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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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JWK vs. raw for key wrapping

Context (TLDR below) So I’m developing an application that uses a high-iteration-count PBKDF2 algorithm to derive a symmetric AES-GCM key from a user-provided (enforced to be reasonably strong) ...
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Multiple Encryption - One-Time Pad

It is known that One-Time Pad(OTP)s are theoretically unbreakable but impractical for use because of the size of the key length. But what if multiple encryption is used? Not to encrypt the first ...
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Half of any bitcoin (crypto) public key - (public key half) is possible

I found a topic on bitcointalk Public key x and y == Double(Half of the Public key x and y) half any public key is possible how that possible , in crypto there is subtraction and multiplication ...
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Is it possible to manage an encrypted dataset for face recognition?

Im in my final year of PhD in computer vision and my supervisor has given me a task that I am not very familiar with. So I am teaching myself homomorphic encryption everyday. This question is mostly ...
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Cutting down the size of a long blowfish key

I am reverse engineering a software that uses blowfish for encryption. The target uses an implementation of blowfish that allows arbitrary positive key length with a key size larger than 56 bytes. I ...
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48 views

How to be sure to retrieve the good key when brute-forcing a cipher?

Imagine the case of the one-time pad. It is proved to be secure because the key could be everything. We have no guarantee that this key or that key was the one used while encrypting our data. ...
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257 views

Reusing IV in AES for encrypting file

Everyone says that you shouldn't use the same IV and Key. Is it safe to use the same IV and Key on only one file. EDIT: I will be using CBC or CFB encryption modes so the IV will be updated based on ...
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98 views

Padding vs Hashing Encryption Key

I am making a program for personal use that will not contain super-sensitive information. I am using this to explore cryptography. Would it be acceptable to use a password to generate a key for AES, ...
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195 views

Multiple key generator

I need an algorithm for "key generator". It should be initialized with some secret data, such as a (hashed) passphrase, or something generated once by some 3rd-party code. Given some small input it ...
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Can someone steal the key between 2 clients which are using Symmetric Encryption?

Can someone which is not authorized be able to listen between the conversation of 2 clients and catch the key? Because if I understood correctly one client needs to send the key through a channel so ...
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1answer
57 views

I'm getting a non-integer (float) private key in Paillier encryption

I'm trying to implement the Paillier cryptosystem in Matlab using the key generation guidance available here: https://en.wikipedia.org/wiki/Paillier_cryptosystem#Key_generation, but the problem is ...
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164 views

decoding a Ed25519 key per RFC8032

RFC8032 Edwards-Curve Digital Signature Algorithm (EdDSA) 5.1.3 Decoding states the following: Decoding a point, given as a 32-octet string, is a little more complicated. First, interpret ...
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Implications of identical round keys in Rijndael

When reading up on the Rijndael key schedule, I learned that the master key itself is used as a round key directly before the key schedule generates additional round keys. When a 256-bit key is used, ...
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1answer
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Can private key be specified on key pair creation?

Without regards to any specific implementation of asymmetric cryptography, I am wondering if it is feasible to come up with a value of private key I want to use, and calculate the corresponding public ...
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2answers
585 views

Appropriate key for AES 256 GCM

I am updating a system that has Rails' OpenSSL on one side and Python's cryptography.io on the other. The Rails side has to generate keys for the AES-256-GCM and here are two methods that appear to ...
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641 views

Should text be hashed before being used as an encryption key?

Let's say I have an API that provides an encryption wrapper around another API. I give the consuming programmer the option of either passing a string or byte array as an encryption key. The byte ...
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1answer
87 views

Is there a feasible way to generate an RSA key manually the same way as it is for an ECC one?

In elliptic curves, a private key is just a random number, and one relatively small compared to other crypto systems (256 bits for ECC vs 4096 bits for RSA for example). Suppose I don't trust ...
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how does OpenSSH use bcrypt to set IV's?

I generated an encrypted OpenSSH private key for test purposes: ...
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Is the private key of a private/public key pair also a symmetric key?

I think I've got a fairly good (practical, not mathematical) understanding of symmetric versus asymmetric cryptorgraphy, so the difference between those is not the question. In a local discussion ...
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Alternative way to provision secret in Intel SGX enclave

I have a case where I have multiple clients(non sgx, assumeed safe) and server(sgx based), talking over a network. I wanted to provision shared (per client) key which is used to encrypt and decrypt ...
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Is There any Risk to Using Meaningful Text as One Time Pad Key?

Let's say two people have the same edition of the same magazine. The knowledge that the magazine will be used as a one time pad is secret. Is there any risk to using this as opposed to randomly ...
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Why is a Diffie-Hellman key exchange required when RSA is already being used for key exchange in TLS?

Specifically with TLS, What is RSA used for during key exchange? What is Diffie-Hellman used for? Since RSA already provides authenticity and confidentiality, why is Diffie-Hellman used during the ...
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Is a cryptographic key of size $N$ equivalent to $N$ bits of entropy?

Are there any caveats to the claim that a cryptographic key of size $N$ bits and $N$ bits of entropy are equivalent?
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How can we encrypt a file to be just readable (and not writable) after decryption?

Is it possible to encrypt a file (e.g., a text document) such that when a user decrypts it, he/she be able to just read the file and not be able to change the content of the file? I mean, the result ...
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2answers
83 views

Brute force encryption keys base on their length

I need to clarify if my understanding is correct. if I am using 4.2 GHz CPU -one core only- that means: 4.2 billions hertz = 4.2 billion operations per second. (about 2^32) So: 32 bit key : 2^32 \ ...
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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 ...
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1answer
139 views

Security strength for encryption and authentication (wrapping) of cryptographic keys

Let $K$ and $M$ be AES secret keys. The purpose is to wrap $K$ using $M$ to allow $K$ to be used at a later time (see, e.g. NIST SP 800-38F, section 3.1). One method to achieve this goal is to use $M$ ...
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Purpose of repeating a 16-byte key for Salsa20

The core of the Salsa20 family of stream ciphers is a hash function that takes a 64-byte block, using it to generate a pseudorandom 64-byte output. The 64 bytes contain space for a 32-byte key a 16-...
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RSA: Given two very large prime $p,q$ and $n=p\;q$, how to quickly find $e$ such that $\gcd(\varphi(n),e)=1$?

I can imagine that finding $p,q,n$ are easy, but my text book also says the $e$ can be found rapidly, so how does modern RSA find this $e$?
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2answers
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Trustless exchange without a third party

Is there a cryptographic (or even not entirely cryptographic) way of exchanging objects between Alice and Bob that would not require a third party, and Alice and Bob would not need to trust each other?...
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49 views

Paper wallet QR codes

What is the purpose for and distinction between each of the following keys commonly used in cryptocurrencies? Address Tracking key Passphrase Private key For context: I got a bytecoin paper wallet ...
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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,...
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1answer
195 views

What is double-length derivation key?

I trying to understand how can an IPEK created from a given KSN and BDK (Triple DES Edition)....
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4answers
1k views

Best way to encrypt lots of private keys with the same passphrase

I'm working on software which deals with lots (several millions) of RSA private keys. Keysize is 2048. I have to store them in a database, and I want them to be encrypted to mitigate risks of ...
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2answers
393 views

How do I calculate a password space if the password only has eight alphabetic characters (not case sensitive)

I read this wiki article and saw this formula for random password's information entropy. Also the wiki article mention that the symbol count for non case sensitive is 36. Is there a way I can ...
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1answer
172 views

What is the purpose of key strengthening?

I recently came across this term and after some research found this article which states the following: An alternative approach, called key strengthening, extends the key with a random salt, but ...
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1answer
156 views

Just a super basic question - Does the key create the algorithm?

I don't understand how the key gives you the algorithm, in other words I am having trouble understanding how the key works in symmetric encryption. My book says: "Symmetric encryption transforms ...
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What is the reasoning behind the PRESENT key schedule?

It seems there are few books on PRESENT and even fewer that give any reasoning behind the mechanics of the key schedule. I understand how it works to the extent that I made a simple Excel program of ...
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1answer
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How much data does a session/data key typically encrypt?

I believe the masker key, $MK$, of a block cipher might be used for several years and is used only to encrypt $\textit{key encrypting keys}$, which in turn are used only to encrypt $\textit{data keys}$...
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132 views

Multiple Keys for an Encrypted Secret

I have the following problem: I want to put a document on a ipfs store. So it is accessible via a distributed network. Now, at first only two persons (Alice & Bob) should have access on the file. ...
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Is it generally considered acceptable for app owners to be able to retrieve private keys from users when their apps offer end-to-end encryption?

E2EE promises that data sending between two endpoints can be decrypted by only those two endpoints. If an app offers E2EE but still has functions to retrieve private keys from users for any purposes ...
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5answers
7k views

Can a hard drive store clear text data that is physically impossible to retrieve?

I'm trying to study how HSM and TPM works when storing secret data in clear text. How can they achieve physical impossibility in retrieving secret data? I get the point in software, if you just have ...
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1answer
2k views

WhatsApp end-to-end encryption

WhatsApp offers end-to-end encryption. However, when I start using it on a second device such as a PC running Windows, I can decrypt incoming messages without providing any private key into my second ...
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2answers
58 views

Should Bob trust a certificate issued by delegated party?

Consider this scenario: Alice sends a message signed under her public key to Bob. Bob has never exchanged a keys with Alice. Alice's key is signed by a certain X. X's key is signed by Y, an entity ...
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281 views

Blowfish-448 Secure Key Generation Algorithm

I am using blowfish-448, until now the keys have been generated using a crypto random number generator full filling the 448bits vector. I read about exploit in case of weak keys and reflection keys ...
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1answer
260 views

8th SharifCTF — What is the advisable way to recover the key of single round DES here?

I am participating in the 8th SharifCTF competition and have a related question: I have 1000 plaintext and its ciphertext, which has been encrypted with DES algorithm (only 1 round). Now, how can ...
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3answers
149 views

What’s the difference between a secret key and a seed?

I always hear that if you have the seed then you can easily obtain the key. So, is the secret key just typically an expanded version of the seed? If so, via some key derivation algorithm? Also, if ...
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1answer
144 views

Length of fields in an RSA CRT Key

In a 2048 bit RSA key. Are $P, Q$, exponent $P$, exponent $Q$, and the coefficient guaranteed to be half of the length of the modulus (128 bytes)?
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For WinRar, how long should a password be to make up for a lack of complexity?

Assuming that the best alternative to complexity is length, how long do you recommend a password or phrase to be when using WinRar? Note that I'm aware that it's not always that simple, but I would ...
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1answer
64 views

How to find the type of symmetric cipher? [closed]

How to find the type of symmetric cipher that was encrypted. I have ciphertext, plaintext, key. there is a command in openssl?