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

2
votes
4answers
9k views

SIPR, NIPR and Centrix Military systems [closed]

This is going to branch into a bunch of separate questions.....here is some background for the question: The Rijndael algorithm was crowned the new AES by Uncle Sam for sensitive, but unclassified ...
9
votes
2answers
1k views

How does the padding scheme impact the security of encryption

After digging a little deeper into cryptography I am wondering what impact the different padding schemes do have an the security of an encryption algorithm. Lets take AES-128 in CBC mode as an ...
20
votes
5answers
2k views

Can ECC be used without infringing on patents?

Can ECC (Elliptic Curve Cryptography) be safely used without infringing on Certicom's patents? I would like to make use of ECC in an embedded system to establish a secure channel. But, I am concerned ...
6
votes
2answers
7k views

The new CCMP attack against WPA/WPA2 PSK

The use of Counter Mode with Cipher Block Chaining Message Authentication Code Protocol (CCMP) for WPA/WPA2 PSK is being attacked. This is a trivial attack (offline brute force) against the initial ...
8
votes
3answers
1k views

time to crack file-encryption password - more than just iteration

I have often seen that takes x amount of time to crack a certain length password. But this just seems to be the amount of time it takes to iterate through all the possibilities. What about the time it ...
4
votes
2answers
4k views

Diffie Hellman c# implementation

Hallo all, For a test project I have tried to implement the (famous) Diffie Hellman algorithm for safe key exchange. Now I have written this in C#: using System; using System.Collections; using ...
5
votes
1answer
1k views

TLS at layer 4 BUT 802.1X EAP-TLS at layer 2?

In the CISSP books, SSL/TLS has been through the arguments and fell rest onto the transport layer 2 instead of the session. OK - Fine. Port security 802.1X and EAP is a data link layer 2 ...
4
votes
3answers
435 views

It is safe to buy a domain if I get this message in Firefox?

Greetings, I want to buy a domain name from a big registar(well known on the internet) but when I go to checkout I see that my link is going from full encrypted to “Connection Partially Encrypted” ...
8
votes
2answers
423 views

Is there a way to negotiate a secret between 2 parties with no prior knowledge?

Is there a way for 2 parties to negotiate a shared secret (for example, a session key) without having a pre-shared knowledge? SSL does this by using asymmetric encryption. Is there any other way to ...
2
votes
2answers
212 views

Is random data inserted into an encrypted stream easy to retrieve?

Given that I have two pieces of data: A large piece of encrypted data. A small, fixed-size piece of random data. I want to be able to transmit both pieces of data together, but I don't want the ...
22
votes
4answers
10k views

how long does it take to actually generate rainbow tables?

I've been reading up about rainbow tables as I think they're quite interesting cause they're actually a pretty simple concept. Anyway, I was wondering, has anyone been involved in actually generating ...
8
votes
2answers
836 views

Stretching a hash, many iterations versus longer input string

I have been reading up on various password hashing schemes, for example the SHA-based Crypt proposed by Ulrich Drepper and used in some Linux versions. A recurring theme here is to 'strengthen' or ...
2
votes
1answer
556 views

IPV6 Cryptographically Generated Address implementation

I am looking to an Cryptographically Generated Address (CGA) implementation in Java or in C++. Would be glad if someone can help.
7
votes
2answers
2k views

Is strong cryptography legal across the internet?

In many countries strong cryptography is outlawed. That means you must store the data of your users in such a way, that government of that country can always decrypt it. And if you don't, you are a ...
5
votes
4answers
479 views

Possibility of undetectable encryption system

I am not sure if it is pre-mature to ask such a question. The question is largely inspired by pondering over the question and discussions in the following link (In his answer, @Dad also raises ...
6
votes
1answer
2k views

Feistel Block Cipher

Can anybody explain, in simple terms, how Feistal Block Ciphers work. I am not a math student so I do not understand the math behind it, just would like the principles.
3
votes
2answers
182 views

Encrypting a fixed format message?

I'm planning to send across TWO pieces of information over the internet from machine A A site identifier which will be like: $SiteName = "EXAMPLE" (in plaintext) Encoded text which will be like: ...
80
votes
6answers
25k views

Password Hashing add salt + pepper or is salt enough?

Please Note: I'm aware that the proper method for secure password storage hashing is either scrypt or bcrypt. This question isn't for implementation in actual software, it's for my own understanding. ...
8
votes
1answer
2k views

Howto seed the PRNG in OpenSSL properly?

I am creating an application which runs on a mobile node with Ubuntu, which does not generate enough entropy bytes to the /dev/random, and does not always stay connected on the Internet to use typical ...
1
vote
2answers
1k views

Thoughts on Tiny Encryption Algorithm (TEA, anyone)?

I'm planning to implement Tiny Encryption Algorithm and exchange data between two PHP sites. Specifically, using the code presented at PHP-einfach.de Does anyone have any experiences / thoughts / ...
19
votes
6answers
1k views

What are the good use cases for disk encryption?

I've been researching disk/file system encryption, and on the surface it seems like a good idea for a lot of things. But as I dig further, the security it offers seems more mirage like than real. ...
13
votes
3answers
3k views

Computationally simple, lightweight replacement for SSL/TLS

Target hardware is a rather low-powered MCU (ARM Cortex-M3 @72MHz, with just about 64KB SRAM and 256KB flash), so walking the thin line here. My board does have ethernet, and I will eventually get ...
29
votes
2answers
9k views

HMAC - Why not HMAC for password storage?

Nota bene: I'm aware that the good answer to secure password storage is either scrypt or bcrypt. This question isn't for implementation in actual software, it's for my own understanding. Let's say ...
45
votes
17answers
3k views

Can we still provide confidentiality when cryptography is outlawed?

In certain jurisdictions, use of cryptography by the private sector is limited: e.g. there are reports that in the UAE and other countries not all of the encryption capabilities of the BlackBerry are ...
4
votes
2answers
149 views

Question about the SessionLock paper

Some time ago there was a big fuzz over Firesheep: by listening to wifi traffic your login session can be stolen which is very bad because now somebody can e.g. send emails on your behalf. Some people ...
18
votes
1answer
2k views

Collision rate for different hash algorithms

Is there any collision rate measure for popular hashing algorithms (md5, crc32, sha-*)? If that depends only from output size, it's quite trivial to measure, but I suppose that depends also of ...
10
votes
1answer
130 views

Is there an organization that reviews/approves crypto implementations?

As I understand it, NIST approves crypto algorithms but doesn't cover specific implementations. I think I've read about IEEE approving hardware implementations of, e.g. AES, but I can't think of any ...
18
votes
3answers
3k views

MySQL OLD_PASSWORD cryptanalysis?

The password hash used for MySQL passwords prior to version 4.1 (now called OLD_PASSWORD()) seems like a very simple ad-hoc hash, without salts or iteration counts. See e.g an implementation in ...
9
votes
4answers
3k views

Is Schneier's “Applied Cryptography” current?

I've been recommended Bruce Schneier's 1994 book Applied Cryptography as an introduction to the use and the inner workings of cryptography. Is this book still current and a good introduction?
6
votes
4answers
358 views

What is the solution to Schneier's Law?

Schneier's law (which should probably be called Babbage's Law). States that: Anyone, from the most clueless amateur to the best cryptographer, can create an algorithm that he himself can't ...
7
votes
5answers
2k views

Should one sign and encrypt using the same key? The Azure Training Labs are taking this approach

I'm taking the Azure lab LoadBalancing with WCF and recognise what I have been told is bad from a security perspective, but am not sure if it applies here. Can someone look at this code and tell me ...
6
votes
3answers
661 views

Patent free symmetric-only key exchange protocols?

I am working with a networked embedded device with AES-128 and no public key cryptography (1KB RAM, 8KB flash). At install, the device is pre-loaded with a longterm AES-128 key known also to the ...
9
votes
2answers
2k views

Data Encryption and Key Management in C#

Which route to take, what are the pros and cons, which is more secure.. Generate AES key, encrypt the data with it and then encrypt the AES key with RSA, save the encrypted data and encrypted AES ...
13
votes
4answers
1k views

Is Steganography considered encryption and subject to USA export restrictions?

I have written an application for Apple's iOS which embeds messages in JPEG files using steganography (see http://en.wikipedia.org/wiki/Steganography). For the purposes of this question lets assume ...
11
votes
7answers
3k views

Why can an encrypted private key be brute forced?

When using SSH keys to authenticate to a server for remote access, why is it possible to devise the true key and therefore the passphrase from an encrypted private key, without checking each guess of ...
5
votes
2answers
176 views

Complexity of web certificate attacks

I heard a while ago about someone exploiting md5 weaknesses to create a web certificate with the same md5 that a different certificate has. They were able to create a certificate through bad issuing ...
41
votes
4answers
12k views

What is the use of a client nonce?

After reading Part I of Ross Anderson's book, Security Engineering, and clarifying some topics on Wikipedia, I came across the idea of Client Nonce (cnonce). Ross never mentions it in his book and I'm ...
13
votes
5answers
1k views

How should passwords be stored if they must be recoverable?

By "encrypting" passwords you are violating CWE-257: Storing Passwords in a Recoverable Format. But this is exactly what the French government wants. They want to be able to obtain the passwords of ...
14
votes
4answers
2k views

Looking for example of well-known app using unsalted hashes

Does anyone know of a well-known application that still uses unsalted hashes for password storage? I'm looking for an example for an upcoming lecture on Rainbow Tables, and I think it would add ...
5
votes
2answers
1k views

Can RSA (or any public/private key algorithm) be repeated for large amounts of data?

I'm working on a small security assignment and I was instructed to implement simple encryption/decryption of files using RSA in C#. When attempting to encrypt/decrypt large files, I was informed by ...
5
votes
2answers
976 views

Generating one-time tokens from API-key?

I have a web-site for which I'm building a Drupal module that allows the users of that Drupal site to navigate to my web-site directly from the Drupal site. I intend to distribute secret API-keys to ...
14
votes
4answers
2k views

What are the chances to generate the same ssh key?

I could generate ssh keys on the client like (without password): ssh-keygen -b 8192 -t rsa -f /home/THEUSER/.ssh/id_rsa -P '' -v and copy the generated id_rsa.pub to the server: ssh-copy-id -i ...
14
votes
4answers
984 views

Doubling up or cycling encryption algorithms

I've occasionally read the suggestion to enhance security by either doubling up on encryption algorithms (encrypt a message once with one algorithm, then encrypt the ciphertext again with a different ...
27
votes
3answers
3k views

Is there any advantage to splitting a password?

I've been reading about the LANMAN (LM) hash and I'm curious about a particular part of the algorithm. The LM hash is computed as follows: The user’s ASCII password is converted to uppercase. ...
8
votes
1answer
1k views

Moving from a one tier to a two tier Microsoft Certificate Authority hierachy

Right now we have a single Microsoft Enterprise Root CA which issues certificates to our VPN users for two factor authentication. We're planning to extend use of the CA to issue certificates for RDP ...
11
votes
1answer
2k views

Renewing Microsoft Certificate Services Root Certificate

We currently have Microsoft Enterprise Certificate Server installed on a domain member machine which issues 1 year certificates to users for authenticating to VPN. We'd like to start issuing web ...
2
votes
2answers
368 views

What is the correct way to assess and compare Certicom's products to the alternatives?

I'm investigating Certicom's API because they are "free" with the Blackberry implementations, and have come to realize that I have several alternatives for implementing crypto such as BouncyCastle, ...
4
votes
3answers
662 views

Is it possible to have authentication without state

In order to login to most websites you need a username and password which is often stored in a SQL database. You are storing per-user information that can change, this is state. Can you prove that ...
4
votes
3answers
382 views

Are there any serious problems with this technique for generating symmetric keys?

I'm using a technique borrowed out of a book by Bruce Schneier and Niels Ferguson called Practical Cryptography. Basically, it boils down to this: Bob does this: pubk_A = Alice's public key ...
6
votes
1answer
160 views

Wireless auto-join on laptops

Maybe I have the wrong idea but this is a question that has been floating in my head for some time. Whenever you use an iPhone (or a Mac, Apple products seem to be more prone to this because it ...