Is it possible to find out the initialization vector for blowfish in CBC mode if the plaintext and ciphertext are known?

Question

Cryptography

There is a ciphertext and a known plaintext.
The encryption key is unknown.
The algorithm is probably blowfish, the encryption mode is CBC.
To run a brute-force key (suppose there is a 32-bit key, what if you really get lucky?), I still need an IV.
Can I compute it from ciphertext and plaintext?
It seems like for this I just need to do an XOR between the second 64-bit ciphertext block and the first 64-bit plaintext block, but the experiment shows that the initialization vector is not the one that was set (well, I just encrypted the string with a certain key and vector, after which " restored" it, but it did not match the real one).
Is it even possible to get the initialization vector knowing the plaintext and the ciphertext?

Answer 1

In short, I thought about it a little, and realized that no, the initial initialization vector (IV) cannot be found out in this way. Because ("IV" XOR "first block of plaintext") is encrypted with a key.
But you can discard the first 8-byte block of plaintext, and for the remaining block of initialization will be the first block of ciphertext.
Thus, we can brute force (at least try) using the first 8 bytes of the ciphertext as the initialization vector, while using the original ciphertext without the first 8 bytes as the ciphertext, and compare the resulting value
with the plaintext without the first 8 bytes at each decryption iteration. 8 bytes.