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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How to decompose a public key into subgroups EC?

Is it possible to decompose the public key into its own subgroups? Suppose we know the order P with which the public key was generated ...
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How to get a common coordinate from two different coordinates on Elliptic Curves? [duplicate]

I am trying to write a SageMath script that multiplies two coordinates on Elliptic Curves into one common coordinate. SageMath Elliptic curves over finite fields ...
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How to encrypt/store private key, if login is with biometrics/OTP/Sign in with Google [migrated]

I am creating a cross-platform application, in which I am encrypting all data using AES-GSM. So my problem is that I want to store private keys locally on the user's device (either Android, IOS, Web, ...
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Block cipher design criteria when specifying key size

For a given block size of N bits, the total number of possible permutations is (2^N)! In order to select from any one of the possible permutations, the key would have to be of length log2((2^N)!) ...
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How to decide if an element is a public key in NTRU encryption scheme?

First, I'm using the settings of https://en.wikipedia.org/wiki/NTRUEncrypt, with $L_f$ set of polynomials with $d_f+1$ coefficients equal to 1, $d_f$ equal to $-1$ and the remaining $N-2d_f-1$ equal ...
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Is Keystore a file, a database, a specification?

What exactly are keystores? I understand they are used to store things like private keys, certificates etc. But how exactly is that done? Is it just an encrypted databases where you put all these ...
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Rivest Cipher 6 (RC6) Key Scheduler

I am trying to understand the Key Scheduler used in RC6 and I have a total of 3 questions. The RC6 Wikipedia page says that the only difference between the RC5 and RC6 key scheduler is that more words ...
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Is it safe to use the same seed phrase for different cryptocurrency protocols

I want to use the same seed phrase for severl cryptocoins (Bticoin, Ethereum, Nano, etc.). I understand that each protocol has its own phrase length and possibly a different way of generating the ...
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Encoding salt as hex before hashing bad practice?

I was reading a question about symmetric keys here and found the answer quite interesting. It mentions: Be sure to pass in the raw bytes, and not, e.g., a hex-encoded string Can someone elaborate on ...
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How To Read Encryption/Hashing Notation

This is very basic, but what I'm wondering is: I have a few notations of hashing/RSA encryption that I'm unsure of when reading. PKE(PW, K) With PW representing a password, K representing a 128-bit ...
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If a Pseudorandom Function (PRF) is supplied with a key with the same size of output block, can 2 or more keys generate the same output for a input?

There a 2 examples: A block cipher with 128 bits of block size taking a plaintext and a 128 bits key (AES-128). A keyed hash function with 1024 bits of block size in its output, taking a message and a ...
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Number of Legitimate Bitcoin Wallets from unsequenced set of 24 Words

If someone found a scrambled BIP-39 24 word sequence how hard would it be to determine the correct sequence that yields someone's wallet. Are there multiple different unique sequences of the same 24 ...
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Can an arbitrary physical image be a key?

Assume an arbitrary secret physical image¹, such as a privately made chemical Polaroid™ similar to this Is there a feasible and secure way that this physical image could be used as cryptographic key, ...
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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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Designing your own Algorithm

I have been told to design my own algorithm as a college assignment. What I could have come up with was a random cipher. For example: Suppose my plaintext is: AND ...
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CBC mode, fixed Key and IV but unique plaintexts

My transport channel is sufficiently tiny that I don't want to give up 16 bytes for an IV (AES block size). My environment is also resource constrained such that I have no RNG. I have read over and ...
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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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Secret key expiration

I am looking for suitable techniques through which secret keys can be expired after a certain time limit. Is there any such method in cryptography?
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What are the explicit usage of different keys derived from SKEYSEED in IKE?

We have seven different keys derived from DH key and nonces via PRF in IKEv2 as skd, skai, skar, skei, sker, skpi, skpr. Why different keys are generated for initator and responder for encryption? ...
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Is PRF XORed with its key still a PRF? (always)

$\forall k \in \{0,1\}^n,m \in \mathbb{M},F_k(m)$ is defined as follows: $F_k(m) = F'_k(m) \oplus k$. It is known that $F'_k$ is a PRF. Note: 𝕄 is the message space and it's assumed that the key $k$ ...
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How to protect a non-extractable Secret Key in indexedDB?

I have encrypted data in AES-GCM with the crypto API. The initialisation vector is then ...
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Domain Keys Identified Mail (DKIM)

If a company uses Domain Keys Identified Mail ("sender adds a special signature which includes author name / date signed by RSA Private Key. Receiver verifies the signature by looking up the ...
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How to generate keys from a 56 bit using DES

First I just want to apologize for my lack of knowledge in this system. The professor kind of gave us an exercise to solve before even going through the lessons. I tired to look at videos online but ...
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Why is it not possible to attack an AES by creating a function to model the substitution that occurs in a s-box?

I realise that s boxes are able to make the transformations done in AES non-linear. However I am unsure how this makes AES secure. For instance if we had no s box then it is possible to calculate the ...
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CrypTool RSA Features [duplicate]

I am attempting to manually encrypt a plaintext message (message = MI) using RSA. I receive an answer of: 33,264 and 21,164. When I enter the same plaintext into CrypTool to confirm that my ...
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Am I Doing RSA Correctly?

I am trying to figure out how to complete RSA manually. I am trying to encode a simple block message (Mi). I used CrypTool to determine the encryption. When I "manually" computed 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 ...
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Online AES Calculator

I am currently looking into how AES works and found a calculator online: http://testprotect.com/appendix/AEScalc I understand that the AES process has 10 rounds of calculations. Does this mean that ...
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Why is this DES key considered weak?

I understand the premise of weak keys in DES and cryptography. From searching online, I understand that keys that are comprised of all zeroes / all ones / alternating ones and zeroes / alternating ...
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Why do you need to apply hash over DH shared key? [duplicate]

I`ve read multiple times that it is not safe to use the shared key resulted from DH key exchange directly and that you need to do a KDF or hash over it and then use the result as a key. Why is it not ...
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How does a forward search attack work? [duplicate]

I just came across this term “forward search attack” while reading about Interchange key and Session key. The book mentioned that using session key helps to prevent attacks such as forward search ...
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Equivalent keys in Hash Functions

Let's suppose I want to use a (keyed) hash function as a stream cipher, I provide a key and a message to be hashed as a counter (like a nonce), and so, XOR each hashed output block on the plaintext. ...
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Assistance with Permutation Cipher (Columnar Transposition) [closed]

I was wondering if someone could provide some assistance with understanding a permutation cipher. I have both the cipher text as well as the plaintext but am having some difficulties trying to find ...
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Is using /dev/hwrng for raw key material secure?

Is using /dev/hwrng for raw key material secure (as long as you trust the hardware)? I tested it using the rngtest tool and it has good output.
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Are there any cryptographic algorithms, which lets the user apply some modifications on the encoded data, without decoding it?

I would like to encode some data with a key, and send it to a third party. They don't know the key to decode it, but I would like to make it possible for them to apply some modifications on it. Then ...
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Can SHA256 hash be considered as a secure key proof?

I want to use PBKDF2 with 1,000,000 iterations (I don't know yet exactly how many I will choose) to derive a 256-bit symmetric key K from a password provided by a user (at least 40 bits of entropy). ...
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Is it possible to increase the encryption security of a short key?

If I encrypt a file with a short 4 digit pin is there any way to make it more secure. I've thought about hashing the 4 digit pin and using the result as the encryption key. I think this would work as ...
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key length considerations

Learning about cryptosystems and basic cryptology and I have a sort of vague understanding of key sizes/key space and think I may have done something wrong in my calculations, can someone please ...
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CNG/BCrypt/NCrypt Import an ephemeral AES key wrapped with a persistent RSA key

I will write some kind of security client/server pair: The server part provides wrapped AES keys. The client part, based on CNG win32 API (ncrypt.h+...
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AES Password Based Key Derivation Iterations

I have been writing my own implementation of the Advanced Encryption Standard with cipher block chaining in python3 for the last several months, mimicking the OpenSSL command line interface. I can ...
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How much data can we encrypt using AES 256 before changing the key?

Although this question has been answered in this link (After How Much Data Encryption (AES-256) we should change key?), I am not satisfied with the answers because the Recommendation for Block Cipher ...
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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 ...
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Using same key pairs in several different encryption tools and version

can we use the same key pairs created by an encryption tool, for encryption decryption, in another encryption tool ? for ex, created by hypercrypt, but being used in cryptermite, or maybe within the ...
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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 are ECC keys stored?

I am trying to figure out what typical formats and sizes, etc. are, for storing ECC public and private keys. Some quick research turned up X9.62 (to which I don't have access) and SEC1. But then there ...
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Randomizing output of HKDF for the same input key material [duplicate]

Given HKDF and a master input material key $k$, I would like to derive ephemeral keys that cannot be linked together. If I understand correctly, the specification of $HKDF$ adding a unique random $...
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Is PyCryptodome's export_key with passphrase secure?

When exporting a private key with PyCryptodome, DER format, PKCS#8 and a suitably strong passphrase, is the resulting exported key secure enough to place somewhere that you would not normally want ...
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How do I multiply two points on an elliptic curve?

Tell me if there is a way to multiply two points on an elliptic curve? For example, as in secp256k1 ...
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Proving I can solve an equation without disclosing the solution (zero-knowledge proof)

Given a (potentially multivariable) equation $f(x)=0$, Peggy wants to prove to Victor that she knows a solution $x^\star$ to it without actually disclosing anything information about the value of $x^\...

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