;
import org.bouncycastle.crypto.params.ECKeyGenerationParameters;
import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.crypto.generators.ECKeyPairGenerator;
import org.bouncycastle.math.ec.ECPoint;

class ECTest {
  public static String toHex(byte[] data) {
    StringBuilder sb = new StringBuilder();
    for (byte b: data) {
      sb.append(String.format("%02x", b&0xff));
    }
    return sb.toString();
  }

  public static void main(String[] argv) {
    // Get domain parameters for example curve secp256r1
    X9ECParameters ecp = SECNamedCurves.getByName("secp256r1");
    ECDomainParameters domainParams = new ECDomainParameters(ecp.getCurve(),
                                                             ecp.getG(), ecp.getN(), ecp.getH(),
                                                             ecp.getSeed());

    // Generate a private key and a public key
    AsymmetricCipherKeyPair keyPair;
    ECKeyGenerationParameters keyGenParams = new ECKeyGenerationParameters(domainParams, new SecureRandom());
    ECKeyPairGenerator generator = new ECKeyPairGenerator();
    generator.init(keyGenParams);
    keyPair = generator.generateKeyPair();

    ECPrivateKeyParameters privateKey = (ECPrivateKeyParameters) keyPair.getPrivate();
    ECPublicKeyParameters publicKey = (ECPublicKeyParameters) keyPair.getPublic();
    byte[] privateKeyBytes = privateKey.getD().toByteArray();

    // First print our generated private key and public key
    System.out.println("Private key: " + toHex(privateKeyBytes));
    System.out.println("Public key: " + toHex(publicKey.getQ().getEncoded(true)));

    // Then calculate the public key only using domainParams.getG() and private key
    ECPoint Q = domainParams.getG().multiply(new BigInteger(privateKeyBytes));
    System.out.println("Calculated public key: " + toHex(Q.getEncoded(true)));

    // The calculated public key and generated public key should always match
    if (!toHex(publicKey.getQ().getEncoded(true)).equals(toHex(Q.getEncoded(true)))) {
      System.out.println("ERROR: Public keys do not match!");
    } else {
      System.out.println("Congratulations, public keys match!");
    }
  }
}

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