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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Solving for a One-time pad cipher help ; crib dragging doesnt work (no surprise) [duplicate]

Basically we're given the text 7ECC555AB95BF6EC605E5F22B772D2B34FF4636340D32FABC29B 73CB4855BE44F6EC60594C2BB47997B60EEE303049CD3CABC29B 64C6401BAF45F6A930435F3DF875C4E102F8742A45C824AFCA9B ...
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Are there any historic examples of breaking the one-time pad because of a careless key re-use? i.e simple attack on a multiple-time pad?

It doesn't have be using a truly random key, (it could be the Enigma) but the attack must be based on XORing two parts of ciphertext.
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Cryptanalysis on two time pad ciphers? [duplicate]

One time pad ciphers are unbreakable if the message is encrypted correctly and if only used once. However if used more than once, it becomes decipherable. How come? Also, would it be smart to use one ...
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472 views

Is my one time pad cipher secure?

This is a program that I made for encrypting text files. It uses a one time pad cipher to encrypt the files, but I do not know if there is any holes in my program that could be a vulnerability. Is my ...
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use the same pad reversed

Suppose I have a random number (eg 625 467 921). I use it once to encrypt a message OTP style, and when I want to use them again, I reverse them (eg to ...
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449 views

Perfect Secrecy, two Definitions

I'm reading the proof of the implication "Def 2.1 $\Rightarrow$ Def 2.4" in these slides about Adversarial Indistinguishability and Perfectly-Secret Encryption. I have a doubt in the slide 10. Here it ...
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1answer
39 views

Can shuffling plaintext produce a useable key?

If I 'shuffle' the characters in a long text, is there some number of shuffles that will produce apparent randomness approaching a cryptographically secure random number generator? A chapter in a ...
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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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1answer
66 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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Randomness of a Key in a One Time Pad

The keys used in an One Time Pad are required to be randomly generated from a keyspace $\mathcal{K}$, we require 256 bit random keys, i.e. $\mathcal{K}=\{0,1\}^{256}.$ Suppose we randomly select an ...
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How to XOR two hex values and am I doing crib dragging correctly? (OTP)

Let's say I have the two cipher texts 7ECC555AB95BF6EC605E5F22B772D2B34FF4636340D32FABC29B 73CB4855BE44F6EC60594C2BB47997B60EEE303049CD3CABC29B According to this website http://xor.pw/? the result ...
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1answer
31 views

How do I decipher a text using a repeating one-time pad?

I have an encrypted message that is 582 characters long. I know that: It is in hexadecimal It has been encrypted using a one time pad The pad's length is exactly 50 characters When the pad reaches ...
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1answer
135 views

XOR = Best encryption? [duplicate]

If you have a TRULY random key (in binary) and you have a text (in binary) that you want to encrypt. Can you simple XOR the key and the text? Is that secure? How secure?
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OTP - Why not reuse key? EDITED! [duplicate]

EDIT: REUSING KEY IS SECURE! OTP - Reusing key IS SECURE! PROVED! This might sound really dumb but why is it bad/insecure too use the same key twice on One-time-pad? Question: Why and how does using ...
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2answers
53 views

Is the one-time pad secure?

I have read about one-time pads (OTP) on Wikipedia. Is this secure? Can I actually use modular addition as ecryption like it said in Wikipedia? And the plaintext is as long as the OTP, so when I send ...
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1answer
62 views

Many Time Attack [closed]

How i can XOR these two cipher texts encrypted by using same key First ...