Getting all possible key sizes for PHP MCrypt Ciphers - php

Question

I'm creating public packages, There are some encryption there, I let developer to choose cipher type and mode and set the key for encryption part of the packeges.
Now I need to check the key size before using it in MCrypt functions.
So what I have to know is:
1) All possible key sizes for the cipher.
2) Byte size of the given key.
Or if you have a better way, please share it.

Answer 1

mcrypt_list_algorithms() gives you the list of ciphers
mcrypt_module_get_supported_key_sizes($cipher) gives you the supported key sizes (is empty if the keysizes are continous)
mcrypt_module_get_algo_key_size($cipher) gives you the maximum key size in case the previous function returned nothing
All key sizes are given in bytes.
Example:
$algorithms = mcrypt_list_algorithms();
foreach ($algorithms as $cipher) {
echo "$cipher:\n";
$keysizes = mcrypt_module_get_supported_key_sizes($cipher);
if (count($keysizes) == 0) {
$max = mcrypt_module_get_algo_key_size($cipher);
echo " max: $max\n";
} else {
foreach ($keysizes as $keysize) {
echo " $keysize\n";
}
}
echo "\n";
}
Use strlen($input) to retrieve the bytes in a given string (should be decoded).