2016-04-08 09:03 编辑： liubinqww 分类：iOS开发 来源：liubinqww 投稿
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"APP的数据安全已经牵动着我们开发者的心，简单的MD5/Base64等已经难以满足当下的数据安全标准，本文简单的介绍下AES与Base64的混合加密与解密"
AES:高级加密标准（英语：Advanced Encryption Standard，缩写：AES），在密码学中又称Rijndael加密法，是美国联邦政府采用的一种区块加密标准。这个标准用来替代原先的DES，已经被多方分析且广为全世界所使用。经过五年的甄选流程，高级加密标准由美国国家标准与技术研究院（NIST）于2001年11月26日发布于FIPS PUB 197，并在2002年5月26日成为有效的标准。2006年，高级加密标准已然成为对称密钥加密中最流行的算法之一。
以上是来自百度百科的解释。
下面我将用代码来阐述其使用方法。 首先我们创建一个NSData的类扩展，命名为AES，创建完如果对的话应该是这样的NSData+AES然后导入如下头文件
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#import 《CommonCrypto/CommonDigest.h》#import 《CommonCrypto/CommonCryptor.h》 |
再增加加解密的方法，方便外部文件的调用，写完.h文件如下
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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编码- (NSString *)newStringInBase64FromData;//同上64编码+ (NSString*)base64encode:(NSString*)str;@end |
.m文件中依次实现这几个方法，具体如下
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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编码- (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= 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</srclen; i += 3) {> |
AES+Base64的加密方式到此已经结束了，下面讲一下单纯的AES字符串加密的。
和上面的基本上差不多，写一个NSString的类扩展，命名为AES，创建完如果对的话应该是这样的NSString+AES导入如下头文件
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#import "NSData+AES.h" |
同样的把加解密的方法写在.h文件中，写完如下
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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实现方法
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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]; //对数据进行加密 NSData *result = [data AES256_Encrypt:key]; //转换为2进制字符串 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{ //转换为2进制Data NSMutableData *data = [NSMutableData dataWithCapacity:self.length / 2]; unsigned char whole_byte; char byte_chars[3] = {' ',' ',' '}; 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]; } //对数据进行解密 NSData* result = [data AES256_Decrypt:key]; if (result && result.length > 0) { return [[NSString alloc] initWithData:result encoding:NSUTF8StringEncoding]; } return nil;} |
到此我们加密的文件基本上都已经OK了，下面我们来简单的的使用一下，具体如下：
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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. //字符串加密 NSString *key = @"12345678";//Key是和后台约定的key哦，不然无法解密.... 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 |
运行得到打印的结果如下：
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是和后台约定的key哦，不然无法解密….
最后留下demo下载地址