Questions tagged [aes]

AES (Advanced Encryption Standard) is a symmetrical block-cipher algorithm with a 128-bit block size, and key sizes of 128, 192 or 256 bits.

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Understanding AES-GCM IV (Nonce), Tag/MAC, Message & Transmission

I am working on a project that uses PAKE (SRP) for authentication. When we send the M1 to the server we are encrypting the payload using AES-GCM. I mention SRP only to set the context: A message is ...
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How do AES Substitution box's offer any additional security since it's 1 to 1?

If the Substitution box is 1 to 1 (a specific value can only ever be a specific box value), and the contents of Rijndael S-box is public, how does this offer any additional security? With AES the ...
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Info AES cryptanalysis

I have some doubts regarding AES weakness and AES cryptanalysis. While it is relatively simple to find Cryptanalysis info on previous ciphers, I get confused about understanding various types of ...
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AES - SBOX avalanche effect question

I am making a program that verifies the avalanche effect for the SBOX of the AES block cipher for a certain number of iterations. This program changed one bit randomly in one of the elements of the ...
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Why AES code is working even with 3 Rows

First of all, I am a student, so even if most of you think it is a useless question, don't dishearten me as it is a platform for me to learn I am using an AES code that has 3 Rows and 4 columns in its ...
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For AES, does the construct two encryptions for a 3rd value have any practical use?

As AES could be considered as a function AES(key, data) that return encrypted data, is there a use of the construct of ...
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AES-CBC collision resistance of hash function [closed]

I'm very new to cryptography and am having some issues with the following question ...
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How do you arrive at this algorithm for dividing by 3 in the Galois field?

This function from Wikipedia calculates the sbox used in AES: ...
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Is the following scheme CCA secure? I purposed a scheme and I am not sure if it is CCA secure, if not, how can it be CCA secure?

Here is my idea: Under the symmetric key encryption. Alice and Bob share the symmetric key K. Let HASH be a secure hash function and ...
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Does file size significantly affect brute-force time?

Suppose you have two files encrypted with AES-256. One of the two files is 5MB, the other one is over 1GB. Their passwords are reasonably strong: >12 characters, letters, numbers, upper and lower ...
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AES-CBC-MAC forgery attack

I have a CBC-MAC scheme using AES as the block cipher (T=H_K1(M)), which gives me a tag and a stream cipher using another key and a nonce, which gives me a cryptotext (C=E_K2(N,M)). So my question is ...
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Is AES-128 quantum safe?

I've been reading lately some contradicting messages with regards to the quantum-safe resistance of AES128. First, there are blog posts by Ericsson people like these ones: Can quantum attackers break ...
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How is $Nb$ (number of columns) calculated in AES (Rijndael)?

The NIST publication for AES defines $Nb$ as: Number of columns (32-bit words) comprising the State. For this standard, Nb = 4. In Section 5.2: Key Expansion, $Nb$ has been used to calculate the ...
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Is it possible to extend CMAC for ChaCha

CMAC is defined for AES for authentication. My question is pretty simple: is it possible to extend CMAC for ChaCha? Does it even make sense? I cannot find anything related and I am wondering if I am ...
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Attacking AES ECB

this is a school challenge. I have a cipher file which is the audio file, and no key of course, encrypted with AES ECB mode. The size is around 550 Kb. I know the key size used is 16 bytes, and I have ...
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Why is ECB mode unsafe if the key is kept secret?

this is my first post so I apologise if the formatting of my post isn't perfect. I should start off by saying that this post is not for any malicious intent, rather for curiosity and understanding AES ...
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KEY using AES-128, If P is less than 128 bits, padded with 0 and create 128 bits, any problem if average pw length is 6

For communication between the client and the website, use password (P) as the key using AES-128. If P is less than 128 bits, it is padded with 0 to create a 128 bits key. is there any problem with ...
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Is 'authenticated' in AEAD actually authentication? Or is it message integrity?

Despite working with AES-GCM and other AEAD algos for a few years, I've struggled with the concept of 'authenticated' in the term 'AEAD'. In my own experience (of Unix, PKI and blockchain) ...
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AES-CTR: using the same key and IV with unique messages

I have short (8-byte) messages which are effectively true random numbers, and I want to encrypt these messages with a (pre-shared) key.... I'm using AES-CTR for this purpose -- but with the SAME IV ...
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Is it normal that cypertext size can be smaller than IV when using AES-256-GCM?

I noticed that when using AES-256-CBC with a 128-bit IV, the ciphertext is always at least 16 bytes long (size of IV). I also noticed that when using AES-256-GCM with a 96-bit IV, the ciphertext size ...
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Secure option for (hybrid) encryption of a secret key using JWE

I want to encrypt a private key $sk$ (it's actually an RSA private key in PKCS#8 format) with another person's (and/or my) public key $pk_A$ for secure storage. With JWE, it is possible to use hybrid ...
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What does AES-GCM provide?

I am wondering does AES-GCM which uses Authenticated Encryption provide us with all 3 properties (Authenticity, Confidentiality, and Integrity), or does it not provide integrity?
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CTF AES attack (ECB, CBC, CFB, OFB, CTR) [closed]

Hi I'm trying to understand the logic behind a CTF challenge basically we are given a program which encrypt some data, we have the following options: Select encryption mode (EBC, CBC, CTR, OFB, CFB) ...
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Beyond birthday bound security in AES-GCM-SIV

AES-GCM-SIV takes a 96 bit nonce, like the original GCM. The RFC states that "it is RECOMMENDED to use this scheme with randomly chosen nonces". It uses the random nonce to generate per-...
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Should I encrypt individual columns or all data?

I want to AES-GCM some user data that I‘m going to persist in a database. I‘m wondering if I should encrypt individual columns (all with an individual IV ofc) or JSON stringify the sensitive data and ...
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Dividing an encrypted file is secure against classical or quantum

I'm very new to cryptography and this may sound so foolish. Often I read quantum computers will brute force keys. Let's assume this is true (does it depend on key length? or on an algorithm? I don't ...
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Password encryption in database

I want to store passwords in a database in a way I can reuse them to authenticate users (symmetrical encryption). I read some good information here: https://cheatsheetseries.owasp.org/cheatsheets/...
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Decryption failure for NIST vector AES-CBC-128

I am learning/exploring the openssl library for encrypting and decrypting data while encryption goes through fine I see standalone decryption not working as I expected. The test vector I am using is <...
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512/N-Bit Key AES

I am implementing the Advanced Encryption Standard from scratch, but I came up with a question that I was unable to answer. Why does no one implement AES with other sizes? I've searched about that, ...
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What is the use of Additional data or associated data in AESGcm. How it is used while encryption and decryption [closed]

I am trying to understand the AESGcm encryption and decryption and there's one field associated data in Encryption and Decryption methods. https://learn.microsoft.com/en-us/dotnet/api/system.security....
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Why is AES better than one-time pad?

From my limited research into this topic, it seems that AES can be brute-forced. One-time pad, on the other hand, cannot. Why then is it better to use AES than it is to use one-time pad? The only ...
Darcy Sutton's user avatar
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Reduce AES-CTR malleability impact by shuffling plain text

I need to cipher and decipher text with randomly access. For this I decided to use AES in CTR mode which is a good compromise between CBC and GCM. But CTR mode is malleable. It is not a big problem ...
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MOSH - Decrypt session when the shared secret is known

Currently I'm working on an intercepting proxy server for mosh connections. I'm able to intercept the ssh session to get the shared secret and alter the connection information for the mosh client. The ...
Manfred Kaiser's user avatar
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Can one infer concatenated ciphertext block boundaries through digital forensics?

Say one encrypts multiple plain text blocks with same IV but different keys using AES-256-CBC, can one infer concatenated ciphertext block boundaries through digital forensics? Example Plain text ...
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Clarification on expected number of plaintext, ciphertext pairs needed to identify AES keys

I'm aware of the many questions on this topic, but I'm still not sure what went wrong with my reasoning here below. I'm assuming use of AES with key size $2^{256}$ and messages of size $2^{128}$, ...
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Is there a security risk to use AES-CBC as stream cipher?

I am building a chat application where I want to encrypt each character while they are typing. I would require a stream cipher for that. I am planning to use AES-CBC mode with HMAC. Are there any ...
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Can one securely use same salt and IV with different KDF-derived keys when using aes-256-cbc?

I know this is theoretically bad practice, but please bear with me… Assuming following spec: Salt and IV are randomly generated using cryptographically-secure RNG. Argon2 is used as KDF so ...
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How is AES256-GCM auth tag used in decryption

I have been playing with AES256-GCM in NodeJS crypto library and it shows that the original message can be decrypted without caring about the auth tag. So can a non-tag verified decryption be secure? ...
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How easy is it to identifiy the key when knowing a certain number of different AES-256/Fixed Nonce encrypted long-integers

Given some intervals of long integers (64 Bits). I need to generate alphanumeric strings which: should be used like passwords(known only by few individuals) must always be the same for the same ...
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How LastPass decrypts database on web browser?

According to video from Dr. Pound, password managers (LastPass in particular) holds encrypted image of your data on their servers and then with master password you authenticate to get encrypted image ...
unalignedmemoryaccess's user avatar
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1 answer
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Is it possible to use aes-ecb-256 decryption algorithm as customer key derivation function to generate the aes key?

I'm sorry if I'm going horribly wrong - I am new to this stuff. My question is: KDFC1,KDFC2,KDFC3 is defined by myself. Key1 is come from outside . Is it possible to use the aes-ecb-256 decryption ...
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AES authoritative recommendations?

I am trying to figure out if there is an authority like FIPS, NIST, NSA, or DOD that has recommendations or standards for implementing AES such as key derivation algorithms and iterations as well as ...
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How is AES-GCM IV and auth tag used?

I have been learning about AES-GCM and AES in general lately and founding: The key is the secret and both sender and receiver keep it hidden forever. The IV and auth tag are public and sent along with ...
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Should I use hash of passphrase as AES256 key

As title I have a password-like passphrase (8 chars at least) that is then hashed with argon2(with the salt is SHA256 of that passphrase). Then use it as AES256 key along with a random IV generated by ...
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What is the importance of superencryption?

Please, can any extensively explain the importance of super encryption in relation to attacks experienced by single standard algorithms
Ubochi Chibueze Nwamouh's user avatar
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How is Diffie-Hellman linked to AES?

I have just learnt about Diffie-Hellman and AES. However, I cannot seem to understand how they link. My initial idea was that Diffie-hellman is used to transfer a key for AES decryption. After further ...
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AES with a different implementation of byte substitution step

I have tried to answer this question for quite some time now. But a complete intuitive understanding still eludes me: suggested a new implementation for AES: The byte substitution step will be ...
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best encryption algorithm for encrypting a string

I am making a password manager , I am new to cryptography, so , can someone tell me if this can be a good solution? 1- the user inputs the email/password 2- all the payload gets encrypted with aes@...
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GnuPG - provide encryption key for AES rather than deriving it from passphrase

I'd like to encrypt a file with AES256 and provide my own 32-bytes for the encryption, rather than having GPG derive it from the passphrase. I could not find such option, but I'm thinking about a ...
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AES vs Kuznechik (GOST R 34.12-2015) comparsion [closed]

Which algorithm is more crypto-resistant: AES or Kuznechik (GOST R 34.12-2015)?
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