一. aes加密* or *解密

    //  NSData+AES.h
   //  MM_FESCO
   //  Created by Mortimey on 16/8/17.
   //  Copyright © 2016年 Mortimey. All rights reserved.
   //
    #import <Foundation/Foundation.h>
    @class NSString;

    @interface NSData (AES)

   - (NSData *)AES365EncryptWithKey:(NSString *)key;   //加密

   - (NSData *)AES365DecryptWithKey:(NSString *)key;   //解密

   @end
      //
    //  NSData+AES.m
   //  MM_FESCO
     //
   //  Created by Mortimey on 16/8/17.
    //  Copyright © 2016年 Mortimey. All rights reserved.
     //

    #import "NSData+AES.h"

   #import <CommonCrypto/CommonCryptor.h>

   @implementation NSData (AES)


- (NSData *)AES365EncryptWithKey:(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 *)AES365DecryptWithKey:(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

二. base64加密 * or * 解密
AES在iOS加过密以后以NSData的形式存下来，如果想以NSString形式存储，那么对NSData进行BASE64位编码。
首先下载GTMBase64文件，在工程中加入下面三个文件
GTMDefines.h
GTMBase64.h
GTMBase64.m
这三个文件请参考: https://github.com/Mortime/MM_EncodeAndCodeFile.git

  //
  //  NSString+BASE64.h
  //  MM_FESCO
  //
  //  Created by Mortimey on 16/8/17.
  //  Copyright © 2016年 Mortimey. All rights reserved.
  //

   #import <Foundation/Foundation.h>

   @interface NSString (BASE64)
    //  输入类型为NSString
   + (NSString*)encodeBase64String:(NSString *)input;
   + (NSString*)decodeBase64String:(NSString *)input;

    //  输入类型为NSData
   + (NSString*)encodeBase64Data:(NSData *)data;
   + (NSString*)decodeBase64Data:(NSData *)data;
   @end

    //
   //  NSString+BASE64.m
   //  MM_FESCO
   //
   //  Created by Mortimey on 16/8/17.
   //  Copyright © 2016年 Mortimey. All rights reserved.
   //

   #import "NSString+BASE64.h"
   #import "GTMBase64.h"

   @implementation NSString (BASE64)


   + (NSString*)encodeBase64String:(NSString * )input {
NSData *data = [input dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];
data = [GTMBase64 encodeData:data];
NSString *base64String = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
return base64String;
 }

+ (NSString*)decodeBase64String:(NSString * )input {
NSData *data = [input dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];
data = [GTMBase64 decodeData:data];
NSString *base64String = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
return base64String;
}

 + (NSString*)encodeBase64Data:(NSData *)data {
data = [GTMBase64 encodeData:data];
NSString *base64String = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
return base64String;
}

  + (NSString*)decodeBase64Data:(NSData *)data {
data = [GTMBase64 decodeData:data];
NSString *base64String = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
return base64String;
}
@end

三. md5加密

//
//  NSString+MD5.h
//
//  Created by Keith Smiley on 3/25/13.
 //  Copyright (c) 2013 Keith Smiley. All rights reserved.
 //

  @import Foundation;

   #ifdef NS_ASSUME_NONNULL_BEGIN
   NS_ASSUME_NONNULL_BEGIN
   #endif

    @interface NSString (MD5)

     - (NSString *)MD5Digest;

    @end

   #ifdef NS_ASSUME_NONNULL_END
  NS_ASSUME_NONNULL_END
  #endif
    //
    //  NSString+MD5.m
  //
 //  Created by Keith Smiley on 3/25/13.
 //  Copyright (c) 2013 Keith Smiley. All rights reserved.
 //

#import <CommonCrypto/CommonDigest.h>
#import "NSString+MD5.h"

@implementation NSString (MD5)

- (NSString *)MD5Digest
{
const char* input = [self UTF8String];
unsigned char result[CC_MD5_DIGEST_LENGTH];
CC_MD5(input, (CC_LONG)strlen(input), result);

NSMutableString *digest = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH * 2];
for (NSInteger i = 0; i < CC_MD5_DIGEST_LENGTH; i++) {
    [digest appendFormat:@"%02x", result[i]];
}

return digest;
}

@end

==========================================================================================
aes、base64、md5 加密和解密方法也可参考本人Github: https://github.com/Mortime/MM_EncodeAndCodeFile.git