Questions tagged [symmetric]

Symmetric cryptosystems assume two communicating entities share a pre-established secret key.

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Why can a symmetric encryption algorithm be considered a pseudo-random number generation algorithm?

I have a question from my teacher: "Why can a symmetric encryption algorithm be considered a pseudo-random number generation algorithm? Can anyone explain it to me? And sorry if my english is not ...
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Symmetric versus asymmetric self encryption

I can encrypt my files with a symmetric encryption algorithm like AES, or with an asymmetric encryption algorithm like RSA or ECC (I encrypt my files with my own public key). No communication is ...
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Explaining Chaotic Cryptography

I will venture myself into studying chaotic cryptography. However, I find it hard to explain what chaotic cryptography entails to those that have some knowledge of cryptography. Neither can I explain ...
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Encrypt symmetric session key with asymmetric or symmetric master key?

Every day, I must backup my server's files, encrypt the backup, and upload it to untrusted cloud storage (dropbox, s3, etc.) I've spent time on security.stackexchange where I discovered the typical ...
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Testing speed of symmetric vs asymmetric encryption and decryption using gpg

I'm aware that symmetric is faster than asymmetric. I want to test this, but my (obviously incorrect) tests show the reverse. Symmetric test: ...
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Encrypting multiple small messages with a single reused symmetric key

What is a good way of doing this? Practical and Secure. This is for a browser environment. For example, let's say there are a few 100 independent messages of about 100 characters each that you want ...
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How Secure is gpg Command Using Symmetric AES-256 From Being Cracked

How secure is any data encrypted using the following command: gpg -o *encrypted_output_file_name* --symmetric --cipher-algo AES256 *file_to_be_encrypted* Can ...
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Security of key bits under indistinguishability for randomized encryption

My question is about symmetric randomized encryption. Let c=E(k,m,r) be a randomized block encryption function where r denotes a random input chosen for each message block m. k and c denote the ...
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Which is the best algorithm for large scale file encryption other than AES?

I've been looking for a fast, powerful and robust algorithm for encrypting large files with authentication . I would like to implement the algorithm on my own without using third party software. I've ...
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Encryption with 2 symmetric keys and decryption with one key

Here is my use case: I need to keep encrypted data in Hadoop. The data is encrypted with symmetric key that is being changed every half a year. When data is retrieved it should be decrypted. Lets ...
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Does ChaCha20/Salsa have the same bit strength as AES for identical key sizes?

Does ChaCha20/Salsa have the same bit strength as AES for identical key sizes? In other words, does ChaCha20 with a 128-bit key theoretically require 2^128 attempts to brute force, as with AES-128? ...
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Can a message and one time pad each encrypted with separate ciphers be weaker than the stronger of either cipher?

Assume you have: A truly random one time pad, $P$ A plain text message, $M$ Two symmetric ciphers, $C_S$ and $C_W$, where $C_S$ is always more secure than $C_W$ Assume the keys have already been ...
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How is the key shared in symmetric key cryptography?

Symmetric key cryptography is an encryption system in which the sender and receiver of a message share a single, common key that is used to encrypt and decrypt the message. Is the key public or it is ...
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Research Question (Part 2): new symmetric key cryptosystem

A few weeks ago I asked about a new symmetric cryptosystem discovered as consequence of some new mathematics work (link here). As per suggestion of commenters, I spoke with a cryptography professor, a ...
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Estimating the probability of success of a Turing-Welchman attack on an enigma machine as a function of the length of the crib (known plaintext)?

Could anyone please tell me how to to Estimate the probability of success of a Turing-Welchman attack as a function of the length of a crib (known plaintext)?? for example we have the : plain text=...
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Role of session identifier in Otway-Rees protocol

According to Wikipedia, Otway-Ress protocol is as follow: The protocol can be specified as follows in security protocol notation, where Alice is authenticating herself to Bob using a server $S$ ($M$...
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Comparison of end-to-end encryption and TLS

I am writing a comparison paper about security of electronic communication and I want to compare end-to-end encryption and TLS by giving two examples such as Whatsapp and Facebook Messenger. However, ...
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Another cut-and-paste attack on CBC mode

I am trying to see specific cases of attacks in the CBC mode, in particular, I am investigating some attacks such as Example of a cut-and-paste attack on CBC. Here I have posted something similar and ...
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Are the signcryption and the authenticated encryption same?

The signcryption and the authenticated encryption are both the combine of encryption and authentication with three natural composition (i.e., EtS, StE, E&S). I am not sure that if they are the ...
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Is the encryption more secure if we apply Pohlig-Hellman cipher twice with different keys but with the same modulus?

To encrypt a message $M$, we compute $C=M^k \bmod p$ and to decrypt a Cipher-text we compute $M=C^{k^{−1} \bmod (p−1)} \bmod p$ But if we use Pohlig Hellman twice like $C_1=M^k \bmod p$, and then $...
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Can symmetric crypto system with counteably infinite message space be perfectly secret?

lets say we have a countable message space for example set of natural numbers then can we have a cryptography system that information-theoretically (Shannon or other equivalence definition) be ...
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Probabilistic Symmetric Key Generation

Here is a brief description: We have two parties, Alice and Bob. Each party must choose either a positive key or a negative key. Subsequently, Alice will generate a 0 or a 1 at random and send it to ...
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Research question: usefulness of newly discovered symmetric key cryptosystem

both myself and my collaborators are pure mathematicians with only tangential experience in the study of cryptographic systems, so if this question is unclear or does not belong here, please do let me ...
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Decrypting data on client side for use inside program

So I am developing a python program and encrypting the trained machine learning models which need to be decrypted when loading them on client side. My program will deployed on the client's machine ...
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Why encrypt symmetric keys first with RSA and then the private-key with a PW?

In for example the Microsoft Encrypting File System, the SYM-Key is first encrypted with a RSA-Pub-key and its corresponding private-key is then encrypted using a users password. Why not encrypt the ...
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Advantages of encrypting a symmetric key with a public key vs using a fixed symmetric key

I am new to cryptography concepts. I am trying to protect some firmware download. Reading some Wikipedia pages, I understand that asymmetric cryptography is time consuming, so, if I want to protect ...
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Non-derivable public key asymmetrical encryption? [duplicate]

The need we have is to pass encrypted messages but such that the encryption key can't be generated from the decryption key. This sounds like with vanilla asymmetrical crypto I know, but in every ...
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I have a new cryptography algorithm, what should I do?

I created a new, unknown symmetric encryption algorithm. It looks like it's very fast and can be useful. I'm kind of independent researcher, hobbyist. Since years I'm interesting in Collatz problem ...
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Is there any existing cipher capable of scaling from a 1 bit key up to a one-time-pad?

We have ciphers that handle small amounts of entropy, such as a 256 bit key for AES; and we have one time pads for enciphering 1:1 entropy, such as a 1GB key for a 1GB file if you could ever harvest ...
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Why is it difficult to encrypt large amounts of information using quantum key distribution?

An article last month claimed that Toshiba Corp. and Tohoku University recently broke the record for the amount of data encrypted using quantum key distribution by transmitting "a few hundred ...
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Forward Security of Symmetric Encryption Schemes with LFSR based PRNG

Forward security can be achieved using symmetric encryption schemes by combining with a pseudo-random number generator (PRNG). Does LFSR based PRNG provide forward security in this case?
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Why probabilistic syntax for encryption schemes?

In Foundations of Cryptography II, Goldreich, the basic mechanism of encryption schemes is written as follows: Definition 5.1.1 (encryption scheme): An encryption scheme is a triple, $(G,E,D)$, of ...
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Example of a cut-and-paste attack on CBC

I am reading the cryptography book by Stamp and there is a cut-and-paste attack on $ECB$ and this is easy to follow because $ECB$ is relatively simple, the problem is that I would like to see an ...
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How does the key agreement process take place in Virgil E3Kit SDK for end to end encryption?

I'm using Virgil E3Kit SDK to implement end-to-end encryption in my App. Their E3Kit SDK is very effective and not too hard to understand, but I still don't understand how does the key agreement ...
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Is 128-bit security still considered strong in 2020, within the context of both ECC Asym & Sym ciphers

Given that much of our ECC crypto primitives provide “only” 128-bit security when defined over a 256-bit curve due to pollard-rho, is it then still safe in 2020 to consider 128-bit security safe for ...
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PCI - Limit Key Injection Capabiltiy 3DES + DUKPT

Current Context: I'm using a Triple DES with a DUKPT Key Management Approach. I have two organization which have access to the BDK Key: Orgzanization 1 which acts as the Secure Decryption ...
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Is there any encryption system where the sender cannot prove that a specific ciphertext belongs to a specific plaintext

I'm trying to create a message-transfer system where The encrypted messages are stored in a public database. It is possible to verify who is the sender of this message. The sender cannot prove to ...
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The magic box puzzle: How to implement a verifiable self-contained secret system?

Imagine we have a magic box that will open only if we pronounce the secret words. Everybody at the beginning of the game have some verifiable proof of the correct secret words. During the first phase ...
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After ECDH with Curve25519, is it pointless to use anything stronger than AES-128?

Is the following reasoning correct: After ECDH with Curve25519, the resulting shared secret will be an EC public key with a bit strength of 128 bits. This public key would then be hashed (let's say ...
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I need two types of easily crackable asymmetric and symmetric encryption

I have a school project in which I'm comparing asymmetric and symmetric encryption. I need two different types of easily crackable encryption, one symmetric and one asymmetric. I am planning on ...
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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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WEP - shared symmetric keys

I know that WEP uses stream cipher encryption. The key stream = RC4(IV, K). My question is: The shared symmetric key is the same for all users? Or each user has it's own symmetric key. Also, how can ...
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What's the utility of the last two messages of Needham Schroeder Symmetric key protocol

The protocol works like this But I can't understand what's the utility of message 4 and 5, what do they protect from? They do not protect from replay attack if Ks gets compromised because B won't be ...
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Randomly initialised global counter used to encrypt the kth message with IV = IV + k mod 2^n

The use of an increasing IV is not secure for a block cipher. That is, using a random IV for the first message then IV + 1 for the second , IV + 2 for the 3rd etc. How can I construct an attack to ...
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Two possible plaintext's using OTP decryption

I am using this cipher-text c = 04 10 12 00 01 08 67 0A 19 65 0F 03 0A 00 with two possible keys ...
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CAESAR finalists: Lightweight case (Ascon vs ACORN)

The Ascon cipher has been selected as the first choice in lightweight case and ACORN as the second. However according to Face-off between the CAESAR Lightweight Finalists: ACORN vs. Ascon paper, the ...
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Is Googles Envelope Encryption the same as Hybrid Encryption?

Google is advertising the use of Envelope Encryption in their products with their KMS. By the description, it sounds very much like Hybrid Encryption. But since I could not find any reference to ...
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Does encrypting the key with itself make it easier to crack the ciphertext? [duplicate]

As the title states; Is there any risk from encrypting the key with itself? EG. $C = AES(K=K, M=K)$ I'd assume not; after all, how does having the key for a safe inside the safe make it easier to ...
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Why isn't there a final permutation on SPN-based ciphers?

I am doing some research on differential cryptanalysis. Most people who are familiar with that cryptanalysis technique do know the tutorial from Heys (Heys Tutorial). I came currently to the question, ...
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Symmetric key crypto secure communication infrastructure

Imagine that public-key crypto stops working. Are there any academic proposals out there that would explain how we could implement commercially viable secure communication based on the current ...

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