iOS開發之AES+Base64數據混合加密與解密

wwreplical8 8年前發布 | 50K 次閱讀 iOS開發加密解密移動開發

"APP的數據安全已經牽動著我們開發者的心，簡單的MD5/Base64等已經難以滿足當下的數據安全標準，本文簡單的介紹下AES與Base64的混合加密與解密"

AES:高級加密標準（英語：Advanced Encryption Standard，縮寫：AES），在密碼學中又稱Rijndael加密法，是美國聯邦政府采用的一種區塊加密標準。這個標準用來替代原先的DES，已經被多方分析且廣為全世界所使用。經過五年的甄選流程，高級加密標準由美國國家標準與技術研究院（NIST）于2001年11月26日發布于FIPS PUB 197，并在2002年5月26日成為有效的標準。2006年，高級加密標準已然成為對稱密鑰加密中最流行的算法之一。

以上是來自百度百科的解釋。

下面我將用代碼來闡述其使用方法。首先我們創建一個NSData的類擴展，命名為AES，創建完如果對的話應該是這樣的NSData+AES然后導入如下頭文件

#import <CommonCrypto/CommonDigest.h>
#import <CommonCrypto/CommonCryptor.h>

再增加加解密的方法，方便外部文件的調用，寫完.h文件如下

#import <Foundation/Foundation.h> #import <CommonCrypto/CommonDigest.h> #import <CommonCrypto/CommonCryptor.h> 
@interface NSData (AES)

//加密 - (NSData *) AES256_Encrypt:(NSString *)key;

//解密 - (NSData *) AES256_Decrypt:(NSString *)key;

//追加64編碼 - (NSString *)newStringInBase64FromData;

//同上64編碼 + (NSString*)base64encode:(NSString*)str;


@end

.m文件中依次實現這幾個方法，具體如下

#import "NSData+AES.h" 
static char base64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

@implementation NSData (AES)

//加密 - (NSData *) AES256_Encrypt:(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;
}

//解密 - (NSData *) AES256_Decrypt:(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;
}

//追加64編碼 - (NSString *)newStringInBase64FromData            

{

    NSMutableString *dest = [[NSMutableString alloc] initWithString:@""];

    unsigned char * working = (unsigned char *)[self bytes];

    int srcLen = (int)[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;

}



+ (NSString*)base64encode:(NSString*)str

{

    if ([str length] == 0)

    return @"";

    const char *source = [str UTF8String];

    int strlength  = (int)strlen(source);

    char *characters = malloc(((strlength + 2) / 3) * 4);

    if (characters == NULL)

    return nil;

    NSUInteger length = 0;

    NSUInteger i = 0;

    while (i < strlength) {

        char buffer[3] = {0,0,0};

        short bufferLength = 0;

        while (bufferLength < 3 && i < strlength)

        buffer[bufferLength++] = source[i++];

        characters[length++] = base64[(buffer[0] & 0xFC) >> 2];

        characters[length++] = base64[((buffer[0] & 0x03) << 4) | ((buffer[1] & 0xF0) >> 4)];

        if (bufferLength > 1)

        characters[length++] = base64[((buffer[1] & 0x0F) << 2) | ((buffer[2] & 0xC0) >> 6)];

        else characters[length++] = '=';

        if (bufferLength > 2)

        characters[length++] = base64[buffer[2] & 0x3F];

        else characters[length++] = '=';

    }

    NSString *g = [[NSString alloc] initWithBytesNoCopy:characters length:length encoding:NSASCIIStringEncoding freeWhenDone:YES];


    return g;

}



@end

AES+Base64的加密方式到此已經結束了，下面講一下單純的AES字符串加密的。

和上面的基本上差不多，寫一個NSString的類擴展，命名為AES，創建完如果對的話應該是這樣的NSString+AES導入如下頭文件

#import "NSData+AES.h"

同樣的把加解密的方法寫在.h文件中，寫完如下

#import <Foundation/Foundation.h> #import "NSData+AES.h" 
@interface NSString (AES)

//加密 - (NSString *) AES256_Encrypt:(NSString *)key;

//解密 - (NSString *) AES256_Decrypt:(NSString *)key;

@end

.m實現方法

//加密
- (NSString *) AES256_Encrypt:(NSString *)key{
    const char *cstr = [self cStringUsingEncoding:NSUTF8StringEncoding];
    NSData *data = [NSData dataWithBytes:cstr length:self.length];
    //對數據進行加密
    NSData *result = [data AES256_Encrypt:key];

    //轉換為2進制字符串
    if (result && result.length > 0) {

    Byte *datas = (Byte*)[result bytes];
    NSMutableString *output = [NSMutableString stringWithCapacity:result.length * 2];
    for(int i = 0; i < result.length; i++){
        [output appendFormat:@"%02x", datas[i]];
    }
    return output;
    }
    return nil;
}

//解密
- (NSString *) AES256_Decrypt:(NSString *)key{
    //轉換為2進制Data
    NSMutableData *data = [NSMutableData dataWithCapacity:self.length / 2];
    unsigned char whole_byte;
    char byte_chars[3] = {'\0','\0','\0'};
    int i;
    for (i=0; i < [self length] / 2; i++) {
    byte_chars[0] = [self characterAtIndex:i*2];
    byte_chars[1] = [self characterAtIndex:i*2+1];
    whole_byte = strtol(byte_chars, NULL, 16);
    [data appendBytes:&whole_byte length:1];
    }

    //對數據進行解密
    NSData* result = [data AES256_Decrypt:key];
    if (result && result.length > 0) {
        return [[NSString alloc] initWithData:result encoding:NSUTF8StringEncoding];
    }
    return nil;
}

到此我們加密的文件基本上都已經OK了，下面我們來簡單的的使用一下，具體如下：

#import "ViewController.h" #import "NSString+AES.h" 
@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib. 
    //字符串加密     NSString *key = @"12345678";//Key是和后臺約定的key哦，不然無法解密.... 
    NSString *secret = @"aes Bison base64";


    NSLog(@"字符串加密---%@",[secret AES256_Encrypt:key]);

    //字符串解密     NSLog(@"字符串解密---%@",[[secret AES256_Encrypt:key] AES256_Decrypt:key]);


    //NSData加密+base64 
    NSData *plain = [secret dataUsingEncoding:NSUTF8StringEncoding];

    NSData *cipher = [plain AES256_Encrypt:key];

    NSLog(@"NSData加密+base64++++%@",[cipher newStringInBase64FromData]);


    //解密 
    plain = [cipher AES256_Decrypt:key];

    NSLog(@"NSData解密+base64++++%@", [[NSString alloc] initWithData:plain encoding:NSUTF8StringEncoding]);

}


@end

運行得到打印的結果如下：

2016-03-30 17:31:55.686 AES_256[14242:198853] 字符串加密---07815ca46d20acc3ba4e43d6930c7537496e851a36dbeac34fa30c5796089b02
2016-03-30 17:31:55.687 AES_256[14242:198853] 字符串解密---aes Bison base64
2016-03-30 17:31:55.687 AES_256[14242:198853] NSData加密+base64++++B4FcpG0grMO6TkPWkwx1N0luhRo22+rDT6MMV5YImwI
2016-03-30 17:31:55.687 AES_256[14242:198853] NSData解密+base64++++aes Bison base64

##值得注意的是Key是和后臺約定的key哦，不然無法解密….

最后留下 demo下載地址

來自： http://allluckly.cn/aes/AES

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iOS開發加密解密移動開發