使用原因：

因為在專案中，需要在與客戶端(IOS,Android)互動的時候，儲存一些私有資訊，不被別人看到，所以，使用了比較流行的可以反向加解密的AES。

PHP 原始碼

<?php

$aes = new aes;
echo $aes->aes128cbcEncrypt("11122222");
echo "\n";
echo $aes->aes128cbcEncrypt("中文aes演示");
echo "\n";
class aes{
    const KEY="625202f9149e061d";
    const IV ="5efd3f6060e20330";
    /**
     * pkcs7補碼
     * @param
 
 string $string  明文
     * @param int $blocksize Blocksize , 以 byte 為單位
     * @return String
     */ 
    private function addPkcs7Padding($string, $blocksize = 32) {
        $len = strlen($string); //取得字串長度
        $pad = $blocksize - ($len % $blocksize); //取得補碼的長度
        $string .= str_repeat(chr($pad
 
), $pad); //用ASCII碼為補碼長度的字元， 補足最後一段
        return $string;
    }

    /**
     * 加密然後base64轉碼
     * 
     * @param String 明文
     * @param 加密的初始向量（IV的長度必須和Blocksize一樣， 且加密和解密一定要用相同的IV）
     * @param $key 金鑰
     */
    function aes256cbcEncrypt($str, $iv, $key ) {   
        return base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key
 
, $this->addPkcs7Padding($str) , MCRYPT_MODE_CBC, $iv));
    }

    /**
     * 除去pkcs7 padding
     * 
     * @param String 解密後的結果
     * 
     * @return String
     */
    private function stripPkcs7Padding($string){
        $slast = ord(substr($string, -1));
        $slastc = chr($slast);
        $pcheck = substr($string, -$slast);

        if(preg_match("/$slastc{".$slast."}/", $string)){
            $string = substr($string, 0, strlen($string)-$slast);
            return $string;
        } else {
            return false;
        }
    }
    /**
     * 解密
     * 
     * @param String $encryptedText 二進位制的密文 
     * @param String $iv 加密時候的IV
     * @param String $key 金鑰
     * @return String
     */
    function aes256cbcDecrypt($encryptedText, $iv, $key) {
        $encryptedText =base64_decode($encryptedText);
        return $this->stripPkcs7Padding(mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $encryptedText, MCRYPT_MODE_CBC, $iv));
    }

    function aes128cbcDecrypt($encryptedText, $iv=self::IV, $key=self::KEY) {
        $encryptedText =base64_decode($encryptedText);
        return $this->stripPkcs7Padding(mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key, $encryptedText, MCRYPT_MODE_CBC, $iv));
    }

    function hexToStr($hex)//十六進位制轉字串
    {   
        $string=""; 
        for($i=0;$i<strlen($hex)-1;$i+=2)
        $string.=chr(hexdec($hex[$i].$hex[$i+1]));
        return  $string;
    }
    function strToHex($string)//字串轉十六進位制
    { 
        $hex="";
        $tmp="";
        for($i=0;$i<strlen($string);$i++)
        {
            $tmp = dechex(ord($string[$i]));
            $hex.= strlen($tmp) == 1 ? "0".$tmp : $tmp;
        }
        $hex=strtoupper($hex);
        return $hex;
    }
    function aes128cbcHexDecrypt($encryptedText, $iv=self::IV, $key=self::KEY) {
        $str = $this->hexToStr($encryptedText);
        return $this->stripPkcs7Padding(mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key, $str, MCRYPT_MODE_CBC, $iv));
    }

    function aes128cbcEncrypt($str, $iv=self::IV, $key=self::KEY ) {    // $this->addPkcs7Padding($str,16)
        $base = (mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key,$this->addPkcs7Padding($str,16) , MCRYPT_MODE_CBC, $iv));
        return $this->strToHex($base);
    }
}

執行結果

線上驗證加解密結果

驗證地址
http://www.seacha.com/tools/aes.html

IOS 原始碼

@implementation NSString (AES256)
-(NSString *) aes256_encrypt:(NSString *)key
{
    const char *cstr = [self cStringUsingEncoding:NSUTF8StringEncoding];
    NSData *data = [NSData dataWithBytes:cstr length:self.length];
    //對資料進行加密
    NSData *result = [data aes256_encrypt:key];

    //轉換為2進位制字串
    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
{
    //轉換為2進位制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];
    }

    //對資料進行解密
    NSData* result = [data aes256_decrypt:key];
    if (result && result.length > 0) {
        return [[NSString alloc] initWithData:result encoding:NSUTF8StringEncoding];
    }
    return nil;
}
@end





@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 ,
                                          keyPtr, kCCBlockSizeAES128,
                                          [AES_IV UTF8String],
                                          [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 ,
                                          keyPtr, kCCBlockSizeAES128,
                                          [AES_IV UTF8String],
                                          [self bytes], dataLength,
                                          buffer, bufferSize,
                                          &numBytesDecrypted);
    if (cryptStatus == kCCSuccess) {
        return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];

    }
    free(buffer);
    return nil;
}

@end

Android

package com.example.aes;


import java.io.UnsupportedEncodingException;


import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;


/**
 * AES加密解密演算法
 */
public class AesEncryptionUtil {
/** 演算法/模式/填充 **/
private static final String CipherMode = "AES/CBC/PKCS5Padding";


/** 建立金鑰 **/
private static SecretKeySpec createKey(String key) {
byte[] data = null;
if (key == null) {
key = "";
}
StringBuffer sb = new StringBuffer(16);
sb.append(key);
while (sb.length() < 16) {
sb.append("0");
}
if (sb.length() > 16) {
sb.setLength(16);
}


try {
data = sb.toString().getBytes("UTF-8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
return new SecretKeySpec(data, "AES");
}


private static IvParameterSpec createIV(String password) {
byte[] data = null;
if (password == null) {
password = "";
}
StringBuffer sb = new StringBuffer(16);
sb.append(password);
while (sb.length() < 16) {
sb.append("0");
}
if (sb.length() > 16) {
sb.setLength(16);
}


try {
data = sb.toString().getBytes("UTF-8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
return new IvParameterSpec(data);
}


/** 加密位元組資料 **/
public static byte[] encrypt(byte[] content, String password, String iv) {
try {
SecretKeySpec key = createKey(password);
Cipher cipher = Cipher.getInstance(CipherMode);
cipher.init(Cipher.ENCRYPT_MODE, key, createIV(iv));
byte[] result = cipher.doFinal(content);
return result;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}


/** 加密(結果為16進位制字串) **/
public static String encrypt(String content, String password, String iv) {
byte[] data = null;
try {
data = content.getBytes("UTF-8");
} catch (Exception e) {
e.printStackTrace();
}
data = encrypt(data, password, iv);
String result = byte2hex(data);
return result;
}


/** 解密位元組陣列 **/
public static byte[] decrypt(byte[] content, String password, String iv) {
try {
SecretKeySpec key = createKey(password);
Cipher cipher = Cipher.getInstance(CipherMode);
cipher.init(Cipher.DECRYPT_MODE, key, createIV(iv));
byte[] result = cipher.doFinal(content);
return result;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}


/** 解密(輸出結果為字串) **/
public static String decrypt(String content, String password, String iv) {
byte[] data = null;
try {
data = hex2byte(content);
} catch (Exception e) {
e.printStackTrace();
}
data = decrypt(data, password, iv);
if (data == null)
return null;
String result = null;
try {
result = new String(data, "UTF-8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
return result;
}


/** 位元組陣列轉成16進位制字串 **/
public static String byte2hex(byte[] b) { // 一個位元組的數，
StringBuffer sb = new StringBuffer(b.length * 2);
String tmp = "";
for (int n = 0; n < b.length; n++) {
// 整數轉成十六進位制表示
tmp = (java.lang.Integer.toHexString(b[n] & 0XFF));
if (tmp.length() == 1) {
sb.append("0");
}
sb.append(tmp);
}
return sb.toString().toUpperCase(); // 轉成大寫
}


/** 將hex字串轉換成位元組陣列 **/
private static byte[] hex2byte(String inputString) {
if (inputString == null || inputString.length() < 2) {
return new byte[0];
}
inputString = inputString.toLowerCase();
int l = inputString.length() / 2;
byte[] result = new byte[l];
for (int i = 0; i < l; ++i) {
String tmp = inputString.substring(2 * i, 2 * i + 2);
result[i] = (byte) (Integer.parseInt(tmp, 16) & 0xFF);
}
return result;
}
}