java实现Blowfish算法加密解密

冷不防 2022-09-06 12:28 157阅读 0赞

# java实现Blowfish算法加密解密 #

BlowFish加密算法是一种对称的分组加密算法，每次加密一个64位分组，使用32位～448位的可变长度密钥，应用于内部加密。

## 一 Blowfish/ECB/NoPadding ##

## 1.前言 ##

*  java中Blowfish/ECB/NoPadding加密时，传入的字符串大小不是8个字节的倍数时，会报异常:

javax.crypto.IllegalBlockSizeException: Input length not multiple of 8 bytes

*  发生此异常的原因也很明显，就是字符串长度不是 8 字节的倍数，但是java默认不会自动填充，并且java默认不支持zeropadding，即默认不填充0，所以会直接抛出上述异常。
 *  按照这个思路，那么进行填充字节，使字节达到8字节的倍数就可以了，那么我们就实现填充0，即实现zeropadding

## 2. 代码 ##

import javax.crypto.Cipher;
    import javax.crypto.spec.SecretKeySpec;
    import java.nio.charset.StandardCharsets;
    import java.util.Arrays;
    
    /** * Blowfish/ECB/NoPadding 工具 */
    public class BlowfishECBNoPaddingUtil { 
    
        public static void main(String[] ags) { 
    
            String data = "90QQHWHSGABXSHWDYD";
            System.out.println("原始字符串:" + data);
            //加密
            String encrypt = encodingToBase64("weqweqwMMA", data);
            System.out.println("加密结果:" + encrypt);
            //解密
            String decodingByBase64 = decodingByBase64("weqweqwMMA", encrypt);
            System.out.println("解密结果:" + decodingByBase64);
    
            System.out.println("是否完全相等:" + data.equals(decodingByBase64));
    
        }
    
    
        /** * Blowfish/ECB/NoPadding 加密并输出base64 * 不足8倍数自动尾部补充0 * * @param key 密钥key * @param data 要加密的字符串 * @return 加密后的字符串 */
        public static String encodingToBase64(String key, String data) { 
            try { 
                Cipher cipher = Cipher.getInstance("Blowfish/ECB/NoPadding");
                int blockSize = cipher.getBlockSize();
                byte[] dataBytes = data.getBytes();
                int length = dataBytes.length;
                //计算需填充长度
                if (length % blockSize != 0) { 
                    length = length + (blockSize - (length % blockSize));
                }
                byte[] plaintext = new byte[length];
                //填充
                System.arraycopy(dataBytes, 0, plaintext, 0, dataBytes.length);
                SecretKeySpec keySpec = new SecretKeySpec(key.getBytes(), "Blowfish");
                cipher.init(Cipher.ENCRYPT_MODE, keySpec);
                return java.util.Base64.getEncoder().encodeToString(cipher.doFinal(plaintext));
    
            } catch (Exception e) { 
                e.printStackTrace();
                return null;
            }
        }
    
        /** * Blowfish/ECB/NoPadding 解密base64的字符串 * 自动去除尾部补充的0 * * @param key 密钥key * @param str 要解密的字符串 * @return 解密后的字符串 */
        public static String decodingByBase64(String key, String str) { 
            SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes(), "Blowfish");
            Cipher cipher;
    
            String cipherInstName = "Blowfish/ECB/NoPadding";
            byte[] doFinal;
    
            try { 
                cipher = Cipher.getInstance(cipherInstName);
                cipher.init(Cipher.DECRYPT_MODE, skeySpec);
                doFinal = cipher.doFinal(java.util.Base64.getDecoder().decode(str.getBytes()));
            } catch (Exception e) { 
                e.printStackTrace();
                return null;
            }
    
            int zeroIndex = doFinal.length;
            for (int i = doFinal.length - 1; i > 0; i--) { 
                if (doFinal[i] == (byte) 0) { 
                    zeroIndex = i;
                } else { 
                    break;
                }
            }
            // 删除末尾填充的0
            doFinal = Arrays.copyOf(doFinal, zeroIndex);
    
            return new String(doFinal, StandardCharsets.UTF_8);
        }
    }

## 二 待续 ##