All Questions

288 views

How to quickly detect incorrect password in encrypted file without compromising security?

I am developing a software to encrypt/decrypt files/streams using symmetrical encryption algorithm. During encryption phase data wil be compressed and encrypted. When decrypting data, I want to be ...
108 views

Deriving 2 shared secrets from one private key and 2 different public keys

I have a key pair, say $(d, Q)$. I send my public key $Q$ to 2 different people. I also get their public keys $Q_1$ and $Q_2$. Now I can derive 2 shared secrets, $d*Q_1$ and $d*Q_2$. The 2 other ...
56 views

How is an epsilon of 1/1000 non-negligible? [duplicate]

Lately I've been studying cryptography and in the current course I'm taking we're reviewing statistical tests and how they can be used to determine if a pseudo-random generator is secure or not. ...
49 views

How to find an impossible differential?

Given an arbitrary SPN-based cipher with X rounds. How to find an impossible differential for this cipher? What are strategies to find one?
130 views

Vigenère cipher frequency analysis not working

I'm writing a C++ program to use the Kasiski method to crack the Vigenère cipher. I'm testing it with a bit of Shakespeare encrypted with the key ABCDEFGHIJKL. It ...
109 views

Unicity Distance - AES

I am quite confused calculating the unicity distance and I was hoping that someone can clarify some things for me. My main issue comes from somewhat a difference of the calculation given by our ...
55 views

Correlation attack on Lagged Fibonacci Generator

Say that one uses a known LFG (2 known lags $a$ & $b$, known inner state length $N$, known modulo $m$) to hide some text with a basic à la Vigenère cipher: $C_i=(P_i + {PRNG}_i) \bmod 26$. Say ...
87 views

Is it possible to encrypt a message's destination as well as its content?

I have imagined a way to break through any kind of censorship but since I don't have enough professional knowledge of cryptography I don't know whether it is feasible or not. If there is a method ...
124 views

Secure Channel - Encryption and Decryption Keys For A Message

I'm currently reading Cryptography Engineering and in Chapter 7, the topic of secure channel is discussed. The channel described is using CTR for encryption. Below I include images with pseudo-code ...
58 views

152 views

Solve a problem, thought it was hash length extension, hours later, am I wrong?

Here is my situation. I'm working with an application for which uses hashing to authenticate data. I have a string, which is hashed. It is, like in a hash length extension attack, H(key:known_value) ...
179 views

Is there a need to encrypt data when send over https? [closed]

I was monitoring web traffic from my Android mobile using Man in the middle proxy. I installed certificate signed from my server in my mobile and I could see all applications sending sensitive ...
102 views

In what countries am I now allowed to talk about technical details of cryptography? [closed]

I hope this is the correct place to post this, otherwise I'm sorry. The OpenSSL Legality section states: OR EVEN JUST COMMUNICATING TECHNICAL DETAILS ABOUT CRYPTOGRAPHY SOFTWARE IS ILLEGAL IN ...
82 views

Is there any pattern in points on EC?

I read some where in crypto.stackexchange answer (related to EC-SRP protocol) that there is pattern in points on elliptic curves, i.e. if given some points containing mix of correct and wrong points ...
38 views

RSA, proof of correct work, if p is not a prime number [duplicate]

Is there any proof of correct work of RSA algorithm, if p is not a prime number? For example: n = p*q, p = p1*p2, where p1 and p2 are primes. Edit: I found that it's called Multiprime RSA, but i ...
72 views

Zero knowledge of two factor

Here I overconfident in myself state that I can show, that n has two factors. This is not completely true, can possibly show $n$ is composite - prover generates RSA key with modulo $n$, and gives $e$ ...
47 views

Security of simple Skein PBKDF mentioned in the paper

From the Skein 1.3 paper section 4.8, Skein as a Password-Based Key Derivation Function (PBKDF), it mentions the following as a simple PBKDF (S = seed and P = password): An even simpler PBKDF is ...
207 views

Construct rainbow table to break DES

I'm facing a project where I need to build a rainbow table to break DES. I've already collected information about Hellman, DP, rainbow table method. Finally, I chose the rainbow table approach. I've ...
29 views

Is RSA-OAEP secure when e=3? [duplicate]

Is RSA-OAEP secure when the exponent is equal to 3?