iPhone 应用程序中的 3DES 加密总是产生与 Java 中的 3DES 加密不同的结果

Question

我必须在我的 iPhone 应用程序中加密一个字符串。加密方案是 3DES/CBC/PKCS5 填充，我必须在 Objective-c 中转换这个 Java 代码：

public class MessageEncrypt {

public String encryptString(String message, String seckey) throws Exception{
    byte[] encData = encrypt(message, seckey);

    return this.getHexString(encData, "");
}

public String decryptString(String message, String seckey) throws Exception{
    return decrypt(this.getBArray(message), seckey);
}

private byte[] encrypt(String message, String seckey) throws Exception {
    final MessageDigest md = MessageDigest.getInstance("md5");
    final byte[] digestOfPassword = md.digest(seckey.getBytes("utf-8"));
    final byte[] keyBytes = acopyof(digestOfPassword, 24);
    for (int j = 0, k = 16; j < 8;) {
        keyBytes[k++] = keyBytes[j++];
    }

    final SecretKey key = new SecretKeySpec(keyBytes, "DESede");
    final IvParameterSpec iv = new IvParameterSpec(new byte[8]);
    final Cipher cipher = Cipher.getInstance("DESede/CBC/PKCS5Padding");
    cipher.init(Cipher.ENCRYPT_MODE, key, iv);

    final byte[] plainTextBytes = message.getBytes("utf-8");
    final byte[] cipherText = cipher.doFinal(plainTextBytes);
    // final String encodedCipherText = new sun.misc.BASE64Encoder()
    // .encode(cipherText);

    return cipherText;
}

private String decrypt(byte[] message, String seckey) throws Exception {
    final MessageDigest md = MessageDigest.getInstance("md5");
    final byte[] digestOfPassword = md.digest(seckey.getBytes("utf-8"));
    final byte[] keyBytes = acopyof(digestOfPassword, 24);
    for (int j = 0, k = 16; j < 8;) {
        keyBytes[k++] = keyBytes[j++];
    }

    final SecretKey key = new SecretKeySpec(keyBytes, "DESede");
    final IvParameterSpec iv = new IvParameterSpec(new byte[8]);
    final Cipher decipher = Cipher.getInstance("DESede/CBC/PKCS5Padding");
    decipher.init(Cipher.DECRYPT_MODE, key, iv);

    final byte[] plainText = decipher.doFinal(message);

    return new String(plainText, "UTF-8");
}

private String getHexString(byte[] barray, String delim) {
    StringBuffer buffer = new StringBuffer();


    for (int i = 0; i < barray.length; i++) {
        int ii = barray[i] & 0xFF;
        String bInt = Integer.toHexString(ii);
        if (ii < 16) {
            bInt = "0" + bInt.toUpperCase();
        }
        buffer.append(bInt);
        if (i < barray.length - 1) {
            buffer.append(delim);
        }
    }

    return buffer.toString().toUpperCase();
}

private byte[] getBArray(String bString) {
    byte[] retBytes;

    if (bString.length() % 2 != 0) {
        return new byte[0];
    }
    retBytes = new byte[bString.length() / 2];

    for (int i = 0; i < bString.length() / 2; i++) {
        retBytes[i] = (byte) ((Character.digit(bString.charAt(2 * i), 16) << 4) + Character.digit(bString.charAt(2 * i + 1), 16));
    }
    return retBytes;
}

public static byte[] acopyof(byte[] orig, int newlength){
    byte[] copya = new byte[newlength];
    for(int i=0;i< orig.length;i++){
        copya[i]=orig[i];
    }
    for(int i=orig.length;i<newlength;i++){
        copya[i]=0x0;
    }
    return copya;
}

}

我制作了这个 Objective-c 方法来匹配这些规范：

+(NSString*)doCipher:(NSString*)sTextIn:(CCOperation)encryptOrDecrypt {

// const void *vplainText; // size_t plainTextBufferSize;

NSMutableData *dTextIn;

if (encryptOrDecrypt == kCCDecrypt)
{



}
else
{

    dTextIn = [[sTextIn dataUsingEncoding: NSASCIIStringEncoding]mutableCopy];

}

NSLog(@"************** Init encrypting **********************************");

NSLog(@"This is data to encrypt %@",dTextIn);

CCCryptorStatus ccStatus;
uint8_t *bufferPtr = NULL;
size_t bufferPtrSize = 0;
size_t movedBytes = 0;
//  uint8_t ivkCCBlockSize3DES;

bufferPtrSize = ([dTextIn length] + kCCBlockSize3DES) & ~(kCCBlockSize3DES - 1);
bufferPtr = malloc( bufferPtrSize * sizeof(uint8_t));
memset((void *)bufferPtr, 0x00, bufferPtrSize);



// Initialization vector; in this case 8 bytes.

uint8_t iv[kCCBlockSize3DES];
memset((void *) iv, 0x8, (size_t) sizeof(iv));



UserAndPassword *userPass = [[UserAndPassword alloc]init];

NSString *userPassword = userPass.password;

NSLog(@"This is my password %@",userPassword);

NSString *key = [userPassword MD5String];

NSLog(@"This is MD5 key %@",key);


NSMutableData *_keyData = [[key dataUsingEncoding:NSASCIIStringEncoding]mutableCopy];

unsigned char *bytePtr = (unsigned char *)[_keyData bytes];

NSLog(@"Bytes of key are %s ", bytePtr);

NSLog(@"******** This is my key length %d *******",[_keyData length]);

[_keyData setLength:24];

 unsigned char *bytePtr1 = (unsigned char *)[_keyData bytes];

 NSLog(@"******** Bytes of key are %s ************", bytePtr1);

 NSLog(@"*********  This is key length %d ***********",[_keyData length]);



ccStatus = CCCrypt(encryptOrDecrypt, // CCoperation op
                   kCCAlgorithm3DES, // CCAlgorithm alg
                   kCCOptionPKCS7Padding, // CCOptions
                   [_keyData bytes], // const void *key
                   kCCKeySize3DES, // 3DES key size length 24 bit
                   iv,  //const void *iv,
                   [dTextIn bytes], // const void *dataIn  
                   [dTextIn length], // size_t dataInLength
                   (void *)bufferPtr, // void *dataOut
                   bufferPtrSize, // size_t dataOutAvailable
                   &movedBytes); // size_t *dataOutMoved

if (ccStatus == kCCParamError) return @"PARAM ERROR";
else if (ccStatus == kCCBufferTooSmall) return @"BUFFER TOO SMALL";
else if (ccStatus == kCCMemoryFailure) return @"MEMORY FAILURE";
else if (ccStatus == kCCAlignmentError) return @"ALIGNMENT";
else if (ccStatus == kCCDecodeError) return @"DECODE ERROR";
else if (ccStatus == kCCUnimplemented) return @"UNIMPLEMENTED";


NSString *result;

if (encryptOrDecrypt == kCCDecrypt)
{

    // result = [[NSString alloc] initWithData: [NSData dataWithBytes:(const void *)bufferPtr length:[(NSUInteger)movedBytes] encoding:NSASCIIStringEncoding]];
    result = [[[NSString alloc] initWithData:[NSData dataWithBytes:(const void *)bufferPtr length:(NSUInteger)movedBytes] encoding:NSUTF8StringEncoding] autorelease];
}
else
{
    NSData *myData = [NSData dataWithBytes:(const void *)bufferPtr length:(NSUInteger)movedBytes];

    NSLog(@"This is my encrypted bytes %@", myData);

    result = [NSString dataToHex:myData];

    NSLog(@"This is my encrypted string %@", result);

    NSLog(@"********************** Encryption is finished ************");

}
return result;

}

我无法匹配使用 Java 代码获得的 3DES 加密，我不明白问题出在哪里。

提前谢谢你， 码头

Answer 1

我没有浏览过你所有的代码，但首先跳出来的是你输入字符串的字符编码方案是不同的。在您的 Java 算法中，您将所有字符串编码为 UTF-8，但在您的 ObjC 算法中，您将字符串编码为 ASCII，这对于除了最简单的输入字符串之外的任何内容都是一个潜在的问题。

Answer 2

您似乎遇到了字符编码问题。您的 Objective-C 代码基于 ASCII（8 位）字符，但您需要在将 Java 字符串解析为字节时切换（16 位）UNICODE 字符解码。另一方面，根据您正在处理的 CPU 架构（小字节序或大字节序）考虑数组中的字节排序可能是个好主意。

Answer 3

Java 版本使用 0 的 IV，而 Objective-C 版本使用 8。

使用一轮 MD5 且不加盐从密码中派生密钥是不安全的。使用像 PBKDF2 这样的密钥派生算法。