Collaborate Disseminate
In GlobalPlatform specification for smartcards, I came accross this rather strange scheme:
To calculate the Message Authentication Code, we take some original data (a host cryptogram and a padding), then we apply multiple chained DES calcu… Continue reading Why do we encrypt then decrypt then encrypt data with different keys?
We have a process that encrypts a URL, it uses DES encryption. I suspect someone may have figured out the key and is decrypting it to crawl information. This was set up many years ago, I just want to make sure whoever set it up is did not … Continue reading Where could I find a list of keys not to use for DES encrypting
I’m playing around with openssl command line to verify my understanding on block cipher mode.
I read that ECB block cipher mode always encrypt the same text to the same output.
AES operates on 16 bytes block, independently on the key lengt… Continue reading Why encrypting with ECB block cipher mode provides different result?
I’ve been searching for a few days in different forums trying to find an example of DES that gives the key/output values for all 16 layers. I found one that gives the encryption which helped me fix that part, but my decryption isn’t workin… Continue reading DES Encryption: Looking for results for each round of encryption/decryption to debug code
Specifically, I’m looking to determine if tripcodes for users on 4chan could have been migrated to 8chan, and then to 8kun.
My (limited) understanding of this mechanism is that each server creates its own unique hash table and therefore DE… Continue reading Is it possible to port or migrate tripcodes from one server to another?
I was reading a book called Serious Cryptography. There is a page saying that block size must be large enough to prevent codebook attacks:
When 16-bit blocks are used, the lookup table needs only 2^16 × 16 = 2^20 bits
of memory, or 128 ki… Continue reading How to calculate size of a codebook lookup table to break block cipher? [migrated]
Since a single hardware pass of an XOR with a 64 bit key is very fast, would Triple DES-X using seven 64 bit keys used in the following manner be virtually identical in terms of code size, memory consumption, and execution speed to 3DES?
… Continue reading Would Triple DES-X with 7 keys be much slower than standard Triple DES? [migrated]
I read this question in my book (that doesn’t have a response).
2DES is doubly more secure than DES?
I know that 2DES can be attacked from meet in the middle attack.
In fact, from Wikipedia Meet in the middle say :
The MITM attack … Continue reading 2Des is double secure of DES? [migrated]
I am a newbie to block cipher and when learning the CBC mode, I start to understand that an IV is being used in this mode and also will be transferred to the message receiver.
So here is my question, what if the IV is tampered? CBC mode … Continue reading What if the attacker tamper the IV used in the block cipher CBC mode?
My professor has posted a couple of practice questions that so far I haven’t been able to find the answer for and I was hoping you could help.
DES would remain invertible—it would still be ablockcipher—even if its … Continue reading DES/AES invertibility