Talk:Block cipher mode of operation

message: The talk page was getting cluttered and I was afraid that some important comments would get overlooked.  Creating: /Archive 1  Lunkwill 20:43, 7 October 2006 (UTC)
replies: text: Yeah, it was starting to get cluttered. Thanks. I added the archive boxes to the top of the pages. --David Göthberg 00:03, 8 October 2006 (UTC)
replies: text: davidpech 201.175.216.173 (talk) 07:20, 29 August 2023 (UTC)
thread_title:  Archives 

message: I've just been looking at the decode diagram for CFB, this has the plaintext being fed back into the cipher encode block.  I think it should the encrypted text that is fed back?
: Right you are.  Fixed. Lunkwill 18:37, 30 May 2005 (UTC)
thread_title:  Is the CFB decode diagram correct? 

message: Does anyone think this is worth adding to the references?
Recommendation for Block Cipher Modes of Operation; Methods and Techniques
http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf
It's a bit more verbose than the descriptions here (covers CBC, CFB, OFB, CTR, ECB) and clarified many things for me. Other things it covers are:
 - test vectors for AES in the 5 modes
 - generation of IVs
 - Error propagation
 - Message padding
 - Counters
: That sounds like an excellent reference. I've gone ahead and added it as an external link. Zetawoof(ζ) 22:21, 17 September 2006 (UTC)
thread_title:  Maybe some external references? 

message: Is it worth mentioning? I'd like to think so.
83.147.140.156 (talk) 11:59, 27 February 2008 (UTC)
replies: text: The article already notes in the section IV that reusing the same IV makes OFB insecure. If you know another "known plaintext attack" then please provide a reference. 85.2.23.131 (talk) 21:04, 27 February 2008 (UTC)
thread_title:  OFB vulnerable to known plaintext attack 

message: I just added a section about using CFB with a shift register. If anyone wants to add a diagram to this that would be awesome. There is an example of one here, but it doesn't make it very clear when the shift register is being updated relative to the other operations. Wingedsubmariner (talk) 20:23, 1 March 2009 (UTC)
thread_title:  CFB used with a shift register 

message: "OFB" redirects here. OFB may also refer to the Austrian Football Association.
IMHO this is wrong. The Austrian Football Association is the ÖFB or OEFB - have a loot at their website, which is http://www.oefb.at/. On the other hand is OEFB not redirecting to the Austrian Football Association.  —Preceding unsigned comment added by 217.194.34.103 (talk) 12:32, 24 November 2009 (UTC)
thread_title:  OFB may also refer to the Austrian Football Association? 

message: The section on cipher feedback mode (CFB) says that "if a whole blocksize of ciphertext is lost both CBC and CFB will synchronize, but losing only a single byte or bit will permanently throw off decryption." Later in the same section, however, it is stated that "a one-bit change in the ciphertext affects two plaintext blocks: a one-bit change in the corresponding plaintext block, and complete corruption of the following plaintext block", but that "Later plaintext blocks are decrypted normally." Likewise, the section on cipher-block chaining (CBC) states that "a one-bit change to the ciphertext causes complete corruption of the corresponding block of plaintext, and inverts the corresponding bit in the following block of plaintext, but the rest of the blocks remain intact."
How are these statements to be reconciled? Does a single-bit or byte error "permanently throw off decryption", or does it only throw off decryption for a couple of blocks? --66.50.16.13 (talk) 14:39, 21 March 2014 (UTC)
thread_title:  Single bit errors and error propagation. Contradiction in text? 

message: Concerning the streaming nature of OFB and CTR modes, it would be good to indicate explicitly that the plaintext does not have to consist of complete blocks. For a partially filled final plaintext block, just the corresponding ciphertext symbols (an incomplete ciphertext block) are transmitted; this can still be decoded.
It might be appropriate to note the relationship between OFB and CTR mode, and the One-time pad. In OFB/CTR mode, the key and the block cipher encryption function are used to generate a (pseudo-random) one-time pad, which is then XOR-ed with the plaintext to yield the ciphertext.
Wstomv (talk) 15:01, 30 May 2014 (UTC)
thread_title:  OFB and CTR modes 

message: It would be helpful to add the concept of explicit initialization vectors. This could be done either in its own section or as a part of CBC mode.  In explicit IV mode a random data block is prepended to the plain text. The encrypted random block then takes the place of communicating the IV because the first block will always be thrown out. An example of where this is currently being used can be found on page 6 of "The Design and Implementation of Datagram TLS"
I could add it, but this is the first time I've edited any wikipedia article and I thought the talk page would be a better place to start.
216.45.141.162 (talk) 17:48, 2 January 2015 (UTC)
thread_title:  Explicit IV in CBC 

message: When j=1, you do not use I(0), you use I(1) and O(0).  Therefore, the IV is O(0), not I(0).  Alternatively you could say that I(1) is the IV.  — Preceding unsigned comment added by 68.11.83.88 (talk) 02:06, 27 February 2015 (UTC)
thread_title:  OFB formula incorrect 

message: It is mentioned here and explained there but I didn't find anything about this mode in the Wikipedia. Who might want to add it here? --RokerHRO (talk) 12:13, 27 April 2015 (UTC)
thread_title:  what about OpenSSL's "Infinite Garble Extension" ? 

message: the usage and primary topic of  is under discussion, see talk:Block chain (transaction database) -- 65.94.43.89 (talk) 04:22, 29 May 2015 (UTC)
thread_title: "Block chain"

message: The usage and primary topic of  is under discussion, see talk:Blockchain -- 65.94.43.89 (talk) 08:39, 29 May 2015 (UTC)
thread_title: "Blockchain"

message: kanatronjitjung@gmail.com 49.237.11.134 (talk) 16:57, 25 January 2022 (UTC)
thread_title:  kanatronjitjung@gmail.com 

message: I noticed that the acronym to the right of "Output Feedback" in the diagram is CFB - a duplicate of the acronym for Cipher Feedback above it. This should be OFB, right? Davidfinnie (talk) 23:44, 15 April 2024 (UTC)
replies: text: You are 1000% correct. Good catch. It has been fixed. Epachamo (talk) 14:10, 16 April 2024 (UTC)
thread_title:  Acronym for Output Feedback in diagram is incorrect