Cryptography Stack Exchange
Cryptography Stack Exchange

Questions tagged [multiple-encryption]

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

Multiple encryption, cascade ciphering or superencryption refers to the process of encrypting the same data several times.

A well known result by Maurer and Massey (1993) shows that, under very general assumptions, a multiple encryption scheme is at least as secure as the innermost layer, provided that the encryption keys for each layer are independent. Furthermore, if the encryption layers commute (as is the case e.g. for additive stream ciphers), this shows that the combined encryption scheme is at least as secure as the strongest layer.

References:

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Is TrueCrypt's multiple/cascading encryption safe?

Is TrueCrypt use of cascading encryption safe? Is it useful? TrueCrypt is arguably one of the most popular and widely used encryption applications in use today, yet it seems to use a very unconventional scheme. The software offers cascading…
hunter
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Can double-encrypting be easier to break then either algorithm on its own?

As was pointed out in Martin Bonner's comment I cannot prove this, but it seems intuitively impossible. An encryption function is supposed to obscure the plaintext to the point where no information can be obtained about it. If the underlying…
Shelvacu
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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 equivalent to a single encryption, then there is no…
AleWolf
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Affine Cipher over an Affine Cipher

I would like to know your view about the title, encrypting a plain text with an affine cipher then encrypting that ciphertext once more using the same cipher, but of course different keys. Would it be more secure? For me, it won't be since it still…
rockStar
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Combining several symmetric ciphers using XOR

I have seen a talk by Rüdiger Weis, where he says that you can combine two symmetric ciphers using XOR. According to him, that has the effect that its sufficient if only one of the ciphers is secure. How does he do that? I have thought…
icehawk
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Would a "Triple AES" (in the sense of how Triple Des works) serve for a dramatic increase in safety?

The system requires to be as paranoid as possible regarding security. One of the few contemplated changes to the current design is to use multiple encryption. First proposal was to use Serpent on top of AES-256, but after looking into it, it seems…
Mamsaac
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Encrypting messages for multiple recipients

With hybrid cryptography, I want to encrypt a message intended for multiple recipients. This can be archived (as described here by creating a symmetric secret key, encrypt the message with this key, and then include an encrypted version of the…
Per Erik Gransøe
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Can Grover's Algorithm be combined with a meet-in-the-middle attack?

We all know and love the meet-in-the-middle attack, which basically makes double encryption pointless using a time-memory trade-off. Now, the NSA recently recommended to use double encryption to adequately protect sensitive data from quantum…
SEJPM
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Combining multiple symmetric encryption algorithms - implications?

I was just wondering if I add more security by combining two or more symmetric encryption algorithms on a plain text. For example: Plaintext → AES → Twofish → Serpent Of course a different key and IV (produced with a cryptographic secure prng) is…
Chris
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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 there is a known plaintext attack which has an…
Jim Rootham
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Is there any way to have a coded string such that it can be decoded in multiple ways?

This is more out of curiosity than anything, having no knowledge of cryptography. But say I have strings "test1" and "test2", is there any way/algorithm to encode the two strings to an encoded string "string" such that when "string" is decoded with…
kawakaze
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Order of multiple encryption algorithms

as you can see on image above, in VeraCrypt you can select either Serpent -> Twofish -> AES or AES -> Twofish -> Serpent what's the point of those permutations? is there any difference if I use A -> B -> C or C -> B -> A combination of…
encore leet
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Encrypt a single file, chunk-by-chunk, each chunk using different key (AES)

Encrypt a single file, chunk-by-chunk, each chunk using different key. I am a security newbie (only took 2 security courses before) But currently I am using this encryption method for my Android application, which perform client-side encryption and…
tcboy88
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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 ciphertext $C = ( M ⊕ K_1 ) ⊕ K_2$.
Mina
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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 $P = D_{k_1}(D_{k_2}(D_{k_3}(C)))$ where $E$ is encryption, $D$ is…
forest
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