1
vote
3answers
91 views

Algorithms for Cyrillic encryption

I am working on a cryptography application which is to be used in my country. I tried looking up to see if there are any algorithms that support the Cyrillic alphabet, but I found none. Do you know of ...
1
vote
0answers
78 views

Block cipher not resistant to collisions

If we have the following block cipher, $E(k,m)$, which is a permutation, why is $f_2 (x,y)$ not collision resistant? $$f_2(x, y) = E(x, x \oplus y)$$
-4
votes
0answers
24 views

partition Recovery in windows 7

I encrypted a partition on my hard drive in windows 7 using bit-locker drive encryption, this partition was formatted, How may I recover it?
0
votes
0answers
14 views

Extension of Diffie Hellman for many participants [duplicate]

How to do the Extension of Diffie Hellman Algorithm for Multiple Participants
3
votes
2answers
52 views

Are there any practical methods of steganography?

There isn't a whole lot of information on steganography in the modern age, from what I can tell. A google search for steganography usually brings up a list of very impractical methods (e.g. tattooing ...
12
votes
1answer
875 views

How does a non-prime modulus for Diffie-Hellman allow for a backdoor?

Recently someone found that a Diffie-Hellman modulus used in a unix tool (socat) was not prime. This led some people to shout "backdoor". What I don't understand ...
0
votes
0answers
6 views

Generating Large Prime Numbers with Py Crypto [migrated]

I'm trying to generate a large prime number (2048 bits) using the crypto library in python in order to implement RSA. However, I do not really understand the syntax of the getPrime() function. I ...
1
vote
1answer
16 views

ABE Schemes - Access Structures & Performance

I'm reading this article, CP-ABE with constant-size keys for lightweight devices and in the Table 1, are there these access structure: Threshold, Tree, ($n$,$n$)-Threshold, LSSS, AND gates. I have 2 ...
3
votes
2answers
38 views

Determining Involutary Keys in Substitution Ciphers

How would I be able to show that a key $K=(a,b)$ is involutary for an Affine Cipher over the integers modulo n? Similarly, is there a way to generalize the conditions for a key to be involutary for a ...
1
vote
1answer
20 views

Key Exchange MAC encryption order of events? Problem

I want to write the sequence of events of how a MAC encryption works for documentation at work. For this purpose I have a document (given by my boss to me) in German and I am trying to translate it ...
1
vote
0answers
63 views

When we use one time pad TWICE in two different ways

Assumption and Notations: All the values defined over the field $\mathbb{F}_p$, where $p$ is a large prime number. We denote multiplicative inverse of value $v$ by $v^{-1}$. All values are non-zero ...
-2
votes
0answers
17 views

How to verify CURLE_PEER_FAILED_VERIFICATION, CURLE_SSL_CERTPROBLEM curl errors [closed]

I want verify below two curl errors CURLE_PEER_FAILED_VERIFICATION, CURLE_SSL_CERTPROBLEM Please provide the source code or steps to verify above two error codes
1
vote
0answers
27 views

Need help with PKCS#12 3 key triple des key expansion

I am trying to decrypt PKCS8-Shrouded Key Bag inside a PKCS#12 pfx file. The oid for the encrypted data is PbeWithSHAAnd3-KeyTripleDES CBC. Iteration count and salt has been provided within the pfx ...
3
votes
1answer
69 views

How does RIPEMD160 pad the message?

For RIPEMD hashing algorithm on hardware I am not exactly getting how padding works So as per my understanding padding will work like explained below: For ripemd 160 message should be multiple of ...
0
votes
1answer
58 views

What is the complexity to break second preimage resistance?

In the context an of hash functions we have three required properties. Preimage resistance Second preimage resistance Collision resistance. The bounds for Pre image collision is $O(2^{n-1})$, the ...
0
votes
0answers
36 views

implementation of authenticated encryption algorithms on GPU

I am trying to implement an authenticated encryption algorithm on GPU. i have selected an algorithm that can be parallel both in Enc and Dec. this new authenticated encryption algorithm has a small ...
4
votes
2answers
92 views

Classification of a stream cipher

How would one classify a stream cipher that is neither synchronous, nor self synchronizing? I would have thought asynchronous, but from all the sources I can find, asynchronous is synonymous with ...
-4
votes
1answer
25 views

Computing inverses in a binary field

Please suggest how can i solve the below question What is the inverse of {03} in GF (2^8) with the irreducible polynomial x8+x4+x3+x+1?
0
votes
0answers
26 views

Effects of varying the key size for AES encryption [closed]

How to investigate effects of varying the key size for aes algorithm encryption of data over the communication channel
0
votes
1answer
45 views

Elliptic curve ElGamal with homomorphic mapping

I am interested in ElGamal due to the fact that you can achieve some degree of homomorphic properties. I became interested in applying ElGamal to elliptic curves, and found this other question with an ...
8
votes
2answers
192 views

Would a Rubik's cube be a trapdoor function?

It's easy to scramble a Rubik's cube but it is hard to solve, unless you know the algorithms for solving it. This makes it a trapdoor function, correct?
0
votes
1answer
55 views

SHA1 collisions and the impact for ECDSA signatures

What will it mean for ECDSA using SHA1 when we have practical attacks breaking the collision resistance property of SHA1? [UPDATE] Added a bit more details to be clear. If $(r,s)$ is the ECDSA ...
3
votes
1answer
66 views

Help with AES decryption with AES-NI Instructions

I am in process of implementing a AES 128 encryption in AVX2 assembly (using AES NI), and am having some problems with decryption logic. I have implemented the encryption sequence without any trouble. ...
0
votes
2answers
17 views

Can an AES-256 key be generated for a large number of cribs? [duplicate]

I have a question in regards to Ransomware type viruses. I know that a number of these viruses use the AES-256 algorithm to encrypt user's files using a randomly generated key. I work in IT support ...
0
votes
1answer
54 views

Multiparty encryption and decryption

Is it possible to send a single encrypted data message to multiple users so that the users receiving the message can only decrypt certain parts of the message, depending on their rights. For example, ...
0
votes
1answer
43 views

Difference of full codebook and non full codebook

While reading a paper about Dynamic cube attack, I saw two terms: full-codebook and non-full-codebook attacks. What do they mean? What is the difference? Regards
-2
votes
0answers
35 views

hashing algorithm [closed]

I have a program which takes an input of username, the a password and then hashes it and gives integral output. It is not fixed for a particular character. I want to know its hashing algorithm. I ...
-3
votes
0answers
17 views

Is there any code implementation of the HMAC-DRBG PRNG? [closed]

I'm looking for the code of HMAC-DRBG in either C# or C++, for use in a cryptography related project. I can't find it anywhere. Would appreciate the help! Thanks a ton!
2
votes
1answer
32 views

Can one passively load-balance HTTPS traffic based on TLS SNI?

Is it theoretically possible to passively snoop into the HTTPS traffic, reliably detect whether or not TLS SNI is attempted to be used by the client, and, if it is, redirect the stream of the ...
-4
votes
0answers
44 views

A way of bruteforcing a hash value without the use of file [closed]

An example is better than explanation. Let's say we have this md5 hash : 15e0adc0213e01ec44acee74ed4ece5b All I know is this hashing method is md5, the length of ...
0
votes
0answers
19 views

Shamir SS: To associate shares to the public values $x_i$, when the shares are permuted [duplicate]

Suppose we use $(t,n)$ Shamir secret sharing as follows: We share the secret $\beta$ as $S=[s_1,..., s_n]$, where $X=[x_1,...,x_n]$ are the public values. For the sake of simplicity, lets assume ...
1
vote
2answers
82 views

MAC algorithm difficulties

Can anyone explain to me why this is a bad idea? I cannot see anything wrong with it except that key K should be different for MAC and AES. MAC algorithm consists of letting the MAC of message M ...
1
vote
0answers
43 views

total effective key length of the AESX-192

If I have a AESX-192 be a block cipher which is similar to DESX but has the DES being replaced by AES and the AES key size is 192 bits. How should I compute the total effective key length of the ...
-1
votes
0answers
34 views

steganography of an mp4 file [closed]

I have 2 mp4 files that might have something hidden in them. I have been using OpenPuff because it is the only app I can find that will handle mp4's. When I go to unhide and try to load the video(s) ...
0
votes
1answer
23 views

how to define the Truncated Polynomial?

In NTRUEncryption, I seen the trucated polynimials, but I cannot understand the trunacated polynomial calculation. So, could tell me anyone How do we calculate the truncated polynomial?
2
votes
1answer
62 views

Why does image size increase after steganography?

I am working on a steganography technique. Sometimes I need to send my steganographed images online to my friends but in the process the image gets compressed destroying all the data. I found ways to ...
3
votes
1answer
47 views

Proving property of Modified Rabin Signature

I'm trying to prove one of the properties of the “Modified Rabin Signature Scheme”: If $gcd(x, n) = 1$, then $x^{\frac{(p−1)(q−1)}{2}} \equiv 1 \pmod n$ This is what I’ve got so far… Proof Let ...
-2
votes
0answers
30 views

Identify encryption method [closed]

I have a large string containing upper and lower case characters as well as digits. It contains "==" at the end of string. How can I decipher this string?
4
votes
1answer
195 views

Any stream cipher with avalanche effect?

As far as I know, all stream ciphers work by generating a stream of pseudo random bytes, and XOR it with the plain text to get the cipher text. It has the property that one bit change in the cipher ...
-3
votes
0answers
36 views

Need help in solving this cryptographic puzzle [closed]

John and Alice came home to find their window broken. Inside, they found a brick with the following note tied to it: ...
-1
votes
0answers
27 views

Re-encrypting this decrypted data

I got this data: ...
1
vote
2answers
54 views

Is there a standard for hashing a list of strings?

I'm working in Python, and my goal is to hash a list of strings with a cryptographic hash function such as sha256. It would need the property that a change in any string, or the order of the strings, ...
0
votes
1answer
35 views

how to determine block size for decryption

a message coded with RSA is broken up into blocks, then padded/transformed prior to encryption via modular exponentiation with the public key. However, the encryption result for each block is not ...
3
votes
2answers
71 views

Long passwords and Bcrypt

I need to store passwords for a web application, and was looking at Bcrypt for a possible solution. After some research, it appears only the first 72 bytes influence the final hash output. While it is ...
0
votes
1answer
43 views

RSA algorithm private key extraction

Decrypting messages can be done by using the following formula: $$M = C^d \mod n$$ Where $M$ is the decrypted message, $C$ is the encrypted message and $d$ is the private key Theoretically ...
5
votes
1answer
76 views

Exactly how bad is using 'mod' to clamp reduce numbers to a given range?

Let's say I'm naive and want to generate a random integer in the range [0, m), so I do the following: ...
0
votes
2answers
48 views

RSA numerical questions

Let $n$ be the modular arithmetic, $p$ and $q$ the two large primes such that $n=p*q$ and $e$ the public exponent. Here they are two "simple" numerical questions: If $p = 13$ and $q = 17$, what is ...
0
votes
3answers
47 views

How to calculate plaintext from modpower cipher

Let $a$ be the plaintext message, $e$ be a small prime exponent (such as 11, 13, 17 etc.), $b$ be cipher text and $n$ be a large modulo (non-prime). Suppose that: $b \equiv a^e \space mod ...
0
votes
0answers
10 views

A standard for multi-key provider encrypted data?

I'm looking for a standard that standardizes data encryption with multiple and diverse key sources to represent a heterogene access structure and culture. The standard must offer the following ...
3
votes
1answer
37 views

What information should I send along with an AES ciphertext and is there any standard to do that?

While using some crypto implementations I got to see that many times a comment is added to the ciphertext. For example: ...

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