BASE64转换，内含:IOS自带DES加解密

最近项目需要保密，于是乎小小研究了一下，发现苹果自带密码库，不错！

//引入IOS自带密码库#import <CommonCrypto/CommonCryptor.h>

IOS支持的加解密算法如下

enum {    kCCAlgorithmAES128 = 0,    kCCAlgorithmDES,            kCCAlgorithm3DES,           kCCAlgorithmCAST,           kCCAlgorithmRC4,    kCCAlgorithmRC2,       kCCAlgorithmBlowfish    };typedef uint32_t CCAlgorithm;

其中前4个位DES/ADES，后两个位RSA，DES/ADES加解密使用相同的key，RSA使用公钥加密、私钥解密。

我就介绍下，把文本转换成为BASE64格式字符串后，再进行DES加密、解密，把BASE64格式字符串转换为文本的过程。

为了调用起来方便，我建立了转换宏

#define __BASE64( text )        [CommonFunc base64StringFromText:text]#define __TEXT( base64 )        [CommonFunc textFromBase64String:base64]

文本与BASE64格式字符串转换实现如下:

/****************************************************************************** 函数名称 : + (NSData *)dataWithBase64EncodedString:(NSString *)string 函数描述 : base64格式字符串转换为文本数据 输入参数 : (NSString *)string 输出参数 : N/A 返回参数 : (NSData *) 备注信息 : ******************************************************************************/+ (NSData *)dataWithBase64EncodedString:(NSString *)string{    if (string == nil)        [NSException raise:NSInvalidArgumentException format:nil];    if ([string length] == 0)        return [NSData data];        static char *decodingTable = NULL;    if (decodingTable == NULL)    {        decodingTable = malloc(256);        if (decodingTable == NULL)            return nil;        memset(decodingTable, CHAR_MAX, 256);        NSUInteger i;        for (i = 0; i < 64; i++)            decodingTable[(short)encodingTable[i]] = i;    }        const char *characters = [string cStringUsingEncoding:NSASCIIStringEncoding];    if (characters == NULL)     //  Not an ASCII string!        return nil;    char *bytes = malloc((([string length] + 3) / 4) * 3);    if (bytes == NULL)        return nil;    NSUInteger length = 0;        NSUInteger i = 0;    while (YES)    {        char buffer[4];        short bufferLength;        for (bufferLength = 0; bufferLength < 4; i++)        {            if (characters[i] == '\0')                break;            if (isspace(characters[i]) || characters[i] == '=')                continue;            buffer[bufferLength] = decodingTable[(short)characters[i]];            if (buffer[bufferLength++] == CHAR_MAX)      //  Illegal character!            {                free(bytes);                return nil;            }        }                if (bufferLength == 0)            break;        if (bufferLength == 1)      //  At least two characters are needed to produce one byte!        {            free(bytes);            return nil;        }                //  Decode the characters in the buffer to bytes.        bytes[length++] = (buffer[0] << 2) | (buffer[1] >> 4);        if (bufferLength > 2)            bytes[length++] = (buffer[1] << 4) | (buffer[2] >> 2);        if (bufferLength > 3)            bytes[length++] = (buffer[2] << 6) | buffer[3];    }        bytes = realloc(bytes, length);    return [NSData dataWithBytesNoCopy:bytes length:length];}

 

/****************************************************************************** 函数名称 : + (NSString *)base64EncodedStringFrom:(NSData *)data 函数描述 : 文本数据转换为base64格式字符串 输入参数 : (NSData *)data 输出参数 : N/A 返回参数 : (NSString *) 备注信息 :  ******************************************************************************/+ (NSString *)base64EncodedStringFrom:(NSData *)data{    if ([data length] == 0)        return @"";        char *characters = malloc((([data length] + 2) / 3) * 4);    if (characters == NULL)        return nil;    NSUInteger length = 0;        NSUInteger i = 0;    while (i < [data length])    {        char buffer[3] = {0,0,0};        short bufferLength = 0;        while (bufferLength < 3 && i < [data length])            buffer[bufferLength++] = ((char *)[data bytes])[i++];                //  Encode the bytes in the buffer to four characters, including padding "=" characters if necessary.        characters[length++] = encodingTable[(buffer[0] & 0xFC) >> 2];        characters[length++] = encodingTable[((buffer[0] & 0x03) << 4) | ((buffer[1] & 0xF0) >> 4)];        if (bufferLength > 1)            characters[length++] = encodingTable[((buffer[1] & 0x0F) << 2) | ((buffer[2] & 0xC0) >> 6)];        else characters[length++] = '=';        if (bufferLength > 2)            characters[length++] = encodingTable[buffer[2] & 0x3F];        else characters[length++] = '=';    }        return [[NSString alloc] initWithBytesNoCopy:characters length:length encoding:NSASCIIStringEncoding freeWhenDone:YES];}

 

DES加密、解密实现如下:

/****************************************************************************** 函数名称 : + (NSData *)DESEncrypt:(NSData *)data WithKey:(NSString *)key 函数描述 : 文本数据进行DES加密 输入参数 : (NSData *)data              (NSString *)key 输出参数 : N/A 返回参数 : (NSData *) 备注信息 : 此函数不可用于过长文本 ******************************************************************************/+ (NSData *)DESEncrypt:(NSData *)data WithKey:(NSString *)key{    char keyPtr[kCCKeySizeAES256+1];    bzero(keyPtr, sizeof(keyPtr));        [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];        NSUInteger dataLength = [data length];        size_t bufferSize = dataLength + kCCBlockSizeAES128;    void *buffer = malloc(bufferSize);        size_t numBytesEncrypted = 0;    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmDES,                                          kCCOptionPKCS7Padding | kCCOptionECBMode,                                          keyPtr, kCCBlockSizeDES,                                          NULL,                                          [data bytes], dataLength,                                          buffer, bufferSize,                                          &numBytesEncrypted);    if (cryptStatus == kCCSuccess) {        return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];    }        free(buffer);    return nil;}

 

/****************************************************************************** 函数名称 : + (NSData *)DESEncrypt:(NSData *)data WithKey:(NSString *)key 函数描述 : 文本数据进行DES解密 输入参数 : (NSData *)data          (NSString *)key 输出参数 : N/A 返回参数 : (NSData *) 备注信息 : 此函数不可用于过长文本 ******************************************************************************/+ (NSData *)DESDecrypt:(NSData *)data WithKey:(NSString *)key{    char keyPtr[kCCKeySizeAES256+1];    bzero(keyPtr, sizeof(keyPtr));        [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];        NSUInteger dataLength = [data length];        size_t bufferSize = dataLength + kCCBlockSizeAES128;    void *buffer = malloc(bufferSize);        size_t numBytesDecrypted = 0;    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmDES,                                          kCCOptionPKCS7Padding | kCCOptionECBMode,                                          keyPtr, kCCBlockSizeDES,                                          NULL,                                          [data bytes], dataLength,                                          buffer, bufferSize,                                          &numBytesDecrypted);        if (cryptStatus == kCCSuccess) {        return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];    }        free(buffer);    return nil;}

 

然后把两者结合起来使用，我认为更加安全，于是我就这样做了:

+ (NSString *)base64StringFromText:(NSString *)text{    if (text && ![text isEqualToString:LocalStr_None]) {        //取项目的bundleIdentifier作为KEY        NSString *key = [[NSBundle mainBundle] bundleIdentifier];        NSData *data = [text dataUsingEncoding:NSUTF8StringEncoding];        //IOS 自带DES加密 Begin        data = [self DESEncrypt:data WithKey:key];        //IOS 自带DES加密 End        return [self base64EncodedStringFrom:data];    }    else {        return LocalStr_None;    }}

 

+ (NSString *)textFromBase64String:(NSString *)base64{    if (base64 && ![base64 isEqualToString:LocalStr_None]) {        //取项目的bundleIdentifier作为KEY        NSString *key = [[NSBundle mainBundle] bundleIdentifier];        NSData *data = [self dataWithBase64EncodedString:base64];        //IOS 自带DES解密 Begin        data = [self DESDecrypt:data WithKey:key];        //IOS 自带DES加密 End        return [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];    }    else {        return LocalStr_None;    }}

 

还没看懂？ 没关系，来看图，看例子

 

PRJ_base64.zip 例子下载地址:http://ishare.iask.sina.com.cn/f/34862560.html