如何在iPhone中使用DES加密NSString值？

Question

我用下面的代碼NSString的值用密鑰來加密，

NSString *token = @"encryptValue"; 
NSString *key = @"encryptKey"; 

NSData * keyData = [key dataUsingEncoding: NSUTF8StringEncoding]; 
NSData * plainData = [token dataUsingEncoding: NSUTF8StringEncoding]; 
NSMutableData * encData = [NSMutableData dataWithLength: plainData.length + 256]; 
size_t bytesWritten = 0; 
CCCryptorStatus ccStatus = CCCrypt (kCCEncrypt, 
        kCCAlgorithmDES, 
        kCCOptionPKCS7Padding, 
        [keyData bytes], 
        kCCKeySizeDES, 
        NULL, 
        [plainData bytes], 
        [plainData length], 
        encData.mutableBytes, 
        encData.length, 
        &bytesWritten); 
encData.length = bytesWritten;  
NSString *encrypted = [[NSString alloc] initWithBytes:[encData bytes] length:[encData length] encoding: NSUTF8StringEncoding]; 
NSLog(@"ENCRYPT : %@",encrypted); 

但我發現了（空）是結果。有什麼問題嗎？如何加密NSString值？

Answer 1

最後，我用下面的代碼，現在它工作正常進行。

- (NSString*) doCipher:(NSString*)encryptValue { 

    const void *vplainText; 
    size_t plainTextBufferSize = [encryptValue length]; 
    vplainText = (const void *) [encryptValue UTF8String];  
    CCCryptorStatus ccStatus; 
    uint8_t *bufferPtr = NULL; 
    size_t bufferPtrSize = 0; 
    size_t movedBytes = 0; 

    bufferPtrSize = (plainTextBufferSize + kCCBlockSizeDES) & ~(kCCBlockSizeDES - 1); 
    bufferPtr = malloc(bufferPtrSize * sizeof(uint8_t)); 
    memset((void *)bufferPtr, 0x0, bufferPtrSize); 

    Byte iv [] = {0x12, 0x34, 0x56, 0x78, 0x90, 0xab, 0xcd, 0xef}; 

    NSString *key = @"encryptKey"; 
    const void *vkey = (const void *) [key UTF8String]; 

    ccStatus = CCCrypt(kCCEncrypt, 
         kCCAlgorithmDES, 
         kCCOptionPKCS7Padding, 
         vkey, 
         kCCKeySizeDES, 
         iv, 
         vplainText, 
         plainTextBufferSize, 
         (void *)bufferPtr, 
         bufferPtrSize, 
         &movedBytes); 

    NSData *myData = [NSData dataWithBytes:(const void *)bufferPtr length:(NSUInteger)movedBytes]; 
    NSString *result = [myData base64Encoding]; 

    return result; 
} 

Answer 2

這裏是AES的方式，可能是DES有異曲同工之處，看看這個作品跟我... 創建一個新的類別AES上NSData
對於的NSData + AES.h

#import <Foundation/Foundation.h> 
#import <CommonCrypto/CommonCryptor.h> 

@interface NSData (AES) 

- (NSData*) EncryptAES: (NSString *) key; 
- (NSData *) DecryptAES: (NSString *) key; 

@end 

對於NSData的+ AES.m

#import "NSData+AES.h" 
    @implementation NSData(AES) 

    - (NSData*) EncryptAES: (NSString *) key 
    { 
     char keyPtr[kCCKeySizeAES256+1]; 
     bzero(keyPtr, sizeof(keyPtr)); 

     [key getCString: keyPtr maxLength: sizeof(keyPtr) encoding: NSUTF16StringEncoding]; 
     size_t numBytesEncrypted = 0; 

     NSUInteger dataLength = [self length]; 

     size_t bufferSize = dataLength + kCCBlockSizeAES128; 
     void *buffer = malloc(bufferSize); 

     CCCryptorStatus result = CCCrypt(kCCEncrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding, 
             keyPtr, kCCKeySizeAES256, 
             NULL, 
             [self bytes], [self length], 
             buffer, bufferSize, 
             &numBytesEncrypted); 

     if(result == kCCSuccess) 
      return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted]; 

     return nil; 
    } 

    - (NSData *) DecryptAES: (NSString *) key 
    { 
     char keyPtr[kCCKeySizeAES256+1]; 
     bzero(keyPtr, sizeof(keyPtr)); 

     [key getCString: keyPtr maxLength: sizeof(keyPtr) encoding: NSUTF16StringEncoding]; 

     size_t numBytesEncrypted = 0; 

     NSUInteger dataLength = [self length]; 

     size_t bufferSize = dataLength + kCCBlockSizeAES128; 
     void *buffer_decrypt = malloc(bufferSize);  

     CCCryptorStatus result = CCCrypt(kCCDecrypt , kCCAlgorithmAES128, kCCOptionPKCS7Padding, 
             keyPtr, kCCKeySizeAES256, 
             NULL, 
             [self bytes], [self length], 
             buffer_decrypt, bufferSize, 
             &numBytesEncrypted); 

     if(result == kCCSuccess) 
     return [NSData dataWithBytesNoCopy:buffer_decrypt length:numBytesEncrypted]; 

     return nil; 
    } 

    @end 

用法： 導入的NSData + AES.h

//Encryption 
NSString *myString = @"This is the content"; 
NSString *key = @"my secret key"; 
NSData *data = [myString dataUsingEncoding:NSUTF8StringEncoding]; 
NSData *encryptedData = [data EncryptAES:key]; 

//Decryption 
NSString *decryptedString = [[[NSString alloc] initWithData:[encryptedData DecryptAES:key] encoding:NSUTF8StringEncoding] autorelease]; // remove autorelease if using ARC