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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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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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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
92 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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Anyone here who can help me to solve these questions? [duplicate]

Please, i need the answers of below questions.
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What is the key to these encrypted messages? [on hold]

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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Please help me to slove below questions, i know its bit childish but someone solve this for me. Please [on hold]

Please help me help me. I would appreciate if someone help to solve this for me Please.
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1answer
36 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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1answer
29 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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Decode a cypher generated by a digit sum algorithm [on hold]

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
45 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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62 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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41 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
37 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
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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
41 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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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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My father left a 64 character cipher in notes, anyone care to take a crack at it [closed]

My father left a 64 character cipher in notes, anyone care to take a crack at it... I've been working on it for months. It was hand written so a few of the characters may not be right. Y!JRNTIOSN!...
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Would a open decentralized blockchain network face any challenges like scalability and security? [closed]

If someone uses a decentralized open network for collecting data and allowing others to see it, would that sacrifice anything in terms of scalability or security for a protocol; for example IOT ...
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3answers
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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
55 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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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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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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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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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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39 views

DES CBC Bruteforce [closed]

I am trying to find an already written or available tool that can help Bruteforce CBC with unknown Key and Unknown IV. I have looked over Hashcat and JTR to no avail, I also would love to know how one ...
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61 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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1answer
287 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
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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31 views

What could you tell from these data? [closed]

I am trying to find the type of encryption used in these two set of data: ...
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1answer
80 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 ...
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1answer
38 views

Why does the Node crypto library do Diffie Hellman this way?

I was sifting through the Node Crytpo library and I came across their Diffie Hellman utility class. Their class implements a generateKeys function that, in their ...
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Why do general encryption key generators also take the algorithm as input?

To my understanding the key generation logic only needs a source of randomness and the length of the key to be generated as input. However, we still provide the algorithm (names) like AES, DES, ...
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Client puzzle protocol implementation or how we can implement puzzle with HMAC functionality?

I'm learning about client puzzles for DoS (Denial of Services) Protection, and I came across this question. Client puzzle protocol implementation, how we can implement puzzle with HMAC functionality? ...
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Is there a partially homomorphic cryptosystem without an inverse (addition without subtraction, multiplication without division)?

I am learning about partially homomorphic cryptography, and was interested to see if there was a system such that one operation was homomorphic, but its inverse was not. For example, if I have two ...
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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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3answers
626 views

Input limitations on the RC6 cipher

RSA has limitation in input size for encryption and decryption. Can RC6 be used for encrytion and decryption of files larger than 5 MB? Is there any limitation for input size? Is RC6 safe for using ...
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2answers
60 views

Can someone explain to me the concept of hashing versus the concept of encryption? [duplicate]

I'm a bit confused over the difference between hashing and encryption. Could someone help explain this to me in simple and concise, yet comprehensive layman's terms? I'm not asking for any specifics ...
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2answers
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How is n-bit security calculated with nested encryption?

What will the total $n$-bit security be if I encrypt a message with a 128-bit XOR cipher and then take that ciphertext and encrypt it with a 128-bit key. Is the total security level now 256? One ...
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Re-encrypting a message and proving that the message has not changed

Is there a method that allows for re-encryption of a message in a way that allows observers who only have access to the two cipher texts to prove that the plain text message is the same in each? More ...
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3answers
69 views

Can I use PGP key for RSA /AES encrpyption

My client provided PGP public key for data encryption. Can I use any OpenSSL [RSA or AES or any encryption] APIs to encrypt the data with this key? What are the different types of keys available for ...
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1answer
75 views

HKDF: ikm, salt and info values

As indicated at Key generation for AES-GCM-256 file encryption I'm currently working on a file encryption software. In the above thread it was suggested that, for performance reasons, I use a ...
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1answer
70 views

How to encrypt plain-text message using Diffie-Hellman algorithm

Let's say bob says Hi and Alice says Hello, With the knowledge of n and ...
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1answer
91 views

A new member. first step towards cryptography. [closed]

I would like to learn about cryptography. How and where to start?
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1answer
33 views

ED25519 Child Key Derivation

Let's say I generate a keypair for a user with go's ed25519 package: pub, private := ed25519.GenerateKey(nil) And I want to generate additional child keys as ...
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1answer
27 views

What encryption/decryption system should I use for media server

There is a server from which media files will be streamed to cross platform mobile/desktop apps. The idea is to encrypt the files while uploading using the web browser, store it in the server and ...
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1answer
108 views

Are SSH key-pairs an example of a zero knowledge proof?

Quoting from source, authentication using SSH key pairs goes something like this: 1) The client begins by sending an ID for the key pair it would like to authenticate with to the server. 2) ...
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30 views

DES twice - with k and then with complementary key?

What if we were to use DES in the following way: for a given text x and key k we would perform ...
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1answer
41 views

Encrypt twice with DES using same key ? $\operatorname{DES}(\operatorname{DES}(x,k), k)$

Does encrypting with $\operatorname{DES}$ in the following way $$\operatorname{DES}(\operatorname{DES}(x,k), k)$$ make $\operatorname{DES}$ as strong as $\operatorname{2DES}$ with 2 keys? Because we ...
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MTI authenticated key exchange protocol and their vulnerabilities?

Can someone please explain the different MTI key exchange protocols (A0, B0, C0, C1) and their vulnerabilities. I've been trying to read about them but couldn't get much information.