使用PBKDF2和AES256进行加密和解密-需要实际示例-如何获取派生密钥

Question

我试图了解如何通过使用PBKDF2和SHA256获得派生密钥。

我很纠结，需要一个清晰易懂的例子。

到目前为止我所拥有的：

>

我找到了https://en.wikipedia.org/wiki/PBKDF2其中有一个示例，但使用SHA1，具有以下值：

密码plnlrtfpijpuhqylxbgqiyipieyxvfsavzgxbbcfusqkozwpngsyjqlmjsytrmd UTF8

盐A009C1A485912C6AE630D3E744240B04 HEX

散列函数SHA1

密钥大小128

迭代1000次

我一直在使用https://gchq.github.io/CyberChef，可以得到输出17EB4014C8C461C300E9B61518B9A18B它与维基百科示例中派生的关键字节相匹配。

我一直在和你一起工作https://mkyong.com/java/java-aes-encryption-and-decryption/其中有一个名为getAESKeyFromPassword的方法，如下所示：

// Password derived AES 256 bits secret key
public static SecretKey getAESKeyFromPassword(char[] password, byte[] salt)
        throws NoSuchAlgorithmException, InvalidKeySpecException {

    SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
    // iterationCount = 65536
    // keyLength = 256
    KeySpec spec = new PBEKeySpec(password, salt, 65536, 256);
    SecretKey secret = new SecretKeySpec(factory.generateSecret(spec).getEncoded(), "AES");
    return secret;

}

我想进行同样的“调查”，就像我对Wikipedia页面、SHA1和CyberChef所做的那样，但使用SHA256（替换Java代码中的值，以匹配示例中的salt、密码和迭代）。

这就是我困惑的开始：

密码plnlrtfpijpuhqylxbgqiyipieyxvfsavzgxbbcfusqkozwpngsyjqlmjsytrmd UTF8

盐A009C1A485912C6AE630D3E744240B04 HEX

散列函数SHA256

密钥大小128

我希望派生密钥在CyberChef中与https://mkyong.com/java/java-aes-encryption-and-decryption/实例

不是。

我不禁认为我的理解有缺陷。

有人可以提供一个简单的（经过处理的）带有SHA256的PBKDF2示例，这样我就可以理解发生了什么。如果派生密钥不是相同的（与SHA1示例一样，请解释原因）。

是Java SecretKey：

SecretKey secret = new SecretKeySpec(factory.generateSecret(spec).getEncoded(), "AES");

与派生密钥相同？

似乎缺少易于理解的例子。

谢谢

英里。

Answer 1

感谢大家的投入，特别是Topaco:）

我要回答我的问题，因为我花了一些时间在MCVE上工作，并设法获得了与网络厨师相同的密钥。

密钥值为：28869b5f31ae29236f164c5cb33e2e3bb46f483867a15f8e7208e1836070f64a

以下是cyberChef的输出：

下面是Java代码，以及运行它的输出：

package crypto;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.GCMParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;
import java.util.Base64;

public class EncryptDecryptAesGcmPassword {

    private static final String ENCRYPT_ALGO = "AES/GCM/NoPadding";

    private static final int TAG_LENGTH_BIT = 128; // must be one of {128, 120,     112, 104, 96}
    private static final int IV_LENGTH_BYTE = 12;
    private static final int SALT_LENGTH_BYTE = 16;
    public static final int ITERATION_COUNT = 1000;
    public static final int KEY_LENGTH = 256;

    private static final Charset UTF_8 = StandardCharsets.UTF_8;

    // return a base64 encoded AES encrypted text
    public static String encrypt(byte[] salt, byte[] pText, String password) throws Exception {
        // GCM recommended 12 bytes iv?
        byte[] iv = getRandomNonce(IV_LENGTH_BYTE);

        // secret key from password
        SecretKey aesKeyFromPassword = getAESKeyFromPassword(password.toCharArray(), salt);

        Cipher cipher = Cipher.getInstance(ENCRYPT_ALGO);

        // ASE-GCM needs GCMParameterSpec
        cipher.init(Cipher.ENCRYPT_MODE, aesKeyFromPassword, new GCMParameterSpec(TAG_LENGTH_BIT, iv));

        byte[] cipherText = cipher.doFinal(pText);

        // prefix IV and Salt to cipher text
        byte[] cipherTextWithIvSalt = ByteBuffer.allocate(iv.length + salt.length + cipherText.length)
            .put(iv)
            .put(salt)
            .put(cipherText)
            .array();

        // string representation, base64, send this string to other for decryption.
        return Base64.getEncoder().encodeToString(cipherTextWithIvSalt);

    }

    // we need the same password, salt and iv to decrypt it
    private static String decrypt(String cText, String password) throws Exception {
        byte[] decode = Base64.getDecoder().decode(cText.getBytes(UTF_8));

        // get back the iv and salt from the cipher text
        ByteBuffer bb = ByteBuffer.wrap(decode);

        byte[] iv = new byte[IV_LENGTH_BYTE];
        bb.get(iv);

        byte[] salt = new byte[SALT_LENGTH_BYTE];
        bb.get(salt);

        byte[] cipherText = new byte[bb.remaining()];
        bb.get(cipherText);

        // get back the aes key from the same password and salt
        SecretKey aesKeyFromPassword = getAESKeyFromPassword(password.toCharArray(), salt);

        Cipher cipher = Cipher.getInstance(ENCRYPT_ALGO);

        cipher.init(Cipher.DECRYPT_MODE, aesKeyFromPassword, new GCMParameterSpec(TAG_LENGTH_BIT, iv));

        byte[] plainText = cipher.doFinal(cipherText);

        return new String(plainText, UTF_8);

    }


    public static byte hexToByte(String hexString) {
        int firstDigit = toDigit(hexString.charAt(0));
        int secondDigit = toDigit(hexString.charAt(1));
        return (byte) ((firstDigit << 4) + secondDigit);
    }

    public static byte[] decodeHexString(String hexString) {
        if (hexString.length() % 2 == 1) {
            throw new IllegalArgumentException(
                "Invalid hexadecimal String supplied.");
        }

        byte[] bytes = new byte[hexString.length() / 2];
        for (int i = 0; i < hexString.length(); i += 2) {
            bytes[i / 2] = hexToByte(hexString.substring(i, i + 2));
        }  
        return bytes;
    }

    private static int toDigit(char hexChar) {
        int digit = Character.digit(hexChar, 16);
        if (digit == -1) {
            throw new IllegalArgumentException(
                "Invalid Hexadecimal Character: "+ hexChar);
        }
        return digit;
    }

    // Random byte[] with length numBytes
    public static byte[] getRandomNonce(int numBytes) {
        byte[] nonce = new byte[numBytes];
        new SecureRandom().nextBytes(nonce);
        return nonce;
    }

    // Password derived AES 256 bits secret key
    public static SecretKey getAESKeyFromPassword(char[] password, byte[] salt)
        throws NoSuchAlgorithmException, InvalidKeySpecException {

        SecretKeyFactory factory =    SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
        // iterationCount = 1000
        // keyLength = 256
        KeySpec spec = new PBEKeySpec(password, salt, ITERATION_COUNT,
            KEY_LENGTH);
        SecretKey secret = new SecretKeySpec(factory.generateSecret(spec).getEncoded(), "AES");

        String encodedKey = hex(secret.getEncoded());

        // print SecretKey as hex
        System.out.println("SecretKey: " + encodedKey);

        return secret;

    }

    // hex representation
    public static String hex(byte[] bytes) {
        StringBuilder result = new StringBuilder();
        for (byte b : bytes) {
            result.append(String.format("%02x", b));
        }
        return result.toString();
    }



    public static void main(String[] args) throws Exception {
        String OUTPUT_FORMAT = "%-30s:%s";
        String PASSWORD = "plnlrtfpijpuhqylxbgqiiyipieyxvfsavzgxbbcfusqkozwpngsyejqlmjsytrmd";

        // plain text
        String pText = "AES-GSM Password-Bases encryption!";

        // convert hex string to byte[]
        byte[] salt = decodeHexString("A009C1A485912C6AE630D3E744240B04");


        String encryptedTextBase64 = EncryptDecryptAesGcmPassword.encrypt(salt, pText.getBytes(UTF_8), PASSWORD);

        System.out.println("\n------ AES GCM Password-based Encryption ------");
        System.out.println(String.format(OUTPUT_FORMAT, "Input (plain text)", pText));
        System.out.println(String.format(OUTPUT_FORMAT, "Encrypted (base64) ", encryptedTextBase64));

        System.out.println("\n------ AES GCM Password-based Decryption ------");
        System.out.println(String.format(OUTPUT_FORMAT, "Input (base64)", encryptedTextBase64));

        String decryptedText = EncryptDecryptAesGcmPassword.decrypt(encryptedTextBase64, PASSWORD);
        System.out.println(String.format(OUTPUT_FORMAT, "Decrypted (plain text)", decryptedText));
    }
}

运行此代码，生成以下内容：

SecretKey: 28869b5f31ae29236f164c5cb33e2e3bb46f483867a15f8e7208e1836070f64a

------ AES GCM Password-based Encryption ------
Input (plain text)            :AES-GSM Password-Bases encryption!
Encrypted (base64)            :/PuTLBTKVWgJB2iMoAnBpIWRLGrmMNPnRCQLBABOkwNeY8BrrdtoRNVFqZ+xmUjvF2PET6Ne2+PAp34QLCUFjQodTMdmzaNAfzcLWOf4

------ AES GCM Password-based Decryption ------
Input (base64)               :/PuTLBTKVWgJB2iMoAnBpIWRLGrmMNPnRCQLBABOkwNeY8BrrdtoRNVFqZ+xmUjvF2PET6Ne2+PAp34QLCUFjQodTMdmzaNAfzcLWOf4
SecretKey: 28869b5f31ae29236f164c5cb33e2e3bb46f483867a15f8e7208e1836070f64a
Decrypted (plain text)        :AES-GSM Password-Bases encryption!

谢谢

英里。