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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Web Cryptography API and low level AES APIs

Does anyone know why https://www.w3.org/TR/WebCryptoAPI/ does not offer also low level AES APIs like: AES block encryption with several allowed block sizes (like for example the one offered in golang,...
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After 20 years of AES, what are the retrospective changes that should have been made?

I realize that this could be very opinion based, but I feel that there should be some solid information on AES at this point that could be referenced. After 20 years, I expect that there should be a &...
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Is it necessary to use an IV in CBC mode when just encrypting one file? [duplicate]

As far as I know, CBC mode, even with a null IV, will encrypt identical plaintext blocks to unique ciphertext blocks within a single file. The purpose of an IV is to obscure the similarities between ...
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Aes 128 input and output size

I'm novice in encryption, i want to use aes 128 to encrypt can bus communication but the can bus data size is different from aes input and output (16 byte) ! How can I modify aes input and output size ...
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Why was Rijndael the only cipher to have a variable number of rounds?

Rijndael was the only AES candidate which defined a different number of rounds for their 128, 192, and 256-bit versions (10, 12, and 14, respectively). The others had a fixed number of rounds (32 for ...
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AES-128 or AES-256 with 18 bytes of key storage?

I have only 18 bytes in which to store a (randomly generated) key. Is it more secure to: use AES-128 and a 16 byte key, use AES-256 and a 18 byte key padded with 14 zero bytes to make a 32 byte key, ...
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Format-preserving encryption

Three modes FF1, FF2, FF3, all 3 modes use Feistel structure. They use different Fk ring functions. So I want to ask are they all built on the use of AES right?
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ECDH/ECDSA key exchange on embedded devices

Two devices are communicating only with each other and shall do this with AES encryption. Both devices are offline, have very limited storage and use a small cryptographic coprocessor which is able to ...
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Best practise for encryption in a password manager

I'm trying to make a password manager for Windows installed computers, and after researching the best ways to encrypt the passwords in the database (I'm new to cryptography) I think I've come up with ...
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Suitable hybrid encryption approach?

I need help for my bachelor thesis. I have a general question regarding hybrid encryption in different ransomware. The hybrid encryption often uses symmetric and asymmetric encryption techniques. ...
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Finding MSB in RSA

Scenario: Alice and Bob send each other encrypted AES (128) messages. In order to change key, Alice has a public RSA key (2049 bits). Bob has Alice's public key. Bob picks a random AES key, encrypts ...
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Modifying SubBytes Operation In AES

Let us assume the SubBytes operation changed to just shift right operation. for example - f(00011101) = 10001110 How we perform a Known/ Chosen Plaintext Attack and find the key? How much time does it ...
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Matrix multiplicative inverse

How to determine the inverse multiplicative matrix of the following two irreducible polynomials GF(2^8) x^8 + x^5 + x^3 + x^2 + 1 and x^8 + x^5 + x^4 + x^3 + x^2 + x +1
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What's the preferable encryption for large data and files in terms of speed and security other than AES?

First of all, I'm relatively new to encryption so please bear with me. I'm looking for a way to encrypt large amounts of data only on my device, no need to transfer my encrypted files/data (10-20GB or ...
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Encryption on one AES mode and decrypting on another, where both use HMAC

Let's say there are 2 ciphers, $enc$ and $dec$, where: $enc$ will encrypt the data, and $dec$ will decrypt it. Both $enc$ and $dec$ must be an AES cipher. $enc$ and $dec$ will use the same key $k$ ...
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Mathematical and empirical analysis of AES

Hello everyone and happy new year in advance. I'm doing a work about the analysis of the AES algorithm, and I have some doubts about this. First, I need to do the mathematical analysis of the ...
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Why Crypto++ library's AES definition is so fast

I am trying to compare the CPU cycle required for two encryption algorithms. One algorithm is AES and lets the other algorithm is B(code name). I implemented algorithm B and having fewer and simpler ...
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Help me understand how to do a crypto assignment about AES/CBC

I'm doing the Coursera cryptography I course from Dan Boneh. I am attempting to do week 2's programming assignment, but I think I am having some sort of misunderstanding of either the theory, the ...
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AES with other SBoxes

I'm not a cryptologist, just an interested engineer (& now retired). I used to design hardware with AES en/decryption blocks & generate test vectors using my own Tcl script using the embedded ...
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DFA on aes Giraud's attack on 10 th round

I am trying to implement an attack on aes using Giraud's attack on the last round of aes using a fault injection of one bytes here is the situation normal byte in the 10th position (1,2) of the 4x4 ...
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Does it increase security if the CBC chunks of a AES-256 encrypted bytestream are uploaded to different clouds?

I want to backup my data according to the 3-2-1 rule. I am already back up to 2 different drives (2 different systems) at home. In addition, I would like to use cloud storage (Google, Amazon, etc.). ...
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Does it increase security if the CBC chunks of a AES-256 encrypted bytestream are uploaded to different clouds? [duplicate]

I want to backup my data according to the 3-2-1 rule. I already backup to 2 different drives (2 different systems) at home. In addition i would like to use cloud storage (Google, Amazon etc.). ...
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Encrypting multiple groups of data with separate keys in a single encrypted column

I will write this question using a database example, but please note this detail may be irrelevant. Let's say I have data belonging to N clients stored in a single column of a database table. Each ...
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Which sub operation is more expensive in the AES encryption process?

In the AES encryption process, there are various sub-operations, like SubByte, MixColumns, ARK etc. My question is which of these operations is more expensive? In a video lecture by Dan Boneh, it is ...
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How to correctly pad by PKCS#7 for AES?

I want to implement AES-CBC mode with PKCS#7 padding, along with a way to validate a correct padding given the ciphertext. My initial understanding was that for an input of size ...
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AES CTR: Random IV

I want to use AES CTR with a random IV, as this would be the easiest way for me. I have a cryptographic module, that supports true random number generation. Due to compatibility, I must use AES CTR. ...
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Multiply by 3 problem with MixColumns in AES

I have problem with multiplying bytes by 3 in MixColumns (as in Cryptography And Network Security) $$\begin{bmatrix}02&03&01&01\\01&02&03&01\\01&01&02&03\\03&01&...
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Post-quantum asymmetric encryption algorithms

One could use Falcon-512 for establishing a private and public key for an asymmetric context. Whereas in a symmetric context, we could use firesaber/saber/variants in order to obtain a shared secret ...
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AES 5 and 6 round SQUARE Attack

SQUARE attack on AES128 requires a single delta set for 4-round variant, or I assume single delta set is enough since keyspace is reduced to few keys which can be easily brute-forced. However, as we ...
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Calculating equivalent substitutions to AES operations(MixColumn/ ARK)

When the AES algorithm is implemented in a table lookup(SubByte, MixColumn) fashion, how many substitutions required in full round encryption? When AES is encrypted without using the table lookup(only ...
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How is the 'Algebraic Degree' calculated in the paper about analysing the white-box AES(Chow et al. 2002) by exploiting internal collisions?

This paper proposed a new attack on the initial white-box AES implementation of Chow et al. In order to determine the good solution, we use the particular structure of the function $S_{0}$. $S^{-1} \...
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AES Encryption With PBKDF2 KDF in pycrypto

I am a bit new to encryption and I've seen a lot of recommendations to use a KDF for encryption and decryption. I'm a bit confused since I've been trying to encrypt the data using PBKDF2 algorithm and ...
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Is Mega.nz encryption vulnerable to brute force cracking by quantum computers?

I am interested in Mega.nz cloud storage. It is using end-to-end encryption. It says that it uses AES-128 to encrypt files And there are more details in their white paper But I saw that quantum ...
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AES256 CTR nonce generation

I am following a wiki diagram for CTR mode of operation in AES256. The documentation states that for it to work you need a random nonce with 8 bytes and then a counter of 8 bytes. So I guess you can ...
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Known plaintext attack on AES with CBC

Assume I have a plaintext and a ciphertext, encrypted using some key and AES with CBC mode. I don't have a service, that I can send something to, so I can't use the Padding Oracle attack. Are there ...
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How to correctly implement an archetypal encrypt-then-MAC AES-CTR + HMAC mode cipher?

I've created an AES implementation in Python as a learning experience (mainly for encrypting/decrypting files), and wanted to make sure that I haven't made any huge mistakes in my logic (of course, ...
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Time and Space complexity of MiniAES

I am currently doing my masters research on security of wireless sensor networks, the topic is "ENHANCING THE SECURITY OF WIRLESS SENSOR NETWORKS BY COMBINING GEOENCRYPTION AND LIGHT WEIGHT ...
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How to know which key was used for an AES encryption?

I am starting a project where several categories of sensitive data have to be accessed within a table. Based on his role, a user can see clear text columns (not encrypted), accessible columns (...
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How was AES Encryption cracked on my app?

I built an app that used AES encryption with 16 characters Key and IV. It seems it could easily be hacked, as someone did it in a day. I feel that I made a few mistakes Used key & IV which was ...
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Is an efficient integer factorisation algorithm a threat to security anymore?

Nowadays, private key systems like AES have replaced RSA. Even for digital signatures, people mostly use ECC, so even if an efficient integer factorization algorithm is made, would it be a threat to ...
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With AES-CTR does the block input need to be implemented as nonce || counter?

I am looking at an AES-CTR implementation (WebCrypto) and it takes an initialization parameter count which is an array of 16 bytes. It then asks you to specify <...
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Is this a provably secure scheme to encrypt a private key?

I got this idea to use the features of the one-time pad, an encryption technique that provably cannot be cracked, but this time applied to encrypt a private key. A possible application could be to ...
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Using AES to create a secured MAC

Considering public message M and private key K, would it be safe to create the MAC tag this way: $$MAC(M,K) = AES(m_1) \oplus AES(m_2) \oplus \cdots \oplus AES(m_n)$$ when $m_1,m_2,\ldots,m_n$ are n ...
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ECIES vs. RSA + AES

I am confused about the distinction between RSA and ECC (Elliptic curve) when it comes to encryption and would appreciate it if someone could confirm if my understanding is correct. When encrypting a ...
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Which AES mode when using Poly1305-AES

I am reading DJ Bernstein's paper on the Poly1305-AES mac (https://cr.yp.to/mac/poly1305-20050329.pdf). I understand that AES is needed to provide the array s. In its paper on page 5 we can read: ...
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Is a stream cipher and a (cryptographically secure) PRNG nearly the same thing?

If I let the authentification tag aside (which is important), encrypting with AES-GCM and a fixed key and nonce: ...
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Encrypt a big file in blocks with AES-GCM: how many nonce do we need?

I need to encrypt big files using AES-GCM, potentially 10 GB or more. For memory (RAM) reasons, I need to processs them by blocks (let's say 16 MB), rather than doing ...
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Why Abstract Algebra in Cryptography?

I come from an engineering background, but not from computer science or anything to do with pure math. I studied applied math in college--never abstract algebra, number theory, or discrete math, ...
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How to be able to change the password to access data encrypted with AES-GCM, without reencrypting?

Let's say you need to encrypt plaintext which is 1 TB big. You have a password pwd. This very classical AES-GCM process is ...
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Byte order in AES-CMAC test code

I'm looking at the AES-CMAC RFC and I found somehow counter-intuitive the way test vectors are used in the test code. Let's look at the key K ...

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