iOS開發之 AES+Base64數據混合加密與解密
編輯：IOS開發基礎
"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准，本文簡單的介紹下AES與Base64的混合加密與解密"
AES:高級加密標准（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准。這個標准用來替代原先的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，高級加密標准由美國國家標准與技術研究院（NIST）於2001年11月26日發布於FIPS PUB 197，並在2002年5月26日成為有效的標准。2006年，高級加密標准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然後導入如下頭文件
#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> 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:@"x", 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是和後台約定的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是和後台約定的key哦，不然無法解密….
最後留下demo下載地址
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