Linked Questions

13 votes
2 answers

Why can't the IV be predictable when its said it doesn't need to be a secret?

I heard multiple times not to reuse the same IV and IV should be random but doesn't need to be secret. I also heard if the IV is something like sequential numbers or something predictable I should ...
user avatar
12 votes
3 answers

Using a Non-Random IV with modes other than CBC

The weakness CWE-329 is an interesting problem with CBC mode. However, does this same weakness affect the other modes of operation that rely upon an IV such as: PCBC, CFB and OFB? My gut feeling is, ...
Rook's user avatar
  • 1,486
3 votes
2 answers

AES + CBC encryption for a stream of UDP packets

I am developing an application that is based on UDP, and I need to send a stream of packets. As you can imagine, packets can get lost or corrupted. I need to make sure that the content of those ...
Matteo Monti's user avatar
  • 1,375
9 votes
2 answers

Will varying plaintext compensate for a fixed initialisation vector?

This is a follow-up question to Relative merits of AES ECB and CBC modes for securing data at rest. I need to store encrypted Personal Account Numbers (PANs) in a database. The only encryption option ...
Brent.Longborough's user avatar
5 votes
2 answers

Encryption for a short packet size

I have an 8051 microcontroller with a radio that can send packets with up to 32 bytes and I want to have the messages encrypted. It is a sensor network so I really only want to send one packet per ...
Baruch Even's user avatar
4 votes
4 answers

Which block cipher modes of operation allow a predictable IV?

Recently I found out that in the modes CBC and PCBC the IV may be passed in cleartext but never must be predictable. However for this part of my app I rather have the IV be predictable and unique (i.e....
user avatar
1 vote
1 answer

Question about IV/initialization vectors

I found some code to get crypto-js to encrypt data in the browser, and with a pointer from someone on SO, it now decodes data as well. My next question is about the use of an IV; is an IV like a salt ...
Lucas Krupinski's user avatar
4 votes
1 answer

Fixed-prefix IV in CBC mode

I know the Initialization Vector needs to be unpredictable. Does it apply to the IV as a whole, or to every bit in the IV? I have multiple devices with poor entropy sharing the same key and I want to ...
Julian's user avatar
  • 43
3 votes
1 answer

Is MCrypt's 8-bit OFB mode secure?

I just stumbled across a Stack Overflow post which points out that the libmcrypt library (notably used in PHP) implements a somewhat unusual set of block cipher modes: it calls the usual CFB and OFB ...
Ilmari Karonen's user avatar
2 votes
3 answers

Deciphering text encrypted with a changing cipher

I know there are many ways to crack basic ciphers were each letter is mapped to some other letter, but what ways are there to decode something that was encrypted using a cipher that changed after ...
AHumbleCoder's user avatar
2 votes
1 answer

Is using CFB in SIV secure?

Is SIV mode variant equally secure, if you replace CTR mode encryption with full-block CFB mode encryption? CFB seems to be safe with predictable IV: Is using a predictable IV with CFB mode safe or ...
LightBit's user avatar
  • 1,649