All Questions

18,432 questions
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Mathematical explaination of file encryption for multiple persons with multiple keys

Let's say I want to encrypt a document which only can be read by John, Mike, and Dave. This can easily done with PGP/GPG: Import John‘s, Mike‘s, and Dave's public key Encrypt the document using those ...
34 views

Using one time pad to unlock data with or without me being present

I am trying to create a system where a box can unlocked with or without me, but if I want to unlock the box I need the user. Here is how I am achieving, I have been trying to think of ways that this ...
10 views

I2P Tunnel Creation Build on Request Record Question en(de)cryption method

Not sure if anyone here can help, but if so, sure would appreciate the help. If we read the https://geti2p.net/spec/tunnel-creation documentation page on how I2P creates a tunnel, we can read on the ...
49 views

Comparing Shank's Algorithm to Brute Force

I'm trying to understand how/why Shank's algorithm solves the discrete log problem $y=g^x \bmod p$ faster than a brute force search does. Any explanation would be great.
62 views

Meet-in-the-middle probability of success

In page 358 of Bruce Schneier's Apllied Crypto, when explaining the meet-in-the-middle attack, he states that the success probability is «1 in $2^{2m - 2n}$» with two plaintext/ciphertext pairs, and «...
17 views

How to use Windows User Certificate (S/MIME) to sign data

I am working on an internal ERP for my company. The portal is written in PHP and the current purchasing process is the following: Create a new order on the ERP portal Print the order (PDF) Ask for ...
92 views

Curve25519 over Ed25519 for key exchange? Why?

I've been reading up on the Signal Protocol (in this PDF) and it seems to be using Curve25519 for ECDH and EdDSA (with Ed25519) for signatures. My question is why not use only Ed25519? This ...
52 views

Honestly I'm really confused about padding in RSA scheme. I don't study computer science, and I'm a beginner learning cryptography (self-taught). Can anyone give me suggestions?
37 views

self-synchronizing cipher recovery from dropped bits

This cryptography book says: There are also asynchronous or self-synchronizing stream ciphers, where the previously produced ciphertext bits are used to produce the current keystream bit. This ...
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Does encrypting a result of AES block cipher provide more security?

I would like to know if encrypting a result of AES256 block cipher provides more security. Concretely, I am developing a system in which a client sends to a server a ciphertext encrypted with AES256. ...
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What is this called: encrypt $X$ with key $E$, decrypt $X$ with key $D$?

I am a software developer interested in developing an application with cryptography. I can explain what I want to accomplish, but I do not know the technical terms for the cryptographic functions I am ...
101 views

Is there an outdated or insecure hash algorithm thats output can be easily reversed back into the input?

I'm looking for a hash algorithm thats output can be reversed back into the input in a reasonable amount of time (a day or less) using a decent consumer computer. If anyone has any information on this,...
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transposition cipher help to solve please thank you [on hold]

"hhxbv vgtkc svnxw uubba mmfay rierq oathh xebbm vkwbi qqkwk tdykq kltgx kojbx vobqv gklkz hfdau mfxso zevou nvsbz gazgy mgkch kthkc zyjfn fzljh fxsic cvkib cv" not sure if it is transposition but i ...
29 views

Confirm something in pubic network [on hold]

Imagine I have mediator service in public network. The mediator is fully transparent and everyone know how it works. I have two parties: Left and Right. Right sends something to Left Right sends ...
16 views

How do I revoke aws smtp oauth token2 on iPhone [on hold]

How do I revoke oauth 2 tokens and phishing emails
54 views

Attacking AES using Round 1 output

I was reading the paper Differential Scan Attack on AES with X-tolerant and X-masked Test Response Compactor and I have a question in the section Differential Scan Attack on AES. What I understand is ...
28 views

How does MD5 divide the padded message in 16 words?

This is the image from a website that shows all the steps of the MD5 Hashing algorithm: The original message is 'Hello World!'. I don't understand where these values are coming from: For example the ...
16 views

What is the difference between API-Key, OAuth Client ID and AWS Secure Token Service

What is the difference between API-Key, OAuth Client ID and AWS Secure Token Service? Are they are all just providing delegation tokens, except they are from different companies? Is there a bigger ...
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How is EC key encoded in PKCS#8?

I just started working with certificates and signatures. For an application I write I need a key pair for ECDSA signatures, using the elliptic curve secp384r1 (aka NIST P-384). I produced such a key ...
36 views

Getting the s-box input from its output in differential cryptanalysis on DES

If we try to get K4 using differential cryptanalysis on 4-variant DES, how can we get the input of a certain S-box if we know it's output? This seems hard to do since the substitution operation is ...
54 views

Information theoretic secure encryption based on Quantum Key distribution [on hold]

Although it seems like a wildly adopted assumption that composing the One-time pad and QKD is secure, Maurer and Renner showed that this composition is not secure in the general sense. Indeed if the ...
52 views

Type of Encryption Given The Ciphertext [on hold]

I am trying to decode a ciphertext that composes of numbers and letters with a length of 56 bits, where the last three characters are ===. I'm not sure which type ...
42 views

How does AWS Secret key and access key work

Those keys are too short to be public/private RSA keys. What are they? How does it use them to authenticate the client? My guess is: AWS access key ID is a form of unique user/account identifier AWS ...
41 views

How Many matrix inverse of mod 26 [on hold]

I want to know is it possible to calculate How Many matrix inverse of mod 26
78 views

Differential and Linear trail propagation in Noekeon

In the Noekeon Cipher Specification they write the following : The propagation through Lambda is denoted by $(a \rightarrow A)$, also called a step. Because of the linearity of Lambda it is fully ...
31 views

Unbreakable Ciphertext using hill cipher [on hold]

Can anyone help me out by solving this ciphertext using m =2 TUNAISYPLUKUDDDPOOCZZLLCUDVDCYXJEKYIKORRPVAIYPGUUC
62 views

Meaning of the $m$ power of a modular world

A cryptosystem is defined by a 5 tuple $(P,C,K,E,D)$=(plain text, cipher text, key, encryption function, decryption function) So, my question is with the definition given for permutation cipher, ...
50 views

How to decode unidentified encrypted string? [on hold]

I have been given a task for decoding this "I5ZGKYLUEBVG6YRAMZUWO5LSNFXGOIDPOV2CAZLOMNXWI2LOM4QSC===" But I am not sure that what type of encryption is this? Can anybody help me out on this?
68 views

Transparent Setup of SNARKs

The STARKs paper states Third, and most important, ZK-PCPs are transparent (or “public randomness” ), which means that the randomness used by the verifier is public; in particular, setting up a ...
18 views

Assumptions underlying the soundness of STARKs

STARKs have recently received quite a lot of attention due to their small proof size and supposedly simple assumptions. The paper introduction itself seems to mainly state that their construction is ...