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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Countermeasures to prevent integral cryptanalysis against 4-rounds AES

Integral cryptanalysis against 4-rounds AES is practical (Security of the AES with a Secret S-box). I did two experiments in order to find the impact and remove the integral distinguisher of 4 rounds:...
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Is it possible to do a known-plaintext attack with this set up of AES CTR mode?

Is it possible to perform a known-plaintext attack to extract the key from AES byte encryption? The encryption is setup with the following two lines: ...
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Hash using AES and key 0

Consider the following hash function for a message x = x1||x2|| · · · ||xn: h(x) = Mn i=1 AES0(xi) = AES0(x1) ⊕ AES0(x2) ⊕ · · · ⊕ AES0(xn) where the key used in AES is k = 0. Can someone explain what ...
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Who said “32 round Rijndael” in the third AES Conference

This is a historical question. In the third AES Conference of NIST (AES3), April 13-14, 2000, New York, near the end of the conference, one representative for each of the last 5 candidates sit on a ...
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AES-CTR-MAC alternative

I have to send small (~10 bytes) authenticated messages over an insecure channel. I was thinking of an alternative to the "conventional" AES128-CTR-MAC, which will take 16 bytes for the CT and ...
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How to find a collision with a given prefix and a known key in an AES ECB symmetric block cipher?

I should be able to find a collision for a vulnerable hash function which uses AES ECB given a prefix, but I am unable to find a reasonable solution (besides brute-force attack). The hash function is ...
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Is it possible to find the key for AES ECB if I have a list of plaintext and corresponding ciphertext?

Assume I have a list of plaintext text and its corresponding ciphertext which was created using a specific key with AES in ECB mode. Can I recover that key? If, how big does the list of plaintext ...
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How secure would AES be with all round keys equal? [duplicate]

In effect the same 128 bit key is XORed at every round and before and after as whitening. Would it be 2^128? What are the dangers of such a naive key schedule and does AES suffer from them? Edit: ...
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157 views

Recovering plaintext from AES-128 given round key 10 and ciphertext

I'm working on an old CTF challenge where AES-128 was used on a 16 byte block. I have the round 10 key and the ciphertext. What techniques exist for obtaining the plaintext?
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Gate count for Ring-LWE

In one of my recent research, I need to compare the number of gates needed in Ring-LWE encryption to AES in the circuit model. For AES we can find some estimation like this site, but for Ring-LWE we ...
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301 views

How to get the datapacket from wireshark? [closed]

I have a pcap of my twitter traffic using wireshark. The cipher suite TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 method is used for for encryption data.. I have a tweet of 42 characters are traced in the ...
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Why does TLS 1.3 support two CCM variants?

One of the important improvements introduced in TLS 1.3 is the pruning of the many previously available cipher suites to only five secure options (for symmetric ciphers), that are each supposed to ...
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Does re-transmission really reduce security?

I am using AES with GCM and a colleague told me "Repeating a VCC with the same key and a different message reduces the security of the key." He did not have any additional detail to offer. What he ...
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210 views

Simulation of Chosen Plaintext Attack on CBC, Predictable IV with OpenSSL

I would like to simulate the CBC IV attack where the IV is predictable. It's described in the answer to this question: chosen plaintext attack on CBC, predictable iv (Only "Yes" and "No" are valid ...
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How to encrypt file with RSA and AES that anyone with RSA key can decrypt them?

How to encrypt a file with RSA and AES-256 that anyone with RSA key can decrypt them?.
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AES and DES - reusing the same round keys

Both DES and AES use key expansion to generate the round keys (for Feistel network or for the AddRoundKey operation). Each round uses a different key. Why do we need that? Why we cannot use the same ...
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261 views

Encrypting AES in ECB mode

I'm fairly new to cryptography and am starting to understand this weird art of Mathematics and theory. One thing I am trying to understand and do is encrypting a plaintext into ciphertext using AES in ...
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Is AES ECB good enough for key spreading?

My apologies if I get my terminology wrong - I am new to this stuff. I am writing a routine (in c) to encrypt plaintext. I am using TinyAES to perform a CBC on the plaintext and sending a (pseudo)...
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Perfect Nonlinearity of AES S Boxes

Can someone give a clear definition of what a perfectly nonlinear function is? Can we say that AES s-boxes are perfectly nonlinear and why?
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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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391 views

AES Mix columns bit example

I have been given a 4x4 matrix and each entry is an 8-bit long byte. I have been given the 4x4 matrix that I need to multiply each column by of the first matrix by. $$\begin{pmatrix}2 & 3 & 1 ...
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Does password length affect AES encrypt/decrypt velocity?

I'm implementing crypto in Node, following this article: https://lollyrock.com/articles/nodejs-encryption/ It defines: ...
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Encrypt multiple files with OpenSSL securely [closed]

I wish to encrypt potentially gigabytes of data on my pc, and I wish to be able to decrypt and use those files. However, I am a noob, so bear with me. My idea is to use ...
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Differences between Webcrypto (js) and Cryptodome.Cipher.AES (python) [closed]

I'm trying to understand the difference in output of AES decrypt (GCM mode) using Webcrypto and Cryptodome.Cipher.AES in python. ...
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AES - MixColumn transformation using the identity matrix

I'm analysing how different components of AES influence its security. However, I cannot find a good explanation to what happens if the MixColumn step would use the identity matrix. Intuition tells me, ...
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Combining classical attacks and quantum cryptanalysis

I'm regularly reading that AES-256 is secure against quantum computers because Grover's algorithm will only halve the key strength (i.e. "only" require $\sqrt{2^l} = 2^{l/2}$ operations instead of the ...
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Mixing block cipher modes (AES)

I'm trying to evaluate some changes to an existing codebase and one question that has come up is the block cipher mode. For legacy reasons we've been using AES in CBC mode, however it's unclear why ...
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Decrypting AES256-CBC with wrong encryption key

Using OpenSSL library is there any chance that decrypting AES256-CBC encrypted data with wrong encryption key will succeed without an error? Asking this because I have read somewhere there is 1/256 ...
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“Weak” implementation of AES-CTR?

Assume an instantiation of AES-CTR like in the following picture: Some details on the input-values for keystream generation: COUNT: a 32-bit value associated with ...
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How to Prevent Correlation Power Analysis Attack on AES?

Which techniques could be applied to AES to prevent these kind of attacks? I can just think of creating noise with a parallel process for random computation, so the signals have the combination of ...
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WebCrypto AES-GCM vs AES-KW for key wrapping

The Web Crypto API available in most browsers supports both AES-GCM and AES-KW for key wrapping. There are examples for AES-KW and AES-GCM performing key wrapping, and a popular live table indicates ...
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Variation on the ECB Penguin problem [closed]

So this is an age-old example of why encrypting images with ECB is a terrible idea, since the underlying pattern of the image remains the same. Referenced from: If you encrypt an image (AES), is it ...
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using a hashed IV for AES128-CBC

I would like to minimize the encrypted packet size. Is it possible to derive the IV from a non-repeatable counter? For example, take a 32 bit counter, hash it with a key (different from the AES key), ...
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How to do Hexadecimal multiplication in GF(2^8)

I'm trying to do a hexadecimal multiplication in GF(2^8). Now, I know the technique of shifting left the binary numbers in some cases, for example: 02 * 9E 0000 0010 * 1001 1110 you shift one time ...
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Practical quantum attacks on AES - Is AES-128 used in a block mode vulnerable to attack using quantum algorithms

Can Grover's (or similar) algorithm be used to attack AES-128 when used in cipher modes like CTR? It seems like the answer is no... Also I have a similar question for SHA256 when used for a MAC. It ...
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How we can calculate AES Inverse SBox?

I am trying to find out the inverse of and SBox, but in vain, I have seen multiple questions over StackExchange, But I cant be able to solve my issue. As in this question, How are the AES inverse S-...
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AES blocks with a counter

I would like to send small separate packets of data. I am thinking of using AES-128 or AES-256, and to add a counter as part of the plain text message. Some clarifications: Each message will be one ...
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461 views

Attacking AES128 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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AES without mode operation

i have field in database. ex: field name. this field maybe more than 16 byte. how to encrypt data more than 16 byte without cbc, etc? any function or another ways to do this?
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What is the shortest type of text encryption?

I have the following text that I want to encrypt with a password: "This is my secret password: 1234567890" encrypted with AES: SgAHzFc3vluxLqZuzZKg8dzhy918N41SUU1BfBXN8CoEDfVJ0R9hox8PT2jKYA== pass:...
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Vulnerabilities of AES method that uses MD5 to create the key

Are there security vulnerabilities given the would a user be able to access the original text and the encrypted text with AES using an MD5 as a key? In other words, if the user had both the original ...
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AES-GCM not using two keys

It is recommended to use different keys for different purposes, such as encryption and integrity protection. As I see it, AES-GCM only requires one key as input. Two different keys are then generated ...
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Why can't decrypt with OpenSSL if salt changed (for CBC and ECB)

A file encrypted with OpenSSL (with, for example, AES 256-bit mode CBC) using the Linux command openssl enc -aes-256-cbc -in texte -out encrypted_texte -k password ...
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AES-128 as compression function in Merkle-Damgard construction

Using a compression function $f : A × A → A$. A basic version given by: $W_0 = IV$ $W_1 = f(W_0, m_1)$ $W_2 = f(W_1, m_2)$ ... $W_n = f(W_{n-1}, m_n)$ $W_n$ is the output of the hash function, $...
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Does it matter how the IV and XOR are applied for a single AES-128 block?

I want to encrypt 128 bits of data. I understand the problem with ECB, so I generate a 128-bit Initialization Vector to use for encryption and send with the encrypted data. Is there a "best" way to ...
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Encrypting/Decrypting sensitive information for storage purpose

I want to store account numbers and routing numbers into SQL database, and i was looking for best way to encrypt/decrypt this sensitive information. After researching i found i can use symmetric (like ...
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Decrypting an encrypted aes 256 cbc text with random IV, decrypts the string [duplicate]

This may be a basic question but bear with me. I started encrypting a text with aes 256 cbc mode generating a random iv of 16 bytes and a key. ...
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357 views

Inverse MixColumns Operation of AES

I am aware that MixColumns is a mixing operation which operates on the columns of the state, combining the four bytes in each column. So we multiply our state with ...
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331 views

AES MixColumns Predefined Lookup 2D Tables and Rcon Predefined Lookup 2D Table

I need to have the a copy of predefined 2D table lookup for AES MixColumns when state is multiplied by 2 and 3, 9,11,13,14 and also the Rcon predefine table. I search it everywhere but I couldn't ...
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702 views

Is AES-CBC mode not secure against chosen cipher-text attacks even if the IV is not predictable?

I've seen questions where people have asked if AES-CBC mode is vulnerable to chosen cipher-text attacks if the IV is predictable. But is it guaranteed to be secure against chosen cipher text attacks ...