Swift(iOS)和PHP中AES256加密的结果不同

我已经看到很多类似的问题围绕密钥大小,模式(CBC或ECB),随机iv的使用等等.但在这种情况下,我发现了一个奇怪的行为,如下所示.

两种环境中的配置：
– 密钥：32字节(256位)
– 块大小：128位(标准)
– iv：16字节(静态用于测试目的)
– 模式：CBC

如果我加密16或32字节的文本(以匹配AES块大小),Swift和PHP中的结果相似但不完全相同：

key = “12345678901234567890123456789012”
plainText = “12345678901234567890123456789012”
iv = “1234567890123456”

Swift cipher = e5RnnlJkv4QGnGhkMwfvgMHr80NWUVhbvvfCdPQ5V2KyKJTx4KfWmn4HXi4dG0b8
PHP cipher = e5RnnlJkv4QGnGhkMwfvgMHr80NWUVhbvvfCdPQ5V2I=

如您所见,PHP Base64字符串的密码长度和最后2个字符存在差异.

但是,如果我使用的文本不是AES128 Block Size乘数,请说“Hello World”,bot环境会报告不同(但大小相同)的密码如下

Swift cipher = bdwO/5C8a+pliIoIXtuzfA==

PHP cipher = oPotHCkxpOwQhIaCz6hNMw==

在这两种情况下(Swift和PHP),无论明文的大小如何,密码都会被正确解密.此外,Swift结果与代码的Objective-C版本一致

附上使用的简化代码：

PHP

$key = "12345678901234567890123456789012"; 
    $iv = "1234567890123456";
    $plaintext = "Hello World";
    $ciphertext = mcrypt_encrypt(MCRYPT_RIJNDAEL_128,$key,$plaintext,MCRYPT_MODE_CBC,$iv);
    $ciphertext_base64 = base64_encode($ciphertext);
    echo  "ciphertext: ".$ciphertext_base64."</br>";

迅速

let keyData: NSData! = (key as Nsstring).dataUsingEncoding(NSUTF8StringEncoding) as NSData!
let keyBytes         = UnsafePointer<UInt8>(keyData.bytes)
let keyLength        = size_t(kCCKeySizeAES256)

let plainData = (plainText as Nsstring).dataUsingEncoding(NSUTF8StringEncoding) as NSData!
let dataLength    = UInt(plainData.length)
let dataBytes     = UnsafePointer<UInt8>(plainData.bytes)

var bufferData    = NSMutableData(length: Int(dataLength) + kCCBlockSizeAES128)
var bufferPointer = UnsafeMutablePointer<UInt8>(bufferData.mutableBytes)
let bufferLength  = size_t(bufferData.length)

let operation: Ccoperation = UInt32(kCCEncrypt)
let algoritm:  CCAlgorithm = UInt32(kCCAlgorithmAES128)
let options = UInt32(kCcoptionPKCS7Padding)

let ivData: NSData! = (iv as Nsstring).dataUsingEncoding(NSUTF8StringEncoding) as NSData!
let ivPointer = UnsafePointer<UInt8>(ivData.bytes)

var numBytesEncrypted: UInt = 0

var cryptStatus = CCCrypt(operation,algoritm,options,keyBytes,keyLength,ivPointer,dataBytes,dataLength,bufferPointer,bufferLength,&numBytesEncrypted)

bufferData.length = Int(numBytesEncrypted)
let base64cryptString = bufferData.base64EncodedStringWithOptions(.Encoding64CharacterLineLength)
println(base64cryptString)

为什么这些不同？