# All Questions

27,478 questions
Filter by
Sorted by
Tagged with
2 views

### identify how to solve this cipher please! its fun and a mystery

I have roughly 25 three digit numbers between 0 and 200, that are a cipher. if i know what some letters are (for instance a=2, c= 9, and f-3) then how can i solve for this?
27 views

### ed448 generator choice in supercop

Mike Hamburg proposed the Ed448-Goldilocks curve and submitted a software implementation for it to the SUPERCOP project. Below you can see that MH picked a generator (or base point) that has a y-...
157 views

### Recover all keys on differential cryptanalysis

I am practically implementing differential cryptanalysis on a cipher from the book "the block cipher companion" . I am successful to get the last key $k_5$. Just to say some words about the ...
6 views

### Data corruption to protect the encryption?

On KeePass help center it's stated that: ... if the header of the database (first few bytes) is corrupted, you're out of luck, too: the repair functionality won't be able to restore any entries (...
243 views

### How do you find the cipher formula for a cipher like this?

I'm new to ciphers and cryptology in general, so apologies in advanced. ((When I say I'm new, I mean I only started looking up cryptography in response to being given this cipher this morning, so I ...
13 views

### Does the p value in randomness tests provide any real value?

In the dieharder test suite there are things like:- diehard_3dsphere| 3| 4000| 100|0.56011310| PASSED and in the NIST IID (brief mode) and randomness ...
15 views

### Why are ZK proofs so dominant in verifiable computing?

There seem to be many ways of verifying computation, and many classes of interactive proof systems which aren't ZK. That being said, most "validity proofs" in blockchain (which seems to be ...
1 vote
348 views

### Diffie-Hellman over $GF(2^{128})$

Can I use Diffie-Hellman over, say, $GF(2^{128}) \bmod$ irreducible poly in $GF(2^{128})$ instead of $GF(p)$? If not, why? Or increase it to $GF(2^{2^{\text{whatever}}})$.
13 views

### Hash tree that covers 16 data block

For a hash tree that covers 16 data blocks, how many hash checks do you need to perform to localize the error? Assume that error occurred on only one block.
1 vote
2k views

### Deriving 2 keys using HKDF

I have an encryption scheme that uses a 256-bit master key, from which 2 separate keys (one for AES-256-CTR encryption and one for a HMAC-SHA256) are derived using HKDF. However, I'm not sure exactly ...
128 views

1k views

### is XChaCha20 stronger than ChaCha20?

Some of the encrypted messenger apps and password managers use extended version of Bernstein's ciphers and some of them not. Viber-Salsa20 Wire-ChaCha20 Threema-XSalsa20 Sid-Salsa20 Nordpass-XChaCha20 ...
38 views

### How to read clock cycle from latency tables?

I see many papers that compare the latency of the signature schemes in terms of clock cycles by two-three numbers. I don't know why they write 2-3 numbers instead of one number to represent clock ...
78 views

### Is it possible to create digital signature with specific p, q, e values by using OpenSSL?

I'm trying to create the digital signature by using these parameters and RSA algorithm: p = 645353605880701501120167331073 q = 350784310265709643169455170929 e = 19 message = "G’day mate! As we ...
7k views

### AES Inverse Key Schedule

I have a 128-bit input-block and the corresponding cipher-block given. Additionally I have the last round-key given. Is it now possible to get (calculate) the associated cipher-key? I already ...
38 views

### Encrypting data before Saas-solution

The compliance department is asking me for recommendations on encrypting data before Saas-solutions. Meaning that the Saas-solution should not be able to see the data when stored and processed. ...
18 views

### Elgamal Problem, cant find the right answer, If anyone could help, would appreciate it [closed]

Joe has a public and private key pair (u𝑘𝐴, p𝑘𝐴) for ElGamal signature. Suppose that Joe signs a message for Arthur every day. If Joe uses the same random number 𝑘 in all signatures. Analyse the ...
75 views

### Show that function isn't a PRF

Let $F$ be a PRF such that $|F(k,x)|=2n$ show that $F_2$ isn't a PRF. Let's assume $F(k,x)=(y_1,...,y_{2n})$ then $F_2(k,x)=(y_1\land y_2,...,y_{2n-1}\land y_{2n})$. I want to prove $F_2$ isn't a PRF ...
31 views

### Randomness of recursive sequence generation

How good from randomness point of view are recursively generated sequences using good encryption algorithms? Let us say I take AES128 which generates good random sequences of outputs for counter ...
116 views

### RSA different ciphertext for the same plaintext

General My goal is to encrypt some strings and store them in a database. I am using RSA OAEP in Go (Golang): ...
94 views

### What is the importance of superencryption?

Please, can any extensively explain the importance of super encryption in relation to attacks experienced by single standard algorithms
1 vote
105 views

### How do I encrypt a bunch of messages by different authors, shared with that group of people?

I'm still getting my head around public/private key cryptography, and I can't quite work out how to ask the right question to get an answer for this problem, but here goes! Alice, Bob, Carol, and ...
144 views

### Which encryption technique should be adopted to keep the search functionalities?

I am in exactly the same situation as described in this post. I must be able to encrypt data from a client workstation then send it to an untrusted server (encrypted at rest), then decrypt it only on ...
34 views

### RSA / RS256 Encryption with the public key I have

safe to say I'm a complete beginner when it comes to cryptography... I believe the example output below is some sort of RSA (or RS256) encrypted string, and was just curious whether it'd be possible ...
1 vote
51 views

### Is ChaCha20 + HMAC(SHA3) output indistinguishable from randomness?

I was wondering, if the output of following type of ChaCha + HMAC scheme is indistinguishable from randomness: ...
36 views

### Clarification for CCA security (or - why is the following not a Rabin CCA attack?)

In three different, highly reputable sources (e.g. "Introduction to Modern Cryptography" by Katz and Lindell, 2007), the definition of CCA attack doesn't allow the adversary to decrypt the ...
48 views

### How to verify an ES256 (ECDSA using P-256 and SHA-256) signature with window.crypto.subtle? [closed]

I'm having trouble figuring out the right parameters to verify a ES256 signature that was created with an ECDSA P-256 public key in web crypto. Below script outputs different results for Node.js vs ...
1 vote
18 views

### Clarification regarding Rabin Cryptosystem being CPA (Chosen Plaintext Attack) secure

Do I understand correctly that the textbook Rabin encryption scheme, where there is no random padding (as is also required in RSA for it to be CPA secure), is not CPA secure? (it is deterministic ...
590 views

### Zero knowledge proof for Paillier addition under multiple keys

Suppose $m_0, m_1, m_2 \in \mathbb{N}$ such that $m_0 = m_1 + m_2$, $m_i > 0$ (none of them can be 0 or lower) Under a Paillier cryptosystem, set $e_0 = E(m_0, r_0)$ for a public key $(g_0, n_0)$ ...
1 vote
65 views

### Why Can't I Use an Nacl Sign Keypair for Encrypt and Decrypt Operations?

I'm aware that the difference between the NaCL sign keys vs the box keys is that the secret key that comes from the NaCL box keypair is the ...
59 views

### Polynomial Breakdown in proof of lower bounds on Discrete Log in the Generic Group

In Shoup's proof of the hardness of discrete log in the generic group in this paper, he mentions that: At any step in the game, the algorithm has computed a list $F_1,\dots,F_k$ of linear polynomials ...
7k views

55 views

### Shamir secret sharing, recovery of keys which have 0 bytes in front of them?

From what I know SSS creates a polynomial with a0 = secret key and interpolates it on recovery using k coeffs. if a0 is a number,...
47 views

### Do digital signatures without contextual information protect you against signed messages replay attacks?

Consider this scenario: A signs a message to B using A's private key. A then encrypts the signed message with B's public key. A sends both plaintext and encrypted message to B so that B can verify. ...
60 views

### is it possible to secure password management using one time pad cipher. I have created a protocol which uses one time pad password storage [closed]

I thought of a secure protocol for password manager. It has single user .My one time pad supports 36 characters [ numbers 0 - 9 and all 26 alphabets , encryption process is similar to method mentioned ...