# All Questions

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### Creating a Password Generator using CSPRNG in React JS

I am building a password generator website using ReactJS (link). I have read a lot about various ways of generating cryptographically secure passwords and I have decided to go with using CSPRNG. I don'...
1 vote
23 views

### Sending encrypted message without public key from recipient (elgamal)

assume Bob and Alice use Elgamal encryption scheme. Alice wants to send Bob a message, but does not know Bobs public key. Is there a way for Alice to find out Bobs public key by receiving multiple ...
• 11
1 vote
21 views

### How to crack sha256 used as streamcipher with known or guessable block

Using SHA-256 as a stream cipher appears to bear cryptographic weaknesses, however, I am not quite sure how to implement them in decryption. Assume that I have an encryption function using 64-byte ...
1 vote
38 views

### How to create a key for AES in a 192 bit key length from a password?

Let's say that I have a password. And it's secure. But it's a 10-character string. So If I wanted to create an AES key for the 128-bit version of the algorithm I would just hash it using MD5. Or If I ...
• 111
15 views

### Has anyone come across any Papers on Statistical analysis of Present cipher? Nist or Dieharder

I need to Perform Statistical Analysis of Present. I choose NIST but I am getting underflow error even though I am taking 10 million bits.
9 views

### How to receive money via from another country via Trust Wallet? [closed]

My friend and I have a Trust Wallet, but haven’t used it before. How can he send some currency to my wallet? He lives in another country.
• 101
11 views

### How to import OpenPGP Card / YubiKey backup encryption key [migrated]

When I generate a new OpenPGP key on a YubiKey, it gives me the option to save a copy of the encryption key as a backup like so: ...
• 101
33 views

### Diffie-Hellman: how to solve an alternative of Diffie-Hellman given an algorithm that solves Square Diffie-Hellman?

A simple question. How can I proof the next polynomial reduction? : $DH’ ≤_{p} SQ$ where DH': given $g^{a}$ and $g^{b}$, compute {$g^{ab}$,$yg^{ab}$} where $y= g^{d/2}$, d is the order of cyclic ...
13 views

### What, if any, are the IETF namespace notations for OpenPGP signatures?

RFC 4880 section 5.2.3.16, "Notation Data," describes how arbitrary additional notations in the form of name-value pairs can be included in an OpenPGP signature packet. Regarding names, it ...
• 101
1 vote
35 views

### Differential cryptanalysis - how to extend the attack to rounds before the last?

Suppose that we have a block cipher such that the last round of the cipher depends on half of the key and the penultimate round uses the other half. Suppose also that I attacked the last round using ...
• 23
56 views

### RSA not encrypting properly when e=d?

I'm trying to implement the RSA algorithm with some random (valid as far as I know) generated values but for this combination, encryption/decryption doesn't work. ...
• 103
35 views

### Proving pairwise independence of a set of hash functions

A collection of hash functions $H=\{h:\{0,1\}^n \to \{0,1\}^m\}$ is pairwise independent if for every $x_1 \neq x_2 \in \{0,1\}^n$ and $y_1, y_2 \in \{0,1\}^m$:  \Pr_{h \leftarrow H}[h(x_1)=y_1 \...
• 137
9 views

### Example of enhanced trapdoor perrmutation (Enhanced TDP)

I am currently reading about Trapdoor Permutations (TDP). While I can totally understand and think of examples of TDP. I cannot think of any examples of Enhanced TDP. The definition of both TDP and ...
• 268
12 views

### Calculate unique secrets of a hash algorithm, which produces a deterministic bit array of length 7

I can't really wrap my head around it. So given a hash algorithm which always produces a 12 bit array. How would I calculate the count of unique secrets with a collision rate of 75%.
• 1
36 views

### Value to proving that breaking a cipher requires large amounts of plaintext

Is there any theoretical value to proving that a cipher cannot be quickly broken by any algorithm, unless that algorithm has some large number of plaintext ciphertext pairs (i.e. a number of plaintext/...
• 432
43 views

### AES CBC: When to use new IV

I am trying to figure out when to use a new IV for an AES-CBC communication and whether my approach is safe. Here is a quote from Thomas Pornin from a similar question: So, to sum up: you must choose ...
• 135
77 views

### What are not non-negligible functions?

I had a brief look at "On Defining Proofs of Knowledge" by Bellare and Goldreich and I am a little confused by their definitions. I was under the impression a negligible function $f$ was ...
• 4,691
42 views

• 805
23 views

### AES GCM mode - what is ouput in that scheme?

I'm trying to understand that scheme: https://xilinx.github.io/Vitis_Libraries/security/2019.2/guide_L1/internals/gcm.html Here on page 11 it looks like GHASH gives only one value "Return $Y_m$&...
• 805
35 views

### How to quantify privacy, when using homomorphic encryption?

How can you measure how secure or private the new variables are relative to the real (actual) variables. I want to compare homomorphic encryption and differential privacy in combination with machine ...
34 views

### Validating AES GCM authentication tag between two different implementations

I'm a bit confused on how to validate the authentication tag between two different AES GCM implementations. One implementation (on my part) is in Java. The other, I don't know. In my implementation, ...
1 vote
64 views

• 1
39 views

### What does it mean to break non-invertible stream cipher?

Let's consider for simplicity Middle-Square Weyl Sequence RNG: https://arxiv.org/pdf/1704.00358.pdf We can choose there parameter for independent stream generation, we can call it key. Let's consider ...
• 805
1 vote
50 views

### Hash of concatenated values (one public, one private)

Assume two end-points $A, B$. $A$ sends to $B$ a $Hash(pv||key)$, where $pv$ is a public value that can be intercepted by attackers. The $key$ is a common secure shared key in both end-points, and $||$...
• 303
1 vote
82 views

### Understanding public key in certificate precisely

Certificates are used very often in crypto. From the search, I am a bit confused what exactly is the "public key" inside a certificate essentially? Is it always a signature verification key, ...
• 113
1 vote
73 views

### Relative bits of security of slower functions

Leaving memory-hardness assumptions aside, some slow hash functions are iterated salted hash-chain versions of regular cryptographic hashes. This is usually defined by a ...
64 views

### Is there any threshold-crypto library that is production-ready?

I am wondering if there is any available threshold crypto library that is well-audited and ready to be used in production. Any pointer is appreciated.
56 views

### Carry-less multiplication vs. multiplication in $GF(2^k)$

I implemented carry-less multiplciation using the CLMUL instruction set. This is similarly fast to simple modulo multiplication. But computating the result mod some polynomial is still very slow. I do ...
• 805
42 views

### How to use symmetric encryption on 1on1 and group chat messenger?

Hi everyone so currently I'm trying to learn about encryption to build secure messaging app (Mobile-app, flutter based). I want the app to have 2 messaging features which are 1 on 1 messaging and ...
• 101
19 views

### Unicity Distance redundancy clarification

I have an example of an exam question here: The open message source is a language with an alphabet represented by an 8-bit ASCII code stored in a byte (=8 bits). The relative redundancy of the ...
552 views

### NIST vs ISO Encryption standardisation process

skinny cipher has been lately considered as ISO/IEC standard while is still competing as building block of Romulus AEAD in NIST LWC finalists. what is the difference between the two ISO and NIST ...
• 1,980