Tag Info

New answers tagged

1

To answer the question of whether they would need some special technique to OTP encrypt a message longer than their key: No, to realize their claim of more than 3000 text messages they can use standard OTP. You are correct that with 0.5MB OTP key you can encrypt at most 0.5MB of data. 0.5MB is 500.000Bytes meaning as many characters can be encrypted ...


2

First, the system as I understand it does not use a one-time-pad at all, but a steam cipher. The keystream is generated via a CSPRNG, and is not truly random, so it cannot be a one-time-pad. They are misrepresenting it. But, to answer your question, let's assume the system did in fact use a one-time-pad, and used it in the manner described. In this ...


4

The system described in the quoted article depends on the security of AES for random keys (not only on the theoretical unbreakability of the OTP) in at least at least two things: the encryption of large files, as apparent in the quotes of the question; the initial establishment of the OTP, as shown by this other quote The first step is always optical, ...


2

Actually, it's not a hare-brained idea at all; you certainly can do integrity checking using a one-time pad. However, I believe that you'll need to use the one-time pad bits a bit faster than you'd expect, to achieve a forgery probability of at most $2^{-32}$, I believe you'll need at least 64 pad bits per packet (assuming informational theoretical security ...


-1

In your case I'd recommend you to try TripleDES, maybe with a paired ARM MCU - it's cheap and fast enough... Try to take a look at STM chips, I used them before and I have a very good recommendations due to price/perfomance. Also you can try to implement DES physically if you have a hi-speed requirement in your device's spec list.


1

Use AES-128, the instruction set in most CPU's (AES-NI) speeds up the encryption and does not put to much load on your CPU. I would use CBC but there might be better mode operations for encrypting files. Also don't forget to use a MAC. Using a one time pad (OTP) is nice but what you're doing is not an OTP it's more a Vigenère cipher. If you were to use OTP ...


0

You can use xinput --test to record mouse movement data and then "crunch" the recorded data into a random hash using a hash algorithm like MD5. E.g. xinput --list (shows your mouse device id is 15) and you want to collect 5 seconds of mouse data: $> mouse_data=$(timeout 5 xinput --test 15) If you want to play around with a script that incorporates ...


1

Here's a more "down to earth" example. The following cryptosystem with plaintext space $\mathcal{M} = \{a,b,c,d\}$, keyspace $\mathcal{K} = \{1,2,3,4\}$ and ciphertext space $\mathcal{C} = \{A,B,C,D\}$ has perfect secrecy: $$\begin{array}{c|c c c c} & 1 & 2 & 3 & 4 \\ \hline a & A & B & C & D \\ b & B & C & D ...


2

Imagine that you have a ciphertext: Perfect secrecy means, that without knowing the key, any plaintext has to be a possible preimage. Because otherwise the ciphertext would give you information about the plaintext. Encryption is an injective function, because otherwise it could not be reversed. That means, for a given key and ciphertext you have at most ...


1

If the key would be smaller than the plaintext then you could brute force the cipher by using less than $N$ steps, where $N$ represents the amount of possible messages. Of course the brute force approach is an upper bound to what can be tried. If there are attacks on the cipher (that are less complex than brute force) then the plaintext may be recovered ...



Top 50 recent answers are included