Tagged Questions

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 ...

learn more… | top users | synonyms

1
vote
0answers
80 views

Putty Event Log

Can anyone explain me the Step by step process of Key Exchange that takes place while accessing Linux machine using Putty ? I found the Event Log of Putty but the Various Key Exchange didn't make very ...
4
votes
4answers
2k views

Does using WPA2-Enterprise just change the attack model vs WPA2-PSK?

As far as I can tell based on the reading I've done so far, WPA2-Enterprise uses the same encryption and security algorithms and methods as WPA2-PSK, with the addition of using another service for ...
0
votes
0answers
39 views

What kind of security do WhatsApp and Viber use? [duplicate]

What kind of security do chat applications implement to preserve message integrity & confidentiality?
0
votes
0answers
68 views

Does the ordering of encryption and hashing matter? [duplicate]

I am now learning keyed hash function, where A and B share a secret key k. I want to know if the ordering of encryption E and hashing H matters? i.e. Is there any difference between H ◦ Ek (m) and Ek ...
1
vote
2answers
100 views

How to sign and encrypt mails using firefox

There is an option under Tools>options>Advanced>Security Devices. How to use that to encrypt and digitally signed your emails.
19
votes
6answers
10k views

“Diffie-Hellman Key Exchange” in plain English

Can someone explain to me what is Diffie-Hellman Key Exchange in plain English? I have read in a non-tech news page that twitter has just implemented this technology which allows two persons to ...
1
vote
1answer
111 views

Using secp256k1 and ECDSA with IKE

I just tried using an IKE daemon and EC certificates. I used the secp256k1 curve for key generation. The daemon claims signature scheme ECDSA-256 not supported by private key Now I am wondering ...
2
votes
0answers
86 views

Main difference between Yahalom and Needham-Schroeder key exchange protocols

I am just wondering what is the main difference between the Yahalom and Needham-Schroeder key exchange protocols? Which protocol uses less computational power?
1
vote
0answers
53 views

Any Suggestion Exchanging shared key between process via port in untrusted machine (infected my malware)?

I am trying to get shared key between Firefox extension and a java program running in same machine. I am communicating both application via socket. My assumption is that malware is running in ...
0
votes
1answer
91 views

Transmission of messages

I am currently developing a game which will be run in a client, they will sign up for this game online and create their account there, their information will be stored into a MySQL database. I am ...
3
votes
0answers
112 views

BSD encryption advantages [closed]

If someone who knows about the BSD project has a moment to answer this, I'm wondering a few things about the encryption used. It's more than what I'm finding in the docs and on Wiki/Google (even the ...
0
votes
2answers
111 views

SSL/TLS Question [closed]

I am currently working on my SSL/TLS assignment and I got a question to ask. What is the use of a login password since it is not needed for establishing secret communication between your computer and ...
2
votes
2answers
225 views

Lightweight block ciphers definition

I've read in many papers something that looks an specialisation of the block ciphers calling them with a lightweight tag, but I couldn't found a definition. If I understand correctly, those ...
38
votes
10answers
2k views

Cryptography that looks like ordinary email

I would like to stay out of the automatic filters in place by security agencies and not be accidentally placed on a no-fly list or such. Say I'm having a political debate with a friend about democracy ...
1
vote
0answers
165 views

Encrypted chat using any smartphone. Is it legal? [closed]

Here's my case. We have written app for Android smartphones which allows users to exchange secured cipher messages. For key-exchange we're using elliptic curve 112 bits, for messaging we're using DES ...
3
votes
1answer
298 views

Symmetric encryption with different encryption and decryption keys

In the book, Applied Cryptography by Bruce Scheier, in the foundations chapter he defines symmetric encryption algorithms as algorithms where the encryption key can be calculated from the ...
-2
votes
2answers
133 views

Is this adaptation of using a One Time Pad safe?

For example, lets say there are two people named, Bob, and Jim. Bob wants to send Jim a long secret message, and he decides to use a OTP to encrypt his message. Both Bob and Jim know a secret ...
3
votes
2answers
4k views

Using AesCryptoServiceProvider in C#, should using an incorrect IV mangle just the first block?

This question was also asked on StackOverflow, but with no answers, and I thought this may be a better exchange, since I have the same question. ...
3
votes
3answers
377 views

If the code to shuffle an array is known, is it possible for the randomized shuffle to stay secure?

I recently was looking at Poker shuffles that were hacked and made to be guessable within a reasonable degree and this was because of the weakness of the shuffles. Is it possible to make a shuffle ...
2
votes
2answers
558 views

How to generate cryptographically strong pseudorandom data very rapidly?

What's the best way to go about generating a fast stream of cryptographically strong pseudorandom data without installing uncommon packages? Drawing from /dev/urandom is far too slow. I had an idea ...
8
votes
4answers
728 views

At what point does adding more iterations to PBKDF2 provide no extra security?

If my true passphrase is used only to generate a hash which is used as the cipher's actual key, doesn't that mean it's possible to try and brute force the cipher itself? I know it would take an ...
6
votes
1answer
882 views

Crypter Anti-Virus Test

I have written a very simple/basic crypter in C++ and I would like to test it. How would I go about writing a simple MessageBox program that is "tainted" so that my Anti-virus will attempt to ...
1
vote
1answer
368 views

Don't use encryption without message authentication

The text is taken from the famous answer: Lessons learned and misconceptions regarding encryption and cryptology: Don't use encryption without message authentication Alternatively, you can apply ...
0
votes
1answer
191 views

At what point is a cryptosystem “rolling your own”? [duplicate]

Everybody knows making your own cipher really sucks. Everybody also knows using existing cryptosystems, such as TLS, totally doesn't suck. But when is the line drawn? For example, would I be rolling ...
1
vote
1answer
1k views

How is the HMAC key exchanged?

Just wondering about this. Does it need a PKI to work?
2
votes
1answer
588 views

Is there any functional distributed timestamp server available? If not what about this homebrew solution?

Objective A secure Arrow of Time with unpredictable future behaviour to stop attackers or DDoS BotNets from pre-calculating proof-of-work and other gateway protections for P2P/F2F. A distributed ...
3
votes
1answer
153 views

S/Key as an alternative to UNIX passwords

There is this password system called S/Key I saw on the Internet. Can someone give me a brief description about S/Key and how it works? Can S/Key be an alternative solution to the UNIX password ...
0
votes
1answer
75 views

Payload authentication + HW-SW Binding

I want to authenticate a (2nd stage) bootloader during the boot process using a symmetric key, which is derived from HW properties of the platform the bootloader is running on. Thus, I want to bind ...
5
votes
3answers
413 views

comparing password hashing algorithms - PoC ideas?

OK so I just started working for a security consulting firm and we recommend SHA 256 (with salt) for password hashing because MD5 is too weak. I have read some brilliant answers (the list is too ...
0
votes
3answers
219 views

Security goals vs ITU-T security services

I am doing a course on cryptography, and there I learned that the major security goals are Confidentiality Integrity Availability Also I Learned that ITU-T provides 5 different security services ...
3
votes
2answers
323 views

Totally secure public key distrubition

Public-key cryptography secures communications provided that you use pre-shared public-keys. The problem is how to share these public-keys while maintaining authenticity? How can we be sure that ...
1
vote
1answer
296 views

MySQL AES Encryption - Is it good idea to store 3rd Party Auth Tokens using AES Encryption?

I need some advice on MySQL AES Encryption. I'm developing an application which connects to various 3rd-Party APIs and retrieves the Access Tokens for the application users. These Access Tokens are ...
1
vote
2answers
242 views

What is (“ASCII” redundancy) which is said to be required to retrieve the original plain text in 2 times pad?

Sorry for the long title :$ In a video speaking about attacks on the one time pad which uses psudorandom generators (PRG), It's said that Eve can retrieve the plain text of 2 messages that have been ...
3
votes
2answers
99 views

System for securely authenticating content acquisition

I'm having trouble designing a system for authenticated content from my site distributed by other people. I'm working in Ruby on Rails, but I don't think that at a theoretical level my question isn't ...
0
votes
2answers
600 views

Algorithm to generate NTLMv2 Hash in PHP

I am trying to develop a PHP function to calculate NTLMv2 hash by providing server & client challenge, domain, account and password. The resulting hash appears to be not correct. Can someone ...
1
vote
0answers
248 views

Configure Asterisk for lan with SRTP enabled SipDroid

I want to have a secured call over internet between two android phones. I have found SipDroid which is an open source SIP client for Android. And also I have followed this to install Asterisk, Dahdi ...
10
votes
3answers
450 views

has scrypt withstood the test of time?

I've always heard that scrypt was better than bcrpyt... because of memory causing GPU a very difficult time to crack. However, the notion always was that scrypt hadn't been tested, it was kind of a ...
6
votes
2answers
2k views

1024-bit DHE vs 2048-bit RSA

Currently with apache/mod_ssl, if DHE is enabled then a 1024-bit ephemeral key will be used. I found the following quote in Adam Langley's blog: Ideally the DH group would match or exceed the RSA ...
1
vote
2answers
2k views

Encryption - which are/aren't NSA backdoored [closed]

I prefer bcrypt because it uses a lot of "power" to decrypt. But which encryption can i use that is most likely safe for NSA (which knows a lot of backdoors) and is relatively slow to decrypt. I ...
3
votes
2answers
613 views

Is it safe to expose an SHA1 hash of an encryption key?

Assume that party 1 and party 2 each possess a key used for AES encrypting data. Assume that the key was properly randomly generated and securely passed between them. Now I need a way for party 1 to ...
1
vote
1answer
238 views

How is the FileVault master key protected?

FileVault has the functionality to both allow and disable user accounts from booting up the encrypted drive. Reference: this cnet article. See also the stack exchange question How does FileVault 2 ...
9
votes
2answers
1k views

How does a weakness in a random number generator lead to a compromise of the entire cryptographic process?

In the news, there are several articles (here, here, and the technical point of view) which have to do with a weakness in a random number generator. The question is somewhat twofold. What symptoms do ...
0
votes
1answer
130 views

Timing analysis attack and cryptosystem

Why is a “Timing Analysis Attack” a problem for a cryptosystem? I've been trying to learn security, and have a question about timing analysis attack.
1
vote
1answer
330 views

OpenSSL DH modp size

If OpenSSL is configured to use a DH for key exchange, e.g. TLS_DHE_RSA_WITH_AES_128_CBC_SHA, where does it take the size for modp (or even modp itself) from? The following is a screenshot from ...
5
votes
1answer
3k views

What block ciphers and algorithms are now safe? [closed]

I work for a large non-US based international organisation. Regarding the recent leaks about the NSA breaking most encryption on the internet, we now know the US and UK governments are actively ...
6
votes
1answer
267 views

Any not totally insecure browser vulnerable to BEAST?

People still worry about BEAST quite a lot when configuring web servers to the point of preferring RC4 over AES-CBC. But most browsers mitigate BEAST even while using TLS 1.0. Is there a browser ...
0
votes
2answers
1k views

applications of double DES and triple DES

what are the applications of multiple encryptions? where the multiple encryption like double DES and triple DES algorithms are use?
2
votes
2answers
1k views

Explain real world symmetric key encryption

I'm new to cryptography. While reading about symmetric key encryption, it was mentioned that it requires secret key exchange so that 2 parties can decrypt the ciphertext. Now, using some encryption ...
0
votes
3answers
541 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 ...
6
votes
1answer
3k views

Consequences of tampered /etc/ssh/moduli

What are the consequences if an attacker is able to modify the /etc/ssh/moduli file?