在本文中，我们将向您展示如何使用RFC 7539中定义的ChaCha20流密码对消息进行加密和解密。

PS ChaCha20流密码可从Java 11获得，请参阅JEP 329 。

注意
您可能对此ChaCha20-Poly1305加密示例感兴趣

1.如何运作？

1.1 ChaCha20加密和解密的输入：

• 256位密钥（32字节）
• 96位随机数（12个字节）
• 32位初始计数（4个字节）

1.2 ChaCha20加密。

(plain text) + (secrect key | nonce | initial count) -> `ChaCha20` -> ciphertext (encrypted text).

1.2 ChaCha20解密。

ciphertext + (secrect key | nonce | initial count) -> `ChaCha20` -> plain text.

1.3 ChaCha20加密使用密钥和IV（初始化值，随机数+初始计数）将纯文本加密为等长的密文。

1.4每次加密的随机数和秘密密钥必须唯一。 随机数和初始计数可以公开知道，但是密钥必须是私有的并对其保密。

ChaCha20 Java实现
下载JDK源代码，并找到用于ChaCha20算法实现的此类ChaCha20Cipher 。

package com.sun.crypto.provider;/*** Implementation of the ChaCha20 cipher, as described in RFC 7539.** @since 11*/
abstract class ChaCha20Cipher extends CipherSpi {//...
}

2. ChaCha20加密和解密。

2.1一个使用ChaCha20算法加密和解密消息的Java示例。

package com.mkyong.java11.jep329.chacha20;import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.ChaCha20ParameterSpec;/*
The inputs to ChaCha20 encryption, specified by RFC 7539, are:- A 256-bit secret key (32 bytes)- A 96-bit nonce (12 bytes)- A 32-bit initial count (4 bytes)
*/
public class ChaCha20 {private static final String ENCRYPT_ALGO = "ChaCha20";public byte[] encrypt(byte[] pText, SecretKey key, byte[] nonce, int counter) throws Exception {Cipher cipher = Cipher.getInstance(ENCRYPT_ALGO);ChaCha20ParameterSpec param = new ChaCha20ParameterSpec(nonce, counter);cipher.init(Cipher.ENCRYPT_MODE, key, param);byte[] encryptedText = cipher.doFinal(pText);return encryptedText;}public byte[] decrypt(byte[] cText, SecretKey key, byte[] nonce, int counter) throws Exception {Cipher cipher = Cipher.getInstance(ENCRYPT_ALGO);ChaCha20ParameterSpec param = new ChaCha20ParameterSpec(nonce, counter);cipher.init(Cipher.DECRYPT_MODE, key, param);byte[] decryptedText = cipher.doFinal(cText);return decryptedText;}}

2.1测试。

package com.mkyong.java11.jep329.chacha20;import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;public class TestChaCha20 {public static void main(String[] args) throws Exception {String input = "Java & ChaCha20 encryption example.";ChaCha20 cipher = new ChaCha20();SecretKey key = getKey();           // 256-bit secret key (32 bytes)byte[] nonce = getNonce();          // 96-bit nonce (12 bytes)int counter = 1;                    // 32-bit initial count (8 bytes)System.out.println("Input          : " + input);System.out.println("Input     (hex): " + convertBytesToHex(input.getBytes()));System.out.println("\n---Encryption---");byte[] cText = cipher.encrypt(input.getBytes(), key, nonce, counter);   // encryptSystem.out.println("Key       (hex): " + convertBytesToHex(key.getEncoded()));System.out.println("Nonce     (hex): " + convertBytesToHex(nonce));System.out.println("Counter        : " + counter);System.out.println("Encrypted (hex): " + convertBytesToHex(cText));System.out.println("\n---Decryption---");byte[] pText = cipher.decrypt(cText, key, nonce, counter);              // decryptSystem.out.println("Key       (hex): " + convertBytesToHex(key.getEncoded()));System.out.println("Nonce     (hex): " + convertBytesToHex(nonce));System.out.println("Counter        : " + counter);System.out.println("Decrypted (hex): " + convertBytesToHex(pText));System.out.println("Decrypted      : " + new String(pText));}// A 256-bit secret key (32 bytes)private static SecretKey getKey() throws NoSuchAlgorithmException {KeyGenerator keyGen = KeyGenerator.getInstance("ChaCha20");keyGen.init(256, SecureRandom.getInstanceStrong());return keyGen.generateKey();}// 96-bit nonce (12 bytes)private static byte[] getNonce() {byte[] newNonce = new byte[12];new SecureRandom().nextBytes(newNonce);return newNonce;}private static String convertBytesToHex(byte[] bytes) {StringBuilder result = new StringBuilder();for (byte temp : bytes) {result.append(String.format("%02x", temp));}return result.toString();}}

输出量

Input          : Java & ChaCha20 encryption example.
Input     (hex): 4a617661202620436861436861323020656e6372797074696f6e206578616d706c652e---Encryption---
Key       (hex): ee416df8b5154a4ac48f3930fcfa53ef7f677c8fd7cd093f1328eedfd831db1a
Nonce     (hex): 9806308f4d1732d2d39beaba
Counter        : 1
Encrypted (hex): 2149db2c32bf82f9e8dc0a709d8c15d5a22eb79d5f692e04f070d46cc7e264631f85e0---Decryption---
Key       (hex): ee416df8b5154a4ac48f3930fcfa53ef7f677c8fd7cd093f1328eedfd831db1a
Nonce     (hex): 9806308f4d1732d2d39beaba
Counter        : 1
Decrypted (hex): 4a617661202620436861436861323020656e6372797074696f6e206578616d706c652e
Decrypted      : Java & ChaCha20 encryption example.

key + nonce + counter必须相同，才能进行加密和解密，不同的单个位将产生不同的结果。

3. ChaCha20…版本2

3.1在此示例中，我们使用System.arraycopy将现时数和初始化计数器附加到密文（加密消息）的末尾，因此我们只需要用于解密的密钥即可。

package com.mkyong.java11.jep329.chacha20v2;import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.ChaCha20ParameterSpec;
import java.nio.ByteBuffer;public class ChaCha20v2 {private static final String ENCRYPT_ALGO = "ChaCha20";private static final int LEN_NONCE = 12;private static final int LEN_COUNTER = 4;public byte[] encrypt(byte[] pText, SecretKey key, byte[] nonce, int counter) throws Exception {Cipher cipher = Cipher.getInstance(ENCRYPT_ALGO);ChaCha20ParameterSpec param = new ChaCha20ParameterSpec(nonce, counter);cipher.init(Cipher.ENCRYPT_MODE, key, param);byte[] encryptedText = cipher.doFinal(pText);// append nonce + countbyte[] output = new byte[encryptedText.length + LEN_NONCE + LEN_COUNTER];System.arraycopy(encryptedText, 0, output, 0, encryptedText.length);System.arraycopy(nonce, 0, output, encryptedText.length, LEN_NONCE);// convert int to byte[]byte[] counterByteArray = ByteBuffer.allocate(4).putInt(counter).array();System.arraycopy(counterByteArray, 0, output, encryptedText.length + LEN_NONCE, LEN_COUNTER);return output;}public byte[] decrypt(byte[] cText, SecretKey key) throws Exception {Cipher cipher = Cipher.getInstance(ENCRYPT_ALGO);// get only the encrypted textbyte[] encryptedText = new byte[cText.length - (LEN_NONCE + LEN_COUNTER)];System.arraycopy(cText, 0, encryptedText, 0, cText.length - (LEN_NONCE + LEN_COUNTER));// get noncebyte[] nonce = new byte[12];System.arraycopy(cText, encryptedText.length, nonce, 0, LEN_NONCE);// get initial counterbyte[] counter = new byte[4];System.arraycopy(cText, encryptedText.length + LEN_NONCE, counter, 0, LEN_COUNTER);/// convert byte array to intint ic = ByteBuffer.wrap(counter).getInt();ChaCha20ParameterSpec param = new ChaCha20ParameterSpec(nonce, ic);cipher.init(Cipher.DECRYPT_MODE, key, param);byte[] decryptedText = cipher.doFinal(encryptedText);return decryptedText;}}

3.2对于解密，我们只需要提供秘密密钥，因为随机数和初始计数器位于加密文本或密文的末尾。

package com.mkyong.java11.jep329.chacha20v2;import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;public class TestChaCha20v2 {public static void main(String[] args) throws Exception {String input = "Java & ChaCha20 encryption example.";ChaCha20v2 cipher = new ChaCha20v2();SecretKey key = getKey();           // 256-bit secret key (32 bytes)byte[] nonce = getNonce();          // 96-bit nonce (12 bytes)int counter = 1;                    // 32-bit initial count (8 bytes)System.out.println("Input          : " + input);System.out.println("Input     (hex): " + convertBytesToHex(input.getBytes()));System.out.println("\n---Encryption---");byte[] cText = cipher.encrypt(input.getBytes(), key, nonce, counter);   // encryptSystem.out.println("Key       (hex): " + convertBytesToHex(key.getEncoded()));System.out.println("Nonce     (hex): " + convertBytesToHex(nonce));System.out.println("Counter        : " + counter);System.out.println("Encrypted (hex): " + convertBytesToHex(cText));System.out.println("\n---Decryption---");byte[] pText = cipher.decrypt(cText, key);              // decryptSystem.out.println("Key       (hex): " + convertBytesToHex(key.getEncoded()));System.out.println("Decrypted (hex): " + convertBytesToHex(pText));System.out.println("Decrypted      : " + new String(pText));}private static String convertBytesToHex(byte[] bytes) {StringBuilder result = new StringBuilder();for (byte temp : bytes) {result.append(String.format("%02x", temp));}return result.toString();}// A 256-bit secret key (32 bytes)private static SecretKey getKey() throws NoSuchAlgorithmException {KeyGenerator keyGen = KeyGenerator.getInstance("ChaCha20");keyGen.init(256, SecureRandom.getInstanceStrong());return keyGen.generateKey();}// 96-bit nonce (12 bytes)private static byte[] getNonce() {byte[] newNonce = new byte[12];new SecureRandom().nextBytes(newNonce);return newNonce;}}

输出量

Input          : Java & ChaCha20 encryption example.
Input     (hex): 4a617661202620436861436861323020656e6372797074696f6e206578616d706c652e---Encryption---
Key       (hex): f95fd5b41783595e41f4cbcd8dc26a782599184e97ccd768ac531aae729781d3
Nonce     (hex): 84133f2261ef44796e3669dc
Counter        : 1
Encrypted (hex): 7738807b409f3349dbefbeae988482e0e5959c35ee8f8ee8987357db459e10d7fb8c7e84133f2261ef44796e3669dc00000001---Decryption---
Key       (hex): f95fd5b41783595e41f4cbcd8dc26a782599184e97ccd768ac531aae729781d3
Decrypted (hex): 4a617661202620436861436861323020656e6372797074696f6e206578616d706c652e
Decrypted      : Java & ChaCha20 encryption example.

查看加密的文本； 它结合了加密的消息，随机数（12个字节）和初始计数器（4个字节）。

Encrypted (hex): 7738807b409f3349dbefbeae988482e0e5959c35ee8f8ee8987357db459e10d7fb8c7e84133f2261ef44796e3669dc00000001## split view
Encrypted (hex): 7738807b409f3349dbefbeae988482e0e5959c35ee8f8ee8987357db459e10d7fb8c7e | 84133f2261ef44796e3669dc | 00000001

注意
如果发现任何错误，请在下面发表评论，谢谢。

下载源代码

$ git clone https://github.com/mkyong/core-java.git

$ cd java-11

$ cd / src / main / java / com / mkyong / java11 / jep329

参考文献

• ChaCha20
• RFC 7539
• Cloudflare –需要两个到ChaCha（Poly）
• ChaCha20计数器实际上通过迭代增加吗？
• Java：ChaCha20带Poly1305作为MAC，用于通用文件加密

翻译自: https://mkyong.com/java/java-11-chacha20-stream-cipher-examples/