Questions tagged [encryption]
Encryption is the process of transforming plaintext using a cipher into ciphertext to make it unreadable to anyone except those possessing the key. Decryption is the process of transforming that ciphertext back into plaintext, using the key.
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Can someone help me decrypting that one? [on hold]
Hello I need help to decrypt that one code. I can't find a solution I only know that is from QR code.
enc:...
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0answers
22 views
DSA signature creation using hash oh the message
I am trying to understand how i can create DSA signature. the arithmetic uses H(M) and it is given a random nunber for the hashing result.( written- lets assume it is 121). Is the number really random ...
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Cryptography RSA 2048 using Cryptowall 3.0 software [on hold]
Help me please to decrypt an encrypted file by persistent cryptography RSA 2048 using Cryptowall 3.0 software.
david.guermonprez88@gmail.com
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Creating a login system [migrated]
I am working on a project where users create a one time use account in a uwp app, then those credentials are entered into a website, where they are used to grant access to a one time use link, then ...
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Is there any stateless authenticated and encrypted communication protocols?
It's like TLS but stateless. In TLS, a handshake is established in at least one round for the key exchange. Thus TLS is stateful.
Suppose we want to have an authenticated and encrypted communication ...
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1answer
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How can I implement the “Multiplication Modulo” and “Addition Modulo” operations in IDEA?
I am currently working on IDEA (International Data Encryption Algorithm), and I don't know how to perform Multiplication Modulo and Addition Modulo.
This is how IDEA operates:
IDEA operates on 64-...
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45 views
Diffie-Hellman exchange problem
I am having trouble to solve this Diffie-Hellman Key Exchange Problem.
Imagine you are sniffing the communication between Carl and David. You are getting the
domain parameters $p$ and $g = 5$ used ...
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29 views
How secure is pdf password protection? [migrated]
I'm assuming PDF password protection uses encryption. How secure are the methods used? Can it be easily cracked or is it more in line with modern GPG encryption in terms of strength?
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2answers
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Choosing a Random Number Generator algorithm to encrypt a message
What are the best cryptographically secure pseudo-random number generator algorithms, and what are their strengths/weaknesses? I can't seem to come up with a list of them (or maybe I do, but they ...
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1answer
32 views
Combining secret/public keys
Suppose that we have three authorities which each of them generate one secret/public key for Alice. It means that Alice has three secret keys and three related public keys. Suppose that Alice combines ...
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1answer
62 views
Attacks on one-time pad, given a property of keys
An adversary $A$, eavesdrops $n$ cipher-texts, $c_{1}, c_{2} ..., c{_n}$. It also knows a value $v$ and a function $f$ such that $$f(k_{1}, k_{2}, ..., k_{n}) = v$$ where, $k_{i}$ is used to encrypt $...
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2answers
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Mutual keys protection/wrapping
Is there a known risk in having two keys wrapping each other?
Let's say, an adversary has access to both AESkey1(key2) and AESkey2(key1).
Does it make it much easier for him to recover the keys?
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1answer
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El Gamal Signatures, Need help explanining a step, Where does the “775” come from? Image included
I understand all of the previous steps, but I don't understand what is happening to "S2" in that the number "775" showed up.
Where does the 775 come from? I can't seem to get it, and I've tried ...
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1answer
61 views
RSA exercise with known $n$ and $e$
Bob decides to use $n = 697 \rightarrow 17 × 41$ and $e = 33$ as his public key for an RSA cryptosystem.
Show that the decryption exponent is $97$.
Find the encrypted form of the message $17$.
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1answer
133 views
RSA encryption/decryption process is not working correctly
I'm trying to apply the RSA cryptosystem to encrypt a byte M=72, using predefined modulus n, public key exponent ...
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1answer
75 views
Computational Complexity of SHA-3 (SHAKE128)
Please, I got the question "what is the computational complexity of SHA-3 (SHAKE128)"?
What does that mean and how can I calculate that??
*I am using SHA-3 (SHAKE128) in my mechanism to hash fix ...
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1answer
110 views
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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What is the key to these encrypted messages? [closed]
So I'm trying to reverse engineer a lock system that consists of a chip reader and a control unit.
There are only two devices on this network, the reader which reads a rfid like chip and the control ...
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1answer
31 views
The goal, the method, and the interface of the signcrypt primitive.
Some time ago, I proposed making the site more educational by teaching correct cryptographic programming. The proposal had had somewhat good reception, but was met with cold ice as there had been ...
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1answer
41 views
Hash Collision Probabilities
Please give help! how can I calculate the probability of collision? I need a mathematical equation for my studying.
Assume, I am using SHA256 to hash 100-bits. Thus:
SHA256 {100} = 256-bits (hash ...
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2answers
76 views
Ring Signatures: Why is the combination function easy to solve?
I'm reading Rivest's How To Leak A Secret and am on the part where they describe their signature scheme ("Generating a ring signature").
Why is computing $C_{k, v}(y_1, ..., y_r) = v$ easy? The ...
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0answers
28 views
Decode a cypher generated by a digit sum algorithm [closed]
I have an algorithm that encodes a number with following rules: -while number has more than one digit, algorithm finds the sum of its digits (e.g. 38 -> 3 + 8 = 11 -> 1 + 1 = 2) -then algorithm ...
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1answer
76 views
Prove that some Cyphertext C encrypts some plaintext D
I have a Paillier Cyphertext C and a counterparty that controls the keypair that was used to encrypt the data D to arrive at C.
How can they prove to me that the Cyphertext C is actually the ...
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1answer
46 views
What does universal look like? What is the complexity(size/depth) of universal circuit
I was reading a paper about attribute based encryption. The authors showed that ciphertext-policy ABE can be constructed from key-policy ABE using universal circuit. But the universal circuit should ...
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2answers
745 views
How Can I decrypt this VNC Authentication handshake?
I'm trying to analyze a mobile application and I believe it is is using DES. Here is a sample of the authentication handshake.
...
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1answer
42 views
Format of hybrid crypto envelope structure?
From posts including the accepted answer to
How to encrypt file with RSA and AES that anyone with RSA key can decrypt them?
hybrid crypto (AKA envelope encryption) a GPG-encrypted file has an ...
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1answer
42 views
Send content to owner of gpg public key, nested content symmetric encryption
If I want to encrypt a text content file using a symmetric algorithm like AES,
is there a standard format gpg will expect, where it can detect a symmetric key (encrypted with recipient gpg public key ...
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2answers
674 views
Determine AES key given encrypted and unencrypted files
Given an encrypted file, the original unencrypted (cleartext) file, and knowledge of which AES encryption algorithm was used, is it possible to determine the key that was used to encrypt the data in a ...
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1answer
3k views
How long does a good AES encryption take?
I am encrypting large file sizes (>1GB) using AES encryption with a key size of 256 and over a 1000 hash iterations. To make the program memory efficient I'm reading the file from the stream, chunk by ...
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67 views
IDEA (International Data Encryption Algorithm)
I don't know how to perform Multiplication Modulo and Addition Modulo in IDEA (International Data Encryption Algorithm).
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1answer
96 views
Rapid partial block decryption of compute intensive full encryption
Given a block of data D: Is there a encryption/decryption scheme that would allow me to perform a resource-intensive (compute/time/memory) encryption of the full data set with a key k, but allow for a ...
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1answer
38 views
RSA limiting down the possible values for $n,q$, and $d$? given only $e$ and $p$ [duplicate]
Suppose someone forgot the value of $n$ and you only knew the values for $e$ and $p$. How could one go about limiting down the possible values for $n,q$, and $d$?
I'm thinking to try and solve $\gcd(...
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1answer
35 views
Decrypting a vigenere cipher with a reused one-time pad
I understand that when a plaintext is encrypted with a key of the same length, it is referred to as a one-time pad. Now when this key is reused to encrypt another plaintext, there is potential for ...
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1answer
737 views
Rainbow tables and blowfish
I'm thinking of implementing rainbow tables for a specific blowfish problem, but I have trouble thinking of the proper way to apply the original paper (and its application to hash functions) to ...
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5answers
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Why are primes important for encryption
Why are primes so important? Why can't we just use a random number?
My guess is that it's because finding a random prime require more computing power, than finding a random number. Can anybody confirm ...
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1answer
116 views
Performing a dictionary attack on RSA/ECB with no padding
I have the exponent $e=2^{16}+1$ and modulus $n$ (154 digit number) of an RSA public key along with the ciphertext (64 bytes) encrypted using the same key with RSA/ECB and no padding.
I am required ...
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1answer
57 views
Is it a cryptographic risk to share the same encrypted data over and over again?
Regular scenario
Let's say I have secret files which I will encrypt. The resulting container will be shared and might be intercepted. Not good, but that's okay - that's why I encrypted the data in ...
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3answers
49 views
For elliptic-curve cryptography, does a 256-bit key imply that $x$ and $y$ are each 256-bits or 128-bits?
In the wikipedia article, the claim is made that "256-bit elliptic curve public key should provide comparable security to a 3072-bit RSA public key". Since, in ECC, the public-key consists of a point $...
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1answer
82 views
Is it common we extended Key size to 512 bit in AES Algorithm? [duplicate]
is it common , we increase key size to 512 Bit in AES Algorithm?
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Is a Diffie-Hellman shared secret with a private and public key from the same ECSDA pair considered less secure? [duplicate]
If I generate two public / private key pairs using ECDSA - pair A and pair B.
Using Diffie-Hellman, a shared secret X is generated using the public key from pair A as the public base and the private ...
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0answers
24 views
Verifying the encryption cipher used in Kleopatra [migrated]
I'm in the process of rolling out Kleopatra and wanted to verify the cipher being used. In Kleopatra, under "GnuPG System > S/MIME > use cipher algorithm NAME", the option is set to AES. Is this the ...
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1answer
49 views
is there a way to specify the encrypted message length when using private and public keys?
is there a way to specify the encrypted message length when using private and public keys? mainly I want the encrypted message to be 32 bytes? as I'm currently using RSA but that results in a length ...
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0answers
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Hide the ID of confidential transactions in blockchain networks
For a confidential blockchain, suppose there are three people which join a series of transactions. To hide the number of transactions among them, they need to do some dummy transactions. Suppose the ...
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0answers
62 views
Proof that CBC mode is not IND-CPA with predicable IV [duplicate]
How can you prove that CBC is not IND-CPA secure if the IV is implemented as a counter starting at 0 and increasing by 1 each time?
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0answers
13 views
Validation of content in encrypted value
Does anyone know if there is a way to (on a very basic level) validate the content of an encrypted value?
I have a string value that is encrypted
I know that the content of the encrypted value should ...
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1answer
289 views
Security of AES after key expansion 4-MB with ECB and CBC
My question is,
how does the security depend or change if I encrypt with AES-128 in total 4-MB of Data?
With Electronic Code Book Mode and
Cipher Block Chaining Mode ?
Does an adversary still ...
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1answer
124 views
Revealing vote after time
Imagine we have 5 different parties, all of these parties test if a particular thing is true or false over the course of 24 hours. The network needs to come to a consensus about the majority outcome ...
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1answer
81 views
In a TLS 1.3 connection, how do the client and server choose a mutual cipher suite?
According to KeyCDN, TLSv1.3 connections are established in a single round trip:
While TLS 1.2 requires two round-trips to complete the TLS handshake, 1.3 gets the job done in just one trip
If ...
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1answer
63 views
Is the scheme $(r, Mac_k(r) \oplus m)$ CPA-secure?
I honestly admit this question is taken from a h.w assignment:
Prove or refute: the following encryption scheme is CPA-secure: Let $(\text{Gen}, \text{Mac}, \text{Vrfy})$ be a secure MAC with tags ...
3
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1answer
75 views
Can perfect forward secrecy introduce vulnerabilities?
Is it always a win or could PFS algorithms introduce new attack vectors or weaken the level of secrecy vs not being used?
