3
votes
1answer
36 views

Is there a way to turn a PGP key into its semi-prime counterpart?

From my understanding of PGP keys they use the RSA algorithms to encrypt/decrypt messages. So, I know that the RSA algorithms use a semi-prime number to encrypt/decrypt messages. So, what I was ...
2
votes
1answer
68 views

Are the following schemes based on a pseudo-random permutation secure?

I am currently working on the following task: Let F be a pseudorandom permutation. Consider the encryption scheme for the message space $\{0, 1\}^n$ defined as follows: $Gen(1^n)$ chooses ...
2
votes
1answer
43 views

How would you name and/or describe this algorithm?

First up: this is not a decoding request or anything. This is about terminology. Twice per year, we email another department to ask for a new licence file for their software. They are always slow to ...
1
vote
2answers
86 views

Levels of strength: The Caesar Cipher

SITREP: I am deciding what form of "Random" Number generation would fit best for a Caesar Cipher that encrypts each letter with a different integer as a shift. This encryption is being handled via C# ...
0
votes
1answer
96 views

How are security proofs done in ABE Schemes?

I have been studying several ABE schemes and I understand the security assumptions and the several types of security models used for the security game between the Challenger and the Adversary. What ...
0
votes
0answers
4 views

encryption used by onepass [migrated]

I use a password storage application on my mac called 1password ( see here: https://1password.com/). I was wondering if it encrypts the data it stores in my computer and decrypts it using a key made ...
0
votes
1answer
64 views

How to decrypt an RSA ciphertext given an oracle providing the lower 8 bits of decryptions?

I have access to an oracle that can encrypt and partially decrypt a number with RSA-1024 algorithm. For encryption: \begin{equation} C = M^e\bmod n \end{equation} But for decryption, result will ...
2
votes
1answer
72 views

Exponential cipher theory misunderstanding

Say I pick modulus $m=2633$ and key $e=13$ My private key $d$ is $13$ inverse in $\bmod 2632$ which I need to compute $(e,m)$ is my public key that anyone can use to encrypt message for me and then ...
0
votes
0answers
71 views

RSA PlainText without Knowing Private Key

I couldn't solve this problem for three days... In RSA, [n = 13, 19] [e = 3] c1 = m^3 = 83 mod 247 [e=5] c2 = m^5 = 97 mod 247 then, use ...
5
votes
1answer
70 views

How do Käsper and Schwabe's Bitsliced AES Mixcolumns work?

The only way I see it possible to do the matrix-multiplication in the MixColumns operation of AES is by shifting the bits in the multiplied number, and then reduce with the polynomial if needed. ...
0
votes
0answers
28 views

correlation between the timing data produced by different keys with similar inputs in AES

Is there or can there be any correlation between the timing data produced by different keys with similar inputs in AES? If yes, what type of correlation?
1
vote
0answers
21 views

How share size is reduced in robust secret sharing?

THIS IS ROBUST SECRET SHARING SCHEME The dealer $\mathcal{D}$ wants to share a secret among the participants $\{P_1, P_2, \ldots, P_n\}$, where at most $t$ participants are malicious and $t<n/2$. ...
1
vote
0answers
37 views

Truly Random Values [duplicate]

I am trying to build a one-time pad encryption software and I am thinking about simply using /dev/random to generate keys. My question is: Is it ...
2
votes
1answer
209 views

Mathematical formula for switching the key for OTP?

Instead of generating the random key for the one time pad cipher over and over again, is there a mathematical formula that allows you to switch the key to a new key? The new key must be as random and ...
5
votes
1answer
412 views

Is my password entropy calculation correct?

I have a password with a prescribed format: 111 + “2 Random lowercase letters” + “random digit” As you can see, it starts with a fixed value of ...
0
votes
0answers
70 views

Compute Modulo exponentiation with prime powers

The problem is to find x such that $$x = M^d \mod p^2$$, where M and d are large numbers, and p is a large prime. Ideally we only want to compute $M^d\mod p$ and then use the result to further ...
0
votes
0answers
30 views

Has this forum been compromised by the NSA BULLRUN programme? [migrated]

Today, this site shows 24 thousand users in Cryptography. It runs in parallel with and is associated with StackOverflow boasting 6 million users. This site then clearly creates some leverage and ...
0
votes
1answer
58 views

How hard is it to generate a simultaneous MD5 and SHA1 collision?

I was recently reading that MD5 is "broken" because it's pretty easy to generate collisions (like 2^(L/2)). And the SHA1 (theoretically) fares no better. The ...
0
votes
1answer
21 views

Hash system to generate same (specified) hash from multiple datasets?

I have a hashed value $X$ and need to ensure that any of the data sets $D_1...D_n$ can be concatenated with a correctional value $C_1...C_n$ and passed into a hashing algorithm to result in the value ...
1
vote
0answers
40 views

Countering Cryptographic Attacks

By reading Camellia Design and Analysis document following is my understanding about few cryptographic attacks from designer point of view. Differential and Linear Crypt-analysis. Number of Active ...
2
votes
6answers
2k views

How secure will this be against brute-force attacks?

I'm looking into encrypting files like this: First, I SHA-1 hash the password. Let's say the password is something normal like "hello123", and then hashed. Then I encrypt a file using this: ...
20
votes
6answers
4k views

Did a certain cryptography method get abandoned due to security flaws in the past?

I am researching how quantum computers affect current encryption methods (RSA and more). However, I remember learning in a course that there used to be a particular encryption method which was ...
1
vote
2answers
37 views

What are KDF parameters in OpenSSL command-line utility for `enc`?

I refer to https://www.openssl.org/docs/manmaster/apps/enc.html and see that the only parameter for key derivation which I can set explicitly (not considering the obvious ...
1
vote
0answers
84 views

How to generate 1000 prime number of 1024-bit with much less time?

I am generating thousand prime number of 1024 bit each. But it takes lots of time. My procedure is as follows. Generate prime number using ...
3
votes
0answers
1k views

Cryptography behind the Turing Imitation Key (TIK)

When browsing the internet I found out about this amazing phone. Well, it would be amazing if it was actually obtainable. It's called the Turing Phone, and it is supposed to come with as good as ...
7
votes
4answers
5k views

Why is AES not a Feistel cipher?

I am studying for an exam right now. And I wanted to make sure I got this point correct. AES is not a Feistel cipher because the operations in AES are not invertible. Is the above statement correct?...
2
votes
2answers
1k views

Am I understanding AES key padding correctly?

I’ld like to ensure I understand AES key padding correctly… Is the initial AES key (expanded to the key schedule) byte padded if less than e.g. 16 bytes? Is there a safe way of determining if ...
0
votes
0answers
18 views

Which bytes in an OTA Command Package are encrypted with the KIc by 3DES CBC?

I have an un-ciphered OTA message in clear and I am trying to cipher it so it becomes secure data. The cryptographic checksum is already generated as part of the un-ciphered OTA message. I have the ...
0
votes
2answers
2k views

If I can crack the AES, how do I crack the wifi [closed]

I am a student major in math. My teacher said that AES (Advanced Encryption Standard) has many applications. For example, the WPA2 in wifi. Then he taught the theory of the AES and never says how to ...
3
votes
1answer
38 views

Concept of “guessed ID” in Authenticated Identity-Based Encryption

In Authenticated Identity-Based Encryption by Ben Lynn, in Proof of Integrity (section 4.3) and Proof of Security (section 4.4), I cannot grab the concept of "guessed ID" . Because encryption differs ...
3
votes
0answers
39 views

How subscriptions are managed in PayTV securely?

Since there are millions of subscriber for each operator in PayTV and each subscriber can subscribe to any of the package or individual channels, how operators transmit Entitlement management messages ...
0
votes
0answers
12 views

Direct Anonymous Attestation

Could anyone explain me Direct Anonymous Attestation in general terms. I have been trying to read the paper but I really cannot seem to get my head around it. It may seem like a dumb question but I am ...
5
votes
0answers
57 views

Increase in AES SBox

AES uses one single Sbox to substitute all 16 bytes in one Round. Will using 16 different Sboxes (with cryptographic properties similar to AES Sbox i.e Non-Linearity of 112, Differential probability ...
-1
votes
0answers
41 views

BDH Problem or Guessing Problem or Discrete Logarithmic Problem

In identity-based encryption, $P\in G1,s\leftarrow Z_{q}, Pub=sP$, Given $P,Pub$ Finding $s$ value, by repeatedly generating random $x$ value. Checking whether estimated value $EstPub=xP$ is ...
1
vote
1answer
86 views

Is it safer to use timestamp in REST authentication?

I am working on a personal project to build a REST authentication system which authenticate clients via three parameters: ...
1
vote
0answers
24 views

To utilize asymmetric cryptography in symmetric manner - demand-of-security-definition?

Cryptography can largely be divided into two classes: asymmetric and symmetric. Like homomorphic encryption now greatly restricted in the asymmetric cryptography, the difference of asymmetric and ...
0
votes
1answer
69 views

What's is the simplest possible example of using cryptography to sign a message?

I am interested in explaining to a total layman the basics of how a network can know that you are authorized without having to compromise your private key. Using an example consisting of simple ...
2
votes
1answer
25 views

Last Sbox of a block cipher for Linear Cryptanalysis

I figured I should try to learn about linear cryptanalysis with a super simple cipher with only one Sbox. The problem is that with that approach the last subkey bits seem to be involved in the linear ...
8
votes
2answers
2k views

On-the-fly computation of AES Round Keys for decryption?

The usual implementation of AES first computes all the Round Keys sequentially starting from the key, and stores them in RAM for later uses. However, when enciphering a single block with a key that ...
4
votes
2answers
79 views

Does a key derivation function always generate an even distribution of bits in the resulting key?

I am a student of crypto. During our study course, we went into the AES-128 algorithm. All the examples given used an initial key k, 128 bits and we only briefly touched on the key derivation of ...
0
votes
3answers
113 views

How can complexity be increased or decreased in AES?

I have been studying data compression for a while. For educational purposes, after a lot of reading, I managed to create a software that performs encryption and authentication using AES256-GCM. ...
0
votes
1answer
58 views

Security when using same salt for different passwords, compared to using different salts?

I have this question I am struggling about: For example, someone suggested improving UNIX authentication by defining 3 different passwords for a user that are stored in the shadow file. All three ...
0
votes
0answers
30 views

How are the coefficients of the polynomial used in Mix Column stage of AES chosen?

In the book (Cryptography, Theory and Practice by William Stallings), it states: the coefficients of the matrix are based on a linear code with maximal distance between the code words, which ...
1
vote
0answers
75 views

Encrypted comms between devices on LAN

I'm trying to encrypt a protocol that shares data between devices on a local area network (i.e.no connection to the internet). I don't want to use predefined keys because they're too easy to read from ...
1
vote
1answer
35 views

How does BB84 fare against an attacker who can entangle qubits?

Consider the following attack on the BB84 quantum key exchange protocol (as far as I can tell, it should work similarly for E91): After Alice sends her key bits encoded in qubits with randomly chosen ...
0
votes
2answers
62 views

Diffie Hellman Exchange Confusion [closed]

I am working on this question and I am wondering I have figured out the secret key, but my problem is I don't know how to use the secret key to decrypt the ciphertext. Thanks for the help!
3
votes
0answers
62 views

How to select corresponding ciphertext in anonymous Identity-based broadcast encryption

In identity-based broadcast encryption, suppose the broadcast ciphertext $(r_1,r_2,\dots,r_i,U,W,V)$ is sent to the receiver. It does not describe which user corresponds to which ciphertext part. User ...
1
vote
1answer
40 views

Is the “Hash Tree” described in this paper the same as a Merkle Hash Tree?

I'm implementing an algorithm from a paper, and part of it calls for using a "hash tree". Since I'd never heard of that data structure I looked it up on Wikipedia. It turns out that the name hash tree ...
4
votes
1answer
106 views

What does the probability subscript mean in Shannon's secrecy definition?

Shannon's secrecy can be defined as: $$P_M (M=m) = P_{SK,M}(M=m|E(SK,m)=c)$$ What does $P_M$ means? (same question for $P_{SK,M}$) I know that is the probability space M, M being the messages; I do ...
-1
votes
1answer
24 views

Which one has better Performance?

Sending secret value in identity-based encryption Using xor : $K \oplus e(g,h)^{\gamma}$ Using symmetric key: Assuming $Key=e(g,h)^{\gamma}$ and encrypt $K$ using $Key$. Which one is better in ...

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