Questions tagged [one-time-pad]

A cipher which uses a different encryption key every time, as long as the message. The key is XOR'ed with the message to render the cipher text which can then be XOR'ed with the same key to get the plain text.

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2answers
317 views

Decrypting two XORed compressed messages?

If through a previous attack, cipher misuse or two time pad etc. I receive $c=m_1 \oplus m_2$. Where $m_1$ and $m_2$ are compressed messages, for instance GZIPped English text documents. Can we ...
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2answers
934 views

Two-timing a one-time pad [duplicate]

Is a one-time pad still breakable on a depth of 2+ if the plaintext is completely random? I'm assuming this idea is wrong, mostly because it occurred to me, but let me walk you through my logic so ...
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2answers
475 views

Can you really insert the text you want in one-time pad?

The Wikipedia article "One-time pad ~ Authentication" says : For example, an attacker who knows that the message contains "meet jane and me tomorrow at three thirty pm" at a particular point can ...
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1answer
114 views

Split encryption into two steps

Are there two step encryption systems that - given the same plain text - support choosing two keys ($k_{A_1}, k_{A_2}$) for a first encryption so, that you can calculate another pair of keys ($k_{B_1},...
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3answers
789 views

One Time Pads and reuse of the decrypted message?

How is it insecure when Alice encrypts a message with a One-Time-Pad to Bob, and Bob then uses the decrypted message from Alice as the next One-Time-Pad? For example: Alice sends Bob a message ...
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6answers
737 views

Does one time pad randomness help brute force attacks?

I understand that attempting to brute force the decryption of a message coded with a one time pad results in generating every possible message. The Wikipedia example is that decoding "EQNVZ" with key ...
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2answers
844 views

What are the correct order of operations for One Time Pad Cipher?

According to Wikipedia the One Time Pad Cipher is unbreakable. On the Wikipedia page it explains how to perform this simple encryption process by hand. For the encryption it adds (+) the message and ...
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3answers
1k views

Does a stream cipher provide perfect secrecy?

From WAR10CK here: If I actually do create a machine using RC4 or AES-CTR and have a TRNG continually feed it a constant steady stream of random bits. Provided that the stream of bits is purged ...
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2answers
759 views

Can I generate OTP secrets by using a hash?

Since I learned about one time pads in last security lecture, I'm quite fascinated how easy the concept is, but how it still is absolutely safe. Learning from implementing a multi time pad attack, ...
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1answer
96 views

Security of one-time-pad without $\bmod $ operation?

Assume $r_1,r_2$ are used only once, and picked uniformly at random (each time we want to mask a value) from finite field $\mathbb{F}_p$, where $p$ is a large prime number. Assume $r_i\neq0$ and $b$ ...
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961 views

Avalanche noise RNG for one-time pad use

I came across this little HRNG widget and was really intrigued as I have been looking for a decent but afordable source for truly random bits to use in a one-time pad. The question is, would a HRNG ...
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1answer
437 views

Unconditionally Secure Authentication

I'm trying to add the authentication for my One-Time Pad implementation. I know that to provide Unconditionally Secure Authentication I need to use the One-Time MAC authentication. But I don't ...
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148 views

My pencil and paper One Time Pad works fine without modular math … or does it?

With no background in higher math or computer science, I could not quite grasp the value of modular math for simple OTP systems as described in other posts here. I have an alphabet size of 40 ...
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3answers
311 views

Generating OTP using Digital Dead Drop

I've had a thought and I'm wondering if this would be a useful way to devise and distribute a one-time pad. It relies on a digital dead drop and a hash function. The digital dead drop could take a ...
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2answers
93 views

Is it possible to use an algorithm to generate an OTP?

I am a software developer, not a cryptologist. I like the idea of perfect secrecy and would like to use a one-time pad (OTP) to encrypt/decrypt files up to, say, 50Mb. Is there a way that I can use ...
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434 views

One-Time Pad Distribution of Keys Between Two Parties

Consider the One-Time Pad (OTP). Suppose two parties, A and B, generate a completely random secret key in a real-life meeting, and they keep this secret. Now A wants to send some message to B using ...
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1answer
207 views

Attacks on Biased OTP

I know that a perfectly random unbiased and not reused OTP cipher is perfect. An OTP under cryptanalysis has a very strong bias (up to 30 % of symbols are represented by 5 out of 255 possible symbols) ...
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1answer
96 views

Perfect Deniability of a MAC Protocol

I proposed an idea of Perfect Deniability of a MAC I tried to come up with a protocol that satisfies those security requirements as well as the normal security requirements of a MAC One-Time MAC ...
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2answers
281 views

Reusing a one-time pad?

I have an embedded device. It produces larges files (200 MB). I want the device to encrypt the file before writing to disk, so I gave them all a 16-byte random key. How can I transform the large ...
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1answer
172 views

Multi-Embedded Xor for Perfect OTP

I am looking for a perfect OTP design, so let's see if this design is good. There are 2 issues when it comes to a good OTP system, the key and the plaintext, we will use XOR as cypher: If the ...
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2answers
239 views

How could consumer level OTP + QKD over the internet ever be practical?

Please note, I am in no way questioning the future usefulness of quantum key distribution (QKD) in certain applications. I have no doubt it will prove useful for large banks, and in certain military ...
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1answer
87 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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313 views

Why does the key for a one-time pad have to be uniformly distributed? [duplicate]

I would like an intuitive argument for what goes wrong in the proof that that a one-time pad provides perfect secrecy, if the key $K$ is not chosen uniformly at random from the entire key space.
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1answer
361 views

One-time pad using RSA and Diffie-Hellman functions

Suppose that Alice and Bob use an encryption algorithm based on a one-way function $F$ (Eve knows it), and $r$, a secret key shared between Alice and Bob (Eve doesn't know it). Key is computed as: $K =...
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1answer
203 views

Can OTP be made practical by using stretched hash algorithms? [duplicate]

One of the main reasons for not using OTP in everydays life is that it is highly impractical - for encrypting 4GB of files we need a 4GB key that needs to be exchanged secure. I've had an idea on how ...
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661 views

Why wouldn't everyone encrypt with a One Time Pad? [duplicate]

A One Time Pad (OTP) sounds perfectly secure if we are to believe Wikipedia. But on the surface it also sounds ridiculously impractical - how does one securely distribute the OTP? Idea: why not have ...
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165 views

Why is the XOR of plaintexts equal to the XOR of ciphertexts with a two time pad?

I have been working in the vulnerabilities of the Two Time Pad. So i found in a lot of places, StackExchange included saying, that if two plain texts are encrypted (using XOR) with the same key the ...
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OTP - Reuse key BUT add IV, is it secure enough?

I have already asked a similar question and now I can continue to this question about adding a "extra key" = IV. My last question was about reusing key in OTP (One-Time-Pad). Now this question is ...

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