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Questions tagged [kdf]

A key derivation function (KDF) is a function used to derive an encryption key from a password.

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Deriving 2 keys from user password - one for login - one for encryption? [duplicate]

Context We have a browser-based client-server application. The client registers with email and password. The password is enforced to some guidelines. Problem The User needs an encrypted vault on ...
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2answers
216 views

How to choose between password derivation or encryption?

Suppose you use a password manager having all possible features of modern password managers: encryption with a key derived from your master password, auto-filling, cloud or local storage, browser ...
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1answer
138 views

When would one use a password hash instead of a KDF?

From what I'm reading, for storing passwords it is recommended to use a KDF (like Bcrypt). If it is more secure to use a KDF for handling passwords, when would you use a password hash instead?
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1answer
55 views

How to find default S2K parameters in GPG

How can I find the default string-to-key parameters in GPG? I am using it in Tails.
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1answer
63 views

How can I find the default KDF for my version of GPG?

I am trying to find the default KDF for my version of gpg: gpg (GnuPG) 2.2.6 libgcrypt 1.8.2 Does anyone know how?
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1answer
1k views

Why brute-force the password instead of the key directly?

This answer on another question on security stackexchange by a very reputed user explains why he prefers GnuPG over OpenSSL for file encryption. From what I understand, it can be summarized as this: ...
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How to tune a KDF algorithm to protect a private key?

I need to protect a private key RSA-4096 with a key derived by a KDF algorithm. Instead of hiding any aspect of the algorithm I would like to tune it such that the key derivation is a proof of work ...
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1answer
668 views

ECDH vs DH secret key size

In the past couple of weeks I have been reading about DH and ECDH which are key exchanging algorithm to compute a shared secret key. According to advices, it is better to use DH with key size 2048 ...
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1answer
155 views

Encryption for a system supporting only basic cryptographic functions [closed]

I am working on an encryption method between a server and multiple clients. The client hardware only supports basic encryption algorithms (Currently Aes 128-bits and HmacSha1). The hardware is too ...
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1answer
938 views

Differences between LUKS and Veracrypt

These two FDE solutions are similar, but I noticed different executions speed: specially mounting a device it seems that Veracrypt takes more time decrypting it. So I would like to compare it with ...
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0answers
54 views

Password manager that uses a mix of long and short key derivation functions [duplicate]

I was reading "A Convenient Method for Securely Managing Passwords, Halderman et al., 2005". In short, the authors say to do the following: cache = very_long_key_derivation_function(salt,...
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3answers
237 views

Encrypt Items With Single Key or Use KDF+Salt To Encrypt Each Item?

I'm currently planning the development of a system where extremely sensitive information for individual users would be stored. There are currently two approaches being discussed. In order to make it ...
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1answer
263 views

Why is the Key Derivation Function important?

Let's consider this openssl command : openssl enc -aes-256-cbc -pass pass:PASSWORD Why is it important to have a good Key Derivation Function? This answer to another question suggest that GnuPG is ...
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1answer
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One Input Two Hashes

Suppose I have some password x, and two different hash functions h1 and h2. I can then compute the hash y1 = h1(x) and y2 = h2(x). Is there any sort of vulnerability in this case? More specifically, ...
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2answers
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Is KeePass's method for key derivation secure?

I'm familiar with how key derivation functions can be used to slow down brute force attacks against passwords by requiring significant computational and/or memory resources to compute the final key. ...
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1answer
178 views

Is there any problem using empty salts with PBDKF for this purpose?

The aim is to generate a secure key for symmetric encryption. I have a master password, from which I want to generate the key for symmetric encryption, in order to encrypt other passwords. The idea ...
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1answer
3k views

What is the difference between Key Derivation Function and (salted) Hash?

I see in this post that the main difference is that KDF outputs have "certain randomness properties", and I don't understand what does it mean. Suposing that that "certain randomness properties" are ...
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2answers
218 views

Is it okay if passphrases to KDFs are “predictable”

I'm looking to do file encryption for small amounts of text (8-100 characters for each item being encrypted). Here's what I have: A secret passphrase and a salt. I Use Rijndael to generate a key and ...
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199 views

Understanding the application of hashes, HMACs, and KDFs

I think that I understand the right application cases for the following crypto functions, but I'd like to confirm my understanding and also propagate the safe use of crypto throughout the intertubes. ...