iPhone开发技巧之数据篇（2）—iPhone程序中的加密处理
在Objective-C语言中，加密时常用到CCCrypt(3cc)Mac OS X Manual Page。下面的代码使用 CCCrypt() ，给 NSData 类增加了AES256EncryptWithKey, AES256DecryptWithKey 方法.
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#import <CommonCrypto/CommonCryptor.h>
@implementation NSData (Additions)
@class NSString;
- (NSData *)AES256EncryptWithKey:(NSString *)key {
char keyPtr[kCCKeySizeAES256+1];
bzero(keyPtr, sizeof(keyPtr));
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [self length];
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc(bufferSize);
size_t numBytesEncrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128,
kCCOptionPKCS7Padding | kCCOptionECBMode,
keyPtr, kCCBlockSizeAES128,
NULL,
[self bytes], dataLength,
buffer, bufferSize,
&numBytesEncrypted);
if (cryptStatus == kCCSuccess) {
return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
}
free(buffer);
return nil;
}
- (NSData *)AES256DecryptWithKey:(NSString *)key {
char keyPtr[kCCKeySizeAES256+1];
bzero(keyPtr, sizeof(keyPtr));
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [self length];
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc(bufferSize);
size_t numBytesDecrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128,
kCCOptionPKCS7Padding | kCCOptionECBMode,
keyPtr, kCCBlockSizeAES128,
NULL,
[self bytes], dataLength,
buffer, bufferSize,
&numBytesDecrypted);
if (cryptStatus == kCCSuccess) {
return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
}
free(buffer);
return nil;
}
@end
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使用的时候就像使用NSData一样。
有的时候需要向服务器上传递base64加密的数据，这个时候我们就可以像下面，给 NSData类追加newStringInBase64FromData 方法。
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- (NSString *)newStringInBase64FromData {
NSMutableString *dest = [[NSMutableString alloc] initWithString:@""];
unsigned char * working = (unsigned char *)[self bytes];
int srcLen = [self length];
for (int i=0; i<srcLen; i += 3) {
for (int nib=0; nib<4; nib++) {
int byt = (nib == 0)?0:nib-1;
int ix = (nib+1)*2;
if (i+byt >= srcLen) break;
unsigned char curr = ((working[i+byt] << (8-ix)) & 0x3F);
if (i+nib < srcLen) curr |= ((working[i+nib] >> ix) & 0x3F);
[dest appendFormat:@"%c", base64[curr]];
}
}
return dest;
}
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同样，使用的时候就像使用NSData一样。
最终的代码如下所示 ：
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//
// NSDataAdditions.h
//
// Copyright 2010 __MyCompanyName__. All rights reserved.
//
#import <Foundation/Foundation.h>
@class NSString;
@interface NSData (Additions)
- (NSData *)AES256EncryptWithKey:(NSString *)key;
- (NSData *)AES256DecryptWithKey:(NSString *)key;
- (NSString *)newStringInBase64FromData;
@end
// -----------------------------------------------------------------------------------
//
// NSDataAdditions.m
//
// Copyright 2010 __MyCompanyName__. All rights reserved.
//
#import "NSDataAdditions.h"
#import <CommonCrypto/CommonCryptor.h>
static char base64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
@implementation NSData (Additions)
@class NSString;
- (NSData *)AES256EncryptWithKey:(NSString *)key {
char keyPtr[kCCKeySizeAES256+1];
bzero(keyPtr, sizeof(keyPtr));
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [self length];
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc(bufferSize);
size_t numBytesEncrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128,
kCCOptionPKCS7Padding | kCCOptionECBMode,
keyPtr, kCCBlockSizeAES128,
NULL,
[self bytes], dataLength,
buffer, bufferSize,
&numBytesEncrypted);
if (cryptStatus == kCCSuccess) {
return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
}
free(buffer);
return nil;
}
- (NSData *)AES256DecryptWithKey:(NSString *)key {
char keyPtr[kCCKeySizeAES256+1];
bzero(keyPtr, sizeof(keyPtr));
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [self length];
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc(bufferSize);
size_t numBytesDecrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128,
kCCOptionPKCS7Padding | kCCOptionECBMode,
keyPtr, kCCBlockSizeAES128,
NULL,
[self bytes], dataLength,
buffer, bufferSize,
&numBytesDecrypted);
if (cryptStatus == kCCSuccess) {
return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
}
free(buffer);
return nil;
}
- (NSString *)newStringInBase64FromData {
NSMutableString *dest = [[NSMutableString alloc] initWithString:@""];
unsigned char * working = (unsigned char *)[self bytes];
int srcLen = [self length];
for (int i=0; i<srcLen; i += 3) {
for (int nib=0; nib<4; nib++) {
int byt = (nib == 0)?0:nib-1;
int ix = (nib+1)*2;
if (i+byt >= srcLen) break;
unsigned char curr = ((working[i+byt] << (8-ix)) & 0x3F);
if (i+nib < srcLen) curr |= ((working[i+nib] >> ix) & 0x3F);
[dest appendFormat:@"%c", base64[curr]];
}
}
return dest;
}
@end
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原文：http://www.cnblogs.com/Camier-myNiuer/p/3601807.html