JAVA之AES_CBC模式解密

import lombok.extern.slf4j.Slf4j;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.springframework.stereotype.Component;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.security.Key;
import java.security.Security;
import java.util.Arrays;

 
@Slf4j
@Component
public class AesCbcUtils {



    // 算法名称
    final String KEY_ALGORITHM = "AES";
    // 加解密算法/模式/填充方式
    final String algorithmStr = "AES/CBC/PKCS7Padding";
    
     private Key key;

    private Cipher cipher;

    

    /**
     * 解密方法
     *
     * @param encryptedData
     *            要解密的字符串
     * @param keyBytes
     *            解密密钥
     *  @param iv
     * 		     偏移量
     * @return
     */
    public byte[] decrypt(byte[] encryptedData, byte[] keyBytes,byte[] iv) {
        byte[] encryptedText = null;
        init(keyBytes);
        System.out.println("IV：" + new String(iv));
        try {
            cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(iv));
            encryptedText = cipher.doFinal(encryptedData);
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return encryptedText;
    }

	public void init(byte[] keyBytes) {
        // 如果密钥不足16位，那么就补足.  这个if 中的内容很重要
        int base = 16;
        if (keyBytes.length % base != 0) {
            int groups = keyBytes.length / base + (keyBytes.length % base != 0 ? 1 : 0);
            byte[] temp = new byte[groups * base];
            Arrays.fill(temp, (byte) 0);
            System.arraycopy(keyBytes, 0, temp, 0, keyBytes.length);
            keyBytes = temp;
        }
        // 初始化
        Security.addProvider(new BouncyCastleProvider());
        // 转化成JAVA的密钥格式
        key = new SecretKeySpec(keyBytes, KEY_ALGORITHM);
        try {
            // 初始化cipher
            cipher = Cipher.getInstance(algorithmStr, "BC");
        } catch ( Exception e) {
        	e.printStackTrace();
        }
    }
     
}