# All Questions

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8 views

### Can someone tell me how to decrypt this code into an email address? [on hold]

How do you decrypt this into an email address ? Njg2MTYzNmI2MTdhNmY2ZTQwNjQ2NTZjNmY2OTc0NzQ2NTJlNjM2ZjZk
13 views

### How secure is this scheme?

Introduction of the cryptosystem Let's say we have a system with a central server SRV that is considered secure (communication with this server is secured too with ...
25 views

### Do these crypto approaches have the same disadvantages of one time pads?

Newhope: Specifically, the message from Bob to Alice (the ciphertext) in NewHope-Simple requires only 2176 bytes (compared to 2048 bytes in NewHope); the message from Alice to Bob (the public key) ...
16 views

### Are the quantum resistant Bitcoin solutions just one time pads? [on hold]

I am talking about integer lattices etc. They all seem otp or some batch of otps. Eventually, you would exhaust the encryption (after very long messages) and it would require a new key. Does this ...
35 views

### Weakness of double encryption

In the "Introduction to Cryptography: With Coding Theory" by Trappe and Washington, in the chapter about DES algorithm the authors say that: "if a cryptosystem is such that double encryption is ...
16 views

### How can we evaluate a polynomials in a group instead of a field? (verifiable secret sharing on elliptic curves)

I am trying to understand how we can have cryptographic schemes that builds on both secret sharing, which is build on top of a finite field, and bilinear maps, which are built on top of elliptic curve ...
16 views

### How to validate the randomness of ECDSA signature generated using HSM?

I need to programmatically(using Python) validate whether the signature generated by using HSM RnG is actually random. Didn't found much content online, hence any help would be appreciated !!
18 views

### Lineary of Sbox in DES

I'm not a mathematician, and i would like to understand in the most concise way (if possible) why choosing linear S-Box functions makes the DES algorithm attackable. Thanks
37 views

### Argon2 library that hashes passwords without a secret and with a random salt that doesn't appear parseable

I am looking at different alternatives to hash passwords in a Python app. First I was settling for Flask-bcrypt (https://github.com/maxcountryman/flask-bcrypt), but then decided to use Argon2. The ...
15 views

### How can AES-CCM behave as an AEAD stream cipher?

AESCCM- Couter with Cipher Block Chaining Message. As it uses cmac for generation for tag , which is internally aes-cbc (block cipher, need block size, may require padding) And Encryption is done ...
19 views

### Does AES encryption of a NTRU pivate key reduce security?

The NTRU crypto system requires quite long keys. For example with parameters N=439 and q=2048 the security is 128 bits and the key_size is 4829 bits. When the private key is encrypted with AES-256 ...
24 views

### How does reusing IV for OFB mode breaks the scheme

Consider a Plaintext P1 and Ciphertext P2, which is known to the attacker. If the attacker knows that the IV used in encrypting P1 in OFB mode is the same used to encrypt another plaintext P2, how can ...
8 views

### Meaning of direction in EPS

In EEA and EIA, what exactly does the direction (uplink/downlink) indicate? It's confusing because for both encryption and direction, the direction has to be same.
43 views

### Was Enigma really that hard to crack, given that you had access to hundreds of messages per network per day?

Well, I guess that I have always been a little bit suspicious ... so to speak ... of the "official stories" about the difficulty of recovering Enigma message texts during WW2, because it seems to me ...
16 views

### Why is it important that determinant is not divisible by factors of the length of the alphabetical modulo

I am doing an assignment and I came across a question which asked "Why is it necessary when using modulo 26 to have a determinant which is not a factor of modulo 26. I have searched everywhere for ...
25 views

### What if the hash code of the genesis block (first block in the block chain) is changed?

If so, what would happen? And if not, what are some limitations to it? The reason I am asking is because I just started getting into the cryptocurrency and am very interested in the cybersecurity ...
4 views

### How to generate V3 Onion domains using web javascript? [migrated]

I am trying to create a web based vanity .onion domain generator. I already have the V2 onion working, but this V3 onion is causing me some real trouble. In my HTML I have... ...
33 views

### Property of a good cipher system

In the "Introduction to Cryptography: With Coding Theory" by Trappe and Washington, in the chapter about DES algorithm the authors say that: "In a good cipher system, each bit of the ciphertext ...
45 views

### Swapping a single bit inside a 40 bytes inputs fed to keccak256. Is it safe to assume no change in the first 20 bytes can result in the same hash?

I have the following data (represented as hex from binary below) where the lower bytes is controlled by attacker in the second case : ...
35 views

### Any way to get the index of a given number in a linear-feedback shift register?

e.g. given a LFSR polynomial for 64-bit: $$x^{64} +x^{63} +x^{61} +x^{60} +1$$ and the initial value of $a_0=42$(as 64-bit representation) and cycle length $2^{64}-1$. Is there any way to get $i$ ...
36 views

### using different IV and SALT with AES-CBC but same KEY

I'm working on this project where a client can send a message, now obviously sending it in plainText is not very smart. So I decided to Encrypt it with AES-CBC. Now, each time I encrypt something, ...
16 views

### Post-quantum aggregate / multi signatures

Are there any practical post-quantum aggregate / multi signatures? Currently, the aggregate / multi signature schemes seem to be limited to pre-quantum elliptic curve assumptions only, e.g., [BDN18], [...
20 views

### Using same key and nonce for different field of the same document

I have some fields, similar to NAME, SURNAME, EMAIL, ADDRESS... I'm using NaCl for symmetric encryption. Is bad If I Encrypt every field with the same key and nonce? They are encrypted and stored ...
20 views

### Whose to stop the coinbase devs from just draining all accounts and running of with the money? [migrated]

I have been wondering, what would happen if the coinbase developers agree to drain all the funds of all their accounts and run off into hiding? Its not like anybody will be able stop them or return ...
21 views

### Choosing the Bernoulli distribution for LPN encryption scheme

The symmetric-key encryption scheme from [1] is based on the LPN (learning parity with noise) problem. The definition of the problem is, informally, that the adversary cannot recover $\mathbf{s}$ from ...
43 views

### Estimate password cracking time given Shannon Entropy

Is there some algorithm that, given the Shannon entropy of a string, compute an estimation of the time that an average home computer will take to crack the password? Thank you.
27 views

### Colliding input to compression function

So I recently started to look into cryptography and found the following question to cryptography scheme using $T = E_{S}(S \oplus M)$ It is said that this is not secure because you can have a ...
52 views

### Is using HMAC signature as a long-term password secure?

I'm considering implementing an authentication service without storing users' passwords/hash. I want to use a key derivation function with a corresponding username...
35 views

### NIST DRBG algorithms' optional parameter

As I'm going through NIST-SP-800-90Ar1 spec for DRBG, I found the mention of security_strength in all of the 3 specified construct in the document: Hash_DRBG, HMAC_DRBG, CTR_DRBG. However, they're all ...
22 views

### Using ePassport with Active/Chip Authentication to sign documents

I'm a complete newby, so please pardon my ignorance when it comes to basic cryptography aspects. My question is whether a biometric passport with Active/Chip Authentication (AA or CA) can be used to ...
26 views

### How can I derive a crypto key pair from argon2 instead of the default ones in PBKDF2? [on hold]

I've rewritten the question as below. Knowing that through PBKDF2 I can derive a key pair based on username/password and a salt repeatedly, and argon2 seems to be a better hasing algorithm, I wish to ...
57 views

### For data shorter than 32 bytes, is it sure that no collision exists?

I’m not talking about if a collision can be found but even simply exists. The point is since it’s shorter than the length of the hash (since I’m talking about keccak256), normally there’s a hash ...
26 views

### BN curves in Charm crypto library

I'm using Charm to implement a scheme and I know it has "SS512", "MNT159" and "prime192v1". I don't know if Charm includes BN curve? If it doesn't, how to implement it with Charm.
99 views

### How much would this AES modification improve security?

How much would using AES-CTR like 3DES improve security? Like so (Using a 512-bit key split into two; $K_1$ & $K_2$, and seperate nonces for all stages): ...
8 views

### Unusual behaviour with a passworded rar being invalid password in winrar but falsely accepted in 7zip [migrated]

I found an old .rar file on my computer but I couldn't remember the password exactly. I had a rough idea of what it was, so I wrote a program using 7ziplib in c# to brute force a bunch of permutations....
11 views

### encrypt data in AES with mode CBC [on hold]

I want to encrypt data in AES with mode CBC and in Padding PKCS7 I'm having trouble displaying encrypted text ...
28 views

### Key derivation scheme with shared secrets?

I want to derive a list of sub-keys derived[t] from a master key mk by a key derivation function ...
30 views

### Encryption scheme that requires fewer keys for decryption than for encryption

I want to attempt creating a decentralized dead man's switch, so I'm looking for an asymmetric encryption scheme, with the following properties (ideally), or something close to them: There is a group ...
39 views

### Is “Bingo voting” insecure against a corrupt election authority?

I am reading about "Bingo voting" (Wikipedia, Paper), and I'm not understanding how it is secure against a corrupt election authority. If the election authority knows all the dummy votes $N_j^i$, ...
35 views

### half-gates in garble circuit

Recently I've been reading papers about MPC protocol, but when I read the paper by Zahur, S., M. Rosulek, and D. Evans. 2015 Two Halves Make a Whole- Reducing Data Transfer in Garbled Circuits Using ...
14 views

### solving chaochiper encoded test [on hold]

**the encrypted text is: UAMN PRUC LPLB IPLO UHXR DODN JSBI DCDK DAFK VJCM YYFA YHJU MULA **
54 views

### Why does the Fiat-Shamir heuristic not work without a random oracle?

Consider the following three stage interactive zero knowledge proof in round $i$ The prover sends some commitment $a_i$ to the verifier. The verifier picks a challenge $c_i\in \{0 ,1\}$ Depending on ...
15 views

### what relation between zkp proof and sigma protocol [on hold]

I don't understand relation between zero knowledge proof with 3 properties : completeness, soundness and zero-knowledge and sigma protocol with 3 properties: completeness, special soundness and honest-...
26 views

### Combine signature with encryption

I have some embedded device for which I want to sign and encrypt firmware files. Firmware updates are generated by me and may be installed by the customer. The encryption is supposed to protect the ...
25 views

### Estimating the probability of sucess of Pollard's p-1

I'm trying to estimate the probability that Pollard's p-1 factorization in its two-stages variant finds a factor of an RSA modulus product of $k$ random $b$-bit primes, as a function of the bounds \$...
30 views

### Finding the token [on hold]

I managed to decrypt the following message with vigenere but I did not manage to have the token at the end knowing that it contains 24 characters. Fkhuv djhqwv, Eudyr ! Yrv plvvlrqv rqw o'dlu gh vh ...
56 views

### Which AES modes can decrypt from anywhere in the ciphertext

CTR is amenable to parallelization because you can split the message into chunks, each chunk having a range of counter values associated with it, and encrypt (or ...
26 views

### Initialization Vector in CBC/DES encryption [on hold]

How can i prove that the Initialization Vector is always set to zero in the Cryptool when using CBC or ECB/DES mode?