Java不可靠的字符串RSA加密/解密

Question

我有一个非常恼人的问题，Java中使用RSA算法对字符串进行不可靠的加密和解密。它似乎只能在大约 35% 的时间内工作，而且我不明白为什么它有时能工作，有时却不能。这是我写的一些测试代码，试图验证加密/解密中的随机性。它运行了 100 圈，每次都对相同的字符串进行加密和解密，并打印成功的次数:

    public static void main(String[] args) throws Exception {
    byte[] dataToEncrypt = "Hello World!".getBytes("UTF-16LE");
    byte[] cipherData = null;
    byte[] decryptedData;

    KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
    kpg.initialize(512);
    KeyPair kp = kpg.genKeyPair();
    Key publicKey = kp.getPublic();
    Key privateKey = kp.getPrivate();
    KeyFactory fact = KeyFactory.getInstance("RSA");

    RSAPublicKeySpec pub = (RSAPublicKeySpec) fact.getKeySpec(publicKey,
            RSAPublicKeySpec.class);

    RSAPublicKeySpec spec = new RSAPublicKeySpec(pub.getModulus(), pub
            .getPublicExponent());
    KeyFactory factory = KeyFactory.getInstance("RSA");

    PublicKey publicKeyRSA = factory.generatePublic(spec);
    Cipher cipher = Cipher.getInstance("RSA");

    int k = 0;
    for (int i = 0; i < 100; i++) {
        try {
            cipher.init(Cipher.ENCRYPT_MODE, publicKeyRSA);
            cipherData = cipher.doFinal(dataToEncrypt);
        } catch (Exception e1) {
            System.out.println("Encrypt error");
        }

        String s = new String(cipherData, "UTF-16LE");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);

        try {
            decryptedData = cipher.doFinal(s.getBytes("UTF-16LE"));
            System.out.println("Decrypted: "
                    + new String(decryptedData, "UTF-16LE"));
            k += 1;
        } catch (Exception e1) {
            System.out.println("Decrypt error");
        }
    }
    System.out.println("Number of correct decryptions is: " + k);

}

我尝试用各种值初始化 KeyPairGenerator 但没有成功。

编辑:现在它就像一个魅力，感谢 Base64 :

    import java.io.FileOutputStream;
    import java.io.OutputStream;
    import java.security.Key;
    import java.security.KeyFactory;
    import java.security.KeyPair;
    import java.security.KeyPairGenerator;
    import java.security.PublicKey;
    import java.security.spec.RSAPublicKeySpec;
    import javax.crypto.Cipher;

    public class Test {

    public static void main(String[] args) throws Exception {
    byte[] dataToEncrypt = "Hello World!".getBytes("UTF-16LE");
    byte[] cipherData = null;
    byte[] decryptedData;


    KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
    kpg.initialize(512);
    KeyPair kp = kpg.genKeyPair();
    Key publicKey = kp.getPublic();
    Key privateKey = kp.getPrivate();
    KeyFactory fact = KeyFactory.getInstance("RSA");

    RSAPublicKeySpec pub = (RSAPublicKeySpec) fact.getKeySpec(publicKey,
            RSAPublicKeySpec.class);

    RSAPublicKeySpec spec = new RSAPublicKeySpec(pub.getModulus(), pub
            .getPublicExponent());
    KeyFactory factory = KeyFactory.getInstance("RSA");

    PublicKey publicKeyRSA = factory.generatePublic(spec);
    Cipher cipher = Cipher.getInstance("RSA");

    int k = 0;
    for (int i = 0; i < 100; i++) {
        try {
            cipher.init(Cipher.ENCRYPT_MODE, publicKeyRSA);
            cipherData = cipher.doFinal(dataToEncrypt);
        } catch (Exception e1) {
            System.out.println("Encrypt error");
        }

        String s = Base64.encodeBytes(cipherData);
        cipher.init(Cipher.DECRYPT_MODE, privateKey);

        try {
            decryptedData = cipher.doFinal(Base64.decode(s));
            System.out.println("Decrypted: "
                    + new String(decryptedData, "UTF-16LE"));
            k += 1;
        } catch (Exception e1) {
            System.out.println("Decrypt error");
        }
    }
    System.out.println("Number of correct decryptions is: " + k);

}

Answer 1

这就是问题所在，或者至少是问题:

String s = new String(cipherData, "UTF-16LE");

您正在获取任意二进制数据 并尝试从中创建一个字符串，将其视为UTF-16 编码文本。它不是。它是任意二进制数据。

要么将其保存为二进制形式(如 byte[])，要么使用 base64 以安全、可逆的方式将其转换为文本。 (例如，This public domain base64 encoder 具有合理的 API。)