I downloaded a compression program known as PeaZip which offers encryption and 2-way authentication also.
PeaZip has an option to encrypt compressed file with variety of ciphers and one of them is Serpent.
It gives option of:
- Serpent 128 CTR OMAC
- Serpent 256 CTR OMAC
I want to know how strong any cipher, specifically Serpent, is in CTR mode. Assuming a strong password or truly random key file of appropriate size is used.
I am not aware of how effectively this cipher is handled in PeaZip, but that is a different matter.
Ideally, in which mode Serpent is more effective.
-- Edited --
The details of crypto library which PeaZip uses are here.
Author of this library says about Serpent:
Serpent (designed by Ross Anderson, Eli Biham, and Lars Knudsen) was one of the AES finalists; it is a 128-bit block cipher with key sizes of 128, 192, or 256 bits. Please note that although my code supports OMAC and EAX, these modes are not tested against public test vectors (the usual C libraries do either not implement Serpent or OMAC/EAX).