How to check if the key is correct when decrypting?

Question

C++ / C#

Hello, I use the Blowfish algorithm in CFB mode to encrypt / decrypt messages, how do I check the correctness of the key and initialization vector when decrypting?
Programming language: C++
Library: OpenSSL
Thanks in advance for your help!

Answer 1

I didn’t quite understand the question, but usually, so that there are no false positives due to incorrect key entry, its checksum is stored somewhere and, before decryption, the checksum of the entered key is compared with the stored one.