Collaborate Disseminate
I have been looking into how Bitlocker performs key derivation[1][2] and apparently Bitlocker’s PBKDF stretches by performing 1048576 iterations of SHA-256 instead of HMAC-SHA-256 as it’s usually done in PBKDF2. Doesn’t that make Bitlocker… Continue reading Is Bitlocker’s KDF flawed/weak in 2025? [migrated]
Recently I was testing whether I could make 7-Zip archives more bruteforce-resistant. Both someone on Wikipedia and @kelalaka on this website make the following claim:
The 7z format supports encryption with the AES algorithm with a 256-bi… Continue reading Does 7-Zip really run multiple rounds of SHA-256 when key stretching?
It is not so difficult to create a password which is exactly 32 characters long.
In this question – AES-256 Key Length Importance @Marc writes:
you absolutely should not be using a password as the raw key
..and in this one @Filip_Franik … Continue reading AES-256 without key stretching
First of all, the understanding I have of the p parameter in scrypt is that it multiplies the amount of work to do, but in such a way that the additional workloads are independent from each other, and can be run in parallel. With the inter… Continue reading Why isn’t it more popular to increase the p (parallelization) parameter of scrypt?
This question already has an answer here:
How to securely hash passwords?
13 answers
Passwords are not stored in plain te… Continue reading Password Length and Key Length [duplicate]
Would using a 256-bit binary string, for e.g.
0000001100101011100101110101101000101000011001011010000111010100000011101100011111110010001000101010010010101101111100010011100111011100110110101001111001110110100011001010100110… Continue reading 256-bit Symmetric Keys As Passwords
Assume that we want to encrypt a file with gnupg using AES-256 as the encryption algorithm. (Hence, symmetric encryption.)
In this mode, gnupg requires a passphrase from the user. I understand that gnupg then derives from … Continue reading Length of a stretched gnupg passphrase that is comparable in strength to an unstretched string of 256 random bits
Ssh-keygen now supports a new key encryption format with -o, and configurable rounds of key stretching with -a. So I want to pick a -a that takes a chosen amount of time on my system.
But I don’t know how to measure how long… Continue reading What’s the easiest way to benchmark the decryption of my "new format" openssl private key?
Under Armour is getting kudos for disclosing breach within weeks, but concerns remain over an unknown portion of credentials reportedly stored using the weak SHA-1 hashing function. Continue reading Under Armour Reports Massive Breach of 150 Million MyFitnessPal Accounts
What are the drawbacks of using a trivially simple key stretching approach such as the below Python example, compared to something like PBKDF2? The purpose is to harden an AES-encrypted file against brute-forcing.
Are there … Continue reading Naive key stretching vs PBKDF2