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Base64编码与DES加密解密算法

Base64编码是网络上最常见的用于传输8位字节代码的编码方式之一，可用于在HTTP环境下传递较长的标识信息。其运算原理基于计算机是8位存储的特点，通过将24位字符分解为4组6位的字符进行处理，并为每组高位补0，转换成ascii码后根据RFC2045～RFC2049表进行转换。

Base64编码示例

public class Test {
    public static void main(String[] args) throws Exception {
        Test test = new Test();
        test.testEncrypt();
        test.testDecrypt();
    }
    public void testEncrypt() throws Exception {
        String pwd = "123456";
        byte[] i = pwd.getBytes();
        String input = new BASE64Encoder().encodeBuffer(i);
        System.out.println(input);
    }
    public void testDecrypt() throws Exception {
        String pwd = "MTIzNDU2";
        byte[] o = new BASE64Decoder().decodeBuffer(pwd);
        String output = new String(o);
        System.out.println(output);
    }
}

输出结果

123456的Base64编码为：MTIzNDU2
解密后的结果为：123456

DES加密算法

DES（Data Encryption Standard）是一种对称加密算法，加密和解密均使用相同密钥进行处理。

public class DESTest {
    public static void main(String[] args) {
        DESTest t = new DESTest();
        String data = "123456";
        String encode_data = t.encode(data);
        System.out.println(encode_data);
        String decode_data = t.decode(encode_data);
        System.out.println(decode_data);
    }
    public static final String ALGORITHM_DES = "DES";
    public static final String SIGN_KEY = "20170313EHR";
    public String encode(String data) {
        if (data == null) {
            return null;
        }
        try {
            String key = SIGN_KEY;
            DESKeySpec dks = new DESKeySpec(key.getBytes());
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
            Key secretKey = keyFactory.generateSecret(dks);
            Cipher cipher = Cipher.getInstance(ALGORITHM_DES);
            cipher.init(Cipher.ENCRYPT_MODE, secretKey);
            byte[] bytes = cipher.doFinal(data.getBytes());
            return byte2str(bytes);
        } catch (Exception e) {
            e.printStackTrace();
            return data;
        }
    }
    public String decode(String data) {
        if (data == null) {
            return null;
        }
        try {
            String key = SIGN_KEY;
            DESKeySpec dks = new DESKeySpec(key.getBytes());
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
            Key secretKey = keyFactory.generateSecret(dks);
            Cipher cipher = Cipher.getInstance(ALGORITHM_DES);
            cipher.init(Cipher.DECRYPT_MODE, secretKey);
            byte[] bytes = cipher.doFinal(str2byte(data.getBytes()));
            return new String(bytes);
        } catch (Exception e) {
            e.printStackTrace();
            return data;
        }
    }
    private static byte[] str2byte(byte[] b) {
        if ((b.length % 2) != 0) {
            throw new IllegalArgumentException();
        }
        byte[] b2 = new byte[b.length / 2];
        for (int n = 0; n < b.length; n += 2) {
            String item = new String(b, n, 2);
            b2[n / 2] = (byte) Integer.parseInt(item, 16);
        }
        return b2;
    }
    private static String byte2str(byte[] b) {
        StringBuilder hs = new StringBuilder();
        for (int n = 0; n < b.length; n++) {
            String stmp = Integer.toHexString(b[n] & 0xFF);
            if (stmp.length() == 1) {
                hs.append('0');
            }
            hs.append(stmp);
        }
        return hs.toString().toUpperCase();
    }
}

编码与解密后的结果

• 编码：1730D210F056D4D8123456
• 解密：123456

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