Linked Questions

6
votes
2answers
2k views

Does having a known plaintext prefix weaken AES256? [duplicate]

I plan on storing data, encrypted with AES256, where the first dozen bytes are known plaintext. ('Hello World!' for example.) Does having this known plaintext prefix weaken AES256? I do not care ...
0
votes
2answers
348 views

Can an AES-256 key be generated for a large number of cribs? [duplicate]

I have a question in regards to Ransomware type viruses. I know that a number of these viruses use the AES-256 algorithm to encrypt user's files using a randomly generated key. I work in IT support ...
-1
votes
1answer
394 views

Can I decrypt messages encrypted with AES 128 knowing the cipher text and the plaintext? [duplicate]

I have access to a pair of plaintexts and their corresponding encrypted texts. Would I be able to decrypt a third message encrypted provided they use the same key? From my little understanding of ...
1
vote
1answer
89 views

Using beginning of TLS ecnrypted data to reveal secret [duplicate]

I have the following question about TLS security: Assume TLS-PSK protected HTTP with AES256-CBC cipher. When a TLS connection is established, client sends some encrypted data, where the plaintext is ...
-1
votes
1answer
61 views

GIven Unencrypted and encrypted data (AES-GCM) both, is it possible to calculate the Chiper key of AES-GCM [duplicate]

Sorry for a simple curiosity, Given Unencrypted and encrypted data (AES-GCM) both, is it possible to calculate the Chiper key of AES-GCM ?
1
vote
0answers
93 views

AES and Known-plaintext attack [duplicate]

Can you help me to finding some papers that shows AES is secure against known-plaintext attack?
193
votes
8answers
88k views

How much would it cost in U.S. dollars to brute force a 256 bit key in a year?

I am often told that any key can be broken and that it is only a matter of time and resources for any key to be broken. I know that this is technically true. However, I think that there is probably a ...
26
votes
4answers
47k views

What is the difference between known-plaintext attack and chosen-plaintext attack?

I am very confused between the concept of known-plaintext attack and chosen-plaintext attack. It seems to me that these two are the same thing, but it definitely is not. Can anyone explain to me how ...
4
votes
2answers
1k views

Determine AES key given encrypted and unencrypted files

Given an encrypted file, the original unencrypted (cleartext) file, and knowledge of which AES encryption algorithm was used, is it possible to determine the key that was used to encrypt the data in a ...
3
votes
2answers
1k views

How to defend AES against chosen-plaintext attack?

I have a server which encrypts files with the same AES key. Users can upload a file and download its encrypted version. A user can upload as many files as he wants. Users can decrypt the documents via ...
0
votes
1answer
2k views

Keeping the key and IV safe when AES256 encrypting publicly known data

I am encrypting some publicly known data, and some private data using the same key, using AES256 with CBC. An attacker does not have the ability to choose what the public data is. Is this safe? (It ...
5
votes
1answer
360 views

AES: Is it safe to encrypt same cleartext with same key but with million diferent IV?

The encryption mode that I am using is CBC. Algorithm is AES and the key size is 128bit. I will be encrypting a 36 byte string over 1.3 million times with the same key but with a random IV. My ...
0
votes
2answers
977 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: ...
0
votes
1answer
874 views

AES-256 example code encrypting multiple subsections of plaintext with the same initialization vector [closed]

I have been dabbling a bit into encryption in C++ using Brian Gladman's implementation found here: https://github.com/BrianGladman/AES I also found some example code that uses this library found ...
0
votes
1answer
861 views

Is the key deducible with AES CTR when we know about the plaintext, IV and the ciphertext? [duplicate]

Simply as stated, with AES running in CTR mode, can somebody work out the key (without brute-forcing) given we know about the plaintext, IV and also the ciphertext. Assuming we also know about the ...

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