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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Why are AES keys increments of 64-bits?

Why are AES keys increments of 64-bits? Rijndael, which subsequently became AES, allowed key increments in 32-bits (128, 160, 192, 224, and 256 bits). However, AES made it 128, 192, or 256. My guess ...
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Is this correct/incorrect password for file encryption scheme secure?

I'm writing an AES file encryption program, and I'd like to put in a way to tell whether or not the user has entered the correct password without decrypting the entire file and GCM telling me the tag ...
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what if key of aes will be more than 32 bytes? [duplicate]

For example, if I use AES-CTR and use key of 44 bytes. Will it be breakable or not and why? How to use AES-CTR correctly?
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find aes key in some messed up files [closed]

hi everybody I have several files in my hand that are generally about booting Linux and somehow one of them is encrypted with AES so that Linux does not loaded. The files are as follows: 1-gpg ...
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Is AES-256 a post-quantum secure cipher or not?

We know Grover's algorithm speedup brute-force attacks two time faster in block ciphers (e.g brute-forcing 128 bit keys take $2^{64}$ operations not $2^{128}$). That explains why we are using 256 bit ...
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Do I need to encrypt the IV?

For example, I'm using AES-CTR. I use fixed (random generated) key and random IV. I know that I have to encrypt key but I don't know about IV. If I will encrypt 1 block of data with fixed key and ...
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AES-256 mix column code generating output bigger than 8 bits [closed]

I'm implementing AES-256 in JavaScript with block size 128 bits and I understand every thing about AES except MixColumn transformation. So I copied this code from ...
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Using Caesar crypt, then encrypting the output with PGP, then encrypting that with AES-256

Is that possible? Well, of course it is, but if you decrypt it, will it show the actual message in the final output? This isn't me actually doing this in practice, just if it is possible. Lets say ...
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AES-256 will double the size of photo after encryption?

I am currently working on my JavaScript project where I am also trying to encrypt attachments with AES-256. Right now I am testing it and I am getting this results. For photo file which has size ...
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crypto design with AES-256 MODE OFB

I have the following APP Design key store (contains 1:n user payload as 1:n key store entries) key store salt (is used to extend to key store password to 256 bits, stored in clear text) key store ...
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What are the advantages of AES-128 cascade vs AES-256?

Ok so let's say I have some top secret data ~ 50-100 MB and I need it to be protected. The cipher operation mode and the KDF is irrelevant for this example. Let's just assume we use ...
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AES-256 GCM IV guidelines

If I use for example AES-256 (GCM), and my message is bigger than 256 bit (broken into smaller 256 bit blocks for encryption), should the IV change for every 256 bits of the message?
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WinZip AES-256 vs PGP

If I use the AES-256 option in WinZip to encrypt a file, is it any less safe or less secure than using PGP encryption?
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Has AES-128 been fully broken?

Has AES-128 been broken over the full 10 rounds? If so, by what means? By a commercial entity? By a supercomputer? If not, why is AES-256 used to replace AES-128 so frequently?
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Rijndael vs. Serpent vs. Twofish: General comparison

Can anyone explain (or give a link to document about) why Rijndaal won the AES, especially comparing it to other finalists (Serpent and Twofish)? What criteria were used to make decision? Or is there ...
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AES CBC Security

I am building an Apache webserver with TLS 1.2 and OpenSSL 1.0.1. So far, I have enabled 2 encryption algorithms - ECDHE AES-256 GCM and ECHDE AES-128 GCM. Firefox and Chrome / Chromium use NSS which ...
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Attacking AES-128 with Grover's algorithm

How many plain text / cipher text pairs are required by Grover's algorithm when it is used to try and discover a secret AES key? I am trying to determine if having a device which limits the speed at ...
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After ECDH with Curve25519, is it pointless to use anything stronger than AES-128?

Is the following reasoning correct: After ECDH with Curve25519, the resulting shared secret will be an EC public key with a bit strength of 128 bits. This public key would then be hashed (let's say ...
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Does re-iterate AES-128 with different keys gives any benefict?

I'm not cryptography expert but I have this doubt… Suppose I have 2 different keys: secretkey1 secretkey2 And a plain text: <...
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AES-128 Decryption in Objective-C just slightly off [closed]

I have been asked to integrate a home-grown CRM system with a 3rd-party data service provider (DSP). The DSP has encrypted the information they are providing. I only have their decryption ...
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Doubts regarding implementing AES-128 bit algorithm in my IOT system

I want to implement AES-128 in my IoT network which consists of a Master device which runs Linux on it and slave devices which are 8-bit micro-controllers that periodically transmit data packets to ...
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Problem with AES-128 AddRoundkey Step

I'm trying to self-learn the AES-128 algorithm and ran into a snag while following these slides I found online: https://kavaliro.com/wp-content/uploads/2014/03/AES.pdf For the sixth round in the ...
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Choice between AES-128 and AES-256 for password protection in MS Office

Why are we still using the default of AES-128 when password protecting a Microsoft Word document. My answer is and always has been - because its good enough and MS don't recommend changing to AES-256. ...
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AES-GCM - what are “Payload Length” and “AAD Length”

For the AES-GCM mode within many cryptomodules, their FIPS-validation certificates list the options: Payload Length: 504, 512, 1016, 1024 AAD Length: 0, 504, 512, 1016, 1024 For example in OpenSSL, "...
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AES key with DES3_CBC_PAD mechainsm

I am new to cryptography and have a question. If I try to wrap some key using an AES key using DES3_CBC_PAD as a wrapping mechanism will this go to work? I am doing this operation inside an HSM.
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Why CryptDecrypt returns NTE_BAD_DATA? [migrated]

I want to create implementation of AES-CBC. I have created this code: encryption process: ...
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Question on PKCS11 2.40 spec and AES_CBC wrap

PKCS11 cryptoki version 2.40 Current mechanism specification (section 2.8.5), says below statement for AES CBC wrap: For wrapping, the mechanism encrypts the value of the CKA_VALUE attribute of the ...
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Is encrypting data with AES-CTR-128 and keys with RSA-2048 secure?

Here's a question. I have a file that have to be encrypted with strong cipher (I've choosen AES-CTR-128). I'm using MVC 2019 to compile C++ program. Firstly, I create RSA-2048 key pair (public and ...
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How to make an AES implementation using lookup tables immune to cache timing attacks?

I recently made a very naive implementation of AES using lookup tables, but it's totally unsafe because of timing attacks. I am not interested in using the processor specific instructions for AES, ...
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Is encrypting a file with AES-CTR and then encrypting the AES key with RSA-4096 secure?

I'm using microsoft visual studio 2019 c++. I have aes-ctr-128 implementation. Encryption process: Generate key pair for aes-ctr-128 using CryptGenKey() function ...
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Argon2 or scrypt instead of PBKDF2 with AES

Is using scrypt or argon2 a better key stretching technique with AES compared to PBKDF2 or bcrypt with regards to a quantum computer brute force attack. The brute force attack I'm referring to is ...
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Is direct RSA encryption of AES keys secure?

I am wondering: If we take this scheme/procedure and each of it seems very secure (to me at least), is it truly secure or is there a vulnerability hidden in the process? This is the scheme: Bob has ...
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In a web application where does diffie-hellman key exchange come in (server or client side)?

I am creating a simple student web application for sending messages (client 1 encrypts the message with AES and then sends it over the server to client 2 where the message is decrypted). The problem ...
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Is there any vulnerability in this scheme?

We want to design a symmetric encryption scheme. Note that the following things are true for our system: The plaintext P will change every time for a given user. A user will choose a password which ...
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What are the popular modes-of-operation (AES-GCM, AES-SIV, AES-GCM-SIV, etc.) geared for?

I'm interested in developing software capable of encrypting personal files (which will ultimately be backed up to the cloud) and have been doing my best to follow best practices. There are many forms ...
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Any good links to learn the maths behind AES?

I'm creating an academic poster for my EPQ on the mathematics of cryptography. I would like to do a section on AES, however, I am struggling to find good resources to understand the maths. I have ...
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Server stored, encypted messaging app

For my personal research, I have to create a messaging app, but security is only important part of application, security from MITM (man in the middle attack), at device end, and at server level. (note:...
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Crypto AES for authentication

Is it secure to use authentication strategy like this: store key in database - crypto.randomBytes(32) store IV and encrypted data in user cookies - ...
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What are easy yet fool proof ways of ensuring that AES encryption algorithm works like it should and no bugs/developer mistakes have sneaked in?

As a developer when it comes to encryption, there is an insane amount of weakness/mistakes/bugs that the programmer can add to the encryption algorithm. So a pretty general question to the crypto pro’...
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What is the difference between PKCS#5 padding and PKCS#7 padding

One runtime platform provides an API that supplies PKCS#5 padding for block cipher modes such as ECB and CBC. These modes have been defined for the triple DES, AES and Blowfish block ciphers. The ...
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If we have chunk encryption for AES-Rijndael-CBC, should we hash Authenticate/tag each single chunk with a hash vs whole file?

was frustrated by which one to pick and my brain could not guess which one is better Authenticate the whole file as one with a hash vs authenticating each ciphered text. So very quickly: i have super ...
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Iterated AES encryption under a fixed key

Is it right that repeated AES encryption under the same key will eventually lead back to the original plaintext? The reasoning is that AES acts like a reversible permutation of the blocks, the ...
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Which character / byte to use to divide AES ciphertext into chuncks?

I am implementing a cross platform AES cipher. Everything works fine except for super large file, those I encrypt by for example taking first 1kb of the file generating a cipher message (all chunks ...
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Is double encryption really a bad idea? Are meet-in-the-middle attacks practical at all?

Meet-in-the-middle attacks are used to justify that attacks on ECC and double encryption will have complexity of $O(\sqrt{n})$ for ECC and $O(2^{n+1})$ for double encryption complexity instead of $O(n)...
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Should I use AES CTR mode?

I have a question. For example I have text: "The quick brown fox jumps over the dog!" It has 32 letters. If I encrypt the first 16 letters with key: "11111111111111111111111111111111" and nonce: "...
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AES CBC in need of multiple IV's, possible to avoid creating duplicate iv's by using resulting cipher text 16 bytes as next iv?

I saw a little close to these questions but not exactly. Encryption method AES-256-Rijndael-CBC: if we have multiple cipher chunks that look like this: {iv}{cipheredchunk}{chiphered chunk}{chiphered ...
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Encryption for continuous, real-time data over an unreliable connection

I have a continuous stream of real-time data. It must be consumed immediately or discarded, so I'm using UDP for transmission without ACK or retransmission (the connection is unreliable). The packets ...
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AES256-GCM - can someone explain how to use it securely (ruby)

I am looking into using AES256-GCM for encrypting some database fields. I know that for AES256-CBC, I need to generate a new IV for each encrypt, but I can use the same key. The IV can be openly ...
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Multiple AES Key Derivation from a master key

I need cryptography advice regarding this issue. Kamus is a service that encrypts secrets for applications running on Kubernetes. When using AES (actually, Rijndael) symmetric encryption, Kamus uses ...
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Given the key, the plain text and the cipher text can I calculate the IV used in CBC mode?

If I have the plain text, the ciphertext and the key for an AES-128 CBC operation, can I determine the IV, even if I don't know the padding (assuming the padding follows one of the more common formats)...