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Questions tagged [multiple-encryption]

Multiple encryption means encrypting a message two or more times using either the same, or a different algorithm.

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Is AES a group?

The question I'm wondering is whether the AES cipher is a closed cipher (which is equivalent to AES being a group). And this question interests me due to the lack of understanding of whether it is ...
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Does using multiple encryption algorithms with different keys on the same cipher text improve security?

I'm looking for maximum possible security. My current scheme is xChaCha20-Poly1305-xSalsa20-Poly1305-AES-CBC-HMACSHA-512. Does combining these algorithms increase security if implemented correctly? ...
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Cascade Encryption with Faulty Inner Layer

First of all a couple of things: I am aware that cascade encryption tries to solve a problem that isn't present often. Attacks are more likely to be mounted against implementation details instead of ...
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Encrypt different inputs with different keys to obtain the same output

I'm researching to see if there is an algorithm that encrypts different inputs with different keys to produce the same output. So let's say I have 2 messages. ...
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Is there a type of method where multiple keys are involved, and final key produces invalid results unless all prior keys are used?

I'm looking for a mechanism for a type of cert/key signing, where multiple keys need to sign/encrypt something, and a final key/method does not product a valid confirmation unless all those keys did ...
New Alexandria's user avatar
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How to encrypt in garbled circuits

I’ve read a lot of articles and a lot of questions here to understand how the encryption is done in garbled circuits. As I understand double encryption is to encrypt the gates and the truth table. The ...
HATİCE MELİSA ERYILMAZ's user avatar
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What is the security of multiple encryption using Even–Mansour scheme (XEX)?

As I know, the best attack on single or double Even-Mansour scheme is N/2, being N the key size (or size of one of the two keys used). I know that encrypting two times using this scheme is susceptible ...
phantomcraft's user avatar
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Multiple Encryption Using GCM For Multi-Key Security

Multiple Encryption For Multi-Key Security I have a hypothetical question about multiple encryption after reading Matthew Green’s blog on multiple encryption. For those who are familiar with GCM…I ...
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Is multiple encryption with XORs between each encryption operation susceptible to meet-in-the-middle attacks?

Let's suppose I take a cipher with key size equal to the block size (Threefish). I XOR a random block in the ciphertext, encrypt with a key, XOR another random block, encrypt again with another key ...
phantomcraft's user avatar
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Is multiple encryption using CBC mode of operation susceptible to Meet-in-the-middle attacks?

I read it once on a page (I don't remember the link and I coundn't find it) that said about a cascade of AES with two 256-bits keys and that it provides 384-bits of security. Maybe not 512-bits of ...
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How could this scheme work?

When we use a secret sharing scheme we usually want to reconstruct the polynomial function $p(x)\in\mathbb{Z}_q[X]$ with the Lagrange interpolation method and then compute $s=p(0)=a_0$. However, the ...
Hunger Learn's user avatar
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Is multiple encryption using a block cipher mode of operation that use only encryption processes vulnerable to Meet-in-the-middle attacks?

Some block cipher modes of operation use only encryption processes, such as CFB, OFB and CTR. If doing multiple encryptions using them, will these encipherment schemes be vulnerable to Meet-in-the-...
phantomcraft's user avatar
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Is there a benefit to "double encryption" when it comes to attacks analyzing attempted decryption results?

This is a beginner's question related to general security, but it fits cryptography exchange because it's more specific to the action of cryptographic attacks and how they work. Assume the following ...
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Decrypt one cipher with multiple and independent passwords

Consider that an online shop subscribes an embedded external service for their customers. This external webpage is accessible through a clickable banner on the online shop. On the subscription area of ...
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Question on double-asymmetric encryption and split knowledge

Moin moin, Let‘s assume there are two keypairs (d1,e1) and (d2,e2), where d1 and ...
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Can we sign and encrypt with RSA keys of both sender and receiver?

By using RSA encryption, it is possible to "encrypt" sign with sender's private key and then with receiver's public key, and decrypt with receiver's private key and then with sender's public ...
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Is multiple encryption with stream ciphers vulnerable to meet-in-the-middle attacks?

Let's suppose I encrypt something with a stream cipher (CSPRNG) two times using two 256-bit keys and different IVs. Will I get 512-bit encryption strength?
phantomcraft's user avatar
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Is multiple encryption with CTR mode vulnerable to meet-in-the-middle attacks?

Let's suppose I want to encrypt my disk partition with AES-256 in CTR mode 2 times using two different keys and IVs. Will I get 512 bits of encryption strength?
phantomcraft's user avatar
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What is the easiest cipher to use in designing double ciphers?

I want to make a double cipher consisting of two encryption method Enc1 and Enc2, and two corresponding decryption mechanisms Dec1 and Dec2. I want it so that: (1) we can encrypt any message M1 to a ...
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Encrypting multiple groups of data with separate keys in a single encrypted column

I will write this question using a database example, but please note this detail may be irrelevant. Let's say I have data belonging to N clients stored in a single column of a database table. Each ...
user12584312's user avatar
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How many collisions (identical pairs) are possible in meet in the middle attack on double DES with two unique keys?

I was reading my professors slides, I understand how meet in the middle works, but I have a few confusions. So we need two $\{(P_1, C_1), (P_2, C_2)\}$. Let $\lg{(k_1)} = \lg{(k_2)} = 56$, we generate ...
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Secure CCA Encryption under Partial Key Exposure

I'm currently learning about chosen ciphertext attack and stumbled across a problem on CCA security. If I have an encryption scheme $(Gen,Enc,Dec)$, which is CCA-secure with $Enc:\{0,1\}^n\times \{0,1\...
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Combining algorithms for password storage?

Is it more secure to combine algorithms for password hashing, for example, Scrypt, Bcrypt, SHA-3, etc.? If an attacker wants to use dedicated hardware, he would need one for each algorithm. However, I ...
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Encrypt files on harddrive with double encryption

So I've been stuck on this question for a very long time. How do you use double encryption to encrypt a hard disk so that all of the following conditions are met: All data on the hard disk is ...
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How to determine the maximum number of times the DES algorithm needs to be run?

I am only a beginner in cryptography and I am getting confused by the following: Question Consider a known-plaintext attack performed on a double-DES cryptosystem. (a) Determine the maximum number ...
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How do additional input output pairs help with a Meet in the Middle attack on Double DES

Double DES is vulnerable to a Meet in the Middle attack where an attacker generates intermediate values and then matches them up to find candidate key pairs. For Double DES using $56$ bit keys and $1$ ...
NotSoTuringComplete's user avatar
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XORing Algorithm Outputs To Guard Against Breakthroughs

My question is how safe is XORing two algorithm outputs together... ...For Symmetric Encryption: Master key from CSPRNG ==> MK HKDF-Expand(...
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Weakness in double encryption [duplicate]

In the "Introduction to Cryptography: With Coding Theory" by Trappe and Washington, in the chapter about DES algorithm the authors say that: "If double encryption is equivalent to single encryption,...
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Why is double encryption that's equivalent to single encryption no better than single encryption?

In the "Introduction to Cryptography: With Coding Theory" by Trappe and Washington, in the chapter about DES algorithm the authors say that: "if a cryptosystem is such that double encryption is ...
AleWolf's user avatar
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The security level of double encryption

Let PKE $\Pi' = (Gen', Enc', Dec')$ and it is secure in the sense of $S'$. Let PKE $\Pi'' = (Gen'', Enc'', Dec'')$ and it is secure in the sense of $S''$. $S'$ and $S''$ may be separation which means ...
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Is an invulnerable code possible (including brute force attack)?

If I double encrypted a text with for example AES wouldn't it be invulnerable to bruteforce attacks due to the computer not knowing when it has reached the plain text? Plain text->1st layer of ...
david david's user avatar
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Best practices when encrypting a file with three different ciphers [closed]

I have some files that contain important information, so I want to encrypt them by the most secure encryption method possible. I've read countless StackExchange answers on similar questions and some ...
COLD  Crypto's user avatar
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Database vs SAN vs Network Encryption

Good day everyone! Please bear with me as this is my first post on the crypto exchange. An interesting question was raised in a meeting recently about the double-encryption problem (i.e. same ...
PrometheusRising's user avatar
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Double encryption - One Time Pad

Can the security of the encryption system be improved by using double encryption with two randomly chosen keys? By double encryption I mean using two keys $K_1$ and $K_2$, each 20-bit long, to obtain ...
Mina's user avatar
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Multiple encryption using the same key

I am a newbie to this area. I have a program that uses a custom algorithm to encrypt a message. I can encrypt it as many times as I want, but using the same key. I have couple of questions so that I ...
Lock Smith's user avatar
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0 answers
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Trading Chosen-Ciphertext-Protection for Double encryption

Straight to the point: I'm trying to implement double encryption using two cipher suites. One (#1) of them is a stream cipher without any checksum/authentication guarantee, the other (#2) is an AEAD ...
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Reverse cascaded AES encryption

I was wondering if it is possible to decrypt a cipher-text using a single key which was encrypted twice. For example: Let's assume that we encrypt a plaintext using AES-CTR and encrypt the output ...
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How can Alice enable Bob to look-up values in a private map

I think this problem is similar to private set intersection, yet distinct in a way where: Alice has an extensive Mapping of say id to name id1 -> John Doe id2 -> Jane Doe id3 -> Edgar Poe ...
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Multiple Encryption - One-Time Pad

It is known that One-Time Pad(OTP)s are theoretically unbreakable but impractical for use because of the size of the key length. But what if multiple encryption is used? Not to encrypt the first ...
Fathima Abdur Rahman's user avatar
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Are some combinations of Substitution + Transposition more vulnerable than others?

Iterating multiple substitution ciphers is not mathematically different from using a single substitution cipher (3 Vigenere iterations with a 31-, a 32-, and a 33-letter key would essentially be a ...
Simpson17866's user avatar
6 votes
2 answers
661 views

When does a multiple Vigenère cipher become intractable?

Multiple Vigenère ciphers do not repeat the key until the message gets longer than the LCM of the cipher lengths. Are messages shorter than that safe? If not, what is the attack strategy? I believe ...
Jim Rootham's user avatar
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2 answers
2k views

Does the double-hash H(H(x)) have greater collision probability than H(x)?

Let $H$ be a collision resistant hash function and $P_c[H](S)$ the collision probability about a sample set $S$ of input elements (eg. random numbers). It increases with double hash? That is, $P_c[H\...
Peter Krauss's user avatar
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1 answer
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Using multiple cryptographic keys for encryption?

I am setting up an encryption methodology for items in a database. To decrease the likelihood of data being compromised due to the keys being compromised I would like to use an application level key (...
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Safely using ciphers that take small key sizes

Is it feasible to use triple encryption for block ciphers with the maximum keysize being the only significant security issue? I mean $C = E_{k_1}(E_{k_2}(E_{k_3}(P)))$ and $P = D_{k_1}(D_{k_2}(D_{k_3}(...
forest's user avatar
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What is the difference between a dual cipher and a tweak?

I have looked at the idea of dual ciphers but I cannot convince myself I really understand them. I think I just need a very simple worked example. I was given the definition: Two ciphers $E$ and $E′$...
Red Book 1's user avatar
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Multisignature or Multi-password File

I want to create a file that I could give to 3 trusted friends, and allow any two of them to decrypt it when together (or in sequence when not physically in the same place). This is similar to a ...
NealWalters's user avatar
1 vote
0 answers
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Revocation of users in encrypted storage system?

How can you design an encrypted storage system, that allows adding and removing users without sharing a common secret and having to re-encrypt everything when a user is removed? My partial idea is: ...
Marc's user avatar
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2 answers
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Finding Vigenere's keys with part of decrypted text?

I have a text that was encrypted twice with two Vigenere keys. However, I know the seven first characters of the decrypted text. I have already implemented a function displaying for the five first ...
UnknownServer's user avatar
4 votes
2 answers
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Signal Double Ratchet - How can Alice send 2+ messages in the beginning of the Signal Protocol?

I'm studying about Signal Protocol and I had a doubt in Double Ratchet Algorithm. This section describes how to derive the receiving and sending key messages. Alice is initialized by Bob public ...
Vivi's user avatar
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Double Ratchet Algorithm - What if the receiving wants to send the second message before the initiator?

I'm studying about Signal Protocol and I had a doubt in Double Ratchet Algorithm. This section describes how to derive the receiving and sending key messages. But in this scenario, only Alice can send ...
Vivi's user avatar
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