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).

Filter by
Sorted by
Tagged with
608
votes
5answers
250k views

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 ...
0
votes
0answers
4 views

Digitally Signing Messages using Multivariate Cryptography [migrated]

I have two questions concerning digital signatures using multivariate cryptography: Firstly, how are messages processed such that they can be digitally signed using multivariate crypto? Secondly, ...
2
votes
3answers
122 views

Do integrity and authentication always come together?

I cannot come up with a case where there is only one of them. When there is integrity, a random person cannot modify the message without being noticed. That is, an unauthenticated user cannot modify ...
4
votes
1answer
101 views

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 "...
2
votes
0answers
49 views

What's on Applied Cryptography? [on hold]

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 ...
0
votes
1answer
59 views

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 ...
3
votes
2answers
687 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 ...
30
votes
4answers
41k views

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.
1
vote
1answer
150 views

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 ...
9
votes
2answers
576 views

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 ...
0
votes
1answer
43 views

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 ...
5
votes
2answers
457 views

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 ...
0
votes
2answers
186 views

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 ...
1
vote
0answers
65 views

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?" ...
2
votes
3answers
115 views

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 ...
26
votes
5answers
14k views

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, ...
0
votes
0answers
12 views

What is linearization attack [migrated]

I know that In cryptography, the linearization attack is a method of cryptanalysis for block ciphers I am looking for an example of linearization attack couldn't find it online Could anyone ...
1
vote
1answer
363 views

BitLocker Recovery Key and Microsoft Account Password

I have a Windows 10 Pro machine; the administrator (and only) account is a Microsoft account. I am trying to set up BitLocker to ensure maximum security and safety, even from Microsoft. I understand ...
1
vote
0answers
37 views

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 ...
1
vote
1answer
66 views

WEP cracking - Why does many IVs allow to actually get the cipher key

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 ...
0
votes
1answer
34 views

How to encrypt user data in app using Google Sign-In

I am currently writing an application which needs to store user data encrypted in the database. One of the requirements is that some of the data stored in the database needs to be encrypted in a way ...
4
votes
1answer
2k views

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 ...
0
votes
1answer
53 views

Should i upgrade old volumes to new cryptsetup encyption mode?

old cryptsetup default is es-cbc-essiv:sha256. the new one is aes-xts-plain64:sha256. i don't know that much about cryptography but i assume the standard was changed for a reason. also there can be ...
1
vote
2answers
76 views

Secure API key mechanism for identification

In my web application, when the user logs in, a pair of JWT(JSON web tokens),access token and refresh token is sent with some fixed time validity. Using access token client is authenticated and using ...
0
votes
0answers
34 views

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 ...
8
votes
1answer
1k views

Identifying, analyzing, and predicting weak session cookies

To elaborate on this, I'm looking at this from the perspective of a hacker/penetration tester. Many times I have seen web applications that I know have weak cookies. I can tell this because I can ...
1
vote
0answers
93 views

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: ...
0
votes
1answer
58 views

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 ...
0
votes
0answers
56 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 ...
-1
votes
0answers
40 views

I want to decrypt some text but I'm not sure on it's algorithm and key [duplicate]

All I know about the following text is that it is supposed to be a list of first names: 226A1B26STjEpiMpLFb3AoipRApf6IzMfUo0Pm7F 6F8F09F4STjEpiMpLFZSQHfxhZYMUsH+n9qU0QNf ...
1
vote
5answers
182 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 ...
0
votes
1answer
63 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 ...
1
vote
1answer
151 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?
-1
votes
0answers
39 views

Penetration testing Padding oracle vs POODLE

I am doing pen-test according to https://www.owasp.org/images/1/19/OTGv4.pdf. I would like to ask you about Padding oracle attack. Is attack "POODLE" the same as Padding oracle in this document? On ...
10
votes
2answers
26k views

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:...
0
votes
0answers
102 views

Most efficient way to break md5? [migrated]

if you know the result of a hash, for this example the resulting hash is: ec664d1d65fd8a58c59b337b11c37a4d And you also know the hash has been made like this: const salt = "asdjbsdhal" const ...
0
votes
3answers
112 views

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 ...
0
votes
1answer
53 views

Risk of issuing a client-certificate for every user in application level

I'm currently working on a project that includes client-authorization using client certificates, where my app is the Certificate Authority. Doing that, every user that registers to my web server gets ...
0
votes
3answers
62 views

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 ...
99
votes
6answers
37k views

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). ...
0
votes
2answers
372 views

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 ...
0
votes
0answers
60 views

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 ...
0
votes
1answer
69 views

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 ...
3
votes
2answers
729 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 ...
0
votes
1answer
46 views

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 = ...
0
votes
0answers
39 views

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
0
votes
2answers
104 views

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 ...
2
votes
1answer
79 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 ...
8
votes
2answers
1k views

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 ...
2
votes
1answer
121 views

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 ...