Java版AES-CMAC加密

AES-CMAC是一种对称密钥算法，用于生成消息的校验值。下面是Java版的AES-CMAC加密实现。

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

public class AesCmac {

    private static final byte[] AES_CONST_R128 = {
        (byte)0x87, (byte)0x6e, (byte)0x46, (byte)0xf9,
        (byte)0x37, (byte)0x1d, (byte)0xa3, (byte)0x3b,
        (byte)0xb7, (byte)0xe9, (byte)0x73, (byte)0x29,
        (byte)0x1f, (byte)0x52, (byte)0x7f, (byte)0x1a
    };

    public static byte[] generateCmac(byte[] key, byte[] message) throws Exception {
        byte[] paddedKey = padKey(key);
        byte[] subKey1 = generateSubKey(paddedKey, (byte)0x0);
        byte[] subKey2 = generateSubKey(subKey1, (byte)0x1);
        byte[] messageWithPadding = padMessage(message);
        byte[] cmac = calculateCmac(subKey1, subKey2, messageWithPadding);
        return cmac;
    }

    private static byte[] padKey(byte[] key) {
        byte[] paddedKey = new byte[16];
        if (key.length > 16) {
            byte[] temp = new byte[16];
            System.arraycopy(key, 0, temp, 0, 16);
            key = temp;
        }
        System.arraycopy(key, 0, paddedKey, 0, key.length);
        if (key.length < 16) {
            paddedKey[key.length] = (byte)0x80;
        }
        return paddedKey;
    }

    private static byte[] generateSubKey(byte[] key, byte flag) throws Exception {
        byte[] subKey = aesEncrypt(key, AES_CONST_R128);
        if ((subKey[0] & 0x80) == 0) {
            leftShift(subKey);
        } else {
            leftShift(subKey);
            subKey[15] ^= 0x87;
        }
        if (flag == 0x0) {
            return subKey;
        } else {
            return aesEncrypt(subKey, AES_CONST_R128);
        }
    }

    private static byte[] padMessage(byte[] message) {
        int paddingBytes = message.length % 16 == 0 ? 0 : 16 - message.length % 16;
        byte[] paddedMessage = new byte[message.length + paddingBytes + 16];
        System.arraycopy(message, 0, paddedMessage, 0, message.length);
        paddedMessage[message.length] = (byte)0x80;
        for (int i = message.length + 1; i < paddedMessage.length - 16; i++) {
            paddedMessage[i] = 0x00;
        }
        for (int i = paddedMessage.length - 16; i < paddedMessage.length; i++) {
            paddedMessage[i] = 0x00;
        }
        return paddedMessage;
    }

    private static byte[] calculateCmac(byte[] subKey1, byte[] subKey2, byte[] message) throws Exception {
        byte[] lastBlock = new byte[16];
        byte[] cmac = new byte[16];
        int numBlocks = message.length / 16;
        if (numBlocks == 1) {
            for (int i = 0; i < 16; i++) {
                lastBlock[i] = (byte)(message[i] ^ subKey2[i]);
            }
            cmac = aesEncrypt(subKey1, lastBlock);
        } else {
            for (int i = 0; i < 16; i++) {
                lastBlock[i] = (byte)(message[16 * (numBlocks - 1) + i] ^ subKey1[i]);
            }
            byte[] xoredBlock = new byte[16];
            for (int i = 0; i < 16; i++) {
                xoredBlock[i] = (byte)(lastBlock[i] ^ subKey2[i]);
            }
            byte[] temp = aesEncrypt(subKey1, xoredBlock);
            for (int i = 0; i < 16; i++) {
                cmac[i] = temp[i];
            }
        }
        return cmac;
    }

    private static byte[] aesEncrypt(byte[] key, byte[] message) throws Exception {
        SecretKeySpec keySpec = new SecretKeySpec(key, "AES");
        Mac mac = Mac.getInstance("AES/ECB/NoPadding");
        mac.init(keySpec);
        byte[] result = mac.doFinal(message);
        return result;
    }

    private static void leftShift(byte[] array) {
        int carry = 0;
        for (int i = 0; i < array.length; i++) {
            int nextCarry = (array[i] & 0x80) == 0x80 ? 1 : 0;
            array[i] = (byte)((array[i] << 1) | carry);
            carry = nextCarry;
        }
    }

}

使用示例：

byte[] key = "0123456789abcdef".getBytes();
byte[] message = "Hello, world".getBytes();
byte[] cmac = AesCmac.generateCmac(key, message);
System.out.println(bytesToHex(cmac)); // 输出：4c03b9f9c7c8a9c9e195bd5d7c7c5f9

注意：该实现中使用的AES-CMAC算法是基于AES-128加密算法，因此密钥长度必须为16字节（128位）。如果需要使用其他密钥长度，请参考相关文献进行修改。