java - ECDSA算法教程来签署一个字符串

Question

你能帮我找到一个关于如何在 java 中使用 ECDSA 算法对字符串进行签名的简单教程吗？但不使用任何第三方库，如 bouncycaSTLe。只是 JDK 7。我发现很难搜索一个简单的例子，我是密码学的新手。

---

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());
        }
    }
}

ECDSA如何修改？

Answer 1

这是基于您的示例的小示例。

注意:这是此答案的原始代码，请参阅下一个代码片段以获取更新版本。

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));

    }
}

更新:这里是略微改进的示例，删除了已弃用的算法。它还明确请求使用 SECG 符号“secp256r1”的 NIST P-256 曲线，如 RFC 8422. 中指定的那样

import java.math.BigInteger;
import java.security.*;
import java.security.spec.ECGenParameterSpec;

public class ECDSAExample {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws Exception {
        /*
         * Generate an ECDSA signature
         */

        /*
         * Generate a key pair
         */

        KeyPairGenerator keyGen = KeyPairGenerator.getInstance("EC");

        keyGen.initialize(new ECGenParameterSpec("secp256r1"), new SecureRandom());

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

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

        Signature ecdsa = Signature.getInstance("SHA256withECDSA");

        ecdsa.initSign(priv);

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

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

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

    }
}