Question

我是RSA的新手并且使用BC从公钥获取SubjectPublicKeyInfo。

String key = "-----BEGIN RSA PUBLIC KEY-----\n" +
             "........\n" +// Multiple lines here
             "-----END RSA PUBLIC KEY-----\n";

Security.addProvider(new BouncyCastleProvider());
PEMParser reader = new PEMParser(new StringReader(key));
SubjectPublicKeyInfo subjectPublicKeyInfo = (SubjectPublicKeyInfo) reader.readObject();

然后我想要加密数据。我发现有人使用RSAEngine来做这件事：

AsymmetricKeyParameter aKey = (RSAKeyParameters) PublicKeyFactory.createKey(subjectPublicKeyInfo);
AsymmetricBlockCipher engine = new RSAEngine();
engine.init(false, aKey);
byte[] dataEncrypted = engine.processBlock(data, 0, data.length);

运行这些代码后，我发现结果并不等于预期。 所以我想知道我的代码中是否有任何错误？

Answer 1

最后我找到了出路。

如果有人熟悉BouncyCastle，他可以指出我的低级错误。

首先，要在Engine函数中首先使用true init初始化BouncyCastle来加密数据。

其次，我的公钥是以＆＃39; ----- BEGIN RSA PUBLIC KEY ----- ＆＃39;开头。它是 PKCS＃1 格式的RSA公钥，应该使用padding来读取，但加密数据应该有RSAEngine。所以，我不应该直接使用PKCS1Encoding，而是使用Security.addProvider(new BouncyCastleProvider()); PEMParser reader = new PEMParser(new StringReader(key)); SubjectPublicKeyInfo subjectPublicKeyInfo = (SubjectPublicKeyInfo) reader.readObject(); RSAKeyParameters rsaKeyParameters = (RSAKeyParameters) PublicKeyFactory.createKey(subjectPublicKeyInfo); PKCS1Encoding engine = new PKCS1Encoding(new RSAEngine()); engine.init(true, rsaKeyParameters); return engine.processBlock(data, 0, data.length);。

最后，发布我的加密代码并解密代码：

加密：

public static byte[] decryptByPublicKey(String data, String key) throws Exception {
    byte[] rawData = Base64.decode(data);
    Security.addProvider(new BouncyCastleProvider());
    PEMParser reader = new PEMParser(new StringReader(key));
    PEMKeyPair pemKeyPair = (PEMKeyPair) reader.readObject();
    SubjectPublicKeyInfo publicKeyInfo = pemKeyPair.getPublicKeyInfo();
    PrivateKeyInfo privateKeyInfo = pemKeyPair.getPrivateKeyInfo();
    RSAKeyParameters rsaKeyParameters = (RSAKeyParameters)     
    PrivateKeyFactory.createKey(privateKeyInfo);
    PKCS1Encoding engine = new PKCS1Encoding(new RSAEngine());
    engine.init(false, rsaKeyParameters);
    return engine.processBlock(rawData, 0, rawData.length);
}

解密：

    Security.addProvider(new BouncyCastleProvider());
    PEMParser reader = new PEMParser(new StringReader(key));
    PemObject obj = reader.readPemObject();
    org.bouncycastle.asn1.pkcs.RSAPublicKey rsaPublicKey = org.bouncycastle.asn1.pkcs.RSAPublicKey.getInstance(obj.getContent());
    BigInteger modulus = rsaPublicKey.getModulus();
    BigInteger publicExponent = rsaPublicKey.getPublicExponent();

    KeyFactory keyFactory = KeyFactory.getInstance("RSA", "BC");
    RSAPublicKeySpec pubKeySpec = new RSAPublicKeySpec(modulus, publicExponent);
    PublicKey pubKey = keyFactory.generatePublic(pubKeySpec);

    Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding", "BC");//This line should use right padding.For PKCS#1 format RSA key , it should be this.
    cipher.init(Cipher.ENCRYPT_MODE, pubKey);
    return cipher.doFinal(data);

对于加密，您可以使用模数和公共指数来创建JDK支持的密钥：

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另请参阅：Basic RSA example.

如何使用SubjectPublicKeyInfo加密数据？

1 个答案: