iOS常用加密方法（aes、md5、base64）

、AES加密

NSData+AES.h文件

//

//  NSData-AES.h

//  Smile

//

//  Created by 周 敏 on 12-11-24.

//  Copyright (c) 2012年 BOX. All rights reserved.

//  

#import <Foundation/Foundation.h>  

@class NSString;  

@interface NSData (Encryption)  

- (NSData *)AES256EncryptWithKey:(NSString *)key;   //加密

- (NSData *)AES256DecryptWithKey:(NSString *)key;   //解密  

@end  

NSData+AES.m文件

//

//  NSData-AES.h

//  Smile

//

//  Created by 周 敏 on 12-11-24.

//  Copyright (c) 2012年 BOX. All rights reserved.

//  

#import "NSData+AES.h"

#import <CommonCrypto/CommonCryptor.h>  

@implementation NSData (Encryption)  

- (NSData *)AES256EncryptWithKey:(NSString *)key {//加密

    char keyPtr[kCCKeySizeAES256+];

    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 = ;

    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 {//解密

    char keyPtr[kCCKeySizeAES256+];

    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 = ;

    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

这里AES在iOS加过密以后以nsdata的形式存下来，如果想以nsstring形式存储，那么对nsdata进行base64位编码。

、BASE64编码

首先下载GTMBase64文件，在工程中加入三个文件

GTMDefines.h

GTMBase64.h

GTMBase64.m

你可以在这里找到这三个文件

http://code.google.com/p/google-toolbox-for-mac/source/browse/trunk/Foundation/?r=87

你也可以在下面的demo里面找到这3个文件，demo会完整实现文章里面常用的3种编码方法。

我在此稍微封装一下：

.h文件

#pragma mark - base64

+ (NSString*)encodeBase64String:(NSString *)input;

+ (NSString*)decodeBase64String:(NSString *)input;

+ (NSString*)encodeBase64Data:(NSData *)data;

+ (NSString*)decodeBase64Data:(NSData *)data;  

.m文件

#pragma mark - base64

+ (NSString*)encodeBase64String:(NSString * )input {

    NSData *data = [input dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];

    data = [GTMBase64 encodeData:data];

    NSString *base64String = [[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] autorelease];

    return base64String;

}  

+ (NSString*)decodeBase64String:(NSString * )input {

    NSData *data = [input dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];

    data = [GTMBase64 decodeData:data];

    NSString *base64String = [[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] autorelease];

    return base64String;

}   

+ (NSString*)encodeBase64Data:(NSData *)data {

    data = [GTMBase64 encodeData:data];

    NSString *base64String = [[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] autorelease];

    return base64String;

}  

+ (NSString*)decodeBase64Data:(NSData *)data {

    data = [GTMBase64 decodeData:data];

    NSString *base64String = [[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] autorelease];

    return base64String;

}  

、MD5加密 www.2cto.com

NSString+MD5.h文件

//

//  NSString+MD5Encrypt.h

//  Smile

//

//  Created by 周 敏 on 12-11-24.

//  Copyright (c) 2012年 BOX. All rights reserved.

//  

#import <CommonCrypto/CommonDigest.h>  

@interface NSString (MD5)  

- (NSString *)md5Encrypt;  

@end  

NSString+MD5.m文件

//

//  NSString+MD5Encrypt.h

//  Smile

//

//  Created by 周 敏 on 12-11-24.

//  Copyright (c) 2012年 BOX. All rights reserved.

//  

#import "NSString+MD5.h"  

@implementation NSString (MD5)  

- (NSString *)md5Encrypt {

    const char *original_str = [self UTF8String];

    unsigned char result[CC_MD5_DIGEST_LENGTH];

    CC_MD5(original_str, strlen(original_str), result);

    NSMutableString *hash = [NSMutableString string];

    for (int i = ; i < ; i++)

        [hash appendFormat:@"%02X", result[i]];

    return [hash lowercaseString];

}  

@end