On Wed, 13 Feb 2002 11:01:43 +0200, Cornel GLIGAN said:
I have some questions about the last three paragraphs:
- Is the Initial Vector encrypted with the algorithm-specific
portion?
The IV is a parameter to the CFB (Cipher Feed Back) encryption mode.
- Let's assume that I encrypt the algorithm-specific portion with
IDEA. What it happens if the length of the algorithm-specific portion is
not multiple of 8 (64 bit)? How can I fill the last block of the
algorithm-specific portion to be an 8 byte (64 bit) block?
Padding is not required with CFB. Don't hardwire the 64 bits; you
have to use the blocksize of the used cipher (e.g. 128 for AES).
You find more information about encryption modes in the standard
literature:
@Book{Men:96:HAC,
author = "Alfred J. Menezes and Paul van Oorschot and
Scott Vanstone",
title = "Handbook of Applied Cryptography",
language = "USenglish",
publisher = pub-CRC,
address = pub-CRC:adr,
pages = "xxvii + 780",
year = "1996",
ISBN = "0-8493-8523-7",
keywords = "cryptograpy",
}
There is an online resource for it, IIRC:
http://cacr.math.uwaterloo.ca/hac/
or
@Book{Sch:96:AC,
author = "Bruce Schneier",
title = "Applied Cryptography",
language = "USenglish",
edition = "second",
publisher = pub-WIL,
address = pub-WIL:adr,
pages = "xxiii + 758",
year = "1996",
ISBN = "0-471-11709-9",
}
Hth,
Werner
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