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 ...

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58
votes
8answers
123k views

How to determine what type of encoding/encryption has been used?

Is there a way to find what type of encryption/encoding is being used? For example, I am testing a web application which stores the password in the database in an encrypted format ...
2
votes
3answers
117 views

Could an Encrypted VG/Image compromised?

I mean if I encrypt my ""full system"" so that everything (besides the /boot) is in an encrypted VolumeGroup (Linux). So I store my /boot on a flash drive, thats always next to me. Q: can the ...
63
votes
4answers
13k views

Recommended # of iterations when using PKBDF2-SHA256?

I'm curious if anyone has any advice or points of reference when it comes to determining how many iterations is 'good enough' when using PBKDF2 (specifically with SHA-256). Certainly, 'good enough' is ...
77
votes
3answers
11k views

Is a rand from /dev/urandom secure for a login key?

Lets say I want to create a cookie for a user. Would simply generating a 1024 bit string by using /dev/urandom, and checking if it already exists (looping until I get a unique one) suffice? Or should ...
8
votes
4answers
2k views

What Partial Homomorphic Encryption implementations exist and how do I leverage them?

It appears that only Partial Homomorphic Encryption(P.H.E.) is practical for modern day (2011) use. However I'm having difficulty locating libraries (FOSS or otherwise) that enable me to leverage ...
38
votes
6answers
5k views

Is using a public-key for logging in to SSH any better than saving a password?

Using a public/private key pair is fairly convenient for logging in to frequented hosts, but if I'm using a key pair with no password, is that any safer (or less safe) than a password? The security ...
14
votes
6answers
588 views

Primary Key as Salt?

Is it okay to use the primary key as the salt in a Users table? The only disadvantage that I can see is if the PK changes (unlikely), then the passwords break. What are your thoughts?
20
votes
10answers
3k views

Can a file contain its md5sum inside it?

Just wondering if it is possible to create a file which has its md5sum inside it along with other contents too.
0
votes
2answers
224 views

How to find out the Chaff packets of WEP?

I have a cap file in which I have lots of 802.11 packets encrypted with WEP key. The problem is lots of Chaff packets of WEP is included in that. I want to remove the Chaff packets and crack the key. ...
21
votes
4answers
83k views

How can I export my private key from a Java Keytool keystore?

I would like to export my private key from a Java Keytool keystore, so I can use it with openssl. How can I do that?
6
votes
1answer
922 views

How do I learn Cryptographic/Mathematical notation

I asked a question earlier where it was recommended that I describe my issue using standard cryptography notation. How do I learn this notation and how to convey my approach? How can I annotate this ...
11
votes
3answers
2k views

Additional security of keyfile on top of a master password for KeePass

I use KeePass + Dropbox to manage and synchronize my passwords across my devices. This system works really great and I trust KeePass' security model. However my biggest remaining concern is the ...
3
votes
1answer
834 views

Peer review of C# cryptography for Azure Table security

Edit: Update - I am researching how to implement AES with authentication in an efficient way for this project. If you have the time I'd appreciate your skill in finding the best implementation for ...
15
votes
4answers
2k views

In what ways does Full or Partial Homomorphic Encryption benefit the cloud?

Can someone explain, in plain English, the practical ways FHE and PHE can be leveraged in the cloud? Some interesting (and confusing) links include this Microsoft Research PDF and this wiki entry. ...
9
votes
1answer
3k views

SSL replay attack when client/server random is missing

Hey studying the SSL protocol, I'm wondering how can someone be able to do a replay attack if the server nonce is missing? All the material I find says that nonces prevent it, but theres no examples ...
22
votes
2answers
5k views

symmetric encryption session keys in SSL/TLS

This question concerns the session send and receive keys used in SSL/TLS protocol. my understanding is that this key uses symmetric encryption (DES, AES, BlowFish, etc.) I'm wondering, if ...
7
votes
2answers
678 views

security of PKI, Certificates, certificate authorities, forward secrecy

I want to understand how certificates add to the security of information exchange. Suppose i have a encrypted bidirectional connection between Alice and Bob, using a public key/private key pair. As ...
11
votes
3answers
2k views

Question about dictionary attacks on GnuPG symmetric encryption

They say algorithms like AES can't practically be broken given a long enough key length (> 128 bits). If I use GnuPG to encrypt a file using AES: gpg -c --cipher-algo AES secretfile it asks me for a ...
7
votes
3answers
673 views

Smartcards for Dummies

Are there any defacto resources for understanding the basics of smart cards? My problem is that I don't know what I don't know about the technology. Any good primers?
56
votes
7answers
40k views

Certificate based authentication vs Username and Password authentication

What are the advantages and drawbacks of the certificate based authentication over username and password authentication? I know some, but I would appreciate a structured and detailed answer. UPDATE ...
21
votes
1answer
1k views

Has SHA-3 Arrived?

I know NIST called for contenders (in 2007) regarding the new hash algorithm to replace SHA-2. Has there been a selection, or finalists selected?
2
votes
1answer
309 views

Cryptography notation

If I wrote RC5-32/12/16, it would mean 32-bit words (which is 64-bit data blocks). What is "words". I know the 12 is rounds and 16 is key size (16 bytes, so 128 bit).
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
5k 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
439 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
427 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
215 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
11k 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
850 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
567 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
485 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
26k 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. ...
14
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
10k 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 ...