关于Objectivec和Java下DES加密保持一致的方式

首先谢谢4楼id0096替我修改的bug，当时由于只用于密码加密，所以没有测试中文，本次更新添加了objective-c的des解密和中文加密失败的修正。

最近做了一个移动项目，是有服务器和客户端类型的项目，客户端是要登录才行的，登录的密码要用DES加密，服务器是用Java开发的，客户端要同时支持多平台（Android、iOS），在处理iOS的DES加密的时候遇到了一些问题，起初怎么调都调不成和Android端生成的密文相同。最终一个忽然的想法让我找到了问题的所在，现在将代码总结一下，以备自己以后查阅。

首先，Java端的DES加密的实现方式，代码如下：

public class DES {
    private static byte[] iv = { 1, 2, 3, 4, 5, 6, 7, 8 };

    public static String encryptDES(String encryptString, String encryptKey)
            throws Exception {
        IvParameterSpec zeroIv = new IvParameterSpec(iv);
        SecretKeySpec key = new SecretKeySpec(encryptKey.getBytes(), "DES");
        Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, key, zeroIv);
        byte[] encryptedData = cipher.doFinal(encryptString.getBytes());
        return Base64.encode(encryptedData);
    }
}

上述代码用到了一个Base64的编码类，其代码的实现方式如下：

public class Base64 {
    private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
            .toCharArray();

    /**
     * data[]进行编码
     * 
     * @param data
     * @return
*/
    public static String encode(byte[] data) {
        int start = 0;
        int len = data.length;
        StringBuffer buf = new StringBuffer(data.length * 3 / 2);

        int end = len - 3;
        int i = start;
        int n = 0;

        while (i <= end) {
            int d = ((((int) data[i]) & 0x0ff) << 16)
                    | ((((int) data[i + 1]) & 0x0ff) << 8)
                    | (((int) data[i + 2]) & 0x0ff);

            buf.append(legalChars[(d >> 18) & 63]);
            buf.append(legalChars[(d >> 12) & 63]);
            buf.append(legalChars[(d >> 6) & 63]);
            buf.append(legalChars[d & 63]);

            i += 3;

            if (n++ >= 14) {
                n = 0;
                buf.append(" ");
            }
        }

        if (i == start + len - 2) {
            int d = ((((int) data[i]) & 0x0ff) << 16)
                    | ((((int) data[i + 1]) & 255) << 8);

            buf.append(legalChars[(d >> 18) & 63]);
            buf.append(legalChars[(d >> 12) & 63]);
            buf.append(legalChars[(d >> 6) & 63]);
            buf.append("=");
        } else if (i == start + len - 1) {
            int d = (((int) data[i]) & 0x0ff) << 16;

            buf.append(legalChars[(d >> 18) & 63]);
            buf.append(legalChars[(d >> 12) & 63]);
            buf.append("==");
        }

        return buf.toString();
    }
｝

以上便是Java端的DES加密方法的全部实现过程。

我还编写了一个将byte的二进制转换成16进制的方法，以便调试的时候使用打印输出加密后的byte数组的内容，这个方法不是加密的部分，只是为调试而使用的：

    /**将二进制转换成16进制 
     * @param buf 
     * @return  String
*/  
    public static String parseByte2HexStr(byte buf[]) {  
            StringBuffer sb = new StringBuffer();  
            for (int i = 0; i < buf.length; i++) {  
                    String hex = Integer.toHexString(buf[i] & 0xFF);  
                    if (hex.length() == 1) {  
                            hex = '0' + hex;  
                    }  
                    sb.append(hex.toUpperCase());  
            }  
            return sb.toString();  
    }

下面是Objective-c在iOS上实现的DES加密算法:

 1 const Byte iv[] = {1,2,3,4,5,6,7,8};
 2 +(NSString *) encryptUseDES:(NSString *)plainText key:(NSString *)key
 3 {
 4     NSString *ciphertext = nil;
 5     NSData *textData = [plainText dataUsingEncoding:NSUTF8StringEncoding];
 6     NSUInteger dataLength = [textData length];
 7     unsigned char buffer[1024];
 8     memset(buffer, 0, sizeof(char));
 9     size_t numBytesEncrypted = 0;
10     CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmDES,
11                                           kCCOptionPKCS7Padding,
12                                           [key UTF8String], kCCKeySizeDES,
13                                           iv,
14                                           [textData bytes], dataLength,
15                                           buffer, 1024,
16                                           &numBytesEncrypted);
17     if (cryptStatus == kCCSuccess) {
18         NSData *data = [NSData dataWithBytes:buffer length:(NSUInteger)numBytesEncrypted];
19         ciphertext = [Base64 encode:data];
20     }
21     return ciphertext;
22 }

下面也是Objective-c的一个二进制转换为16进制的方法，也是为了测试方便查看写的：

+(NSString *) parseByte2HexString:(Byte *) bytes
{
    NSMutableString *hexStr = [[NSMutableString alloc]init];
    int i = 0;
    if(bytes)
    {
        while (bytes[i] != '\0') 
        {
            NSString *hexByte = [NSString stringWithFormat:@"%x",bytes[i] & 0xff];///16进制数
            if([hexByte length]==1)
                [hexStr appendFormat:@"0%@", hexByte];
            else 
                [hexStr appendFormat:@"%@", hexByte];
            
            i++;
        }
    }
    NSLog(@"bytes 的16进制数为:%@",hexStr);
    return hexStr;
}

+(NSString *) parseByteArray2HexString:(Byte[]) bytes
{
    NSMutableString *hexStr = [[NSMutableString alloc]init];
    int i = 0;
    if(bytes)
    {
        while (bytes[i] != '\0') 
        {
            NSString *hexByte = [NSString stringWithFormat:@"%x",bytes[i] & 0xff];///16进制数
            if([hexByte length]==1)
                [hexStr appendFormat:@"0%@", hexByte];
            else 
                [hexStr appendFormat:@"%@", hexByte];

            i++;
        }
    }
    NSLog(@"bytes 的16进制数为:%@",hexStr);
    return hexStr;
}

以上的加密方法所在的包是CommonCrypto/CommonCryptor.h。

以上便实现了Objective-c和Java下在相同的明文和密钥的情况下生成相同明文的算法。

Base64的算法可以用你们自己写的那个，不一定必须使用我提供的这个。解密的时候还要用Base64进行密文的转换。

iOS下的Base64算法在后面 。

JAVA下的解密算法如下：

　　private static byte[] iv = { 1, 2, 3, 4, 5, 6, 7, 8 };    
　　public static String decryptDES(String decryptString, String decryptKey)
            throws Exception {
        byte[] byteMi = Base64.decode(decryptString);
        IvParameterSpec zeroIv = new IvParameterSpec(iv);
        SecretKeySpec key = new SecretKeySpec(decryptKey.getBytes(), "DES");
        Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, key, zeroIv);
        byte decryptedData[] = cipher.doFinal(byteMi);

        return new String(decryptedData);
    }

Base64的decode方法如下：

　　public static byte[] decode(String s) {

        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        try {
            decode(s, bos);
        } catch (IOException e) {
            throw new RuntimeException();
        }
        byte[] decodedBytes = bos.toByteArray();
        try {
            bos.close();
            bos = null;
        } catch (IOException ex) {
            System.err.println("Error while decoding BASE64: " + ex.toString());
        }
        return decodedBytes;
    }
    private static void decode(String s, OutputStream os) throws IOException {
        int i = 0;

        int len = s.length();

        while (true) {
            while (i < len && s.charAt(i) <= ' ')
                i++;

            if (i == len)
                break;

            int tri = (decode(s.charAt(i)) << 18)
                    + (decode(s.charAt(i + 1)) << 12)
                    + (decode(s.charAt(i + 2)) << 6)
                    + (decode(s.charAt(i + 3)));

            os.write((tri >> 16) & 255);
            if (s.charAt(i + 2) == '=')
                break;
            os.write((tri >> 8) & 255);
            if (s.charAt(i + 3) == '=')
                break;
            os.write(tri & 255);

            i += 4;
        }
    }
    private static int decode(char c) {
        if (c >= 'A' && c <= 'Z')
            return ((int) c) - 65;
        else if (c >= 'a' && c <= 'z')
            return ((int) c) - 97 + 26;
        else if (c >= '0' && c <= '9')
            return ((int) c) - 48 + 26 + 26;
        else
            switch (c) {
            case '+':
                return 62;
            case '/':
                return 63;
            case '=':
                return 0;
            default:
                throw new RuntimeException("unexpected code: " + c);
            }
    }

Objective-c在下的DES解密算法:

 1 +(NSString *)decryptUseDES:(NSString *)cipherText key:(NSString *)key
 2 {
 3     NSString *plaintext = nil;
 4     NSData *cipherdata = [Base64 decode:cipherText];
 5     unsigned char buffer[1024];
 6     memset(buffer, 0, sizeof(char));
 7     size_t numBytesDecrypted = 0;
 8     CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmDES,
 9                                           kCCOptionPKCS7Padding,
10                                           [key UTF8String], kCCKeySizeDES,
11                                           iv,
12                                           [cipherdata bytes], [cipherdata length],
13                                           buffer, 1024,
14                                           &numBytesDecrypted);
15     if(cryptStatus == kCCSuccess) {
16         NSData *plaindata = [NSData dataWithBytes:buffer length:(NSUInteger)numBytesDecrypted];
17         plaintext = [[NSString alloc]initWithData:plaindata encoding:NSUTF8StringEncoding];
18     }
19     return plaintext;
20 }

下面是objective-c 实现的Base64工具对象，当然你也可以选择使用google的那个Base64类——GTMBase64（功能很强大）,初步测试使用GTMBase64和使用我写的这个Base64效果都是一样的。

  1 static const char encodingTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  2 
  3 @interface Base64()
  4 +(int)char2Int:(char)c;
  5 @end
  6 
  7 @implementation Base64
  8 
  9 +(NSString *)encode:(NSData *)data
 10 {
 11     if (data.length == 0)
 12         return nil;
 13     
 14     char *characters = malloc(data.length * 3 / 2);
 15     
 16     if (characters == NULL)
 17         return nil;
 18     
 19     int end = data.length - 3;
 20     int index = 0;
 21     int charCount = 0;
 22     int n = 0;
 23     
 24     while (index <= end) {
 25         int d = (((int)(((char *)[data bytes])[index]) & 0x0ff) << 16)
 26         | (((int)(((char *)[data bytes])[index + 1]) & 0x0ff) << 8)
 27         | ((int)(((char *)[data bytes])[index + 2]) & 0x0ff);
 28         
 29         characters[charCount++] = encodingTable[(d >> 18) & 63];
 30         characters[charCount++] = encodingTable[(d >> 12) & 63];
 31         characters[charCount++] = encodingTable[(d >> 6) & 63];
 32         characters[charCount++] = encodingTable[d & 63];
 33         
 34         index += 3;
 35         
 36         if(n++ >= 14)
 37         {
 38             n = 0;
 39             characters[charCount++] = ' ';
 40         }
 41     }
 42     
 43     if(index == data.length - 2)
 44     {
 45         int d = (((int)(((char *)[data bytes])[index]) & 0x0ff) << 16)
 46         | (((int)(((char *)[data bytes])[index + 1]) & 255) << 8);
 47         characters[charCount++] = encodingTable[(d >> 18) & 63];
 48         characters[charCount++] = encodingTable[(d >> 12) & 63];
 49         characters[charCount++] = encodingTable[(d >> 6) & 63];
 50         characters[charCount++] = '=';
 51     }
 52     else if(index == data.length - 1)
 53     {
 54         int d = ((int)(((char *)[data bytes])[index]) & 0x0ff) << 16;
 55         characters[charCount++] = encodingTable[(d >> 18) & 63];
 56         characters[charCount++] = encodingTable[(d >> 12) & 63];
 57         characters[charCount++] = '=';
 58         characters[charCount++] = '=';
 59     }
 60     NSString * rtnStr = [[NSString alloc] initWithBytesNoCopy:characters length:charCount encoding:NSUTF8StringEncoding freeWhenDone:YES];
 61     return rtnStr;
 62 
 63 }
 64 
 65 +(NSData *)decode:(NSString *)data
 66 {
 67     if(data == nil || data.length <= 0) {
 68         return nil;
 69     }
 70     NSMutableData *rtnData = [[NSMutableData alloc]init];
 71     int slen = data.length;
 72     int index = 0;
 73     while (true) {
 74         while (index < slen && [data characterAtIndex:index] <= ' ') {
 75             index++;
 76         }
 77         if (index >= slen || index  + 3 >= slen) {
 78             break;
 79         }
 80 
 81         int byte = ([self char2Int:[data characterAtIndex:index]] << 18) + ([self char2Int:[data characterAtIndex:index + 1]] << 12) + ([self char2Int:[data characterAtIndex:index + 2]] << 6) + [self char2Int:[data characterAtIndex:index + 3]];
 82         Byte temp1 = (byte >> 16) & 255;
 83         [rtnData appendBytes:&temp1 length:1];
 84         if([data characterAtIndex:index + 2] == '=') {
 85             break;
 86         }
 87         Byte temp2 = (byte >> 8) & 255;
 88         [rtnData appendBytes:&temp2 length:1];
 89         if([data characterAtIndex:index + 3] == '=') {
 90             break;
 91         }
 92         Byte temp3 = byte & 255;
 93         [rtnData appendBytes:&temp3 length:1];
 94         index += 4;
 95 
 96     }
 97     return rtnData;
 98 }
 99 
100 +(int)char2Int:(char)c
101 {
102     if (c >= 'A' && c <= 'Z') {
103         return c - 65;
104     } else if (c >= 'a' && c <= 'z') {
105         return c - 97 + 26;
106     } else if (c >= '0' && c <= '9') {
107         return c - 48 + 26 + 26;
108     } else {
109         switch(c) {
110             case '+':
111                 return 62;
112             case '/':
113                 return 63;
114             case '=':
115                 return 0;
116             default:
117                 return -1;
118         }
119     }
120 }
121 
122 @end

这个和java端的Base64的是一个算法，只是根据语言的特点不同有少许的改动。

Java端的测试代码如下：

    String plaintext = "abcd";
    String ciphertext = DES.encryptDES(plaintext, "20120401");
    System.out.println("明文：" + plaintext);
    System.out.println("密钥：" + "20120401");
    System.out.println("密文：" + ciphertext);
    System.out.println("解密后：" + DES.decryptDES(ciphertext, "20120401"));

输出结果：

明文：abcd
密钥：20120401
密文：W7HR43/usys=
解密后：abcd

Objective-c端的测试代码如下：

    NSString *plaintext = @"abcd";
    NSString *ciphertext = [EncryptUtil encryptUseDES:plaintext key:@"20120401"];
    NSLog(@"明文：%@",plaintext);
    NSLog(@"秘钥：%@",@"20120401");
    NSLog(@"密文：%@",ciphertext);

输出结果：

2012-04-05 12:00:47.348 TestEncrypt[806:f803] 明文：abcd
2012-04-05 12:00:47.350 TestEncrypt[806:f803] 秘钥：20120401
2012-04-05 12:00:47.350 TestEncrypt[806:f803] 密文：W7HR43/usys=