#import <Foundation/Foundation.h>

 #import <CommonCrypto/CommonDigest.h>

 #import <CommonCrypto/CommonCryptor.h>

 #import "NSData+AES.h"

 @interface NSString (AES)

 //加密字符串

 - (NSString*)aes128Encrypt:(NSString *)aKey;

 //解密字符串

 - (NSString*)aes128Decrypt:(NSString *)aKey;

 @end

 #define gIv             @"0102030405060708" //自行修改16位 -->偏移量

 @implementation NSString (AES256)

  - (NSString *)aes128Encrypt:(NSString *)aKey

 {

     char keyPtr[kCCKeySizeAES128+];

     memset(keyPtr, , sizeof(keyPtr));

     [aKey getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

     char ivPtr[kCCBlockSizeAES128+];

     memset(ivPtr, , sizeof(ivPtr));

     [gIv getCString:ivPtr maxLength:sizeof(ivPtr) encoding:NSUTF8StringEncoding];

     NSData* data = [self dataUsingEncoding:NSUTF8StringEncoding];

     NSUInteger dataLength = [data length];

     int diff = kCCKeySizeAES128 - (dataLength % kCCKeySizeAES128);

     int newSize = ;

     if(diff > )

     {

         newSize = dataLength + diff;

     }

     char dataPtr[newSize];

     memcpy(dataPtr, [data bytes], [data length]);

     for(int i = ; i < diff; i++)

     {

         dataPtr[i + dataLength] = 0x00;

     }

     size_t bufferSize = newSize + kCCBlockSizeAES128;

     void *buffer = malloc(bufferSize);

     memset(buffer, , bufferSize);

     size_t numBytesCrypted = ;

     CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt,

                                           kCCAlgorithmAES128,

                                           kCCOptionPKCS7Padding,  // 补码方式

                                           keyPtr,

                                           kCCKeySizeAES128,

                                           ivPtr,

                                           dataPtr,

                                           sizeof(dataPtr),

                                           buffer,

                                           bufferSize,

                                           &numBytesCrypted);

     if (cryptStatus == kCCSuccess) {

         NSData *result = [NSData dataWithBytesNoCopy:buffer length:numBytesCrypted];

         if (result && result.length > ) {

             Byte *datas = (Byte*)[result bytes];

             NSMutableString *output = [NSMutableString stringWithCapacity:result.length * ];

             for(int i = ; i < result.length; i++){

                 [output appendFormat:@"%02x", datas[i]];

             }

             return output;

         }

     }

     free(buffer);

     return nil;

 }

 - (NSString *)aes128Decrypt:(NSString *)aKey

 {

     char keyPtr[kCCKeySizeAES128 + ];

     memset(keyPtr, , sizeof(keyPtr));

     [aKey getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

     char ivPtr[kCCBlockSizeAES128 + ];

     memset(ivPtr, , sizeof(ivPtr));

     [gIv getCString:ivPtr maxLength:sizeof(ivPtr) encoding:NSUTF8StringEncoding];

     NSMutableData *data = [NSMutableData dataWithCapacity:self.length / ];

     unsigned char whole_byte;

     char byte_chars[] = {'\0','\0','\0'};

     int i;

     for (i=; i < [self length] / ; i++) {

         byte_chars[] = [self characterAtIndex:i*];

         byte_chars[] = [self characterAtIndex:i*+];

         whole_byte = strtol(byte_chars, NULL, );

         [data appendBytes:&whole_byte length:];

     }

     NSUInteger dataLength = [data length];

     size_t bufferSize = dataLength + kCCBlockSizeAES128;

     void *buffer = malloc(bufferSize);

     size_t numBytesCrypted = ;

     CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt,

                                           kCCAlgorithmAES128,

                                           kCCOptionPKCS7Padding,

                                           keyPtr,

                                           kCCBlockSizeAES128,

                                           ivPtr,

                                           [data bytes],

                                           dataLength,

                                           buffer,

                                           bufferSize,

                                           &numBytesCrypted);

     if (cryptStatus == kCCSuccess) {

         NSData *resultData = [NSData dataWithBytesNoCopy:buffer length:numBytesCrypted];

         return [[NSString alloc] initWithData:resultData encoding:NSUTF8StringEncoding];

     }

     free(buffer);

     return nil;

 }

 @end

 @implementation NSString (StringToHexData)

 //

 // Decodes an NSString containing hex encoded bytes into an NSData object

 //

 - (NSData *) stringToHexData

 {

     int len = [self length] / ;    // Target length

     unsigned char *buf = malloc(len)

     unsigned char *whole_byte = buf;

     char byte_chars[] = {'\0','\0','\0'};

     int i;

     for (i=; i < [self length] / ; i++) {

         byte_chars[] = [self characterAtIndex:i*];

         byte_chars[] = [self characterAtIndex:i*+];

         *whole_byte = strtol(byte_chars, NULL, );

         whole_byte++;

     }

     NSData *data = [NSData dataWithBytes:buf length:len];

     free( buf );

     return data;

 }

 @end

 @implementation NSData (DataToHexString)

 - (NSString *) dataToHexString

 {

     NSUInteger          len = [self length];

     char *              chars = (char *)[self bytes];

     NSMutableString *   hexString = [[NSMutableString alloc] init];

     for(NSUInteger i = ; i < len; i++ )

         [hexString appendString:[NSString stringWithFormat:@"%0.2hhx", chars[i]]];

     return hexString;

 }

 @end

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