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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139 views

Device authentication, common method

My question is: What are some standard device authentication methods, in a scenario when: The desktop computer is being authenticated on web service I provide the .exe on the desktop I control the ...
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How Digital Certificate is bound to a perticular identity?

I'm trying to understand the following: Lets say Alice wants to encrypt a message with the public key of bob. There can be a man-in-the-middle attack who impersonates bob. So we uses digital ...
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127 views

RFC 5755 Attribute Certificate Validation

According to this explanation: Manually walking through the signature validation of a certificate I'd like to know how is the validation process of an RFC 5755 attribute certificates, because it ...
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1answer
78 views

Is it bad practice to reuse private EC key as a shared secret for a symmetric algorithm?

The encrypted text is public, embedded in the binary of my software which is published on the internets. I know the open text but there’s large circle of third parties who might know it too, despite ...
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determine type of encoding/encryption [duplicate]

Is there a way to find out what type of encryption is being used on this data? I was playing around with a game data and i cant get around it . This Is the data im trying to decrypt, any help? Code: ...
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Wondering what “v” is, in SJCL Library encryption output

SureSure = sjcl.encrypt("password", GetUserInputSTUFF, { adata: "{4687f36d-99d4-4223-ae53-46041297bef5}sbDU9DHzf0v3doe7aouZjEbW92750001489303Ktqr" }); Output: {"iv":"a6J6pjHFos2HOIghbEkGLw==","v"...
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Do any security experts recommend bcrypt for password storage?

On the surface bcrypt, an 11 year old security algorithm designed for hashing passwords by Niels Provos and David Mazieres, which is based on the initialization function used in the NIST approved ...
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1answer
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PBKDF2 doesn't seem to have a standardised implementation?

I recently read about the bug in Django with regards to PBKDF2 causing Denial of Service with large passwords: https://www.djangoproject.com/weblog/2013/sep/15/security/ This is because PBKDF2 "...
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What's on Applied Cryptography? [closed]

Just wondering what is the story behind the front cover image of Schneier's Applied Cryptography book https://www.schneier.com/books/applied_cryptography/ Who is the author? Is it some famous picture ...
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What are the steps of hashing and steps of verifying password using salt and key? [duplicate]

What are the steps of hashing password during registration and login to an application using salt and key? Are the following steps considered correct if applied to an application?: 1- During ...
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689 views

Lightweight block ciphers definition

I've read in many papers something that looks an specialisation of the block ciphers calling them with a lightweight tag, but I couldn't found a definition. If I understand correctly, those ...
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Whats the difference between MAC vs hash

What is the difference between the two algorithms? One difference that I know of, is that MAC is keyed and hash is not.
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1answer
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How to store a user's password in a database in 2019? [duplicate]

This question, but focused on .NET's given PBKDF2 implementation, has been asked here now. Situation I am currently updating a password storage mechanism for a website. My plan for storing a ...
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The reason of using XOR operation in cryptographic algorithms

I notice that some cryptographic algorithms involve using XOR operation with the key (Even AES uses XOR to derive the round keys). My question is why specifically XOR? How about OR or NAND or some ...
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Generate DEK from password using hashing on client-side

Important to know Will not be passing the DEK from client to the server The DEK will be used to encrypt all the data being placed within a github repository, it is possible that cipher-text will be ...
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A site supports Public key length of 256 bits while best practice is 1024+ - what does this mean?

Given that this is asymmetric cryptography with private/public key, I am not sure if reduced bit length is breakable easier than longer keys. I understand that the key population is reduced (hence ...
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Can anyone give feedback on this encryption program? [closed]

I am 14 years old and I have just created an encryption program with a friend. I wanted to know if anyone here could give me back any feedback on it. Here is how the program works, Imagine you want ...
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Outcome of Needham-Schroeder protocol

I am studying Needham-Schroeder protocol in my course subject and I understood it well, but there is a homework problem which is asking, "what is the outcome of Needham-Schroeder protocol?" ...
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3answers
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Use RSA key to encrypt/decrypt personal document

Suppose I have generated a public/private RSA4096 keypair using GPG. Is it secure to use this keypair to encrypt/decrypt documents solely for personal use, i.e., have an encrypted backup of some very ...
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OS with encrypted RAM?

Are there any applications, JIT frameworks or operating systems that focus on encrypted virtual memory, or perhaps virtual machines that do something similar? I know there are processors (albeit old, ...
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TDE - Does Key Rotation involve full tablespace Decryption and Re-Encryption?

In Oracle DB 12c, which uses TDE-Tablespace level. If i want to implement key rotation policy, what is the impact? 1. Is it the Tablespace key that will be rotated or the Masterkey? 2. Does key ...
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1answer
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WEP cracking - Why does many IVs allow to actually get the cipher key [duplicate]

I've been reading a lot about WEP cracking on online resources very recently, however there is one question that no website gives answer to I believe. I would like to first understand the theory very ...
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Is there any functional distributed timestamp server available? If not what about this homebrew solution?

Objective A secure Arrow of Time with unpredictable future behaviour to stop attackers or DDoS BotNets from pre-calculating proof-of-work and other gateway protections for P2P/F2F. A distributed ...
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How long shall a password be to resist a botnet brute force? [duplicate]

Imagine that I'm an evil genius, and I had the brilliant idea of creating a botnet for brute forcing passwords. Or I'm just the owner of the Echelon, and I have a farm of distributed servers around ...
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DTLS CertificateVerify doubt

In DTLS 1.2 RFC 6347, section 4.2.6: CertificateVerify and Finished messages have the same format as in TLS. Hash calculations include entire handshake messages, including DTLS-specific fields: ...
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How applications are installed in TEE and REE

I am trying to understand the difference between the TEE (Trusted Execution Environment) and REE (Rich Execution Environment) in an electronic component. I understand that for security reasons, there ...
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57 views

Password authentication using a master key and KDF without storing password

I want to make a service stateless(has no data to store or mantain). But the service shoule be able to authenticate user. What I'm considering is using key derivation function with a shared master ...
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5answers
211 views

Can I use a cryptographic hash function to prove my authorship of an anonymous article?

From what I understand, hash functions are one-way functions. Let's say that I want to publish an opinion article anonymously, but there is a possibility that I later want to prove that I was the one ...
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1answer
77 views

Authentication without sending password over network

I was reading this question about ssh authentication and there's a good discussion about authentication schemes. First, there's the answer that yes, ssh sends the full password to the server (but ...
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1answer
164 views

What does this Bruce Schneier fact mean?

I came across a website called Bruce Schneier Facts, a parody along the lines of Chuck Norris facts, and saw the following fact: Schneier knows if Reiser did it. What does it mean?
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Generate CSR and private key with password with OpenSSL

I am using the following command in order to generate a CSR together with a private key by using OpenSSL: openssl req -new -subj "/CN=sample.myhost.com" -out newcsr.csr -nodes -sha512 -newkey rsa:...
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Encrypt Different Users with unique keys

I have a database that I want to implement an encryption per x amount of users. Say I have 1000 Users in the database and I wanted every 1000 encrypted differently then I would generate a new key and ...
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3answers
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Can the username be used in HMAC during client-side hashing?

I am very new to authentication and cybersecurity in general, so I apologize if I have anything completely wrong. My goal is to have the client side hash passwords before sending them to server side ...
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Why should one not use the same asymmetric key for encryption as they do for signing?

In an answer to a question about RSA and PGP, PulpSpy noted this: It is possible to generate an RSA key pair using GPG (for both encryption and signing -- you should not use the same key for both). ...
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2answers
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Server-side encryption mechanism (Nextcloud)

I've been looking around how server-side encryption works. Thanks to the nextcloud doc I understand the implementation. Basically, when you first log in a key pair is created, and the private key ...
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Does Windows CNG Keystore support exporting a key or keypair in ciphertext?

As Windows CNG Keystorage offers API to export key(pair)s: SECURITY_STATUS NCryptExportKey( /* The handle of the key(pair) to export */ NCRYPT_KEY_HANDLE hKey, /* The handle of a key to encrypt ...
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How to obtain body from RSA signed document without verifying signature?

According to my understanding of computational cryptology, the body of a signed document can be retrieved disregarding whether or not the signature is authentic. However, I cannot apply this ...
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2answers
783 views

Brute force algorithm to break symmetric key. How to find the program when current key is the correct one?

In a brute force program, sequential keys are tested against the public key in order to find the correspondent private key. My question is, how is the test done with each key that let you conclude ...
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1answer
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Why rijndael.key value is different with rijndael.iv?

someone can tell me how rijndael works? for now i need to handle key and iv generated from C# (using rijndael + rfc2898derivebytes) to match with CryptoJS code snippet of C#: byte[] saltArray = ...
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I found this easter egg, any ideas what kind of encryption it is? [duplicate]

I am looking to have the cryptography identified of this encrypted message aHR0cHM6Ly9nb28uZ2wvZXY5SDN1 Any ideas what crypto was used here? Thank you
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2answers
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Can JavaScript from different origins communicate securely

I want to know if there is a way for JS from one Origin to delegate a task to JS from another origin in a secure way. The use case is to have a JS Agent from the users' home origin use the ...
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1answer
95 views

SSH Public Key / Host Key - Can Client Request Key Length?

In SSH, does the client have any power in determining the key size of the host key, or is it completely dependent on what the servers host key is? For instance, say the client and server agree on ...
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How to encrypt using a private key file generated by OpenSSL?

When I use openssl genrsa -out yourdomain.key 2048 command to generate a key. I understand the yourdomain.key file contains both the private and public keys. But when I check the content of this key ...
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1answer
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Is there a name for this (unconventional?) use of RSA for authentication?

I am writing an article about a late-1980s system that uses the RSA algorithm for the purpose of authentication. However, rather than the usual approach of encrypting a hash of the message using a ...
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2answers
638 views

Convert ECDSA keys (PEM, OpenSSH)

To work with ECDSA keys I am using the python-ecdsa library. Unfortunately this library can not process keyfiles properly if they are provided in the OpenSSH format. Instead I generate them in the PEM ...
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Does Thunderbird Enigmail plugin decrypt attached files?

From my research I have found out that you can easily send encrypted messages to one another using Enigmail. If first I encrypted a file,then attached it to an email, sending it through Enigmail to a ...
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How were Cryptographic nonces used in the Yahoo! data breach?

How does an attacker use Cryptographic nonces to generate access cookies through a script on a server? As what happened to Yahoo! servers.
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1answer
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RSA key size in TLS ciphersuite with RSA key exchange

I'm using the TLS cipher suite TLS_RSA_WITH_AES_256_CBC_SHA56. The Public Key of the Server's Certificate is RSA (2048 Bits) I understand that the RSA algorithm is used here for for key exchange, as ...
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2answers
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technical difference between TLS and a certificate [duplicate]

I don't quite understand what the difference is between TLS and a certificate. TLS secures the transmission by encrypting the data. So normally no man in the middle attack is possible and nobody else ...
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2answers
269 views

ECDHE_RSA_WITH_AES_128_GCM_SHA256 - How to determine ECDHE Key Length?

Server: SSL Certificate, 2048-bit RSA Public Key, Signature Algorithm is sha256RSA What am I missing here? ! I've scoured the RFC's, and I have yet to find anything on how to determine the ECDHE key ...

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