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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is it unsafe to AES encrypt using multiple modes?

Example: ...
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Which is more secure using a CSPRNG for a One-time pad, or AES?

In reading about the One-time pad it appears to need truly random key for the pad. Since true random values are not practical to generate this presents a problem (thus making One-time pad less ...
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Using AES-CTR as a PRNG

AES-CTR is not considered as a CSPRNG, why ? Is it unsecure to use it when a password is hashed with Argon2id to produce the seed to generate all random data needed for an end-to-end encyption system ...
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Pseudorandom numbers [closed]

Your boss at a security company wants your group to design a PRF whose input length is 192 bits and output length is at least 192 bits and uses keys of length 128 bits. But, you have other plans this ...
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AES vs RSA - Which is stronger given two scenarios?

Let's say we have some plaintext. Let's say that we encrypt this plaintext with a random 32 byte key using AES-256. Let's say that we also encrypt this plaintext with an RSA 2048 public key. If only ...
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AES encryption for repetitive small data packets

I'm trying to implement simple AES encryption for small data packets (8bytes, fixed length) being sent from nodes with very little computational resources. Ideally the encrypted data would be a single ...
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Client-Side Encryption for a small app

I'm designing a small personal journal web application for my wife. I'm a crypto newb, but I want her to feel secure knowing only she will have access to her journal entries. I am thinking of the ...
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Quadruple DES vs AES-128 security

I came across this question regarding the security of Quadruple DES (hypothetically DES done four times) in CBC encryption mode vs security of AES-128 in CBC encryption mode. What parameters help to ...
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Constant time multiplication in GF(2^8)

I am trying to implement AES in C; I would like to make it resistant to side-channel attacks but I can't implement the multiplication in constant time. My current code: ...
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7zip : Why does encrypting the same file with AES-256 not give the same output?

Using 7-zip 19.00, on Windows 10 1909, build 18363.592, I encrypted a text file with the contents "hello there" using AES-256 and the password "123". I did this two times, the exact same procedure, ...
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How can AES 256 be implemented in C?

I want to implement AES 256 encryption in a program written in C (using OpenSSL, which I have installed) which would accept a string or a .txt file from the user and encrypt it with a hash of a user ...
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Why we can't implement AES 512 key size?

Out of curiosity why we can't implement AES 512 key size? Please explain somehow i can understand! I'm not an expert.
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What will be appropriate AES padding characters?

I am completely noob in terms of cryptography and security. So I decided AES Cipher for encrypting my data. I pad my input data String with blank white spaces to fit it in multiples of my cipher ...
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Using HMAC with AES modes that do NOT require padding [closed]

I'm trying to use HMAC with AES modes that do not require any sort of padding. Although I am aware that modes like AES-GCM and ...
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1answer
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Can repeatedly encrypting a message with a secure cipher ever produce the original input like what happens in ROT13?

Lets say we have a message 'm'. We encrypt 'm' using a stream cipher or any other type of cipher with cryptographic security that produces an output equal in length to the length of 'm'. Then if we ...
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AES-256, CBC, plaintext length is multiple of block size: Does PKCS #7 padding weaken the encryption?

Of course, padding is superfluous when AES with CBC is used if you know that the plaintext length is a multiple of the block size. But does the padding precipitate a weakness in the encryption? ...
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DTLS vs direct use of AES. What are the threats unique for direct use of AES instead of DTLS?

For regular traffic in mesh network (between Internet of Thing devices) customer decided to use one of two options: DTLS PSK ciphersuite - DTLS based on pre-shared symmetric key or direct use of AES -...
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File encryption using per-user-encrypted shared key

So I'm looking to encrypt files using AES CTR, using a shared key that would be accessed via a per-user password. My two main concerns are: making sure that the algorithms in use are appropriate for ...
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AES/ECB vs AES/CBC for <16 bytes

AES/ECB is commonly considered "weak" to the point that some static analysis software identifies it as not secure and suggests using AES/CBC instead. The question is: what if size of ...
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Encrypting/Decrypting using RSA and AES; standards?

I'm looking for a standard way of encrypting and signing a message using RSA and AES. I understand that in pseudo-code the actions taking place are like this: Alice's actions for sending a secret ...
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how to Design an AES like block cipher with block length and key length equal to 64 bits

Design an AES like block cipher with block length and key length equal to 64 bits.
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Hash-Then-Encrypt or Encrypt-the-Hash?

My question is would it make any difference if I hash a block of data and then encrypt it using RSA is most secure to do the reverse? The question is about Site-To-Site transmission where the ...
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Construction of a “simple”, nothing-up-my-sleeves, provably KPA resistant symmetric cipher

Why is AES secure? Apparently there is no answer - Why is AES resistant to known-plaintext attacks?. With this in mind, one would obviously want a cipher that is mathematically provable to be ...
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Text encrypted with key1, key1 encrypted with key2, meaningful?

Simplified Question Does it make sense from a security / cryptographic standpoint to encrypt a text in the following way: create only one AES key K_Azure create ...
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What is the difference between key size and block size (for AES)?

We are working on AES and want to develop a website which should provide an encryption facility but we are not understanding the difference between key and the block size. More appropriately what does ...
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Is there a way to change encryption scheme from AES to FHE without data leakage?

So let's say that we have encrypted some data using symmetric encryption in this case AES. And we want to change it to homomorphic encryption but without decrypting the data and encrypting it again ...
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Verification of data on an untrusted remote storage server

I was looking at tahoe-lafs which accepts a file, encrypts it, does erasure coding on it which generates n shares and then distributes it over the storage servers. The distribution is Share 1 = Server ...
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Is precomputing AES-CTR key stream secure?

Q0 : Is the precomputed key stream vulnerable to side-channel attacks like a lookup table for exemple ? I don't think it is because a lookup table is accesed very often, that's what makes it non ...
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I do many searches but can't find any explanation about “AES analysis using entropy”

I found this scenario in CRYPTOOL2 templates but there is no explanation how entropy is used. There is just a short description "This template shows how to use a brute-force search to attack an ...
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Looking for a way to enlarge a message so that any modification to the “enlarged” message makes recovering the original message impossible

Let's say we have a message m of small size. I am looking for a system $S$ so that $S(m)$ is arbitrarily large, we can easily compute the inverse $I(S(m)) = m$, and any modification to $S(m)$ makes it ...
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Alter plaintext through IV in block cipher AES in CBC mode

IV: 69bb375aa919c72aa561dd7b7ffacf66 Ciphertext: "c28ea025d10186510855d083747d6435c808d9857075abd9bfc54b094e60eaf3" Plaintext: "SEND ENCRYPTED DATA" I want to be able to change the resulting ...
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Find IV and the key ? AES with CFB or OFB

I have a question about the AES-128 and AES-256 encryption method. I need to encrypt 64-bit size data in and out. I want to encrypt them with AES. So I turned to AES-OFB or AES-CFB because these ...
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Content Key Encryption for Multi-User data access

I recently worked out a concept for a use-case, but I'm not sure if my approach is good enough. So I would appreciate feedback and things to look out for, as I'm fairly new to this field. A User can ...
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RCON for AES 192 and 256

This is question about how many RCON values are used in AES 192 and 256. I read the NIST Publication introducing AES and in Appendix A.2 and A.3 (Key Expansion for 192 and 256-bit keys), only $rcon_1$ ...
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The Security of AES-N-GCM

In the paper The Security and Performance of the GaloisCounter Mode(GCM) of Operation,it shows the AES GCM SECURITY in Corollary 1. there are no distinguishing attacks against AES-N-GCM that work ...
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When will AES be “upgraded”?

AES is secure, but compared to other encryption algorithm which are marked as secure, it's slow. For example, ChaCha20 is faster than AES, but still secure. Also other standard-algorithms like SHA ...
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Which cryptographic attacks can AES 128-bit withstand?

Most of the articles and forums are stating that the Brute Force attack can test the strength of an encryption algorithm. However, I am looking for those attacks that AES can withstand for the testing ...
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Frequency Analysis on DES, AES, 3DES using Cryptool2

I am trying to analyze symmetric block ciphers like DES, 3DES and AES, using Cryptool 2. I want to do a frequency analysis on each of these ciphers, in order to comment whether this is an effective ...
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Any white-box cryptography for asymmetric-key? What is the latest status of white-box cryptography?

I am learning white-box cryptography. So far, I find the following historical research or implementations, for examples: Published white-box AES algorithms E.g., Chow's WB AES and WB DES (2002), WB ...
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Authenticating and encrypting data for an automated system

I wish to distribute a file from A to an automated system B. The requirements are: Contents are encrypted Contents are tamper proof Contents origin is verified To do this I have devised the ...
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The security effect caused by an MDS matrix in word-oriented designs

Considering a design where the MixColumns operation of AES is replaced by a lighter MDS matrix where by the term lighter we mean the number of required XOR to implement an MDS matrix. As you know ...
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Is AES without T-Tables nor S-Box resistant to side-channel?

T-Tables and S-Boxes are prone to side-channel attacks, is an implementation without any lookup tables resistant to side-channel ? In this answer, https://crypto.stackexchange.com/a/63520/80926, the ...
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Is there a point to having a large IV in AES

I've always known that the IV should be 128 bits, because that's the block size of AES, regardless of the key. However, I just saw one vendor advertising AES-256 with a 256 bit IV. Is there any point ...
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Proper way of encrypting large files with AES-256-GCM

I would like to encrypt and decrypt files with AES-256-GCM. I need a solution that works with Java, PHP and JavaScript. In practice, users can upload, download files via web browser and/or desktop app ...
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Is AES S-Box resistant to side-channel attacks?

I know that implemntations with T-tables such as Golang's are prone to side-channel attacks, but is AES's S-Box wihtout any additional table also insecure ?
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Encryption with Web Crypto API (SubtleCrypto)

I want to end-to-end encrypt items in a stateless environment. These items have an identifier (random string). Now I want to add encryption by adding a random key. The URL could be ...
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Is AES ECB mode with salt and frame counter still comparatively weak?

Many advice against using AES in ECB mode as it always produces same cipher text for a given plain text. That shortcoming can be addressed by using salt appended to original message so that the ...
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How convert Point on Curve into AES key?

I'm playing around with ECC, trying to encrypt traffic between my webapp and backend (its not a product, im trying to learn and understand more about ECC) I managed to generate keys, successful run ...
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Why cant we use AES to hash a password, instead of a hash function?

AES needs a key in order to work, hashing-algorithms do not. Suppose we have a fixed key for AES, why don't we simply hash our keys with that? As with hash functions, AES has arbitrary input size, ...
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Is ShiftRows(SubtBytes(x)) = SubtBytes(ShiftRows(x)) the same for the same entry : in AES

Is ShiftRows(SubtBytes(x)) = SubtBytes(ShiftRows(x)) the same for the same entry : in AES It seems like these two are equal, can someone explain in theoretically?

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