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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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-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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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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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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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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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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I'm getting 'CKR_WRAPPED_KEY_INVALID' error while unwrapping. How to unwrap an AES key as DES2 key? [closed]

First I wrapped an AES key using another AES key through AES/CBC algorithm. Then I tried to unwrap that AES key as DES2 key using AES/CBC algorithm by passing the key type as DES2. But while ...
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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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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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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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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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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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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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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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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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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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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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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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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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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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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)...
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How can we implement a PRF with 1bit input space and 1024bit output space using AES securely?

I'm considering an implementation of PRF $F:\{0,1\} \times \mathcal{K} \rightarrow \{0,1\}^{1024}$ with a key space $\mathcal{K}$ in particular with AES-128 in counter mode. Since output space is ...
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How are implementations of PRF and PRG via AES-CTR different?

I heard that AES-CTR can be used for implementation of PRF and PRG. What is the difference between these implementations?
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Can I Modified AES for enhaced security of WPA-2?

I have topic for my research paper is modified AES algorithm for enhaced security of WPA-2 , it posible ? what i should learn ? thanks
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What is AES subkey? [closed]

I saw the AES algorithm that at the end of algorithm the buffer that stored in the beginning of algorithm the encrypt/decrypt key. now is store the last subkey. What is the last subkey? Why do I ...
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How does AEAD guarantee authenticated encryption and plain AES does not?

This is a follow up to my earlier question. This is more out of curiosity in how AEAD (like CCM or GCM) works compared to encryption in other modes (like CBC or ECB). Suppose you have AES-256-CBC ...
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Asymmetric or Symmetric encryption

I'm currently looking into OpenSSL and its API and I'm not really familiar with cryptography. So I was looking at the example on asymmetric encryption of an envelope. And it says the message is ...
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Is using AES-256 with a key of less than 256 bits of entropy still quantum-resistant?

Encrypting with AES-256 is widely claimed to be post-quantum secure. But let's take a case where you use an initial key that has less than 256 bits of real entropy. In this example, let's work with a ...
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AES Encryption theory and calculation [closed]

(a) Briefly explain the following round transformations of AES Encryption. Please indicate if it helps diffusion or confusion or both. SubBytes ShiftRows MixColumns AddRoundKey (b) Suppose you are ...
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From where can i get complete AES encryption source code?

I have been searching many websites for source code of AES whether it is ECB, CBC, CTR or any other method but can't find any. Can anyone please help me in getting the source code? I have to implement ...
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Serpent vs AES,, theoretical security

In the lets-choose-the-next-aes contest in 1998, they chose Rijndael because of speed. Now, not taking speed into account, is Serpent more secure or not? Since it has 32 rounds (of course that's not ...
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How is the keystream actually generated in AES CTR

I've been trying to find out how the keystream in AES-CTR is generated, but I can't actually figure it out. Wikipedia and any other sites that "explain" it just say the nonce is padded with the ...
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Error propagation in CBC [duplicate]

I am doing an error propagation experiment with the CBC mode.I have encrypted a 100 byte text file with openssl. I made the 55th bytes of my encrypted file corrupted.As per theory the corresponding ...
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128 bit AES CBC bit flipping on second block

I have a 128 bit AES cipher in CBC Mode with the IV prepended to the message. I am aware of the security issues here, but that is exactly the point of my example. I would like to change the plain text ...
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MixColumns layer in the last round of AES [duplicate]

My prof said that the last round of the AES algorithm doesn't use the MixedColumns layer, yet this doesn't decrease security. If so, why the MC layer is used in the other rounds?
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AES CTR - Pause and resume encryption?

I am using AES/CTR/NoPadding to encrypt while downloading files in one of my application. The encryption is done along with downloading. When the internet is not available in the middle of downloading,...
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How to encrypt files using AES256-GCM cipher under Linux? [closed]

I'm struggling to implement AES256-GCM on a Linux machine to encrypt files outgoing to another party. We're usually exchanging files using PKI, but this particular party insists on AES256-GCM and ...
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aeskeygenassist with only one imm8

I'm analyzing a binary which for its AES encryption, its only calling aeskeygenassist once and for the last argument (imm8, the ...
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AES, is this method to say “The password you entered is wrong” secure?

(TL;DR at the end) Let's say the plaintext hello is encrypted with AES (CFB mode). I noticed that decryption works no matter the given password! Of course if the ...
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How does AES-GCM produce different ciphertexts, and how can the algorithm decrypt the values if they're random?

The title explains it. How does AES-GCM (or other modes for that matter) generate random ciphertexts per execution, and how does the algorithm decrypt a random value since the sender randomizes the ...
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AES-CTR key reuse attack with same IV and known plain text [duplicate]

this is from an IT Security exercise which my friend and me cannot solve. Given 2 AES-CTR stream-cipher encrypted files Same known initalizing vector Same (unkown) key Same 128bit Counter ...
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Run AES for 2 rounds

I am trying to figure out AES in two rounds with 128 keys. If I have a known plaintext and the ciphertext that comes from this procedure. I get another plaintext which is similar to the previous with ...
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AES Sbox with alternative polynomial

I've used the C++ prog I found on the web to generate the standard Sbox with poly 0x11b, and also modified it to use a lookup table of all the multiplicative inverses of the 256 values, which also ...