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7h
comment Is there a standardized tree hash?
Related: "Optimal Parameter Selection for Efficient Memory Integrity Verification Using Merkle Hash Trees".
Jan
13
comment Simplied DES why 10-bit key?
Mark, are you maybe referring to one of the simplified variants of DES mentioned at en.wikipedia.org/wiki/Data_Encryption_Standard#Simplified_DES ?
Oct
29
comment Coin flipping with limited communication between participants
@Victor: You are right. As often happens to all programmers, I have a first part of something that solves part of the problem, and then I add a second part that solves the rest of the problem; and later I realize that this second part can be used to solve the entire problem and I don't need the first part any more.
Jun
6
comment Is the one-time-pad a secure system according to modern definitions?
@CodesInChaos: I realize the original title "Has the one-time pad been broken?" was a little provocative, but I think "Does the one-time-pad meet modern security definitions?" is ambiguous. The answer is either trivially "no" (a OTP doesn't do or meet anything; people and machines do things and meet people) or trivially yes (The modern definition of a OTP has critical details not present in early cryptography definitions, and of course a real OTP matches that definition, even though other things that people might mistakenly call a OTP do not). Feel free to tweak the title further.
Mar
28
comment Are there any simple and yet secure encryption algorithms?
@archie: Did you maybe mean to link to the Simeck tweet on p. 23 of "Revisiting Counter Mode to Repair Galois/Counter Mode and Simeck: An Authenticated Cipher Design"?
Mar
28
comment Are there any simple and yet secure encryption algorithms?
@archie: Did you maybe mean to say that the SPECK128 cipher fits in one tweet ?
Dec
21
comment Any efficient text-based steganographic schemes?
Related: "Steganography to hide text within text"
Sep
29
comment Cryptographic data structure: sparse array without membership test
If the person writing data could keep track of exactly what key,value pairs he has written so far (in some in-RAM structure that the attacker, and hence the reader, won't have access to once the computer is shut down), then perhaps the surprising-to-me dirty paper coding approach could be used -- rather than "most recent value wins" every collision, sometimes "let the older value win this collision" is better when there is enough error correction that the new value can still be recovered from other, non-colliding bits.
Sep
29
comment Cryptographic data structure: sparse array without membership test
+1. And thank you for making "Is deniable error-correction possible?" a separate question.
Sep
29
comment Cryptographic data structure: sparse array without membership test
@gmr: yes, very similar to your solution, except this proposal doesn't require decrypting the 'k' value and checking if the decrypted 'k' value matches the current 'k' value. So this proposal apparently runs a little faster.
Sep
27
comment Cryptographic data structure: sparse array without membership test
This sounds distantly related to multiple-message encoding in steganography. Alice carefully constructs an image that appears to be an innocent cat photo, but embeds multiple messages inside such that Oscar can extract one message from Alice, Trent can extract another message from Alice, but Oscar and Trent (assuming they don't collaborate) can't even detect that any other message exists in the image. Can one of the multiple-message encoding techniques be adapted to solve this problem?
Sep
24
comment Understanding Pseudo Random Generators
@TravisMayberry: Would you mind telling me what "n" is for RC4/CipherSaber, Salsa20, or some other real PRNG implementation? Or are you pointing out a difference between the theoretical definition, and what I see in practice?
Sep
21
comment Single-purpose symmetric encryption scheme for single files
For the "file" command to work properly, you're going to want the first few bytes of the file to describe what kind of file this is -- often the the name of the program that produces the file (in UTF8 characters), followed by a version number.
Sep
21
comment Single-purpose symmetric encryption scheme for single files
What is the advantage over " 7z a -p outfile infile.txt "? (Perhaps using 'tar', as described in the 7z man page, to store the metadata). See "7-Zip's AES encryption".
Sep
2
comment Repeatable crypto
Yes, a system that lets the attacker get the encryption key -- is broken. However, there is a way to attack the deduplication, even if the attacker doesn't know the original key.
Aug
29
comment What is the most secure hand cipher?
@AaronToponce: by "this", do you mean the cipher is impractical, or that the cipher is practically secure against this attack because this particular attack is impractical?
Jul
29
comment Is there a cryptographic hash function that can be performed with pencil and paper?
@JohnDeters: I agree that colluding web site admins is unrealistic. However, I have accounts on so many different websites that it is not unreasonable to suspect that at least 2 of those sites will accidentally leak my password to an attacker.
Jun
11
comment Can you help me understand what a cryptographic “salt” is?
@Mike: Who? Someone says "You should always assume the attacker knows the salt.". People at another page says "Salts are public", and later says "the salts are known, because that's the industry-standard use of the word salt." Another says "the salt are public knowledge, or at least should be treated as public knowledge.".
Apr
21
comment encrypt message with one digest 0-9 instead of 01-26
I've been told that historically this Gronsfeld cipher was actually used more often than the Vigenère cipher.
Mar
22
comment Do any one-key-of-many cryptographic schemes exist?
+1. Perhaps you might also mention: This standard construction is standardized in more detail in "RFC 4880: OpenPGP Message Format".