iOS开发之Objective-c的AES加密和解密算法的实现

//
//NSData+AES256.h
//
 
#import <Foundation/Foundation.h>
#import <CommonCrypto/CommonDigest.h>
#import <CommonCrypto/CommonCryptor.h>
 
@interface NSData(AES256)
-(NSData *) aes256_encrypt:(NSString *)key;
-(NSData *) aes256_decrypt:(NSString *)key;
@end
 
 
//
//NSData+AES256.m
//
#import "NSData+AES256.h"
 
@implementation NSData(AES256)
 
- (NSData *)aes256_encrypt:(NSString *)key   //加密
{
  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;
}
 
 
- (NSData *)aes256_decrypt:(NSString *)key   //解密
{
  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;
}
@end

//
//NSString +AES256.h
//
 
#import <Foundation/Foundation.h>
#import <CommonCrypto/CommonDigest.h>
#import <CommonCrypto/CommonCryptor.h>
 
#import "NSData+AES256.h"
 
@interface NSString(AES256)
 
-(NSString *) aes256_encrypt:(NSString *)key;
-(NSString *) aes256_decrypt:(NSString *)key;
 
@end
 
 
//
//NSString +AES256.h
//
 
@implementation NSString(AES256)
 
-(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:@"%02x", datas[i]];
    }
    return output;
  }
  return nil;
}
 
-(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] = {'\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];
  }
 
  //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]autorelease];
  }
  return nil;
}
@end