How to encrypt with MCRYPT_ARCFOUR in WAMP?
$td = mcrypt_module_open(MCRYPT_ARCFOUR, '', MCRYPT_MODE_CBC, '');
$iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
mcrypt_generic_init($td, $key, $iv);
$output = mcrypt_generic($td, $input);
mcrypt_generic_deinit($td);
mcrypt_module_close($td);

mcrypt_module_open(): Could not open encryption module

foreach(mcrypt_list_algorithms() as $alg) {
    printf("n%20s:", $alg);
    foreach(mcrypt_list_modes() as $mode) {
        $mc = @mcrypt_module_open($alg, null, $mode, null);
        if(is_resource($mc)) echo "t$mode";
        else echo "t!!FAIL!!:$mode";
    }
}
echo "n";

cast-128:   cbc cfb ctr ecb ncfb    nofb    ofb !!FAIL!!:stream
            gost:   cbc cfb ctr ecb ncfb    nofb    ofb !!FAIL!!:stream
    rijndael-128:   cbc cfb ctr ecb ncfb    nofb    ofb !!FAIL!!:stream
         twofish:   cbc cfb ctr ecb ncfb    nofb    ofb !!FAIL!!:stream
         arcfour:   !!FAIL!!:cbc    !!FAIL!!:cfb    !!FAIL!!:ctr    !!FAIL!!:ecb    !!FAIL!!:ncfb   !!FAIL!!:nofb   !!FAIL!!:ofb    stream
        cast-256:   cbc cfb ctr ecb ncfb    nofb    ofb !!FAIL!!:stream
          loki97:   cbc cfb ctr ecb ncfb    nofb    ofb !!FAIL!!:stream
    rijndael-192:   cbc cfb ctr ecb ncfb    nofb    ofb !!FAIL!!:stream
       saferplus:   cbc cfb ctr ecb ncfb    nofb    ofb !!FAIL!!:stream
            wake:   !!FAIL!!:cbc    !!FAIL!!:cfb    !!FAIL!!:ctr    !!FAIL!!:ecb    !!FAIL!!:ncfb   !!FAIL!!:nofb   !!FAIL!!:ofb    stream
 blowfish-compat:   cbc cfb ctr ecb ncfb    nofb    ofb !!FAIL!!:stream
             des:   cbc cfb ctr ecb ncfb    nofb    ofb !!FAIL!!:stream
    rijndael-256:   cbc cfb ctr ecb ncfb    nofb    ofb !!FAIL!!:stream
         serpent:   cbc cfb ctr ecb ncfb    nofb    ofb !!FAIL!!:stream
            xtea:   cbc cfb ctr ecb ncfb    nofb    ofb !!FAIL!!:stream
        blowfish:   cbc cfb ctr ecb ncfb    nofb    ofb !!FAIL!!:stream
          enigma:   !!FAIL!!:cbc    !!FAIL!!:cfb    !!FAIL!!:ctr    !!FAIL!!:ecb    !!FAIL!!:ncfb   !!FAIL!!:nofb   !!FAIL!!:ofb    stream
             rc2:   cbc cfb ctr ecb ncfb    nofb    ofb !!FAIL!!:stream
       tripledes:   cbc cfb ctr ecb ncfb    nofb    ofb !!FAIL!!:stream

foreach(mcrypt_list_algorithms() as $algo) {
    echo $algo;
    $td = mcrypt_module_open($algo, '', MCRYPT_MODE_CBC, '');
    echo "n";
}

cast-128
gost
rijndael-128
twofish
arcfourPHP Warning:  mcrypt_module_open(): Could not open encryption module in php shell code on line 1
PHP Stack trace:
PHP   1. {main}() php shell code:0
PHP   2. mcrypt_module_open() php shell code:1

cast-256
loki97
rijndael-192
saferplus
wakePHP Warning:  mcrypt_module_open(): Could not open encryption module in php shell code on line 1
PHP Stack trace:
PHP   1. {main}() php shell code:0
PHP   2. mcrypt_module_open() php shell code:1

blowfish-compat
des
rijndael-256
serpent
xtea
blowfish
enigmaPHP Warning:  mcrypt_module_open(): Could not open encryption module in php shell code on line 1
PHP Stack trace:
PHP   1. {main}() php shell code:0
PHP   2. mcrypt_module_open() php shell code:1

rc2
tripledes