如何在Linux下用C语言实现MD5DES解密

相关库函数如下：

#include <openssl/md5.h>

unsigned char *MD5(const unsigned char *d, unsigned long n,unsigned char *md)

int MD5_Init(MD5_CTX *c)

int MD5_Update(MD5_CTX *c, const void *data,unsigned long len)

int MD5_Final(unsigned char *md, MD5_CTX *c)

只有写的不好的程序，还没听说过报异常的算法，楼主真乃神人也！

你搞清楚UNIX/Linux同Windows的在处理文件上的区别了吗？之前我也一度写过这类东西，Windows的换行同Linux的是不同的，所以如果用终端输入去测试的话，很可能会有考虑不周的地方，试着用同一个字符串变量去测试，就能知道是否是算法的问题了。

// C 语言 DES用的是 ECB模式， 没有填充

// 因此Java端要对应， 你的明文是 liubiao 吗？

// 另外 DES已经不安全了， 如果可以改为 3DES或者 AES吧。

public class LearnDes {

public static void main(String[] args) {

try {

System.out.println(encrypt("liubiao", "12345678"))

System.out.println(decrypt("26d086be3a3a62fc", "12345678"))

} catch (Exception e) {

e.printStackTrace()

}

}

public static String encrypt(String message, String key) throws Exception {

//Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding")

Cipher cipher = Cipher.getInstance("DES/ECB/NOPADDING")

DESKeySpec desKeySpec = new DESKeySpec(key.getBytes("UTF-8"))

SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES")

SecretKey secretKey = keyFactory.generateSecret(desKeySpec)

IvParameterSpec iv = new IvParameterSpec(key.getBytes("UTF-8"))

//cipher.init(Cipher.ENCRYPT_MODE, secretKey, iv)

cipher.init(Cipher.ENCRYPT_MODE, secretKey )

return toHexString(cipher.doFinal(message.getBytes("UTF-8")))

}

public static String decrypt(String message, String key) throws Exception {

byte[] bytesrc = convertHexString(message)

//Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding")

Cipher cipher = Cipher.getInstance("DES/ECB/NOPADDING")

DESKeySpec desKeySpec = new DESKeySpec(key.getBytes("UTF-8"))

SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES")

SecretKey secretKey = keyFactory.generateSecret(desKeySpec)

IvParameterSpec iv = new IvParameterSpec(key.getBytes("UTF-8"))

//cipher.init(Cipher.DECRYPT_MODE, secretKey, iv)

cipher.init(Cipher.DECRYPT_MODE, secretKey )

byte[] retByte = cipher.doFinal(bytesrc)

return new String(retByte)

}

public static byte[] convertHexString(String ss) {

byte digest[] = new byte[ss.length() / 2]

for (int i = 0i <digest.lengthi++) {

String byteString = ss.substring(2 * i, 2 * i + 2)

int byteValue = Integer.parseInt(byteString, 16)

digest[i] = (byte) byteValue

}

return digest

}

public static String toHexString(byte b[]) {

StringBuffer hexString = new StringBuffer()

for (int i = 0i <b.lengthi++) {

String plainText = Integer.toHexString(0xff &b[i])

if (plainText.length() <2)

plainText = "0" + plainText

hexString.append(plainText)

}

return hexString.toString()

}

}

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