Recover plaintext from truncated ciphertext using AES for FPE
In the decrypting steps use AES_encrypt itself instead of AES_decrypt, AES decrypt is never needed.

Remember while encrypting, AES_encrypt is only used as a Pseudo Random Function, we don't really need AES_decrypt method even in decrypting phase. This might seem little confusing at first but not needed. Please check the proof given for this answer