Questions tagged [symmetric]
Symmetric cryptosystems assume two communicating entities share a pre-established secret key.
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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 ...
2
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1answer
47 views
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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1answer
63 views
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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1answer
77 views
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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23 views
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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42 views
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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0answers
47 views
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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1answer
31 views
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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27 views
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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1answer
100 views
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 ...
3
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2answers
608 views
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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1answer
37 views
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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1answer
39 views
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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2answers
81 views
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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1answer
69 views
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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1answer
228 views
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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2answers
77 views
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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1answer
42 views
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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2answers
156 views
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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3answers
75 views
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 ...
2
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3answers
636 views
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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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 ...
0
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1answer
47 views
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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1answer
72 views
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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3answers
8k views
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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49 views
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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2answers
78 views
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 ...
0
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1answer
71 views
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 ...
2
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1answer
40 views
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 ...
2
votes
1answer
58 views
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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0answers
871 views
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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1answer
58 views
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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0answers
27 views
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 ...
2
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2answers
204 views
How does a key actually work in symmetric ciphers
My sky-high level understanding of modern cryptography is as follows: There is an algorithm and a key. The key or key pair is a randomly generated number (I think). The algorithm describes ...
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0answers
33 views
Security reason for introduction of PCI Key Blocks [closed]
MAC and encryption keys used in financial transactions have always been stored encrypted as cryptograms (of same length) on ostensibly unassailable hardware devices using 3DES. Now the requirement is ...
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2answers
94 views
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
...
2
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4answers
258 views
Why use symmetric encryption with Public Key?
A. From what I heard (and I am beginner at a security/cryptography), if you have a payload that is very large, asymmetric is a no-go.
B. Also, if you do have secret symmetric (e.g. AES) keys, you ...
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1answer
43 views
Commitment based on authencticated encryption
Let $(E,D)$ be the encryption/decryption of an authenticated encryption scheme. Consider the following commitment scheme.
Generate a random key $k$. Commit to $m$ by sending $c=E_k(m)$.
Reveal $m$ by ...
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1answer
39 views
Is it possible to execute elliptic curve encryption on small sensor-tags CC2650?
I am working on a project wherein ECC needs to be implemented on small devices, namely, CC2650 sensor-tags for authentication. The ECC implementation should be on Contiki OS. I have read some articles ...
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1answer
71 views
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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0answers
38 views
Lightweight provably secure design [closed]
Is it possible to device lightweight (i.e. without asymmetric crypto and PKI; and without third party Trent) provably secure (in the exact security sense) scheme? Were there any attempts? Is it ...
0
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1answer
55 views
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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1answer
81 views
How is Shamir's Secret Sharing better than this simple 2-password technique?
I'm looking for a solution to protect a message, such that both password1 (usually given to trusted person #1) and password2 (...
1
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1answer
217 views
Are there any other highly trusted and secure symmetric encryption algorithms besides AES?
AES is the gold standard for symmetric encryption. It is highly trusted and highly secure. Do any other symmetric ciphers - besides OTP - come close to AES's usability, security, trust-ability?
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1answer
51 views
Is it possible to narrow down the possible keys used for AES CBC encryption, knowing a given plaintext and its ciphertext, where IV=0? [duplicate]
I'm brute forcing a ciphertext with a given dictionary to figure out which key was used. However, it's been hinted at that there is a way to narrow down the dictionary to a smaller subset of ...
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4answers
939 views
Why do one-time pads not provide message authentication?
It is often said that one-time pads do not provide message authentication. But, if you and I have a one-time symmetric key, and I send you a message, and it is not complete gibberish, is that itself ...
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2answers
683 views
Is it possible to identify a Serpent encryption key in memory?
It has been shown that AES keys that are in use can be identified in memory. This identification relies on discovering expected round keys in memory that are contained within the key schedule.
My ...
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0answers
72 views
Extracting RC4 and 3DES keys from system memory
I have read papers [1], [2] that have presented techniques on extracting symmetric encryption keys from memory during the process of encryption. There are tools [3] that can extract AES keys from ...
2
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1answer
125 views
Key derivation for AES-GCM using HKDF?
I have a system comprising N >1000 nodes. At each node I would like to use HKDF to derive a unique 256-bit key, Kn (for the nth node), from a pre-shared master key, K0, and a locally-generated random ...
2
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1answer
121 views
How does gpg know what cipher algorithm is needed for decryption?
I am using gpg to make encrypt a tar.gz.
My first try uses --verbose --symmetric and then the decryption is done with ...
