Linked Questions

2 votes
1 answer
419 views

Security of HKDF when part of output is exposed

There is a system in which Alice and Bob need to establish a secure communication channel. Their conversation happens via a "public" server whose only purpose is to rely messages between users. This ...
Deril's user avatar
  • 41
2 votes
2 answers
193 views

Is it safe to use cipher block sizing instead of padding?

I'm using this kind of technique instead of padding of cipher buffer (here goes pseudo-code): ...
Barmaley's user avatar
  • 145
2 votes
1 answer
608 views

AES mode which verifies data integrity AFTER decryption

I wonder if there is an AES mode which would verify data integrity after decryption operation. Due to the reasons which does not matter here, there is a possibility that AES implementation I use may ...
olegst's user avatar
  • 171
2 votes
2 answers
299 views

Does a key need to be signed if it is being used to decrypt a message that is already signed?

I am trying to better understand authentication. Lets say I have posted my 128-bit AES symmetric key on some forum, encrypted asymmetrically to my friend using 256-bit ECC (25519). The forum isn't ...
Sam's user avatar
  • 23
2 votes
2 answers
1k views

Is there any advantage on encrypting the CMAC together with the message?

I'm reading a protocol specification where the procedure is to generate a CMAC, take the first 4 bytes of it, append this authentication tag to the message and then encrypt the message + CMAC together ...
RubenLaguna's user avatar
2 votes
2 answers
2k views

Is HMAC necessary if the AES ciphertext of a message includes the CRC of the message?

I've seen that encrypting an image with AES-CBC then calculating the HMAC-MD5 value for authentication is a somewhat common and sound way to secure data. Alternatively, can I just calculate the CRC of ...
Trevor's user avatar
  • 31
2 votes
1 answer
558 views

The security of an encrypt-and-MAC

I would like to know what is the security of an encrypt-and-MAC with different keys for each transaction For example: the one-time-pad with $k_1$ and the HMAC with $k_2$ $$C = M \oplus k_1\\ MAC = ...
zof's user avatar
  • 399
2 votes
2 answers
234 views

What drivers are causing an increase in authenticated encryption modes?

So I'm currently working through this cryptography question and so far I have the answer of an increase of hackers due to increase in computational power. But apart from that I don't know what else. ...
Thanos's user avatar
  • 193
2 votes
1 answer
346 views

How is RSA key exchange protected against tampering?

The public key is defined by (N, e) where N is the product of two large primes and e is ...
Abhisek Dash's user avatar
2 votes
1 answer
164 views

Is the tag generated in MAC equal for equal messages in CBC-MAC?

The Cipher Block Chaining algorithm for generating message authentication codes uses a 0 IV . So my understanding is that same messages will generate same MACs which seems to violate semantic ...
Abhisek Dash's user avatar
2 votes
1 answer
165 views

Authenticated encryption and file data integrity

I've got a task to provide the integrity and an authenticated encryption for files in our application. I need an assurance if my way of thinking is correct. I can't use AES GCM, I have to stay with ...
user avatar
2 votes
2 answers
2k views

Some questions about encrypting (AES) a file with password

I'm relatively new to encrypting, and I have some questions. I intend to write a standalone C# program that will write and read an encrypted file with sensitive data using a password entered by the ...
Marc's user avatar
  • 123
2 votes
1 answer
689 views

Authenticated Encryption mode & AEAD

I'm studying Authenticated encryption with Associated Data (AEAD). My questions are About AE - I heard that when it comes to Encrypt-then-MAC, if an attacker forges the ciphertext then he gets the ...
pioneer's user avatar
  • 325
2 votes
1 answer
850 views

Review of AES encryption concept for an open source project

i'm working on an opensource project, A generator for static (html/js), password protected photo galleries. The generator AES 256 encrypts many images with the same key in PyCrypto, and decrypt them ...
ierror's user avatar
  • 123
2 votes
2 answers
103 views

Using the MAC to verify if Cipher Only attack has succeeded

I am working on an experiment to compare the efficiency of brute-force attacking block ciphers like AES and DES with reduced key sizes for different programming languages and library implementations. ...
Matt's user avatar
  • 21

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