这两天为移动App开发API，结果实现加密验证时碰到一大坑。这里不得不吐槽下又臭又硬的iOS，Windows Server无法解密出正确的结果，Android则可以，后来使用了通用的AES256加密算法才最终搞定。

搞服务器端小伙伴没有接触过iOS，所以也没料到过这种情形。他使用了AES128 with IV的加密算法，Android端可以顺利通过加密验证。

但是iOS端使用AES128算法后出现问题，虽然可以在本地加密解密，但是无法被服务器解密成功。

后来经过多方查找，才了解到一个蛋疼的事实，iOS只支持AES PKCS7Padding算法，在服务器端修改为响应算法后，顺利通过。

这里主要参考一篇博文，以下给出通用AES算法：

//头文件
#import <Foundation/Foundation.h>

@interface NSData (AES)
- (NSData *)AES256EncryptWithKey:(NSString *)key;
- (NSData *)AES256DecryptWithKey:(NSString *)key;
@end

实现代码：

#import "NSData+AES256.h"
#import <CommonCrypto/CommonCryptor.h>


@implementation NSData (AES)

-(NSData *)AES256EncryptWithKey:(NSString *)key {
    // 'key' should be 32 bytes for AES256, will be null-padded otherwise
    char keyPtr[kCCKeySizeAES256+1]; // room for terminator (unused)
    bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)
    
    // fetch key data
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
    
    NSUInteger dataLength = [self length];
    
    //See the doc: For block ciphers, the output size will always be less than or
    //equal to the input size plus the size of one block.
    //That's why we need to add the size of one block here
    size_t bufferSize = dataLength + kCCBlockSizeAES128;
    void *buffer = malloc(bufferSize);
    
    size_t numBytesEncrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
                                          keyPtr, kCCKeySizeAES256,
                                          NULL /* initialization vector (optional) */,
                                          [self bytes], dataLength, /* input */
                                          buffer, bufferSize, /* output */
                                          &numBytesEncrypted);
    if (cryptStatus == kCCSuccess) {
        //the returned NSData takes ownership of the buffer and will free it on deallocation
        return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
    }
    
    free(buffer); //free the buffer;
    return nil;}

-(NSData *)AES256DecryptWithKey:(NSString *)key {
    // 'key' should be 32 bytes for AES256, will be null-padded otherwise
    char keyPtr[kCCKeySizeAES256+1]; // room for terminator (unused)
    bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)
    
    // fetch key data
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
    
    NSUInteger dataLength = [self length];
    
    //See the doc: For block ciphers, the output size will always be less than or
    //equal to the input size plus the size of one block.
    //That's why we need to add the size of one block here
    size_t bufferSize = dataLength + kCCBlockSizeAES128;
    void *buffer = malloc(bufferSize);
    
    size_t numBytesDecrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
                                          keyPtr, kCCKeySizeAES256,
                                          NULL /* initialization vector (optional) */,
                                          [self bytes], dataLength, /* input */
                                          buffer, bufferSize, /* output */
                                          &numBytesDecrypted);
    
    if (cryptStatus == kCCSuccess) {
        //the returned NSData takes ownership of the buffer and will free it on deallocation
        return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
    }
    
    free(buffer); //free the buffer;
    return nil;
}
@end

C#：实现方法

#region

        /// <summary>
        /// 256位AES加密
        /// </summary>
        /// <param name="toEncrypt"></param>
        /// <returns></returns>
        public static string Encrypt(string toEncrypt)
        {
            // 256-AES key    
            byte[] keyArray = UTF8Encoding.UTF8.GetBytes(key);
            byte[] toEncryptArray = UTF8Encoding.UTF8.GetBytes(toEncrypt);

            RijndaelManaged rDel = new RijndaelManaged();
            rDel.Key = keyArray;
            rDel.Mode = CipherMode.ECB;
            rDel.Padding = PaddingMode.PKCS7;

            ICryptoTransform cTransform = rDel.CreateEncryptor();
            byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);

            return Convert.ToBase64String(resultArray, 0, resultArray.Length);
        }

        /// <summary>
        /// 256位AES解密
        /// </summary>
        /// <param name="toDecrypt"></param>
        /// <returns></returns>
        public static string Decrypt(string toDecrypt)
        {
            // 256-AES key    
            byte[] keyArray = UTF8Encoding.UTF8.GetBytes(key);
            byte[] toEncryptArray = Convert.FromBase64String(toDecrypt);

            RijndaelManaged rDel = new RijndaelManaged();
            rDel.Key = keyArray;
            rDel.Mode = CipherMode.ECB;
            rDel.Padding = PaddingMode.PKCS7;

            ICryptoTransform cTransform = rDel.CreateDecryptor();
            byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);

            return UTF8Encoding.UTF8.GetString(resultArray);
        }

        #endregion

Java：实现方法

public class AESUtils {
    /** 
     * 加密 
     * param content 需要加密的内容 
     * param password  加密密码 
     * return 
     */  
    private static String Key="GcA*23jKJf0df09Osf09834ljlJF0920";

    public static String encode(String stringToEncode) throws NullPointerException {

        try {
            SecretKeySpec skeySpec = getKey(Key);
            byte[] clearText = stringToEncode.getBytes("UTF8");
            final byte[] iv = new byte[16];
            Arrays.fill(iv, (byte) 0x00);
            IvParameterSpec ivParameterSpec = new IvParameterSpec(iv);
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
            cipher.init(Cipher.ENCRYPT_MODE, skeySpec, ivParameterSpec);
            String encrypedValue = Base64.encodeToString(cipher.doFinal(clearText), Base64.DEFAULT);
            return encrypedValue;
            
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (InvalidAlgorithmParameterException e) {
            e.printStackTrace();
        }
        return "";
    }         
    
    private static SecretKeySpec getKey(String password) throws UnsupportedEncodingException {
        int keyLength = 256;
        byte[] keyBytes = new byte[keyLength / 8];
        Arrays.fill(keyBytes, (byte) 0x0);
        byte[] passwordBytes = password.getBytes("UTF-8");
        int length = passwordBytes.length < keyBytes.length ? passwordBytes.length : keyBytes.length;
        System.arraycopy(passwordBytes, 0, keyBytes, 0, length);
        SecretKeySpec key = new SecretKeySpec(keyBytes, "AES");
        return key;
    }    
    
}

作者：msp的昌伟哥哥