2
votes
2answers
135 views

Which characters to take into account when calculating unicity distance?

I need to calculate the unicity distance of a block cipher. Assuming I know that the plaintext is an English message I considered using 53 as the size of the alphabet, since the message could contain ...
0
votes
2answers
113 views

Multiple encryption of part of block

Is there any security risk in encrypting parts of blocks twice? I'd like to get around block sizes and make encrypted messages just as long as the unencrypted ones: Block 1: Byte 0 - 7 Block 2: Byte ...
0
votes
2answers
101 views

Is CBC theoretically harder to brute force when compared with ECB?

Theoretically is CBC mode harder to bruteforce when compared with ECB? Assumptions We ignore computational cost for the XOR operations IV is made public
0
votes
0answers
38 views

AES mode scheme feedback [duplicate]

I've been studying encryption on a hobby basis, and wanted to know if I got this basic cypher construction right (this is another experiment, see the AES ECB experiment thread earlier). Encryption: ...
0
votes
2answers
60 views

AES key from encrypted text and VI

So I'm trying to figure out if it's possible to extract the private key if you have the ciphertext and the IV corresponding to that ciphertext. It's for some kind of a challenge, and can't really ...
0
votes
1answer
33 views

AES different modulo operations

I don't get the modulo 10001 operation in mixColumns so much. If I have to take the byte computations mod 100011011 anyway what leads me to a result of 4byte length, why do I need the mod 10001 ...
-1
votes
1answer
79 views

Vigenere ciphers : Need help for math analysis

I've been learning about Vigenere ciphers and then thought of another method to Encrypt and decrypt that. This's my method to encrypt : ...
1
vote
1answer
49 views

Koblitz encoding a message to a point, what is the “associated auxiliary base parameter”?

I am looking at the Koblitz method for encoding a message as an elliptic curve point. The first step given in the paper I'm reading is: "Choose an elliptic curve and its associated auxiliary base ...
4
votes
2answers
394 views

How do we compute IV+1 in CTR mode?

This may be a very simple question, but I have not found info about this in any place. My question is about CTR mode: When it says $IV+1$… How do we make this operation? For example, if I have the IV ...
4
votes
1answer
1k views

What is “Implicit Authentication”?

What is “Implicit Authentication” in the context of authentication methods? I searched the Web but could not find any article that describes this. If anyone can describe it, that would be a great ...
2
votes
1answer
119 views

AES as Integer Program

I read that AES can be broken by solving a Linear Integer Program (IP). From a given encrypted text, how can one construct this IP? How big is the system?
0
votes
1answer
33 views

One-one correspondance complete function

I am reading the paper by John B. Kam and Georges I. Davida (1979) titled Structured Design of Substitution-Permutation Encryption Networks. On page 749 it reads ...
2
votes
1answer
108 views

What is the advantage of using the socialist millionaire protocol to authenticate vs HMACing some random number?

Say Alice and Bob have a shared secret $s$. Alice and Bob establish an encrypted channel and verify that it hasn't been MitM'ed by exchanging $r_1$ and $r_2$, where $r_1$ and $r_2$ are randomly ...
0
votes
1answer
137 views

Predicting Google Authenticator OTP Codes [closed]

I use Google Authenticator to generate OTP codes for logging in. As you know, the numbers change every 30 seconds or so, and (AFAIK) use an RSA key to generate those numbers. If someone were to ...
0
votes
1answer
67 views

DH and PKI for KeyExchange

My question is fairly simple. I have more than two nodes which needs to communicate very efficiently from computational point of view. One of the nodes can become a coordinator between the nodes. ...
0
votes
1answer
62 views

Asymmetric sign in public enviroment

I have RTS game, where all players run game and server just relays messages. Game can generate and store text file on player pc. I want to allow some players to be moderators, so I need to sign or ...
0
votes
1answer
41 views

Will the complement of a 64-bit key and message produce the complement ciphertext if ECB is used in DES?

Say I have a 64-bit message/key: P1: 1011....... K1: 0101....... I run this message/key pair through DES in ECB mode and obtain some cipher that looks like the ...
2
votes
1answer
38 views

Recombination thresholds in degree reduction of multiplied Shamir shares

Shamir's secret sharing can be considered multiplicatively homomorphic, if one is aware of the fact that multiplying two shares of a (n,t)-threshold shared secret yields a share of the same secret, ...
4
votes
2answers
271 views

Is Chaocipher a secure cipher under ciphertext-only attack?

Chaocipher was invented by John F. Byrne in 1919. The algorithm was recently revealed – see Moshe Rubin's Chaocipher Revealed, the Algorithm (PDF). While a known plaintext attack successfully finds ...
3
votes
2answers
106 views

Power analysis and exponentiation by squaring

I am trying to understand how one can retrieve the secret exponent via a simple power analysis. Lets suppose that the exponentiation by squaring algorithm is implemented in its simplest form : ...
3
votes
3answers
574 views

128 bit 3DES Key and AES Key: what's the difference?

Apologies if this is really basic but I couldn't find the answer to this. I have heard some Info Sec colleagues talking about creating an AES key in preference to a DES or 3DES key but I don't know ...
2
votes
1answer
52 views

Is format preserving encryption suitable for use with words or names?

Is it possible to use FPE to encrypt names and language words like 'Bob' 'the' 'tree', in order to preserve both length and format (like keeping characters within a certain range like A-Z a-z) The ...
1
vote
1answer
206 views

Creating serial key generator using ECDSA, how to get signature short enough?

I've written some questions in this stackoverflow and got great responses but now I'm trying to wrap it all together. I have for the last couple of weeks been building a serial key generator project ...
1
vote
1answer
31 views

How to choose the integer m in the general number field sieve (GNFS)?

Given an integer you want to factor $N$, GNFS starts by selecting a monic irreducible polynomial $f \in \mathbb{Z}[X]$ and an integer $m$ such that $f(m) \equiv 0 \text{ mod } N$. In practice, if $m$ ...
0
votes
0answers
26 views

BLAKE2 input parameters [migrated]

Being a newbie, I was reading papers on the recent crop of hash functions and BLAKE2 intrigued me. Then I wanted to play around with the "blake2s" code in the code package. If I were to implement a ...
0
votes
0answers
32 views

Pseudorandom function and hash function [duplicate]

What is the difference between a pseudorandom function and hash function ? I have already read the answer in this link What is the difference between a hash function and a pseudorandom function? but ...
1
vote
1answer
57 views

ccrypt and its security

I would like to know how secure is ccrypt to encrypt files (like images, videos and other non-plain text data) using single password of 20+ chars length. It uses Rijndael with 256-bit block size and ...
10
votes
1answer
10k views

How does RSA signature verification work?

I understand how the RSA algorithm works for encryption and decryption purposes but I don't get how signing is done. Here's what I (think) I know and is common practice: If I have a message that I ...
0
votes
1answer
77 views

Drawback of ElGamal encryption

I am trying to find out some disadvantages of ElGamal cryptography but I'm not able to figure out what's wrong with the algorithm. The only one I found is that a known-plain text attack is possible in ...
2
votes
0answers
44 views

What are the steps to decrypt a TLS 1.1 record?

My question is related to another question in Cryptography about TLS 1.1 and 1.2. I have read both RFC 2246 The TLS Protocol Version 1.0 and RFC 4346 The TLS Protocol Version 1.1. What I know is that ...
1
vote
1answer
62 views

How does ccrypt work?

On many Linux/GNU distributions CCrypt (ccrypt) by Peter Selinger is available as a command line utility to encrypt files. How does the protocol work and is it ...
0
votes
1answer
58 views

Are there cryptographic schemes that mask as unencrypted traffic?

Are there cryptographic schemes that make encrypted traffic look like unencrypted traffic?
1
vote
0answers
131 views

Evaluating Algebraic Complexity of a S-box

While studying the design and the desirable properties of an AES S-box , I came to know that Algebraic Complexity is also an important property of an S-box which is usually considered while evaluating ...
0
votes
2answers
155 views

Possible hashing scheme

Plaintext(binary) : 10101100 //very short for easy understanding Suppose we have 4 predefined schemes/functions, rotate (101 -> 011) flip (1101 -> 1011) exchange (11011 -> 10111) stretch (1100 -> ...
-4
votes
2answers
58 views

Why would cryptography fall apart if there were a finite number of primes? [closed]

I vaguely know that prime numbers are very important in cryptography, but I assume for most encryption methods, they tend to stay rather 'small'. Are we really using massive prime numbers for ...
0
votes
2answers
122 views

How secure is it to use password as AES key?

I am developing a steganography app where user encrypt any file into an audio file. The user can enter a password to protect the hidden data. The same password is converted as a 256 bit key and the ...
2
votes
2answers
59 views

How obvious is it to decrypt numerics encrypted with a reused one time pad?

For instance say you encrypt text using the one time pad and you end up with some scrambled text that appears illegible. If you reused the key for multiple times for enough text, someone could ...
0
votes
1answer
88 views

Twofish vs. Serpent vs. AES (or a combo)

I've seen some posts and info online, but they are from 2009, 2010, 2011 or 2012, which is 3-6 years ago, which is a very long time. So I'm looking for an up-to-date answer about which of these is the ...
0
votes
1answer
91 views
0
votes
1answer
52 views

Calculation of time needed to crack DES with my CPU

I have a laptop that has the CPU and the RAMs shown below in the images. My question is that, using this CPU and the RAMs, how much time would it take for me to crack an old school DES algorithm ...
1
vote
0answers
65 views

What are the well known protocols that offer perfect forward secrecy? [closed]

As far as I know these are the well known protocols that offer PFS TLS/SSL (with DHE-RSA, DHE-DSS, ECDHE-RSA or ECDHE-ECDSA) SSH (RFC4253) OTR (Protocol Version 3 Spec) IPsec (with IKEv1 and IKEv2) ...
1
vote
2answers
131 views

Is there any existing cipher capable of scaling from a 1 bit key up to a one-time-pad?

We have ciphers that handle small amounts of entropy, such as a 256 bit key for AES; and we have one time pads for enciphering 1:1 entropy, such as a 1GB key for a 1GB file if you could ever harvest ...
6
votes
3answers
689 views

Shannon confusion and diffusion concept

I read the document(not the whole document) from Shannon where he speaks about the concepts of confusion and diffusion. I read in many places(not in the document but around the internet) that ...
1
vote
1answer
94 views

In HMQV, can one use multiple identities with one public key?

The HMQV protocol has 2 "identity" fields $\hat{A}, \hat{B}$ that are used in the dual signature - and it tries to guarantee that any properly-generated session key is only shared by a single $(A, B, ...
0
votes
1answer
58 views

Multiple keys for the same ciphertext [duplicate]

Say you have a plain text: How are you today? and you encrypt it so it becomes: LKD03Loel03skj1Q03 Now you have multiple people that need to know the plain text of this cipher text but ...
0
votes
0answers
69 views

What do you think about this message encryption?

I am currently working on my diploma project, a high security NFC door lock and need to exchange very sensible data. That's why I thought of PGP encryption, which is as far as I know one of the ...
2
votes
1answer
38 views

Differences between Work Factor and Time Complexity

I am interested to know if work factor means the same thing as time complexity. Quoting Work Factor : Uncovering keys in cryptosystems The Work Factor of a cryptosystem is related to its ...
5
votes
2answers
76 views

Are there any known weaknesses with ElGamal algorithm?

I am working on a messaging system and plan to use ElGamal asymmetric encryption to protect the message contents during storage and transmission. (This would be in addition to TLS used during ...
1
vote
0answers
79 views

Zero Knowledge Non Interactive Proof with random oracle

I am trying to write an assay about Non Interactive Zero-Knowledge proofs and would like to take the simple discrete logarithm problem example fallowing the Feige-Fiat-Shamir heuristics. I understand ...

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