Questions tagged [cryptography]

Cryptography is the practice and study of logical means used to achieve information confidentiality, integrity and authenticity. It covers, among other things, encryption (making some data unreadable except for those who know a given secret element, called a key), data hashing (in particular for password storage) and digital signatures (provable integrity and authenticity with non-repudiation).

Filter by
Sorted by
Tagged with
2
votes
1answer
289 views

Browsers and export regs. Is SGC still valid?

I was reading a rather dated book on SSL/TLS, which mentions International Step Up certificates and Microsoft's Server Gated Certificates which were the way around the US export rules for economic ...
2
votes
1answer
932 views

What are the requirements for a random number generator to a be safe to use in cryptography?

When I look at most RNG's (random number generators), I see a disclaimer that looks similar to this: Caution: Mersenne Twister is basically for Monte-Carlo simulations - it is not cryptographically ...
2
votes
2answers
320 views

Which private-key encryption should I use for server to server communication?

I am tempted to write my own which covers: Checksum to ensure data is not tampered with. Long and multiple rotating keys so that it is (practically) impossible to decrypt. Will use /dev/random for ...
2
votes
1answer
618 views

Few questions about group keys family in WPA/WPA2

In my previous question I learnt something about Group Temporal Key (GTK), but after searching the internet I have another questions: 1. How is Group Master Key (GMK) derived? What is GMK derived ...
2
votes
0answers
76 views

Disallowing Similar Passwords [duplicate]

Upfront, I want to clarify that I am not a professional cryptographer, I am more curious about playing with the math and science behind it, and also want to improve my habits with my own personal and ...
1
vote
2answers
2k views

Which encryption algorithms will be used to replace RSA when quantum computers become common? [duplicate]

Possible Duplicate: Are the encryptions "broken" with great computing power? I just wondered which algorithms will be used once quantum computers become common. Are there already ...
1
vote
1answer
1k views

Propagating certificates stored in a CNG Key Store Provider

I am developing a CNG Key Store Provider (KSP) that will store keys and certificates remotely in a backend server in order to be used not only on Windows, but also on other OS without the need to ...
1
vote
1answer
348 views

The Requirements of a Cryptographic Algorithm [closed]

I remember reading a book on cryptography with a section detailing the objectives that modern cryptography must accomplish, one being that even if the algorithm is known, the method remains secure. I....
1
vote
2answers
332 views

What's the best place to hide long lived encryption keys

I am considering encryption options for a new Sybase project (internal facing only, sitting in our intranet) for a client that has a security policy that requires all sensitive data to use DB ...
1
vote
2answers
703 views

Recommended authenticated stream cipher for minimum overhead?

I'm running my TCP/IP protocol secured by encrypting each packet with AES128/CBC, bundling a SHA256 HMAC over that packet. This causes quite a bit of space overhead for small packets, so at first I ...
1
vote
2answers
288 views

TCrypto - Comments about design decisions I made?

I have pushed some code to GitHub to demonstrate the usage of symmetric key encryption in PHP. It is a small key-value storage library and it (optionally) offers ability to encrypt the stored ...
1
vote
1answer
2k views

SRP 6a implementation C#

I'm trying to implement the SRP crypto; 6a. However I'm not familiar with the cryptography and it's computing. I'm using the public implementation of the BouncyCastle lib, but I have no idea how it ...
1
vote
2answers
465 views

Standard AES vs additional parameters with Rijndael - what is more secure?

I know that Rijndael and AES are pretty similar and AES is just a subset of Rijndael, and I have read that Rijndael can have 256 bit blocks while AES has "only" 128 bit blocks. The problem is that I ...
1
vote
1answer
424 views

Design of Initialisation Vector

I understand that an IV (initialisation vector) should be both unique and unpredictable, but I have found little guidance as to which is most important. For an AES cipher I have a block size of 128 ...
1
vote
1answer
128 views

Deniable proof of authorship

The title may read like a contradiction, but I would like to know whether a cryptographic solution exists to the following problem: Problem statement Suppose Alice wants to write a document using a ...
0
votes
0answers
52 views

Secure Personal Information for Restful API

I need to implement a web application for user to update personal information. It consists of a page listing masked personal information and then a button which allows user to edit & update them. ...
0
votes
2answers
122 views

Is there a cryptographic function that generates a reconizable visual pattern?

I have to build a system that will ultimately print a pass allowing access to a building. The validation of this ticket will be done manually (it can also be automatic but that's not likely at this ...
0
votes
3answers
1k views

Protecting data through an XOR operation with sufficiently long keys

Suppose two parties S and D would like to protect a communication channel. Therefore, S and D exchange two sufficiently long key sequences SB und DB of random bits over a secure channel [e.g not over ...
0
votes
1answer
61 views

Updating Sender-Keys and Key-Management

This question is related to an earlier question I had: Encryption on Mobile Devices - Multiparty Encryption - Key Management My situation: I have many mobile devices that want to send sensitive ...
0
votes
2answers
569 views

How can I get notified about the publishing of ransomware decryption keys

My computer had been hijacked by "Cryptolocker" a ransomware you might be well aware of. The nasty ransomware has encrypted most of my documents and video files. I used an anti-malware and removed the ...
0
votes
3answers
2k views

Looking for some steganography guidance

I am currently trying to figure out a steganography challenge. I was given 3 images, a secret.txt file and a "binary" file. There are no instructions as this was part of another challenge. I am ...
0
votes
5answers
246 views

Snapchat clone: How do I secure pre-downloaded notifications so that they cannot be opened outside of the app?

Say I'm making a snapchat clone app for Android and iOS. Let's say that I get a snapchat from Baz. I want to pre-download the audio for this snapchat. However, as the developer, I want to secure this ...
0
votes
1answer
599 views

How to decrypt file that was attacked by ransomware? [closed]

there are a ransomware attacking on of my computer and most of the file has been renamed to something like id-2832SGndfDcbv.supportfriend@india.com.xtbl The file isn't corrupted as the file still ...
0
votes
1answer
987 views

Encryption and Hash in Veracrypt

I have already read some topics about Veracrypt's cryptography algorithms. It said that if we want to focus on security we need to chose a 3 layer encryption like AES(Twofish(Serpent)) or Serpent(...
0
votes
1answer
420 views

Detecting end-state of decryption process with unknown key

Note: this question arises purely from a theoretical interest in security research. Frequently in popular fiction we see white-hat hackers decrypt secret information in a matter of seconds. While ...
-1
votes
1answer
81 views

Shouldn't multiple images always exist even in most powerful hashing algorithm?

I have a confusion in mind that since in hashing we transform a large string into a smaller fixed size string, so its unlikely that any large string has a unique hash. There had to be collisions and ...