Linked Questions

1
vote
1answer
51 views

Is it possible to narrow down the possible keys used for AES CBC encryption, knowing a given plaintext and its ciphertext, where IV=0? [duplicate]

I'm brute forcing a ciphertext with a given dictionary to figure out which key was used. However, it's been hinted at that there is a way to narrow down the dictionary to a smaller subset of ...
19
votes
1answer
6k views

Could we break MD5 entirely in the future?

Even of today MD5 is (sadly) still heavyly used in some applications. Even big tools like ApacheMD5. But even today there are more then enough MD5 hashes which are still not cracked. According to ...
8
votes
2answers
4k views

DES — Can I recover the key when I have both ciphertext and the plaintext?

Given a message and DES encrypted form of said message, is it possible to efficiently compute the key used to encrypt the data?
5
votes
2answers
5k views

Decrypting DES with decrypted and encrypted data [duplicate]

I got two 8-byte strings. One which is decrypted is: FF FF FF FF FF FF FF FF and one which is encrypted is: ...
4
votes
3answers
710 views

Generate 2 independent keys from a master key

The scenario is like this: I need 2 keys for different purposes (encryption + encryption, encryption + mac, or whatever). Because it is not good practice to reuse the same key, I'd like the 2 keys to ...
2
votes
3answers
2k views

When is a cipher considered broken?

We've all read how some people claim AES is broken because there was supposedly a way to get the plain text from a cipher text faster than brute-force. But is this the definition? Is a cipher broken ...
3
votes
1answer
3k views

AES-256 password cracking time

My question is kinda simple. I want to use AES-256 encryption to encrypt my backup. Using a password like this: ...
1
vote
3answers
661 views

How to deterministically generate a 256 bit ECC key from 128 bits of entropy without a CSPRNG

A safe way to generate a 256 bit ECC key from 128 bits of entropy is to use a CSPRNG, according to this answer: https://crypto.stackexchange.com/a/56551/43864 However, it's difficult to find a cross ...
0
votes
1answer
421 views

How to use cryptography to assure data integrity?

I only understand assurance of integrity using a hash function. How to use cryptograpy to assure data integrity?
3
votes
2answers
330 views

Using HKDF to derive symmetric keys from a hybrid public-key encryption scheme

RFC 5869 describes HMAC-based Extract-and-Expand Key Derivation Function (HKDF). In section 4, entitled "Applications of HKDF", it states that one of the intended uses is: derivation of symmetric ...
3
votes
2answers
388 views

What is special about an entropy count (RNDGETENTCNT) of 160 for libsodium initialization?

(Moved from StackOverflow) In the Usage documentation for libsodium, before calling the initialization function sodium_init, they suggest you check the entropy ...
2
votes
2answers
166 views

Mechanism of PBKDF in encryption key generation with passphrase

I want to roughly understand how the mechanism works of generating an encryption key from a passphrase, by which we encrypt a volume or file. I'm familiar with public key encryption, the concept of a ...
0
votes
0answers
97 views

Aes brute force when part of data known [duplicate]

I have buffer of 16 bytes that encrypt with AES 128 cbc with IV =000000......(all IV is 0) I have the encrypted buffer, and I know 7 bytes from 16 bytes before the encryption , I dont know the key . ...