使用 SHA1 和 RSA 与 java.security.Signature 对比消息摘要和密码

StackOverflow https://stackoverflow.com/questions/521101

题

我试图理解Java是什么 java.security.Signature 类确实如此。如果我计算 SHA1 消息摘要，然后使用 RSA 加密该摘要，我会得到与询问不同的结果 签名 类来签署相同的东西：

// Generate new key
KeyPair keyPair = KeyPairGenerator.getInstance("RSA").generateKeyPair();
PrivateKey privateKey = keyPair.getPrivate();
String plaintext = "This is the message being signed";

// Compute signature
Signature instance = Signature.getInstance("SHA1withRSA");
instance.initSign(privateKey);
instance.update((plaintext).getBytes());
byte[] signature = instance.sign();

// Compute digest
MessageDigest sha1 = MessageDigest.getInstance("SHA1");
byte[] digest = sha1.digest((plaintext).getBytes());

// Encrypt digest
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
byte[] cipherText = cipher.doFinal(digest);

// Display results
System.out.println("Input data: " + plaintext);
System.out.println("Digest: " + bytes2String(digest));
System.out.println("Cipher text: " + bytes2String(cipherText));
System.out.println("Signature: " + bytes2String(signature));

结果（例如）：

输入数据：这是正在签名的消息
消化：62b0a9ef15461c82766fb5bdaae9edbe4ac2e067
密文：057dc0d2f7f54acc95d3cf5cba9f944619394711003bdd12...
签名：7177c74bbbb871cc0af92e30d2808ebae146f25d3fd8ba1622...

我一定对什么有一个根本性的误解 签名 正在做 - 我已经追踪过它，它似乎正在调用更新 信息摘要 对象，按照我的预期将算法设置为 SHA1，然后获取摘要，然后进行加密。是什么导致结果不同？

编辑：

列奥尼达斯让我检查签名方案是否应该按照我的想法进行。签名中定义了两种类型 RFC:

这 首先是这些 (PKCS1) 是我上面描述的。它使用哈希函数创建摘要，然后使用私钥对结果进行加密。

这 第二种算法 使用随机盐值，更安全但具有不确定性。如果重复使用相同的密钥，上面代码生成的签名不会改变，所以我认为它不可能是PSS。

编辑：

这是 bytes2string 我使用的方法：

private static String bytes2String(byte[] bytes) {
    StringBuilder string = new StringBuilder();
    for (byte b : bytes) {
        String hexString = Integer.toHexString(0x00FF & b);
        string.append(hexString.length() == 1 ? "0" + hexString : hexString);
    }
    return string.toString();
}
有帮助吗？

解决方案

好的，我已经弄清楚发生了什么事。我真是太傻了。Leonidas 是对的，加密的不仅仅是哈希值，还有与摘要连接的哈希算法的 ID：

  DigestInfo ::= SEQUENCE {
      digestAlgorithm AlgorithmIdentifier,
      digest OCTET STRING
  }

这就是为什么它们不同。

其他提示

要产生相同的结果：

MessageDigest sha1 = MessageDigest.getInstance("SHA1", BOUNCY_CASTLE_PROVIDER);
byte[] digest = sha1.digest(content);
DERObjectIdentifier sha1oid_ = new DERObjectIdentifier("1.3.14.3.2.26");

AlgorithmIdentifier sha1aid_ = new AlgorithmIdentifier(sha1oid_, null);
DigestInfo di = new DigestInfo(sha1aid_, digest);

byte[] plainSig = di.getDEREncoded();
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding", BOUNCY_CASTLE_PROVIDER);
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
byte[] signature = cipher.doFinal(plainSig);

嗯，在理解你的问题后：您确定签名方法仅创建 SHA1 并对其进行加密吗？GPG 等人提出压缩/清除数据签名。也许这个 java-signature-alg 还创建了一个可分离/可附加的签名。

bytes2String 方法的一个稍微高效的版本是

private static final char[] hex = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
private static String byteArray2Hex(byte[] bytes) {
    StringBuilder sb = new StringBuilder(bytes.length * 2);
    for (final byte b : bytes) {
        sb.append(hex[(b & 0xF0) >> 4]);
        sb.append(hex[b & 0x0F]);
    }
    return sb.toString();
}

以@Mike Houston 的答案为指针，这里是一个完整的示例代码，用于签名、哈希和加密。

/**
 * @param args
 */
public static void main(String[] args)
{
    try
    {
        boolean useBouncyCastleProvider = false;

        Provider provider = null;
        if (useBouncyCastleProvider)
        {
            provider = new BouncyCastleProvider();
            Security.addProvider(provider);
        }

        String plainText = "This is a plain text!!";

        // KeyPair
        KeyPairGenerator keyPairGenerator = null;
        if (null != provider)
            keyPairGenerator = KeyPairGenerator.getInstance("RSA", provider);
        else
            keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        keyPairGenerator.initialize(2048);

        KeyPair keyPair = keyPairGenerator.generateKeyPair();

        // Signature
        Signature signatureProvider = null;
        if (null != provider)
            signatureProvider = Signature.getInstance("SHA256WithRSA", provider);
        else
            signatureProvider = Signature.getInstance("SHA256WithRSA");
        signatureProvider.initSign(keyPair.getPrivate());

        signatureProvider.update(plainText.getBytes());
        byte[] signature = signatureProvider.sign();

        System.out.println("Signature Output : ");
        System.out.println("\t" + new String(Base64.encode(signature)));

        // Message Digest
        String hashingAlgorithm = "SHA-256";
        MessageDigest messageDigestProvider = null;
        if (null != provider)
            messageDigestProvider = MessageDigest.getInstance(hashingAlgorithm, provider);
        else
            messageDigestProvider = MessageDigest.getInstance(hashingAlgorithm);
        messageDigestProvider.update(plainText.getBytes());

        byte[] hash = messageDigestProvider.digest();

        DigestAlgorithmIdentifierFinder hashAlgorithmFinder = new DefaultDigestAlgorithmIdentifierFinder();
        AlgorithmIdentifier hashingAlgorithmIdentifier = hashAlgorithmFinder.find(hashingAlgorithm);

        DigestInfo digestInfo = new DigestInfo(hashingAlgorithmIdentifier, hash);
        byte[] hashToEncrypt = digestInfo.getEncoded();

        // Crypto
        // You could also use "RSA/ECB/PKCS1Padding" for both the BC and SUN Providers.
        Cipher encCipher = null;
        if (null != provider)
            encCipher = Cipher.getInstance("RSA/NONE/PKCS1Padding", provider);
        else
            encCipher = Cipher.getInstance("RSA");
        encCipher.init(Cipher.ENCRYPT_MODE, keyPair.getPrivate());

        byte[] encrypted = encCipher.doFinal(hashToEncrypt);

        System.out.println("Hash and Encryption Output : ");
        System.out.println("\t" + new String(Base64.encode(encrypted)));
    }
    catch (Throwable e)
    {
        e.printStackTrace();
    }
}

您可以使用 BouncyCastle Provider 或默认的 Sun Provider。

我有类似的问题，我测试了添加代码并发现了一些有趣的结果。通过我添加的这段代码，我可以推断出，根据要使用的“提供商”，公司可能会有所不同？（因为加密中包含的数据在所有提供者中并不总是相同）。

我的测试结果。

结论 - 签名decipher = ???（垃圾） + imevesinfo（如果我们知道“垃圾”的值，数字签名将相等）

IDE Eclipse 输出...

输入数据：这是正在签名的消息

消化：62b0a9ef15461c82766fb5bdaae9edbe4ac2e067

摘要信息：3021300906052b0e03021a0500041462b0a9ef15461c82766fb5bdaae9edbe4ac2e067

签名解密：1ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff003021300906052b0e03021a0 500041462b0a9ef15461c82766fb5bdaae9edbe4ac2e067

代码

import java.security.InvalidKeyException;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.SignatureException;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import org.bouncycastle.asn1.x509.DigestInfo;
import org.bouncycastle.asn1.DERObjectIdentifier;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
public class prueba {
/**
* @param args
* @throws NoSuchProviderException 
* @throws NoSuchAlgorithmException 
* @throws InvalidKeyException 
* @throws SignatureException 
* @throws NoSuchPaddingException 
* @throws BadPaddingException 
* @throws IllegalBlockSizeException 
*///
public static void main(String[] args) throws NoSuchAlgorithmException, NoSuchProviderException, InvalidKeyException, SignatureException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException {
// TODO Auto-generated method stub
KeyPair keyPair = KeyPairGenerator.getInstance("RSA","BC").generateKeyPair();
PrivateKey privateKey = keyPair.getPrivate();
PublicKey puKey = keyPair.getPublic();
String plaintext = "This is the message being signed";
// Hacer la firma
Signature instance = Signature.getInstance("SHA1withRSA","BC");
instance.initSign(privateKey);
instance.update((plaintext).getBytes());
byte[] signature = instance.sign();
// En dos partes primero hago un Hash
MessageDigest digest = MessageDigest.getInstance("SHA1", "BC");
byte[] hash = digest.digest((plaintext).getBytes());
// El digest es identico a  openssl dgst -sha1 texto.txt
//MessageDigest sha1 = MessageDigest.getInstance("SHA1","BC");
//byte[] digest = sha1.digest((plaintext).getBytes());
AlgorithmIdentifier digestAlgorithm = new AlgorithmIdentifier(new
DERObjectIdentifier("1.3.14.3.2.26"), null);
// create the digest info
DigestInfo di = new DigestInfo(digestAlgorithm, hash);
byte[] digestInfo = di.getDEREncoded();
//Luego cifro el hash
Cipher cipher = Cipher.getInstance("RSA","BC");
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
byte[] cipherText = cipher.doFinal(digestInfo);
//byte[] cipherText = cipher.doFinal(digest2);
Cipher cipher2 = Cipher.getInstance("RSA","BC");
cipher2.init(Cipher.DECRYPT_MODE, puKey);
byte[] cipherText2 = cipher2.doFinal(signature);
System.out.println("Input data: " + plaintext);
System.out.println("Digest: " + bytes2String(hash));
System.out.println("Signature: " + bytes2String(signature));
System.out.println("Signature2: " + bytes2String(cipherText));
System.out.println("DigestInfo: " + bytes2String(digestInfo));
System.out.println("Signature Decipher: " + bytes2String(cipherText2));
}
许可以下： CC-BY-SA 和 归因
不隶属于 StackOverflow
scroll top