iOS开发之Objective-c的AES加密和解密算法的实现

原文：http://www.lidaren.com/archives/1470

高级加密标准（Advanced Encryption Standard，AES），又称Rijndael加密法。 以下实现代码中分别为NSData和NSString增加了一个Category。使用时直接调用即可。

            
                需要注意的是，AES并不能作为HASH算法，加密并解密后的结果，并不一定与原文相同，使用时请注意进行结果验算。例如解密原文的长度，格式规则等。 NG实例

原文：170987350
密码：170
Objective-c的AES加密和解密算法的具体实现代码如下： 1.拓展NSData，增加AES256加密方法
            
        

              1
            //
              2
            //
            NSData+AES256.h

              3
            //

              4
              5
            #import <Foundation/Foundation.h>
  6#import <CommonCrypto/CommonDigest.h>
  7#import <CommonCrypto/CommonCryptor.h>
  8  9@interface NSData(AES256)
 10 -(NSData *) aes256_encrypt:(NSString *)key;
 11 -(NSData *) aes256_decrypt:(NSString *)key;
 12@end 13 14 15// 16//NSData+AES256.m
 17//
 18#import"NSData+AES256.h" 19 20@implementation NSData(AES256)
 21 22 - (NSData *)aes256_encrypt:(NSString *)key   //加密 23{
 24char keyPtr[kCCKeySizeAES256+1];
 25   bzero(keyPtr, sizeof(keyPtr));
 26   [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
 27   NSUInteger dataLength = [self length];
 28   size_t bufferSize = dataLength + kCCBlockSizeAES128;
 29void *buffer = malloc(bufferSize);
 30   size_t numBytesEncrypted = 0;
 31   CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128,
 32                       kCCOptionPKCS7Padding | kCCOptionECBMode,
 33                      keyPtr, kCCBlockSizeAES128,
 34                      NULL,
 35                      [self bytes], dataLength,
 36                      buffer, bufferSize,
 37                       &numBytesEncrypted);
 38if (cryptStatus == kCCSuccess) {
 39return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
 40  }
 41  free(buffer);
 42return nil;
 43}
 44 45 46 - (NSData *)aes256_decrypt:(NSString *)key   //解密 47{
 48char keyPtr[kCCKeySizeAES256+1];
 49   bzero(keyPtr, sizeof(keyPtr));
 50   [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
 51   NSUInteger dataLength = [self length];
 52   size_t bufferSize = dataLength + kCCBlockSizeAES128;
 53void *buffer = malloc(bufferSize);
 54   size_t numBytesDecrypted = 0;
 55   CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128,
 56                       kCCOptionPKCS7Padding | kCCOptionECBMode,
 57                      keyPtr, kCCBlockSizeAES128,
 58                      NULL,
 59                      [self bytes], dataLength,
 60                      buffer, bufferSize,
 61                       &numBytesDecrypted);
 62if (cryptStatus == kCCSuccess) {
 63return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
 64 65  }
 66  free(buffer);
 67return nil;
 68}
 69@end 702.拓展NSString，增加AES256加密方法，需要导入NSData+AES256.h
 71 72 73// 74//NSString +AES256.h
 75//
 76 77#import <Foundation/Foundation.h>
 78#import <CommonCrypto/CommonDigest.h>
 79#import <CommonCrypto/CommonCryptor.h>
 80 81#import"NSData+AES256.h" 82 83@interface NSString(AES256)
 84 85 -(NSString *) aes256_encrypt:(NSString *)key;
 86 -(NSString *) aes256_decrypt:(NSString *)key;
 87 88@end 89 90 91// 92//NSString +AES256.h
 93//
 94 95@implementation NSString(AES256)
 96 97 -(NSString *) aes256_encrypt:(NSString *)key
 98{
 99constchar *cstr = [self cStringUsingEncoding:NSUTF8StringEncoding];
100   NSData *data = [NSData dataWithBytes:cstr length:self.length];
101//对数据进行加密102   NSData *result = [data aes256_encrypt:key];
103104//转换为2进制字符串105if (result && result.length > 0) {
106107     Byte *datas = (Byte*)[result bytes];
108     NSMutableString *output = [NSMutableString stringWithCapacity:result.length * 2];
109for(int i = 0; i < result.length; i++){
110       [output appendFormat:@"%02x", datas[i]];
111    }
112return output;
113  }
114return nil;
115}
116117 -(NSString *) aes256_decrypt:(NSString *)key
118{   
119//转换为2进制Data120   NSMutableData *data = [NSMutableData dataWithCapacity:self.length / 2];
121   unsigned char whole_byte;
122char byte_chars[3] = {‘\0‘,‘\0‘,‘\0‘};
123int i;
124for (i=0; i < [self length] / 2; i++) {
125     byte_chars[0] = [self characterAtIndex:i*2];
126     byte_chars[1] = [self characterAtIndex:i*2+1];
127     whole_byte = strtol(byte_chars, NULL, 16);
128     [data appendBytes:&whole_byte length:1];
129  }
130131//对数据进行解密132   NSData* result = [data aes256_decrypt:key];
133if (result && result.length > 0) {
134return [[NSString alloc] initWithData:result encoding:NSUTF8StringEncoding];
135  }
136return nil;
137}
138@end