Questions tagged [keys]

Private and secret keys consists of secret information used as input to various kinds of cryptographic algorithms such as encryption, signature and MAC to select the concrete transformation done by the algorithm.

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Offline Group Key Agreement - Cross Device Syncing

I have a specific use case I am interested in. I have spent the better part of the night reading research papers. I am beginning to believe what I want is not possible so I wanted to confirm here. ...
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Alternative way to provision secret in Intel SGX enclave

I have a case where I have multiple clients (non SGX, assumed safe) and server(SGX based), talking over a network. I wanted to provision a shared (per client) key which is used to encrypt and decrypt ...
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Anonymisation resilient to key leak

Problem statement Elbonian citizens have been issued a card holding a random $B_j\in\{0,1\}^b$, $0\le j<2^n$, $b\ge n+20$ (representative example $b=64$, $n=28$). The habit has grown to use this ...
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AES subkey calculation not working for subkeys beyond 0 and 1

How should I generate the remaining keys when performing subkey generation in AES encryption? I generated keys 0 and 1 first, but the other keys I generated later were wrongly generated, so what steps ...
Mohamed Mohamed Mourad Abdel W's user avatar
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AES first and last round key whitening

I've found this question from 2014 on Key Whitening: How exactly does key whitening manage to increase security? where is said that AES applies key whitening internally by adding a sub-key prior to ...
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Can initialization of the Spritz cipher state by a randomly chosen permutation securely act as a key?

The Spritz cipher is a "sponge-like" construction that the authors show can be used as a hash, MAC, stream cipher, re-seedable pseudo random number generator, and/or an authenticated cipher. ...
cookiecipher's user avatar
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Decrypt the same ciphertext to multiple messages of my choice if I can use any key I want to decrypt

In a modern secure encryption scheme, is it possible(both theoretically and practically) to encrypt a message using a key to get the following ciphertext c = Enc(M1,k1) and later find another key so ...
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How is the time intereval calculated for symmetric key re-negoatition in UK Security Standard – Use of Cryptography?

According to point 10.6.4 (Encryption in Transit) in Security Standard –Use of Cryptography, one of the criteria for key renegotiation is timeout , Encrypted sessions MUST re-negotiate new symmetric ...
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Where shoul I store private/public keys and how should I share it?

I'm new in terms of encryption and I have to encrypt the data between two Java Spring applications, one have serves as MVC framework and other as Web Service, I'm implementing an asymmetric encryption ...
Carlos Robles's user avatar
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Cracking a key using a combination of partial keys

As part of a cryptanalytic attack I've carried out, I used a divide-and-conquer strategy to divide the secret key $k$ into several equal-sized partial keys $k = {k_1, k_2, ...}$. The attack works ...
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How can I find or reverse engineer the whitening in an AES algorithm?

I am working with this black box cryptography scheme. I know the plain text, cipher text, and everything else except how they whiten the data (or key?). Everything is 128 bit, 16 bytes. I have two ...
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How much information is required to specify a new variant of AES beyond the key length and the number of rounds?

Three different versions of the Advanced Encryption Standard (AES) have been standardized, which use keys of bit length 128, 192, and 256 respectively. They also use different numbers of rounds: 10, ...
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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 ...
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How Secure Is Splitting A Bitcoin Private Key?

NOTE: This question cannot be posted to Bitcoin SE because it will not render there due to the mathematical notation. Since the mathematical notation is part of the question, this is the more ...
Crypto L Plate's user avatar
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Extracting RC4 and 3DES keys from system memory

I have read papers [1], [2] that have presented techniques on extracting symmetric encryption keys from memory during the process of encryption. There are tools [3] that can extract AES keys from ...
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Are there a way to progress or age key pairs

I am searching for a way to make the noise X pattern fully forward secret. The X pattern is a way to encrypted and authenticated messages. As a building block to achieve this I started pondering if ...
Håkan Olsson's user avatar
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Why would one split HKDF output into multiple parts instead of expanding it multiple times

Reading the implementation details of Signal's approach on double ratchet algorithm I noticed the following key derivation procedure for using AES-CBC with HMAC: HKDF is used (...) to generate 80 ...
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GPG Sub Key Renewal Questions

Last year, I followed this guide to create two GnuPG Smart Cards; one card with the Primary Key and the other card with the Sub-keys. I noticed that the sub keys were close to expiring so I renewed ...
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RSA - find d,e with restrictions

For academic purposes, assuming $n, p, q$ with $n\approx 2^{4096}$ and $p,q\approx 2^{2048}$. I need to find ($e,d$) such that: $e$ is smaller than $2^{64}$ $d\approx 2^{4096}$ and will have as ...
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Does the length of the keyword used for keytable for Playfair matter?

So for Playfair, we choose a keyword and put that in the keytable with no duplicates. Then, we fill the rest of the table with alphabets in order that are not in the keyword without 'J'. Does the ...
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Generating interactive, secure multiple ECC key pairs deterministically

In Elliptic Curve Cryptography (ECC) assuming user A has a private public key pair of $S$, $P$ accordingly with generator point $G$ which as we know is: $$P=S*G$$ Assuming that user A wants to ...
abeikverdi's user avatar
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IV and Headers inside cipher text

I am a bit confused about the use of IV, and key hash. Is the key hash and IV stored inside the headers of the cipher text? Isn't it a security risk to store this header information? By key hash I ...
doesnt_matter's user avatar
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can permutation matrix be found in parallel processing technique?

Let us say there exists a permutation matrix $n \times n$ for some large $n$. Then, there are $n!$ possible permutations. If one to use brute-force to find the secret permutation among $n!$ ...
Faith's user avatar
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Key binding with hidden public key

In my scenario we have the Issuer I, Verifier V and Prover P. Now the prover send some messages to I and I signs these messages with I's private key. These messages can be easily sent from P to V and ...
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Accidentally leaked my main gpg private key!

I only use one gpg key, which I use with pass, which currently holds a ton of password stuff. I also use that key to sign my github commits and a ton of other stuff....
Hashem A. Damrah's user avatar
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183 views

How web browsers and WebCrypto API protects secrets

I tried to search and take a look at a way to securely generate or import secret keys on client-side. First I tried to see if it is possible to take advantage of TPM in Windows but as far as I ...
John's user avatar
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Multiple Encryption Using GCM For Multi-Key Security

Multiple Encryption For Multi-Key Security I have a hypothetical question about multiple encryption after reading Matthew Green’s blog on multiple encryption. For those who are familiar with GCM…I ...
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How can a generate a key with defined key size with a hash function with its security/internal state shorter than the key?

Let's suppose I took a high resolution photo full of entropy and I want to convert in a key with 2048-bits of security. Practically all the known hash algorithms have maximum 512-bits of security. Is ...
phantomcraft's user avatar
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Encryption of data with multiple possible decryption keys

I'm new to the Cryptography Stack Exchange, so my question might be very naive. What encryption algorithms are out there that will allow different decryption keys to decrypt the same piece of ...
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decryption in IDEA if the encryption was made without the output transformation

I'm implementing IDEA encryption and decryption and I'm trying to implement it in different variants(e.g if we didn't do the output transformation or if we don't do full 8-round encryption). I got the ...
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Key stream instead of key schedule

Let's consider a block cipher in CTR mode. And let's consider a keyed PRNG or just a good PRNG with a seed as the key. The PRNG has to be very fast. Is it a good idea to put away the key schedule and ...
Tom's user avatar
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Help needed for IBM KCV

I found old key letters used in EFT HSMs with TDES keys, parted in two halfs. The check value printed on this letters is called IBM CV and doubled IBM CV. My newer HSM does not support this kind of ...
user2032902's user avatar
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Looking for an algorithm to encrypt with a single key and decrypt with a lot of keys without consuming too much space

Is it possible to have an encryption scheme that could be encrypted with a particular key, then decrypted with a large amount of keys without massively inflating the size of the final result? I am ...
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Generating a XOR Hash function for a given group of numbers to maximise collisions

Given $x$, a vector of $m$ distinct bit vectors of bit length $N$, I want to use an XOR-hash $h$ such that all $x_i$ collide to the same value. I define an XOR hash $h$ which takes bit vector $q$ as ...
Acinonyx's user avatar
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Generating a recovery phrase for a RSA key-pair

What is an optimal way to associate a RSA key-pair with a recovery phrase/seed for access recovery purposes? I've seen a lot of cryptocurrency wallets provide this feature, however, I'm not looking to ...
NowsyMe's user avatar
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Prove how to brute-force the double encryption with complexity 2^57 rather than 2^112?

We know that DES has key length that is too short to defend brute-force attack. One idea to improve DES was to encrypt a message using DES twice with two different keys. Let E be the encryption ...
Haseeb Saeed's user avatar
1 vote
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114 views

If they exist a relation between decisional Diffie-Hellman assumption and composite decisional residuosity assumption

From the cryptographic hardness assumptions, we have DDH and CDR assumptions. It is known that the composite decisional residuosity assumption is related to a factoring problem, while the DDH is ...
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If 1 can be a random number in Diffie-Hellman Algorithm

I've done some calculations and Diffie-Hellman Algorithm worked for all chosen random numbers except $1$. In the description of the algorithm, I can't find information that the random number has to be ...
Luke's user avatar
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PCI DSS requirement 3.5.3

3.5.3 Store secret and private keys used to encrypt/decrypt cardholder data in one (or more) of the following forms at all times: ............ As at least two full-length key components or key shares, ...
Michael's user avatar
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GlobalSign cert in Trusted root for Google Services shows Sha1. Security postures

"GlobalSign" certificate in Trusted Root Certification Authorities for Google Services shows Sha1. Security postures are different than just 2-3 yr ago. At my home, router bought 2016, networked; ...
Tom Hege's user avatar
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Asyncronous Rachet tree: How user movability is handled is the Rachet tree being recreated?

As I have read the latest state of art in group key agreement is the Asyncronous Rachet Tree. But in applications like IRC that exists high user movability (users join in ans leave the room). Is ...
Dimitrios Desyllas's user avatar
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Nature of risk(s) from KeeChallenge XML file stored in cloud at Onedrive

As a noob user of KeePass2 on Windows desktop and Keypass2Android on my phone, supplemented by YubiKey Neo configured for hmac-sha1 challenge response, I noticed that Keepass2Android appears to store ...
greybeered's user avatar
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Is there hierarchical key generation that completely tolerates leakage?

Is there a hierarchical key construction algorithm that achieves forward/backward privacy with any (unlimited) leakage of private non-master keys? What I mean is that if there's an unbounded number ...
Some Guy's user avatar
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How does the authd protocol work?

So far, I have been able to research on what it is: authentication; authorization; using resource authd. I still have not come across a definitive answer or ...
ARK's user avatar
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MAC with key supplied afterwards

Looking at HMAC and KMAC it seems that the key is always required up front, i.e. before starting to process any other data. However, in many protocols the key may not be known it advance. For instance,...
Maarten Bodewes's user avatar
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Question on recovering a key in the algorithm

Let $E$ be a block cipher that has block size and key size both equal to 64 bits. Let $E'$ be a block cipher that has 64-bit block size and is defined as follows: For a 128 bits key $K \mathbin\Vert ...
KengoTokukawa's user avatar
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See the RSA's $n = p q, e \text{ and } d$ from ssh-keygen

For learning purposes, how to get the RSA's parameters (I use standard notation): $n = p q $, where $p$ and $q$ are prime and $e$, $d$, such that $ed = 1 \ (mod\ \varphi (n)) $ when doing ...
Basj's user avatar
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Specifications for key management

Does anyone know of any commonly accepted or standard specifications for languages, modelling, diagramming, etc. for specifying and describing the life cycle of keys in a system? Thanks.
Mr. Stone's user avatar
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Why does facebook uses two secrets to secure API

I am working on a public API for my personal forum. Concerning the authentification of the requests and responses I plan to hash the payloads with a secret, known to me and the API user, and send the ...
01capitain's user avatar
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Handling key invalidation

I'm writing an Android app which will need to store some data for the user as a byte array of unknown length. The data must be encrypted. I have gone down the path of the hardware-backed keystore and ...
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