Cryptography

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Updated: 11 min 43 sec ago

mask ver.chew

Thu, 09/20/2018 - 18:13
Categories: Information Security

What cipher/code is this?

Wed, 09/19/2018 - 18:53

Hey guys, any clue what this is: Xp7tg\pVAeu/;ZfDtArQgr3ENWNvTCX6qgGgpxLLLDB9tWN3N:29spA84ruxSHBNYXP|e5PctnQeQV45Km9ATdxtffbe://uysgd.oay/smxxqdk/mWmAcUtrcR2dUQs9aAYaTi2fHyV6HvWDvNHVPw6wNgrf:/,QzLYo8bpzty3fU7MEMg324uEQiCa3r6SKXXjUoxDAmj7XUKafamRh9rXu8Q8vcRJJxwFon4uj

The tffbe://uysgd.oay/smxxqdk/mWmAcUt is https://imgur.com/gallery/aKaOqIh after you shift 12 alphabet letters Can't figure out the rest

submitted by /u/M1k01sH3r3
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Categories: Information Security

This might be a simple question or not. I am not sure but could you help me out

Wed, 09/19/2018 - 11:25

So I would like to prove the RSA Encryption system in my work and got stuck at this part below. lets say my public and private keys are 'e' & 'd'. e*d = n. Lets say 'm' is the message that needs to be encrypted and 'T' is the text that we get after encrypting.

I am going to write below the 2 equations I understand and I used these equations to make an example of my own

(1st equation)..... med is congruent to m mod(n)

(2nd equation).... e*d is congruent to 1 mod (phi of n) I would like to know how I can show the relationship between these equations. More specifically how can I show that the First equation is true with the information in the second equation.

submitted by /u/Ithinkmefunnie
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Categories: Information Security

Need help to know how it has been done

Wed, 09/19/2018 - 10:35

Original code: Mv cxt lniigv huorgth ntxciieg mseti. Axy edaaslncp xl rpzw potmsercu asn eu cj nicgaghn uh dxr vkew

After Decoding: We are living through exciting times. The landscape of what computers can do is
changing by the week

Can someone tell me how it has been done?

submitted by /u/Hot_Ices
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Categories: Information Security

Appropriate key size/material for LUKS?

Tue, 09/18/2018 - 15:51

I'm trying to encrypt some hard drives for offline backups. I'm on Debian so I'd like to use LUKS. I'll be using a randomly generated 20-character string for a password, written in a physically secure location, but only as a method of backup/recovery. For daily use, I wish to use key files with my GPG smart-card.

My plan is to asymmetrically encrypt key files to my GPG public key, which will require a smartcard and pin to unlock. However, reading online guides, the advice for the correct key size and generation procedure varies a lot. Some pages say to use "4 KB of random data" generated with dd but that seems too small? Another: tr 512 characters of alphanumeric output from /dev/urandom. Yet another suggests using openssl genrsa to make 4096-bit RSA key.

Is my plan to use a smartcard for LUKS key files sound and how should I make said key files? I'll also be storing the LUKS headers separately, if that makes a difference.

submitted by /u/TerribleHalf
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Categories: Information Security

Besides frequency analysis, are there any free online tools I can use to measure the randomness of strings of letters?

Mon, 09/17/2018 - 23:50

I found a site that require several megabytes of numbers, but I'm looking for something for text that doesn't have a limit like that.

submitted by /u/GirkovArpa
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Categories: Information Security

Would Friedman's attack on the Vernam-Vigenere cipher work if it used 3 strips?

Mon, 09/17/2018 - 14:41

In this declassified document, Friedman describes in great detail how he met the government's challenge to break the Vernam-Vigenere cipher:

  • "Vernam offered an alternative solution: a key generated by combining two shorter key tapes of m and n binary digits, or bits, where m and n share no common factor other than 1 (they are relatively prime). A bit stream so computed does not repeat until mn bits of key have been produced."

By the way, the encyclopedia article is misleading, since this was Morehouse's (not Vernam's) idea.

Much of Friedman's article deals with attacking faulty implementations of this cipher. If one pays attention to only his attacks on the correct implementation of the system, it's clear that he requires knowledge of the relative offset between the two tapes, as well as knowledge of the location of significant portions of the plaintext. I think his shortest example of a plaintext guess was TRANSPORTATION.

What I'm interested in is would his attacks be merely complicated, or would they be utterly defeated, if one employed a 3rd strip?

submitted by /u/GirkovArpa
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Categories: Information Security

Anyone know what the fuck this means

Mon, 09/17/2018 - 00:07

Anyone know what the fuck this means ¤(¤« ‘(’(“£(›£™((o{h(“‘œ¤£(§‘¢Mn

submitted by /u/arealsuperretard
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Categories: Information Security

Need help solving a puzzle.

Sun, 09/16/2018 - 18:35

I am working with a group of about 13-18 people on solving an ARG. After some investigation we came upon a mysterious youtube channel (https://www.youtube.com/channel/UCVNTZJXAuvE3C7SfOsPNgEA/featured?ab_channel=tenretniolleh). The icon to this channel held what we believe is the next clue in the form of a code (https://cdn.discordapp.com/attachments/490985650460557315/491006254106411009/unknown.png). If someone is willing to help pls contact me.

Edit: The original image found in the youtube channel icon was upside down and really dark

submitted by /u/Manly_Mc_Andy
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Categories: Information Security

Secure way of encryption?

Sun, 09/16/2018 - 09:19

I'm implementing something similar to this project: https://github.com/sebsauvage/ZeroBin

It's a tool where you can post a message which is saved encrypted on a server, so that the server don't have any information about how to decrypt. The information for decryption is provided with a certain generated link. So you can encrypt a message, send the generated link to a friend and he can only read the message in case he enters the correct link.

My idea to produce sth similar is: Encrypt: Create MD5 Hash of a given message in browser. Using AES with the hash as password to encrypt the message in browser. Send the encrypted message to server. Provide a link for user which includes the ID of the encrypted message on the server as well as the MD5 Checksum.

Decrypt: Using the ID given in the generated link to get the encrypted message from server. Using the MD5 Checksum given in the generated link to decrypt the message.

Is this basically a good idea? Any suggestions for improvements?

submitted by /u/marvpaul
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Categories: Information Security

The Vernam-Morehouse Cipher

Fri, 09/14/2018 - 12:59

My quest to discover whether a Vigenere ciphertext which is shorter than the length of the product of its multiple, coprime-length (random) keys is unbreakable has finally come to an end!

It's not breakable!

:D

It was actually created in the early 1920s by Morehouse and patented by Vernam. Friedman said using it would "assure absolute safety"! [1]

This means one may use, for example, two one-time pads of lengths 101 and 103 to securely encrypt a plaintext up to 10,403 characters long.

  • [1] p. 57, The Mechanics of Differential Primary Keys
submitted by /u/GirkovArpa
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Categories: Information Security

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