CBC mode with same plaintext I'm working on a file encryption system where multiple versions of the same file might exist. The filenames are encrypted using AES in CBC mode with a random IV and stored in metadata. Since versions of the same file share the same filename, this information may be used by an adversary. Is there any additional information to be derived from multiple ciphertexts which are known to share the same plaintext, just with a different IV?
the key and plaintext is the same. The attacker knows this and the IVs used but doesn't know the plaintext. Is there anything to learn about the plaintext when multiple ciphertexts are available instead of only one?


No. Giving the attacker multiple encryptions of a single plaintext using a randomly chosen IV and a fixed key with AES-CBC does not leak any more information about the plaintext than does a single ciphertext.

In fact if the attacker didn't know whether or not they were the same plaintext (but had the same length), the attacker couldn't tell you whether or not they encrypted the same plaintext.