OpenSSL C ++加密问题

Question

So what I'm trying to do is have an encryption key on my PC that is based off of the time, and have the server generate the same encryption key. I have done that successfully, except for the cipher on my PC. I am trying to encrypt text in AES-256-CBC on the server and on my PC. On my PC I have:

std::string Encrypt( const unsigned char *szPlainText, const unsigned char *szKey, unsigned char *szIV, const int iTextLength )
{
    unsigned char szOutput[ 16 ];
    memset( szOutput, 0, sizeof( szOutput ) );

    std::string strOutput { };
    AES_KEY enc_key;
    AES_set_encrypt_key( szKey, 256, &enc_key );
    AES_cbc_encrypt( szPlainText, szOutput, iTextLength, &enc_key, (unsigned char*)szKey, AES_ENCRYPT );
    strOutput.append( reinterpret_cast< const char* >( szOutput ) );
    return strOutput;
}

std::string MD5Hash( const unsigned char *szPlainText, const int iCharacters )
{
    unsigned char chDigest[ MD5_DIGEST_LENGTH ] { };

    MD5( szPlainText, iCharacters, reinterpret_cast< unsigned char* >( &chDigest ) );

    char mdString[ 33 ];

    for ( int i = 0; i < MD5_DIGEST_LENGTH; i++ )
        sprintf( &mdString[ i * 2 ], "%02x", ( unsigned int )chDigest[ i ] );

    return mdString;
}

int main( )
{
    const unsigned char *szPlainText = reinterpret_cast< const unsigned char* >( "test" );
    std::string strCipher { };
    std::string strResponseBuffer { };
    std::string strEncryptionKey { };
    strEncryptionKey = MD5Hash( reinterpret_cast< const unsigned char* >( std::to_string( int( std::chrono::duration_cast< std::chrono::seconds >( std::chrono::system_clock::now( ).time_since_epoch( ) ).count( ) / 10 ) ).c_str( ) ), std::to_string( int( std::chrono::duration_cast< std::chrono::seconds >( std::chrono::system_clock::now( ).time_since_epoch( ) ).count( ) / 10 ) ).length(  ) );
    strEncryptionKey = strEncryptionKey.substr( 0, 16 );
    std::cout << "Our enc key before encryption: " << strEncryptionKey << std::endl;
    strCipher = Encrypt( szPlainText, reinterpret_cast< const unsigned char* >( strEncryptionKey.c_str( ) ), ( unsigned char* )( strEncryptionKey.c_str( ) ), strlen(reinterpret_cast< const char* >( szPlainText ) ));

    curl_global_init( CURL_GLOBAL_ALL );
    void *vCurl = curl_easy_init( );
    curl_easy_setopt( vCurl, CURLOPT_URL, strURL );
    //curl_easy_setopt( vCurl, CURLOPT_POSTFIELDS, strPostData.c_str( ) );
    curl_easy_setopt( vCurl, CURLOPT_WRITEFUNCTION, WriteCallback );
    curl_easy_setopt( vCurl, CURLOPT_WRITEDATA, &strResponseBuffer );
    curl_easy_perform( vCurl );
    curl_easy_cleanup( vCurl );

    std::cout << "Our time: " << std::chrono::duration_cast< std::chrono::seconds >( std::chrono::system_clock::now( ).time_since_epoch( ) ).count( ) / 10 << std::endl;
    std::cout << "Our enc key: " << strEncryptionKey << std::endl;
    std::cout << "Our cipher: " << strCipher << std::endl;
    std::cout << "Our plain text: " << szPlainText << std::endl;
    std::cout << strResponseBuffer << std::endl;

    system( "pause" );
    return 0;
}

On the server, where the PHP code is, I have:

<?php
    $encmethod = "AES-256-CBC";
    $plaintext = "test";
    $time = microtime(false);
    $time = substr($time, 11, strlen($time) - 11);
    $time = floor($time / 10);

    $enckey = substr(md5($time), 0, 16);
    $cipher = openssl_encrypt($plaintext, $encmethod, $enckey, 0, $enckey);
    die("Server's time: ".$time."\r\n"."Server's enc key: ".$enckey."\r\n"."Server's cipher: ".base64_decode($cipher)."\r\n"."Server's plain text: ".$plaintext);
?>

I do realize that I am using my encryption key for an IV. I Base64 decode the encryption because OpenSSL for PHP apparently encodes the cipher by default. What I don't understand is the output I get:

Our enc key before encryption: bd40cb464c24382e
Our time: 151693026
Our enc key: ▐τA╕cæσ@c¿svcî
Our cipher: ▐τA╕cæσ@c¿svcî╠╠╠╠HÇ~╖D·█
Our plain text: test
Server's time: 151693026
Server's enc key: bd40cb464c24382e
Server's cipher: nr"δµûa¢╝│)║\ß■V
Server's plain text: test
Press any key to continue . . .

This changes every 10 seconds because that's what it's based on. What appears to be happening is after encryption, my encryption key is becoming encrypted and I don't know what my cipher is supposed to be. The 4 repeating characters ╠╠╠╠ appear to be there every time the encryption changes. If anyone knows what I'm doing wrong I would appreciate it.

Answer 1

The bug comes from bad casting. In this line of code:

strCipher = Encrypt( 
    szPlainText, 
    reinterpret_cast< const unsigned char* >( strEncryptionKey.c_str( ) ),
    ( unsigned char* )( strEncryptionKey.c_str( ) ), 
    strlen(reinterpret_cast< const char* >( szPlainText ) ));

The second cast is a bit abusive. Apparently the function expects a non-const buffer. You should provide the address of a separate 16 bytes work array there.