Questions tagged [pbkdf-2]
The Password-Based Key Derivation Function 2 (PBKDF2) is a method of securely deriving encryption keys from a passphrase entered by a user. It features an iteration count that can be deliberately adjusted (key stretching) to slow down brute force password guessing attacks.
218
questions
0
votes
0answers
25 views
Using pin code as a lockscreen for a mobile application
So I am developing an iOS & Android Application where a lock screen is used for authenticate a user.
There are 4 options to unlock the screen: Password, biometric, pin code and nothing.
I wanted ...
1
vote
0answers
41 views
E2E Encryption w/ PBKDF2 + AES-GCM
I'm currently developing a product that requires user data to be encrypted on the client side.
The product is a web app + a browser extension, so the focus is encrypting user data with Javascript. The ...
0
votes
1answer
140 views
Best practise for encryption in a password manager
I'm trying to make a password manager for Windows installed computers, and after researching the best ways to encrypt the passwords in the database (I'm new to cryptography) I think I've come up with ...
1
vote
2answers
66 views
Static salt for PBKDF2, but unique salt for HKDF?
Hypothetical. Lets say you have an application where you generate a master key from a user password using PBKDF2 (static salt) and then use the master key to derive two passwords keys for an encrypt-...
3
votes
1answer
61 views
Is PBKDF2 with 1 iteration acceptable for a simple random key expansion?
I have a 128 bit randomly generated key. I need to expand this key to 512 bits to use with an existing encryption library that does AES-256 encryption in CBC mode with HMAC-SHA256 authentication.
The ...
2
votes
1answer
44 views
PBKDF2-HMAC Collisions
Trying to understand the well known property of these collisions when used with SHA1, SHA256, etc. where a given key is larger than the block size of the digest function. In these cases the smaller of ...
2
votes
1answer
60 views
Random salt and PBKDF2 key
Suppose I wrote a function $$(salt,IV ) = \text{keyIVGenerator}(passwd)$$ which generates a random salt of size 32-bytes and a random Initialisation Vector (IV) of size 16-bytes. Then, use a Key ...
3
votes
1answer
65 views
Why does PBKDF2 use HMAC?
When I learn PBKDF2, I found out most of the articles say that the PBKDF2 use HMAC as PRF. Why is HMAC? Can I use other pseudorandom functions? Is HMAC safer than any other functions for PBKDF2?
1
vote
1answer
40 views
Issue with decrypting self-coded AES
Summary: As a trainee, I got the task to extract encrypted passwords of our external password manager (Zoho Vault) and decrypt them. The documentation regarding how to decrpyt them is...none. I ask ...
0
votes
0answers
57 views
Client-Side Encryption for a small app
I'm designing a small personal journal web application for my wife. I'm a crypto newb, but I want her to feel secure knowing only she will have access to her journal entries. I am thinking of the ...
2
votes
1answer
63 views
Generate AES key from weak string
I'm trying to generate AES256 key from user input password.
The size of the password can be anything from 4 bytes long to 32 bytes long but let's assume
it is the smaller one.
My API support either : ...
2
votes
1answer
34 views
What are the randomness requirements for inputs to PBKDF2?
I need to generate one 160-bit HMAC-SHA1 key for each user in my system. Can I use the username as the input to PBKDF2 function to generate the key?
Is it safe to use known values like username as ...
2
votes
0answers
57 views
Content Key Encryption for Multi-User data access
I recently worked out a concept for a use-case, but I'm not sure if my approach is good enough.
So I would appreciate feedback and things to look out for, as I'm fairly new to this field.
A User can ...
-1
votes
1answer
73 views
Are there issues in how cryptography is used in this short code sample?
I want to encrypt some small text files so I can put them online, in non-restricted access (not the best idea, but it's cheap and simple). I know I should use something like Truecrypt instead of this, ...
1
vote
0answers
29 views
AES implementation for non-password multi-document decryption usecase
I am trying to encrypt/decrypt multiple user documents (consider text) in an application. Unlike the use case of passwords where decryption happens once during an API call, in this application during ...
5
votes
1answer
462 views
Is it necessary to stretch/derive an AES key when I already have enough bytes from a 'cryptographically secure RNG'?
I'm using AES-CBC-256 with PKCS#7 compatible padding. I already have 32 bytes that come from a 'cryptographically secure random number generator'. In this scenario, does it make sense to use PBKDF2 to ...
1
vote
2answers
335 views
Meaning of the term “Key Material”
I am reading specifications from my client that focuses on the topic of security. In these specs, the term key material has appeared many times.
I used Google to look for what the term means. ...
0
votes
2answers
108 views
KDF and salt storage
Regardless of the KDF I will use, let's imagine that I have to generate two keys: one for authentication and the other for encryption (which will always remain on the device that generates it until ...
1
vote
1answer
142 views
Are there cryptographical flaws in this e2ee website chat widget?
For a product I'm developing I want to verify if the thinking behind it is cryptographically strong and secure. The product is a chat widget on websites of customers. Like an e2ee version of Intercom.
...
0
votes
1answer
121 views
Security of using constant salt when saving encrypted data to database
Let's say that I want to save some encrypted data to a database through a Spring Boot microservice. For that I will be using Spring Security Crypto that, as the documentation says it uses AES256 with ...
1
vote
2answers
153 views
Safest alternative for hashing credit card numbers to use the hash as fingerprint?
Same question asked here in 2014 but since a lot has changed since then, I would like to get feedback from experts on the latest best practices.
The problem
Our requirement is to provide the ...
5
votes
1answer
96 views
Line by line encrypted logging stored with iv/salt/iterations. How safe is it?
I'm building an encrypted logging application. Log entries are encrypted with AES-256-GCM, using password-derived keys with PBKDF2.
The application must support log rotation, and I would like to make ...
1
vote
1answer
369 views
AES PKCS5 Padding when it's not needed
I'm using AES/ECB with PKCS5 Padding (From what I've read, PKCS7 Padding is actually used internally) and PBKDF2(HMAC-SHA256) to encrypt some passwords in Java. I enter a password, that goes through ...
0
votes
1answer
169 views
is PBKDF2 reversible?
Given an AES key that is wrapped using another AES key, the second one being generated using PBKDF2, and given that I know the wrapped key: can I derive the passphrase that went into the PBKDF2? (...
1
vote
1answer
57 views
can I use PBKDF2 instead of hmac as a hashing tool for sensitive data
I have read about hmac and PBKDF2.
PBKDF2 - is mainly used for password hashing. It uses ...
1
vote
1answer
498 views
Argon2 or scrypt instead of PBKDF2 with AES
Is using scrypt or argon2 a better key stretching technique with AES compared to PBKDF2 or bcrypt with regards to
a quantum computer brute force attack. The brute force attack I'm referring to is ...
0
votes
0answers
48 views
What's the use of HMAC in PBKDF2? [duplicate]
As far as I know, PBKDF2 uses an underlying pseudorandom function in order to generate a hash (like SHA256) so as far I understood PBKDF2 is basically a hash function that uses an underlying function ...
1
vote
1answer
555 views
Why use PBKDF2 over SHA-512 to derive AES encryption key? [duplicate]
Suppose I am using user passwords to derive AES-128-CBC encryption key. This key will be used to encrypt some sensitive data for the user so that even the website owner / operator can not decrypt it.
...
1
vote
2answers
258 views
PBKDF2 with SHA-256/512 for low entropy input?
Is there any reason to use something stronger than SHA-1 with PBKDF2 if my input is fairly low entropy? I.e. if the passwords being hashed are only about 30-bits of entropy.
I can't find it now, ...
3
votes
1answer
348 views
Why does LastPass use exactly 100100 PBKDF2 rounds
LastPass encryption scheme is recently changed to use more PBKDF2 rounds, specifically 100100. This seems like a really weird number choose. From what I understand brute force time scales linearly ...
2
votes
2answers
159 views
What is the purpose of salting when integrating PBKDF2 with AES?
I'm a bit new to cryptography and I'm trying to wrap my head around PBKDF2 and AES. As a disclaimer, this is not going to be used in an actual application, I'm just testing things locally as a fun ...
2
votes
2answers
641 views
using different IV and SALT with AES-CBC but same KEY
I'm working on this project where a client can send a message, now obviously sending it in plainText is not very smart. So I decided to Encrypt it with AES-CBC.
Now, each time I encrypt something, ...
2
votes
1answer
63 views
What value for a Rfc2898 (PKBDF2) is overkill?
I am working on a project which needs to share messages, and part of that project is deriving a password, I am currently using a value of 65537, totally arbitrary (...
5
votes
2answers
1k views
Why cryptsetup default KDF is PBKDF2 and not Argon2(id)?
I plan to do a clean install of ArchLinux with Full Disk Encryption (with LUKS) but I'm not sure to understand the default KDF choice (PBKDF2+SHA-256).
I didn't manage to find any pieces of evidence ...
2
votes
0answers
51 views
Is there any difference in security between S2K and PBKDF2?
S2K is a KDF designed for the OpenPGP standard which concatenates a password and salt and feeds this, repeating, into a hash function for a configurable number of bytes. PBKDF2 is a KDF which uses a ...
4
votes
3answers
991 views
Should we run PBKDF2 for every plaintext to be protected or should we run PBKDF2 only once?
I am going to store secrets from users. The secrets need to be stored confidentially. For this question, I am concerned only with confidentiality (not integrity).
Here is how my encryption scheme is:
...
1
vote
4answers
1k views
How is PBKDF2 so much better than normal Hashing or even using HMAC
I do not know how the Key Length extension attack works. So if we leave that aside for once, and say just about usual brute-force attack on the hash, I don't really know how is PBKDF2 so much better ...
0
votes
0answers
38 views
What is used as a KEY and MESSAGE when using HMAC within a PBKDF2? [duplicate]
I was studying WPA2 and it's security when I came across this problem. I know that WPA2 uses PBKDF2 to generate a Pairwise Master Key. It does something like this;
...
1
vote
1answer
210 views
Can you derive a 128 bit AES encryption key using PBKDF2 with SHA-256
I got confused about key derivation functions. For my project, I need to derive a 128 bits AES encryption key in CTR mode. To do so, I'm using a PBKDF2 to derive this encryption key using an initial ...
2
votes
3answers
117 views
“Work factor” and “iteration count” nomenclature in adaptive functions
In adaptive functions like PBKDF2 / bcrypt I often read people refer to "iteration count" and others refer to "work factor", and they seem to be used interchangeably (even though they're not - the ...
-1
votes
2answers
2k views
How to validate a PBKDF2 password
I want to encrypt several files correctly with a PBKDF2 generated key (using a password and salt), I am currently doing so but if I enter the wrong password, as expected an exception occurs.
Note: ...
1
vote
1answer
97 views
One way hash of data records (PBKDF2?)
I'm looking for a way of one way hash data for multiple records. We have a privacy requirement to anonymise information "after it's used for its intended purpose" which is a little wooly at best.
I'd ...
6
votes
1answer
767 views
Why derive keys from a master key instead of generating random keys?
I noticed AWS KMS generates encryption keys based off of a master key, using a key derivation function (HKDF).
What's the practical advantage of deriving keys based on a master key? Isn't it simpler ...
4
votes
1answer
241 views
Using a KDF (PBKDF2) properly
I am new to crypto.
I have a password for my user, e.g. &&38:while:HAVE:havana:60&&
I want to encrypt several documents with 10 pages each with AES....
3
votes
1answer
471 views
Is it safe to split the output of PBKDF2?
I would like to know if splitting a key generated by PBKDF2 to derive two keys is a safe practice.
Concretely, in my system, I need to derive two keys. One for symmetric cipher used in the client ...
2
votes
3answers
233 views
Deriving a key from a pseudo-random string
I would like to know if deriving a key from a pseudo-random string with a single iteration is secure.
Concretely, I am designing a system where a secret key is derived in the client side, and then ...
1
vote
1answer
223 views
How to make my hash more robust to the brute force?
I'm using PBKDF2 SHA 256 with 100 000 iterations to generate a secret.
I want to increase the cost of brute forcing the passphrase I use to generate the secret.
I'm thinking of using scrypt after ...
3
votes
1answer
177 views
What is the most secure way to check that a given masterkey is valid?
For the purposes of learning, I'm writing a small utility that allows encrypting a list of passwords using a single master key (using AES-256 and PBKDF2)
Before encrypting or decrypting any password ...
-1
votes
1answer
123 views
How many bits should I request from PBKDF2 to create a strong password?
I'm building a tool which generates passwords by hashing a service name with a master key. PBKDF2 was primarily chosen due to availability in the Web Crypto API.
What would be a secure value for the ...
3
votes
2answers
679 views
KDF Salt: How/When is it Okay for it to be public?
Post Structure:
Prior source material studied
Question & Details
Assumed threat model
Example
Assumptions
Clarifications
Prior source material studied
0.1. RFC 2898
0.2. HAC (Handbook of ...
