iOS中用到的3DES密码算法

加密需要后台与前端统一，使用3DES加密算法：

//
//  NSString+ThreeDES.m
//  3DE
//
//  Created by Brandon Zhu on 31/10/2012.
//  Copyright (c) 2012 Brandon Zhu. All rights reserved.
//

#import "NSString+ThreeDES.h"
#import <CommonCrypto/CommonCryptor.h>
#import <CommonCrypto/CommonDigest.h>
#import "GTMBase64.h"

// 前端与后台商量KEY
#define gkey @""
#define gIv  @""
#define kSecrectKeyLength 24

@implementation NSString (ThreeDES)

+ (NSString*)encrypt:(NSString*)plainText withKey:(NSString*)key{
    const char *cstr = [key cStringUsingEncoding:NSUTF8StringEncoding];
    NSData *keyData = [NSData dataWithBytes:cstr length:key.length];
    
    uint8_t digest[CC_SHA1_DIGEST_LENGTH];
    
    CC_SHA1(keyData.bytes, (CC_LONG)keyData.length, digest);
    
    uint8_t keyByte[kSecrectKeyLength];
    for (int i=0; i<16; i++) {
        keyByte[i] = digest[i];
    }
    for (int i=0; i<8; i++) {
        keyByte[16+i] = digest[i];
    }
    
    NSData* data = [plainText dataUsingEncoding:NSUTF8StringEncoding];
    size_t plainTextBufferSize = [data length];
    const void *vplainText = (const void *)[data bytes];
    
    CCCryptorStatus ccStatus;
    uint8_t *bufferPtr = NULL;
    size_t bufferPtrSize = 0;
    size_t movedBytes = 0;
    
    bufferPtrSize = (plainTextBufferSize + kCCBlockSize3DES) & ~(kCCBlockSize3DES - 1);
    bufferPtr = malloc( bufferPtrSize * sizeof(uint8_t));
    memset((void *)bufferPtr, 0x0, bufferPtrSize);
    
    const void *vkey = (const void *) keyByte;
    const void *vinitVec = (const void *) [gIv UTF8String];
    
    ccStatus = CCCrypt(kCCEncrypt,
                       kCCAlgorithm3DES,
                       kCCOptionPKCS7Padding,
                       vkey,
                       kCCKeySize3DES,
                       vinitVec,
                       vplainText,
                       plainTextBufferSize,
                       (void *)bufferPtr,
                       bufferPtrSize,
                       &movedBytes);
    
    NSData *myData = [NSData dataWithBytes:(const void *)bufferPtr length:(NSUInteger)movedBytes];
    NSString *result = [GTMBase64 stringByEncodingData:myData];
    return result;
}

+ (NSString*)decrypt:(NSString*)encryptText withKey:(NSString*)key{
    
    const char *cstr = [key cStringUsingEncoding:NSUTF8StringEncoding];
    NSData *data = [NSData dataWithBytes:cstr length:key.length];
    
    uint8_t digest[CC_SHA1_DIGEST_LENGTH];
    
    CC_SHA1(data.bytes, (CC_LONG)data.length, digest);
    
    uint8_t keyByte[kSecrectKeyLength];
    for (int i=0; i<16; i++) {
        keyByte[i] = digest[i];
    }
    for (int i=0; i<8; i++) {
        keyByte[16+i] = digest[i];
    }
    
    NSData *encryptData = [GTMBase64 decodeData:[encryptText dataUsingEncoding:NSUTF8StringEncoding]];
    size_t plainTextBufferSize = [encryptData length];
    const void *vplainText = [encryptData bytes];
    
    CCCryptorStatus ccStatus;
    uint8_t *bufferPtr = NULL;
    size_t bufferPtrSize = 0;
    size_t movedBytes = 0;
    
    bufferPtrSize = (plainTextBufferSize + kCCBlockSize3DES) & ~(kCCBlockSize3DES - 1);
    bufferPtr = malloc( bufferPtrSize * sizeof(uint8_t));
    memset((void *)bufferPtr, 0x0, bufferPtrSize);
    
    const void *vkey = (const void *) keyByte;
    const void *vinitVec = (const void *) [gIv UTF8String];
    
    ccStatus = CCCrypt(kCCDecrypt,
                       kCCAlgorithm3DES,
                       kCCOptionPKCS7Padding,
                       vkey,
                       kCCKeySize3DES,
                       vinitVec,
                       vplainText,
                       plainTextBufferSize,
                       (void *)bufferPtr,
                       bufferPtrSize,
                       &movedBytes);
    
    NSString *result = [[[NSString alloc] initWithData:[NSData dataWithBytes:(const void *)bufferPtr
                                                                      length:(NSUInteger)movedBytes] encoding:NSUTF8StringEncoding] autorelease];
    return result;
}
- (NSString*) sha1
{
    const char *cstr = [self cStringUsingEncoding:NSUTF8StringEncoding];
    NSData *data = [NSData dataWithBytes:cstr length:self.length];
    
    uint8_t digest[CC_SHA1_DIGEST_LENGTH];
    
    CC_SHA1(data.bytes, data.length, digest);
    NSMutableString* output = [NSMutableString stringWithCapacity:CC_SHA1_DIGEST_LENGTH * 2];
    
    for(int i = 0; i < CC_SHA1_DIGEST_LENGTH; i++)
        [output appendFormat:@"%02x", digest[i]];
    
    return output;
}

@end