# Tag Info

2

The question describes a stream cipher with key $S$, using $C_S(R)$ to transmit a random session key $R$, and a keystream (or pad) generated from $R$ using a CSPRNG to encipher the message. This is not an OTP; and contrary to an OTP, it is not secure against a computationally unbounded adversary, who hypothetically, knowing a plaintext/ciphertext pair ...

1

What you are actually looking for, which is a way to reuse a one-time pad, is not possible. For OTP reuse to be in any way secure, you need an algorithm with enough "complexity" to be a secure cipher (where the "pad" is actually a key). For example, in the comments you raise the idea of including a random number and using the 8-bit CBC that Richie Frame and ...

-4

If you use the OTP it has been used since its invention you will not get away with it. But there is a way that you can beat an attacker (Eve). For the purpose of sending only text we will add a comma, full stop and a space character into an alphabet and randomise it. This will be the initial key that Alice and Bob share. The possible permutations for the ...

0

Here is how to make a Caesar Shift Cipher work with a One-Time Pad. First you write your message down: "ABCD" Then instead of shifting the alphabet for the whole message. You shift the alphabet for each letter based on a number in your pad. "13, 3, 11, 0" So in this case: For A you shift the alphabet 13 times to get N. B you shift the alphabet 3 ...

0

What you are essentally describing is a Pseudo-Random Generator in which the base numbers act as the seed. This does not make a good method for generating OTPs because if you know the seed then you just work from there and crack the message.

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Letters only allow you to use letters and nothing else. So you would only be able to send a message like this: MEETA GENTV LADAT DINER ATTWO Where as if you use numbers you can send messages with virtually all the different characters you want: Meet Agent Vlad at diner at 2.

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The only really effective way of using OTPs is running a Numbers Station. Or at least relaying your message through a Numbers Station. I would check out a document called "Guide to Secure Communications using the One Time Pad" (PDF) for proper CryptSec and OpSec procedures when it comes to using them in the field.

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Modern computers are quite fast, and modern cryptographic algorithms are quite efficient. Most computers benchmark hardware accelerated AES in CTR mode well above 1GB/s, which would be a fraction of a millisecond for a 100KiB file. Since the standard system timer generally runs at 1ms intervals, the entire encryption operation ([file data] XOR [AES] XOR ...

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