# All Questions

19,143 questions
47 views

### Diffie-Hellman Primitives in SP800-56A

I wonder if someone can give an explain about the different between two Diffie-Hellman Primitives defined in SP800-56A, CH5.7.1 5.7.1.1 Finite Field Cryptography Diffie-Hellman (FFC DH) Primitive 5.7....
26 views

### Bit based Division Property of AES MixColumn

I'm studying about division property that is proposed by todo et al. I have a question about division property for AES mixcolumn. In bit based division property, how can I calculate output division ...
69 views

### How should I address message size limits in RSA encryption?

I am making an end-to-end encryption software program in Java using RSA. I am using BigIntegers and its number theory methods. (I know this is a very slow approach, but I just want to learn to the ...
85 views

### Could a quantum computer recover files from ransomware if the attacker doubly encrypted them with RSA-4096?

How would a quantum computer decrypt a file (or find the keys to such a file) if it were encrypted with standard RSA 4096 encryption, but encrypted two times with different keys? The keys are known by ...
94 views

### Why aren't Complex number fields used in cryptography?

Most of the cryptography is limited to use of real integer fields. Complex numbers are seldom used. Is there any reason for it? Wouldn't complex numbers provide more structure? If there is already ...
42 views

### Question regarding of the ECC test vector format

I am trying to find some ECC test vector for using. I just find some post (like this) and github resource (like this ) They are good reference to my C test code but I'd like to get some more advice... ...
66 views

### As of 2019, what are the most important questions in zero-knowledge research? [on hold]

Important meaning; where the most research is being focussed. Maybe because a break-though seems possible or a break-through would have big consequences. Any questions that are being researched ...
71 views

### how to decrypt if p=q in RSA [duplicate]

p,q should be different,but if I let p = q,and encrypt the plaintext,then I can't decrypt it,so can decrypt it?
40 views

### How to calculate RSA public key by modulus unknown format and exponant value?

I'm trying to calculate the RSA public key by modulus value and exponent value. I got the values from an API by Apple. You can find the API here. The documentation for the API can be found here. ...
31 views

### Meet-in-the-middle attack (on custom encryption scheme)

This is a question I had from an exercise session. Exercise: First we do DES in CBC encryption mode using a key $K_1$ and $IV_1 = O^n$. Then we do DES in ECB decryption mode using $K_1$. And then DES ...
65 views

### In GnuPG, what's the difference between --s2k-cipher-algo and --cipher-algo? [duplicate]

I want to change some encryption options while using GnuPG to encrypt a file symmetrically. 1) However, for choosing the cipher algorithm, GnuPG has two commands and I don't know which one to use. ...
67 views

### RSA - Very big Modulus and Ciphertext

Is there a known weakness in RSA when the value of modulus (n) is very large? n = 2466 digits e = 65537 c = 2466 digits n cannot be factorized. I checked on ...
85 views

### Invalid curve attack: finding low order points

Background Here's a description of page 182 of "Guide to Elliptic Curve Cryptography" by Hankerson, Menezes and Vanstone. Here's a quote from that page: The main observation in invalid-curve ...
50 views

### Is it possible to change the generator without knowing the private key used?

For example, prover sends P = xG and verifier somehow sends back P = xH without learning x. Is this possible?
61 views

### How would I prove a number is not within a range?

This would be the opposite of a rangeproof. For example, I wanted to prove that my number was not between 0 and 200 in zero knowledge? On a separate note: how would I prove that I hold a number, but ...
54 views

### How do I find an efficient sqrt algorithm for primes? [closed]

For example, If my prime was congruent to 3 mod 5. Is there a list where I can find for these primes which do not take the form 3 mod 4? Edit: Excluding the general tonelli-shanks algorithm
534 views

### Soft question: What are examples of beautiful proofs in cryptography? [on hold]

These may include any proofs, reductions, constructions, etc. For example, simple solutions to problems which at first sight seem difficult. Elegant construction that hide deep mathematical concepts, ...
38 views

### Symmetric encryption construction (meet-in-the-middle attack)

This is a question I had from an exercise session. First we do DES in CBC encryption mode using a key $K_1$ and $IV_1 = O^n$. Then we do DES in ECB decryption mode using $K_1$. And then DES in CBC ...
307 views

160 views

### Asymmetric CSPRNG where the public key only works backward

Is there an asymmetric cryptographically secure pseudo random number generator in which the public key only goes backward? For example, I'd like to generate 5,000 digits, then provide the public key ...
81 views

### What is the “brand X” cipher mentioned in the Usenet thread about RC4?

In the original Usenet thread about RC4 when it was finally reverse engineered, a user by the name of Michael Johnson mentioned that the RC4 algorithm looked surprisingly like another proprietary ...
37 views

### Security of Nomenclators [closed]

A nomenclator is a type of cipher which has a codebook attached. The one I have in question is a numerical codebook with two homophonic ciphers and two distortion tables for the code groups. Could one ...
24 views

### Does the oracle have to have access to the encryption key to the padding oracle attack to work (CBC & PKCS#7)?

Does the oracle have to have access to the encryption key to the padding oracle attack to work (CBC & PKCS#7)? I tried much to get a attach to work, but the oracle doesn't have access to the ...
93 views

### Asymmetric keys (e.g. RSA) must be so much longer than symmetric keys (e.g. AES). Why? [duplicate]

I have been reading that RSA has to do with math (prime numbers), while symmetric key encryption deals with blocks of data and modifying the blocks with replacements and remappings, but I still don't ...
156 views

### Is there any theory to measures and determine the strength of an encryption protocol?

To determine the strength of an encryption protocol, there are elements like key size, Strength of an algorithm, Performance of an algorithm or etc, I have studied these topics but I could not find ...
27 views

### File Compare Deduplication In Cloud Computing

I want to implement a file level deduplication program in the clouds as part of my research paper. What are the basics that I need to get covered first before being able to proceed with this research. ...
43 views

### What is the Knowledge Of Secret Key Assumption (KOSK)

From what I've read it seems to be where an entity must prove that they own the secret key. Which is done by signing a message M using said secret key. Is this ...
37 views

### Rijndaelcipher mix column query

I quote a wikipedi para that says The operation consists in the modular multiplication of two four-term polynomials whose coefficients are elements of ${\displaystyle \operatorname {GF} (2^{8})}$. ...
48 views

### How does the random oracle model simplify proofs versus using the standard model?

If I use the standard model, then the proof must rely on mathematical assumptions. Will this security proof, generally be longer/more complex? Is there an example where the random oracle has been ...
19 views

### Does proving security in the random oracle model ensure that using a hash function is secure?

In security proofs, I have seen the random oracle model and the standard model. If I prove security in the random oracle model, does this mean that if I use SHA-3, assuming sha-3 cannot be broken, ...
43 views

### Ciphers based on Keywords

I am looking for different ciphers that use a key word (like "hello" or "awesome") to encrypt a given text. I know about the Keyword Cipher already; I'm looking for others.
21 views

### Key Value Based Key Derivation

For a system that is using public key cryptography to authenticate users and their actions I'm trying to solve (ease) UI/UX problem so that users will be able to use login/passwords they're accustomed ...
25 views

### Can randomness protect a list of signatures against forgery attacks?

Suppose we have a list of signatures $S = [s_1, .., s_n]$ for a list of messages $M = [m_1, .., m_n]$, and we want to verify that $S$ is a valid signature of $M$, so each $s_i$ should be valid for ...