“APP的資料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資料安全標準，本文簡單的介紹下AES與Base64的混合加密與解密”
AES:高階加密標準（英語：Advanced Encryption Standard，縮寫：AES），在密碼學中又稱Rijndael加密法，是美國聯邦政府採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，高階加密標準由美國國家標準與技術研究院（NIST）於2001年11月26日釋出於FIPS PUB 197，並在2002年5月26日成為有效的標準。2006年，高階加密標準已然成為對稱金鑰加密中最流行的演算法之一。
以上是來自百度百科的解釋。
下面我將用程式碼來闡述其使用方法。
首先我們建立一個NSData的類擴充套件，命名為AES，建立完如果對的話應該是這樣的NSData+AES然後匯入如下標頭檔案
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#import <CommonCrypto/CommonDigest.h> #import <CommonCrypto/CommonCryptor.h> |
再增加加解密的方法，方便外部檔案的呼叫，寫完.h檔案如下
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#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檔案中依次實現這幾個方法，具體如下
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#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字串加密的。
和上面的基本上差不多，寫一個NSString的類擴充套件，命名為AES，建立完如果對的話應該是這樣的NSString+AES匯入如下標頭檔案
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#import "NSData+AES.h" |
同樣的把加解密的方法寫在.h檔案中，寫完如下
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#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
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//加密 - (NSString *) AES256_Encrypt:(NSString *)key{ const char *cstr = [self cStringUsingEncoding:NSUTF8StringEncoding]; NSData *data = [NSData dataWithBytes:cstr length:self.length]; //對資料進行加密 NSData *result = [data AES256_Encrypt:key]; //轉換為2進位制字串 if (result & result.length > 0) { Byte *datas = (Byte*)[result bytes]; NSMutableString *output = [NSMutableString stringWithCapacity:result.length * 2]; for(int i = 0; i 0) { return [[NSString alloc] initWithData:result encoding:NSUTF8StringEncoding]; } return nil; } |
到此我們加密的檔案基本上都已經OK了，下面我們來簡單的的使用一下，具體如下：
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#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. //字串加密 NSString *key = @"12345678";//Key是和後臺約定的key哦，不然無法解密.... NSString *secret = @"aes Bison base64"; NSLog(@"字串加密---%@",[secret AES256_Encrypt:key]); //字串解密 NSLog(@"字串解密---%@",[[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 |
執行得到列印的結果如下：
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2016-03-30 17:31:55.686 AES_256[14242:198853] 字串加密---07815ca46d20acc3ba4e43d6930c7537496e851a36dbeac34fa30c5796089b02 2016-03-30 17:31:55.687 AES_256[14242:198853] 字串解密---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是和後臺約定的key哦，不然無法解密….
最後留下demo下載地址
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