iOS常用加密算法

iOS常用加密方法（aes、md5、base64）

NSData+AES.h文件

    //  
    //  NSData-AES.h  
    //  Smile  
    //  
    //  

    #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  
    //  

    #import "NSData+AES.h"  
    #import <CommonCrypto/CommonCryptor.h>  

    @implementation NSData (Encryption)  

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

這里AES在iOS加過密以后以nsdata的形式存下來，如果想以nsstring形式存儲，那么對nsdata進行base64位編碼。

首先下載GTMBase64文件，在工程中加入三個文件
GTMDefines.h
GTMBase64.h
GTMBase64.m
你可以在這里找到這三個文件
http://code.google.com/p/google-toolbox-for-mac/source/browse/trunk/Foundation/?r=87

你也可以在下面的demo里面找到這3個文件，demo會完整實現文章里面常用的3種編碼方法。

我在此稍微封裝一下：

.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;  
    }  

3、MD5加密

NSString+MD5.h文件

 

    //  
    //  NSString+MD5Encrypt.h  
    //  Smile  
    //  
    //  

    #import <CommonCrypto/CommonDigest.h>  

    @interface NSString (MD5)  

    - (NSString *)md5Encrypt;  

    @end  

NSString+MD5.m文件

    //  
    //  NSString+MD5Encrypt.h  
    //  Smile  
    //  //  

    #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 = 0; i < 16; i++)  
            [hash appendFormat:@"%02X", result[i]];  
        return [hash lowercaseString];  
    }  

    @end