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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How secure is AES 256bitkey generated from PBKDF2

I am using CryptoJS AES 256 encryption: CryptoJS.AES.encrypt(realData, generateKey(passphrase), {iv: iv}); The secret is generated through: ...
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Crack AES encryption via passphrase dictionary attack?

How easy would it be to crack a AES-256 encrypted file, that is protected by a passphrase? I understand that the trying to brute force a AES-256 encryption key would be on the unfeasible side, even ...
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Why is it not possible to attack an AES by creating a function to model the substitution that occurs in a s-box?

I realise that s boxes are able to make the transformations done in AES non-linear. However I am unsure how this makes AES secure. For instance if we had no s box then it is possible to calculate the ...
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Deterministic data masking

We are building out data masking framework mainly to mask PIIs. Our scale is pretty large, and masking will be done at ingest time, so we want the masking to be done in a very performant manner. Some ...
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Does my asymmetric/symmetric mixed file encryption pseudo code pass sanity check?

I realize this depends on my implementation and the implementation of the libraries I use. I am asking about my process assuming that the encryption libraries and my code are not flawed/compromised, ...
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A few questions regarding the 4-Round AES-Distinguisher (by Gilbert and Minier) and DS-MITM

I am struggling to understand the DS-MITM attack on AES (Original Paper). Especially the 4-rounds distinguisher by Gilbert and Minier (section 3). I get the basic idea that we check exactly on which ...
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Online AES Calculator

I am currently looking into how AES works and found a calculator online: http://testprotect.com/appendix/AEScalc I understand that the AES process has 10 rounds of calculations. Does this mean that ...
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How to minimize AES output size?

I work on a project about CAN bus and I want to encrypt the data among nodes but I have have a problem because CAN bus nodes receive and send 8 bytes among each others and I know the size of AES ...
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Is OpenSSL enc using AES-256-CBC to encrypt large files safe?

I first generate a keyfile with openssl rand -hex 64 -out keyfile. I then encrypt the file with ...
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Decrypt encryptedKey session key using - AES-128 - PKCS-1#rsaes-kem-kdf2-kw-aes128

I have basic knowledge about how encryption algorithms work such as RSA, AES and so on. I have an XML response encrypted with both AES and RSA. I tried using OpenSSL to decrypt with several steps but ...
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AES-GCM can IV be stored alongside in DB?

I'm trying to encrypt and store strings in PHP as per example #1 on the PHP openssl_encrypt documentation. ...
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How to use nonce, counter, and IV in AES-256-CTR?

preface: i am not cryptographically savvy. there are similar questions on this board but they do not give the answer i need. how do i construct a valid IV, given a nonce? What does this have to do ...
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Is this a valid AES instruction reordering?

I'm trying to understand a verilog AES implementation. I know the order of the AES encryption steps to be as shown: However the code I see doesn't do this. They do the following flow graph: at the ...
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in what condition, 2 different AES 128-bit Keys generate at least 6 bytes identical ciphertext on same plaintext

as mentioned in the title, and read some past discusstion on AES collison here. it shows it's possible that, AES(k1, m1)=AES(k2, m1) just wondering what condition those 2 keys need to meet. Thanks.
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Is it possible to crack AES-256 ECB when provided with the ciphertext and a portion of the corresponding plaintext? [duplicate]

AES-ECB encrypts the message by breaking it into blocks and encrypting them one by one. Provided the knowledge of the ciphertext, a portion of the plaintext that corresponds to a block in the message, ...
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Do some Block Cipher Modes encrypt the nonce and then XOR it with the data?

Reading https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Counter_(CTR) it looks like CTR (and some other modes) encrypt the nonce (plus count, for CTR) rather than the plaintext. The ...
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Multiplication in Tower Field $GF(2^4)^2$

I'm currently reading an article which deals with "Squeezing Polynomial Masking into Tower Fields " for performing an efficient multiplication of elements in $GF(2^8)$. Thereby it is ...
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Can an encryption key be inferred by knowing the plaintext and the corresponding ciphertext?

Thinking about validation methods for guaranteeing a proper key is used. Will keeping a dummy plaintext value and its corresponding ciphertext in plaintext code expose any risk?
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Is it possible to do partial message authentication?

I want to authenticate part of a message, not all of it, while creating the MAC over the entire message. Let's say I create a 16B MAC over one hundred message blocks that are 64B each. Then I send one ...
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Is a Test Vector feature a Security Hole?

I have a system where a block cipher key (likely AES) is entered via a 'command line' over a serial console, probably as hex. The system has no 'print key' feature, so the key is hopefully 'ingest ...
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Security of generating one long hash and using half as a secret key and half as a “public” hash vs generating two hash values?

My question is what would be more secure, generating 2 hashes (one key and one hash) with the same password and two different salt values, or generating one long hash with a single salt, taking the ...
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Random data CBC padding scheme?

When using AES in CBC mode, padding is required when the last plaintext block has not the length required by the cipher. Let's say $k$ mode bytes would be required to fill the block. My idea was to ...
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7-Zip Encryption: Practical Effect of Lacking Salt

A previous discussion on Cryptography StackExchange leads me to understand that 7-Zip does not use salt to derive an encryption key from password to use its AES-256 encryption; that this is a ...
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How do I preform the inverse key expansion of aes decryption? [duplicate]

I’m working on an aes encryption and decryption project in 8086 assembly! I managed to code an encryption algorithm and it worked perfectly. No I’m working on the decryption algorithm. I’ve managed to ...
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Where to get AES GCM NIST-like test cases

I'm implementing AES GCM 256 bit at the moment. Now I'm finished with copying the content of the standard as a program and now have to make it actually work. With the test cases in the official NIST ...
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Finding IV for forgery of AES CBC-MAC with non-fixed IV

As CBC mode might do several rounds, how it could be possible to find another IV for forgery attack? This is an example from my course: Assume you receive a pair with the plaintext $P_1$ and its MAC ...
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Decrypting the same message with the same IV using aes-256-cbc

Is it safe to use the same IV when decrypting the exact same encrypted message. From my understanding, there is a security flaw when using the same IV for numerous different messages, as attackers can ...
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Ciphertext length in TLS 1.3 additional data

RFC8846 says: ...
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How to prove the pseudorandomness of CryptoPAn

in my cryptography course, we are learning about pseudo randomness and the prefix-preserving function known as CryptoPAn invented in 2002. It is said that the scheme is highly insecure. So in that ...
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How to calculate how long it will take to break deliberately weakened AES encryption?

for a project I'm looking to make as an art project a series of encrypted "time capsules" that have deliberately weak encryption, enough that it isn't feasible to crack them now, but could ...
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AES-128 CBC encryption : ciphertext size seems too large

I am trying to encrypt messages with the AES symmetric algorithm using C language. I am using a key, an Initialization Vector (IV) and a plaintext, all with a length of 16 bytes. I expected as output ...
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Is AES/CBC/PKCS5Padding vulnerable if used for store data on a db

Is padding oracle attack applicable to data stored on a DB in AES/CBC/PKCS5Padding? Specifically I would like to be able to use Postgres with pgcrypto https://www.postgresql.org/docs/13/pgcrypto.html#...
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Is it cryptographically insecure to use fixed-length AES-GCM messages?

Is there any weaknesses to encrypting fixed-length messages? Should a random amount of padding be added to the message to decrease the odds of some sort of attack?
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AES (or otherwise): can you decrypt concatenated encrypted messages as one?

Say I have 20 distinct encrypted messages. Using AES, I am only getting the correct output if I decrypt each of the 20 messages individually. Is it possible using AES or another method to call my ...
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Benchmark for CSPRNG as stream ciphers?

My limitation in my security protocol is that I want my RNG as CSPRNG and I also want it to be super fast. If I use Salsa20 or ChaCha or AES counter mode, I don't get the desired speed. I want my PRNG ...
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Secure AES IV with static salt

I have an (offline) shared secret key (symmetric) which is used to encrypt/decrypt data. Now this data belongs to a specific user which is known on the backend and frontend. My idea was to use the ...
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Stick figure AES: what does “I take each column and mix the bits in it” do? [duplicate]

I've been reading A Stick Figure Guide to the Advanced Encryption Standard (AES) to help me understand how AES works. In this picture it says: I take each column and mix the bits in it. But then ...
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AES CBC Encryption Key & Special ASCII characters [duplicate]

Can we add characters like α π Σ µ ...
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What is this AES SBOX triplet property?

While playing around with the AES SBOX, I found out that there are 85 unordered triplets (a, b, c) that have the following characteristics: ...
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Special characters in AES Encryption Key

We all know that AES uses Key, IV and salt. But what if we add special ASCII characters like Alternate 255 (" ") or Alternatively 163 ("£") or Alternate 224 ("α") in the ...
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AES speed compared to permuted LCG

What is the speed of AES and how to estimate it well? Here: https://security.stackexchange.com/questions/92074/aes-algorithm-encryption-time they wrote it could be 700 MB/s. But here: https://www.cse....
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Linear AES : expression of K in AES(P) = AP+K

I am currently trying to attack a modified AES with an identity S-box. I found this topic which explains that we have the equation $AES(P) = AP + K$, with $A$ a 128x128 matrix that is not key-...
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Does AES encryption work like a padlock or like a safe?

If I encrypt a plaintext p using AES-256 in GCM mode with the keys $k_1 ... k_n$ and I want to decrypt it later, can I use the keys in any order when decrypting or do I have to use the same order as ...
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Number of false keys in exhaustive key search for block ciphers

I'm doing a self study through Understanding Cryptography by Christof Paar and I have a question about Theorem 5.2.1 in the book: Given a block cipher with a key length of $k$ bits and block size of $...
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Encrypting cryptocurrency seeds for cold storage

I’d like some feedback on an encrypting algorithm. I’m not rolling my own, but even putting together well-proved pieces may create many pitfalls. (I don’t know if I'm stretching questioning in this ...
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AES GCM : is it acceptable to return the wrong plaintext if the tag is incorrect?

Let's start by saying I'm no cryptography expert, I'm just a developer, so feel free to correct me (using words, not downvotes) if what I'm saying is non-sense. Context: I'm doing some crypto as a ...
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find master key given all but last decryption round keys

I have all but the last round key in AES-256 CBC decryption, and would like to build the master key, but I am unsure how to go about it. I have read I can convert decryption roundkeys to encryption ...
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AES plaintext is smaller than 128 bits [duplicate]

I'm currently developing a AES implementation in a graduation project at university. As far as I know, AES uses a 128 bit block length as input . if the entered string to encrypt is not 128 bits such ...
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what is auth data in AES-GCM

I am trying to understand AES-GCM and I do not understand what I should transmit to Auth Data during encryption. What kind of data is that?
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How to do unmasked addition on SSS masked shares?

I'm trying to understand how Shamir's Secret Sharing algorithm is applied to AES when doing threshold masking. I understand how the secrets are created and the secret is calculated and I'm now trying ...

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