Questions tagged [cryptography]
Cryptography is the practice and study of logical means used to achieve information confidentiality, integrity and authenticity. It covers, among other things, encryption (making some data unreadable except for those who know a given secret element, called a key), data hashing (in particular for password storage) and digital signatures (provable integrity and authenticity with non-repudiation).
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How to crack luks crypto 2, encryption? [closed]
I recently forgot my phrase to unlock my laptop which i bought a new one several month's ago i needed some document then suddenly i can't remember the password, can anyone help!!!
Note: I tried ...
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RSA vs Shor's Algorithm/Fast Factoring — Server Credentials & MITM
I've watched a lot of videos on Shor's Algorithm and Quantum Computers. Most of these videos say these two things undermine RSA via fast-factoring, but they never really explain how fast-factoring is ...
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Over-Optimizing Security? Storing Encrypted Data on a Server While Private Key Remains With User
Assume that I have a server storing sensitive user information (think medical records). I want this data to be encrypted on my server at almost all times. Only when a doctor needs to access the data ...
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Is it possible to detect Stealthy False Data Injection attack through chaotic cryptography? [migrated]
I am doing a research on detecting Stealthy False Data Injection (SFDI) attacks in a smart grid context (a related paper). Besides I am working on a chaotic cryptography (e.g. with Lorenz attraction) ...
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Why in "openssl pkeyutl -verify" is needed both public and private keys? Why isn't public key enough?
I created a signature with:
openssl pkeyutl -sign -inkey rsa.key.bob -in plain -out plain.sig.bob
and to verify, Alice just needs to use Bob public key to check the authenticity of the message.
So ...
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Working Rfc2898DeriveBytes.Pbkdf2 in Java [migrated]
I have some passwords hashed with C# using Rfc2898DeriveBytes.Pbkdf2(bytes,src,5000,HashAlgorithmName.SHA1,24) (an older implementation) and would like to port this code to java.
However I don't seem ...
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Construction of Blake2 and Cha Cha [migrated]
Recently, I was reading about Blake2B and its properties regarding randomness and security, and its connection to Daniel Bernstein's CHA CHA digest. As a budding cryptographer, I find it doable to ...
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Remote eIDAS Qualified Signatures: Control of Signature Activation Data
In eIDAS Remote Qualified Signatures, but also in other Remote-Signature Solutions, the cryptographic keys are held by the Remote Signature Provider. The user uses some method, e.g., a smartphone app, ...
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How to break poorly implemented One-Time-Pad
I have a cipher text, that was created using One-Time-Pad, but the idea is that it was encrypted badly. The message, a section of a book, was encrypted using a pad 256B long repeated many times over (...
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DHE key exchange with p value 257 bytes but a pubkey of 256 bytes
I came across a packet capture in Wireshark where p length = 257 bytes and pubkey length = 256 bytes. See the ServerKeyExchange snip below:
Diffie-Hellman Server Params
p Length: 257
p: ...
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Any idea on how this 36 character long string generated? [duplicate]
I have a personal id "U1KFhYtMqZhCYya6sy31PVLM8DlM5HLCkwy3", I have checked some hash functions but cannot make sure how this generated? Is this just random string generated with [a-zA-z0-9]?...
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Security implication of loading untrusted private keys
The FIPS draft for Dilithium signature scheme (official name ML-DSA) had just been released not long ago. In the specification for skDecode (which is the subroutine that loads the private signing key) ...
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LUKS: How many iterations are enough?
The luksFormat command accepts iteration time as a parameter, not iterations. That obviously leads to quite different number of iterations depending on the hardware doing the encryption. However if ...
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Bypassing AES encryption if the keys are not in local,but in server
When I conduct a mobile pentest, I have run into payload encryption in HTTP traffic. In general, the AES key and IV ( initialization vector) are located in APK, and can be used to encrypt the payload ...
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Why are there so many different encryption algorithms?
Taking a quick look at Wikipedia, there happens to be a vast amount of different encryptions/cryptographic algorithms. Yet, many of the listings show that these encryption methods are not in use today ...
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How to secure hundreds of AES keys
I need to store a large amount of AES keys and provide an API to decrypt user-provided ciphertext.
The application flow is as follows:
The user authenticates
The user makes a POST request with some ...
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Key Hash With Securely-Optimal Setting : For Encryption vs For Password
Do you have to make a key hash with securely-optimum setting (eg. 100MB memlimit, 3 opslimit) for encryption ?
So I'm making a text encryption function with javascript, using XChaCha20-Poly1305 and ...
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Which algorithm does CryptGenRandom use on my laptop?
I have an Ideapad Gaming laptop by Lenovo, with an Intel(R) Core(TM) i5-10300H processor. On this laptop I have Windows 10 installed. To generate random numbers, I use the CryptGenRandom function. ...
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Passing user identity to a different REST service
I have two use-cases I am trying to solve.
A HTTP Service-A hosted on XYZ domain tries to access HTTP Service-B on ABC domain. Service-B is a stateless HTTP API which does not have user concept. ...
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Is backing up the seed used to generate an RSA key pair a secure practice?
Assume I wanted to generate an RSA key pair, and create a backup of it. It is possible to back up the randomness source used to generate the keypair instead of the keypair itself and still recover the ...
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How to decrypt ECDSA_secp256k1 private key from PEM format generated with OpenSSL
I'm trying to decrypt an encrypted ECDSA_secp256k1 private key generated using the OpenSSL CLI command openssl ecparam -genkey -name secp256k1 | openssl ec -aes-128-cbc -out ecdsa_priv.pem but I want ...
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SymmetricKey vs SecRandomCopyBytes
Can SymmetricKey be used as substitute for SecRandomCopyBytes? I found this code snippet in WWDC19 video
var key = Array(repeating: 0, count: 32)
let err = SecRandomCopyBytes(kSecRandomDefault, ...
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Why AES256 with SHA384 in TLS [closed]
Is there any concrete/solid rationale for this choice of cipher? Seems to be the default when I connect via TLS1.2 to an Apache2 server (whatever latest version on Debian 11) with configuration lines ...
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What is the point of the “AES Key Wrap” algorithm?
What is the point of the “AES Key Wrap” algorithm prescribed for use with CMS-like contexts in IETF RFC 3394?
Just look at the algorithm (tacked on to the end of this post), informally, it smells a ...
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Is there any good way of calculating a brain-generated password's entropy?
After reading this post, I understand that a password's entropy depends on the assumptions made when it is to be attacked (e.g. if it is generated randomly from a list of 2048 words, etc.).
Let's ...
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What are the ranges of values for DH parameter a and DH parameter b [closed]
I have discovered that Diffie Hellman(DH)shared key is unequal in Apple Numbers, Google Sheets, and Mac Excel (2008).
In Section 1.0, the first try at a solution uses a small Prime to produce certain ...
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What's the shortest message you need to claim ownership of another message?
Hypothetically, I'd like to demonstrate that I am the owner of a piece of published information. The requirements are the following.
The hash/ characteristic string is compact enough (ideally a few ...
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Does openssl3.1 support UEFI target with FIPS enabled?
I am trying to build openssl 3.1 in FIPS mode for the UEFI target. But the config option enable-fips as defined in the documentation does not define the flag FIPS_MODULE for UEFI targets. Also, I ...
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Is it possible to generate a file with a given sha256sum checksum?
Is it possible to generate a file with a given sha256sum checksum?
That is, reverse the process of a sha256sum checksum. That is, if we have a checksum, can we generate txt file data (need not be ...
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Are there any downsides to publically available encrypted data?
I have a key-value database that uses asymmetric RSA-OAEP encryption to encrypt the data. The data is stored in tuples of (public key, encrypted data). The user identifies their data by the public key,...
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Is using weak random numbers for the initialization vector of AES just a theoretical issue?
I'm the maintainer of pypdf, a Python library for reading/manipulating PDF documents. I recently discovered that pypdf used random instead of secrets for ...
Generating the initialization vector (IV) ...
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Java Cryptography classes - program agnostic usage
We are planning on implementing encryption or digital signatures using any of the available classes provided by the Java Cryptography Architecture (e.g. KeyPair, MessageDigest, Cipher, KeyStore, ...
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How to find the correspond hash algorithm? [duplicate]
I'm currently working on a project. but i still facing some issue due to some crypted data. i know the plaintext and got the correspond hash.
plaintext: C018AE45B37DAE665486F4151E0C1E6F
Hash: rROkd+...
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eSIM/eUICC relay attacks
I'm trying to understand how the eSIM is protected against cloning. Here is the diagram from GSMA standard:
Now the ICT operator has its own security domain in which all the GSM related keys ...
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Is SRP/PAKE equivalent to an asymmetric crypto challenge?
As an amateur cryptographer and professional slowpoke, I just learned about SRP (and other PAKE protocols), and my thoughts immediately wandered to asymmetric crypto challenge protocols, like WebAuthn(...
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Decrypting a Base64 ciphertext [duplicate]
I am working on a challenge that includes decrypting a piece of ciphertext. The sample decryption provided is as follows:
...
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Encrypted semantic search
I want to implement semantic search but in an encrypted fashion.
For storing passwords, we store Enc(password) in a database, and when a user logs in, we check if Enc(query) == entry in the database.
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Using a Client and Server secret to double salt a hash
I want to log IP addresses visiting my site, for aggregated statistics only and to see if the same IP address has visited twice. But I don't want to expose them.
My Idea is in my database.
$...
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Cryptographic primitive for delegating authority to another pubkey recursively
Is there a cryptographic primitive that allows pubkeys to delegate authority to each other without preserving the whole chain?
I'm considering an authorization scheme where all authentication is based ...
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How to achieve an authentication method FIPS 140-3?
I've been studying the FIPS 140-3 but I still have questions about how to determine if an authentication protocol is FIPS compliant or not:
1- Is RADIUS over EAP-TLS FIPS 140 compliant? I know that ...
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How to use (py)NaCl/libsodium for key wrap, key encapsulation
We want to wrap / encapsulate
a symmetric key with an asymmetric keypair,
a symmetric key with a symmetric key,
a private key with a symmetric key.
In each case, we'd like to allow several keys to ...
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Hashing a secret key with a random string to generate a new key
Lets say Alice and Bob have a secret key k1. This key is 50 chars long and is cryptographically random. Alice generates a cryptographically random string (e.g. 16 chars long) and hashes this string ...
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Question regarding DH/RSA/Public key cryptography [closed]
Courses giving introduction to cryptography often refer to an example where Alice and Bob need to communicate through an evil postman, and dispose each of a lock, its key and a box in which to send ...
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Does the ssh client compute the public key from the private key?
If I use ssh like this ssh -i id_rsa it means im passing the private key to ssh. Does ssh now then compute the public key from it and then send it to the server? Then the server would look if the ...
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Client side encryption for a user with multiple devices
I am currently developing an app that sends the data encrypted to a server, because the important thing with the app is that the server should never know what data is there, only the client should ...
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Can parts of WebCrypto AES-GCM be reused between encryptions
I am trying to better understand the processes involved in e2ee using WebCrypto on the browser.
I understand that the only real method to use a passphrase to generate a symmetric key on the browser is ...
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Why should I re-generate a server's SSH host keys?
This server hardening guide suggests re-generating the RSA and ED25519 host keys. What is the advantage of re-generating the default key?
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Why should I disable insecure SSH hostkeys if I never plan on using them?
A number of articles suggest removing insecure (broken) SSH key types in order to have a more secure server. In practice, if I only connect to the server with secure key types, why should I bother ...
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Is it possible to retrieve seed from a few random numbers?
Let's say I have generated 16 integers (between 0 and 128) using Python
from random import seed, randint
seed(1234)
randoms = [randint(0, 128) for _ in range(0, 16)]
If we have a rough knowledge of ...
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Can secret recipients be included in PGP cryptography
Can we be sure that a cleartext message that becomes encrypted by pgp or openpgp which is intended for one-or-more specific recipients doesn't also get secretly decipherable by a third party? Since i ...
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