Use #pike 7.4 or update your code to the newer Crypto api. The compat wrappers for Crypto.AES as found in lib/7.4/modules/Crypto.pmod/aes.pike:
string name() { return "AES"; }
int query_key_length() { return 32; } int query_block_size() { return block_size(); } string crypt_block(string p) { return crypt(p); }