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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Is there any cryptography-based assured data deletion technique currently as a standard?

I've recently read part of a book exploring secure data deletion techniques for many storage mediums. In particular, I read about assured data deletion techniques developed for data outsourced to the ...
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Is it possible for a given plaintext and ciphertext to have two different keys? [duplicate]

This has probably been asked before but for a given ciphertext and plaintext pair, is it possible to have two different keys producing said pair? Or there are no collisions in AES, unlike hashing ...
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Signature Chains: Ensuring Authenticity and Trust

I'm studying for an exam and came across this question: When an electronic signature of a message claimed to be produced by Alice is verified we typically verify (at least the first time): that the ...
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Is there a way to defeat statistical information leak in Vigenère cipher when the ciphertext is reasonably larger than the key size?

I read in this answer here that if the ciphertext is reasonably larger than the key size, Vigenère cipher is easily breakable. Is there a way to repeat the key if it is reasonably smaller that the ...
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Can we use several times the same RSA and ECC keys?

For RSA or elliptic cryptography, can we use the same public/private keys for several exchanges, or is that unsafe? Does it lower the security of the protocol? To me it doesn't matter, as receiving ...
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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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Shared Key message-encryption multiple receiver communication

Say there are 5 parties. 1 is the sender, and 4 are the receivers. The sender has a unique shared key with each receiver. k1 - between sender and receiver1 k2 - between sender and receiver2 k3 - ...
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Can a PPT adversary get secret $a$ from public messages $m_i=x_i-a \mod p-1$ for i=1,2, ...,n?

Consider I have a secret $a \in Z_P^*$ and n public messages where $m_i=x_i -a \mod p-1$ and $x_i \in Z_p$ for i=1,2, ..., n. Given that $a$ and $x_i$ for $i=1,2, ..., n$ are secrets, can a PPT ...
Mahmoud Abdelsatar's user avatar
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Is KangarooTwelve hash function suitable for generating very large key material as Shake-256 is?

If I take a large truly random portion of data, I know that I can generate a 2048-bits key with it (assuming the random data has more entropy than the key). I read in this forum that Shake-256 has ...
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Decrypt RSA knowing N, invp, and invq

im having a problem while solving a RSA problem, so i have python script to create a RSA key and cipher, from that i have n, invp, and invq. so my question is possible to decrypt the message only with ...
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Key exchange for encrypted firmware update

I'm trying to implement encrypted firmware update functionality for an embedded device. The goal is to prevent reverse engineering of our firmware when the update files are shared with our customers. ...
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Double- and -add algorithm

I am currently doing the elliptic curves and I'm stuck for 8 hours without finding solutions. I under stand the process of double and add but don't know how to obtain 5 * 8P = 4OP =11 P. 11 P was in ...
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Enigma - Bombe - Understanding the relative values of ring settings to key settings

For a project, I am writing Enigma and Bombe simulators in Python. I have coded up both and so far so good. My Enigma simulator gives the same results as the online simulator here: https://people....
Andy Robinson's user avatar
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Why does symmetric encryption not provide authentication and integrity? Is it only this type of encryption or cryptology in general have this issue?

Studying for Cryptology and came across a presentation regarding on "Integrity vs Authenticity" where the discussion briefly mentions how Encryption "does not provide integrity or ...
omar7439's user avatar
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Key blinding security in Ascon

This article explains the role of key blinding in Ascon. Key blinding in Ascon involves XORing the key with the capacity part after the permutation in both the initialization and finalization stages. ...
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How to calculate key length in bits?

On a technical forum discussion, an example key of 16 hexadecimal numbers was said to be 2048 bits in length. I do not understand this as each number would be 4 bytes - 32 bits - therefore to me 16 ...
Zonnkq Shad's user avatar
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How to determine the prefix of a SECP256K1 compressed public key

I need to store a public key in a variable of maximum 32 bytes. I recover the compressed key and remove its prefix, but then I have to do the opposite: I have to rebuild the compressed address from it ...
Sino's user avatar
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Security Analysis: Adversary's Ability to Recover Concatenated and Hashed Secret with Partial String Knowledge

Suppose I have the following secret, calculated by concatenating and hashing the results of two random strings: secret = H( H( random_string1 ) || H( random_string2 ) ) Let's assume that the adversary ...
Kadir Korkmaz's user avatar
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Manual entropy collection from sources with an arbitrary base

I'm writing a tool for manually collecting entropy from sources like coins and dice, and I'm wondering how to best deal with the case where the desired number of bits of entropy is not representable ...
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How does the key generation of a homomorphic secret-sharing protocol works?

I am new to cryptography and do not have sufficient background knowledge, and I am sorry for any possible vagueness in my question. I am reading a paper (https://eprint.iacr.org/2019/129.pdf) about ...
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Safe implicit value validation: $H_k(k \oplus m) \sim H_k(m)$?

$H_k$ is a cryptographic hash function that's keyed using a section of key material $k$ (for whatever definition of "keyed" that's appropriate for the given hash function $H$). Are the ...
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CTF - DES Challenge

I am trying to solve a CTF challenge based on DES. I attached the code of the challenge to the question. So far I have noticed that the otp used for the encryption is the same for the entire session, ...
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Are the null bytes produced by a True Random Number Generator a security issue when using it as a source of entropy for keys in One-time pad?

I can see that True Random Number Generators can produce some null bytes, after some megabytes of data, even 2 consecutive null bytes are produced: ...
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May I use the same One-time pad key two times if I encrypt it with a block cipher using two different block cipher keys?

Let's suppose I have two 2GiB files and I want to encrypt them using One-time pad (Vernam cipher), but I don't want to store two big keys. May I use only one key for the two files if I encrypt the One-...
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Derrive a new key from Trusted Third Party (e.g. Kerberos) session key

Kerberos (and I assume other Trusted Third Party protocols) use (hash) an existing shared secret key to create a session key used for authentication. I read that this authentication secret key can ...
Elliot's user avatar
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Security of keys that are as long as the data

If both communicating sides end up with the same secret 3000-bit key, is it enough to XOR each byte of the messages with each byte of the secret key to make it secure? Wikipedia says it is, but I ...
Kevin Stefanov's user avatar
1 vote
2 answers
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What is simple asymmetric encryption that use arbitrary key?

While XOR is used as simple symmetric encryption with arbitrary custom key, what is a simple asymmetric encryption that use arbitrary custom key? That means I want to be able to set custom private key ...
Muhammad Ikhwan Perwira's user avatar
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3 answers
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If I encrypt a plaintext with different keys for each block, will I have the same security as a one-time pad?

Let's suppose I encrypt an 1MiB plaintext with AES-256 in ECB mode but using different keys for each 16-byte block (I know this is weird but it's just an example). Remembering that a different 256-bit ...
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Genrerate n numbers based on a string [duplicate]

I wanna generate a list of numbers based on a unique string. They shouldn't be predicatble and every time to generate they are the same. Could someone help me pleeease :)?
Jonathan Krützel's user avatar
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If encrypting with a hash function in counter mode, will the security of this scheme be at most minimal{input,output}?

It's possible to use a hash function as an encipherment scheme if used in counter mode. Let's suppose I take a 64-bytes (512-bits) seed/key and hash it concatenated with counters, and use it as a ...
alpominth's user avatar
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How do I decrypt a key encrypted by my HSM under a ZMK?

I've generated a key using an HSM Thales PayShield and i have share it with a counterpart. I followed these steps: i generated key usign KG console command i use FK to form ZMK from clear components ...
MaXbeMan's user avatar
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How to find the round key in AES 256

Can anyone explaine how to find the every 15 round key by the 64 hex digit master key of AES 256 please. I will be really greatfull
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DES encryption Key from a passphrase

I have been given a DES encryption assignment. I was given the Cipher text, the Plain text and the "passphrase". The passphrase consist of a 4 byte hex string. I have studied several ...
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1 answer
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Are asymmetric encryption and decryption same function? [closed]

In asymmetric key encryption, we have 2 functions, encrypt(m,k) and decrypt(m,k), and 2 keys, ...
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PCI compliance - use of ANSI X9.17 for export keys

we have a concern about a key export. We completed the migration to Key Block LMK in our environment (with HSM Thales 10K). Now, we have to exchange keys with third-parties that still use Keys in ...
MaXbeMan's user avatar
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Clarification on the use of Key block Version ID with Thales HSM

Clarification on the use of Key block Version ID For the first time since we migrated to the Key Block we are exchanging keys with third parties, The keys were all generated by choosing Key Scheme &...
MaXbeMan's user avatar
8 votes
2 answers
266 views

Providing tokens for anonymous survey

I want to conduct an anonymous Internet survey (e.g. “What’s your favorite fruit?” with a multiple choice answer) among a given set of people. Double answers by the same participant are not allowed. ...
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Issue with AWS Encryption SDK for JavaScript in Browser: 'Buffer is not defined' [closed]

I'm trying to implement AWS Encryption SDK for JavaScript in a browser environment within a React application. When I attempt to construct an instance of the encryption client using buildClient ...
CreativeDesign's user avatar
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1 answer
98 views

Security of RLWE encryptions of secret keys

Under which conditions is it secure to publish an encryption of the secret key $s$ under itself in terms of an $RLWE_s(s)$ ciphertext? Because for some schemes this is (repeatedly) used in ...
opag's user avatar
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2 votes
1 answer
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Key management problem in federated learning based on homomorphic encryption

In federated learning using homomorphic encryption, all participants in most schemes share the same pair of keys, which can easily cause key leaks and lead to data privacy leaks. After research, I ...
sunmu's user avatar
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3 votes
1 answer
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What is the result of not connecting the 1st register to the xor gate in LFSR?

I designed 8 bit lfsr in vhdl. According to mathematical theory, I xor processed the outputs of registers 1, 4, 5, 6 and 8 and connected them to the input of register 1. theory says that if I give the ...
Doğukan Karakaya's user avatar
2 votes
2 answers
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DES initial key generation

I am working through a textbook on crypto, currently on DES section. What bothers me is that there was no explanation about where do we get initial 64-bit key from. This question is also very hard to ...
Michael Hammer's user avatar
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If I encrypt two plaintexts with different keys, XOR the ciphertexts and send to an adversary, what can he/she do with what I sent?

Let's suppose I encrypt two blocks of 1MiB with AES-256 in CBC mode, each one using different keys, XOR the resulting ciphertexts and send this XORed block to an adversary. Remembering that the ...
alpominth's user avatar
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Hashing a seed full of entropy with a cryptographic hash function and emiting a key with the same size as input: can a collision attack occurs?

I read this in the documentation of HighwayHash: By contrast, 'strong' hashes such as SipHash or HighwayHash require infeasible attacker effort to find a hash collision (an expected 2^32 guesses of m ...
alpominth's user avatar
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Is it safe or reasonable to use the key parameter in a cryptographic hash function as a counter?

Not all the cryptographic hash functions have the counter parameter for making messages be different for each counter value. But many accept a key parameter. Is reasonable to use the key parameter as ...
alpominth's user avatar
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How does the public key cryptography algorithm generate a public key based on the private key? [closed]

Because of the need of the project, I want to develop a simple public key cryptography algorithm, but I have doubts when generating the key pair. I have learned about the key generation process of RSA....
SN-Grotesque's user avatar
1 vote
2 answers
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How is asymmetric encryption possible if you need a passcode in order to encrypt something?

Cant you look at the algorithm used to encrypt and find the private key from the public key that way? As an example, here's a simple python algorithm that encrypts an input: ...
Javier Albarracin's user avatar
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Can new decryption keys be issued without modifying the encrypted contents? [closed]

I'm curious if there's an encryption scheme where content may be encrypted to a public key where the associated private key can generate new decryption keys for the same content. The goal is to ...
Kai's user avatar
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1 answer
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Why hashing a seed to generate a key and using chaining to get the rest of key matterial is not secure?

Here, an user says about using a seed to generate a key that is larger than the digest size: "Do not use hash chaining: that's a bad way of constructing a key derivation function from a hash. If ...
alpominth's user avatar
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SPKI Public Key to Compressed Public Key

I currently have a DER-encoded X.509 ECC SECP256K1 public key, also known as SubjectPublicKeyInfo (SPKI) from AWS KMS. How do I convert it to a 66 hexadecimal compressed public key string?
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