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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3k views

Is HTTP compression safe?

The CRIME attack taught us that using compression can endanger confidentiality. In particular, it is dangerous to concatenate attacker-supplied data with sensitive secret data and then compress and ...
3
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1answer
182 views

CMC (RFC 5272) compatible CA server

I need a CA server or any tool that supports Certificate Management over CMS (CMC) format, described in RFC 5272 (RFC 2797). I need a possibility to generate different Full PKI requests and responses ...
0
votes
1answer
280 views

How key_derivation and key_verification functions are implemented of a 7-zip archive's encryption mechanism?

I am curious about how password recovery works for password protected files. And I want to know the exact flow of the 7-zip encryption mechanism :) !! 7-zip uses the AES-256 encryption algorithm in ...
1
vote
1answer
262 views

Can I combine two of SHA-3 candidates cryptography hash functions and obtain more secure Algorithm? [duplicate]

Possible Duplicate: Are different hash algorithms ever used together? For example, Is possible to combine (Concatenate or Chain or XOR) Skein SHA-3 candidate with Grostl SHA-3 candidate to ...
3
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2answers
646 views

What risk does commoditized dedicated SHA256 processors pose to IT Operations?

With the advent of GPU-based computing, and now commoditized/dedicated SHA256 processors, what risk does this hardware pose to cryptography? What security algorithms should be closely watched or ...
0
votes
2answers
951 views

Diffie-Hellman key-exchange: securing prime and base

As we know DH algorithm based upon 2 large prime numbers, which are used to be called as prime and base I am writing app which implements DH key exchange algorithm. From security point of view should ...
10
votes
2answers
3k views

Estimating the size of a rainbow table

What are rainbow tables and how are they used? Gives a very precise answer about what rainbow tables are and how they are used. I had always confused hash-tables and rainbow tables. My question is ...
13
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4answers
4k views

Generate cryptographically strong pseudorandom numbers in Javascript?

Is there any good way to generate cryptographically strong pseudorandom (or true random) numbers in Javascript? The crucial requirement: if a.com's Javascript generates some random numbers, no one ...
4
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1answer
4k views

Is PBKDF2 only SHA1 in C#?

I can't find a way of specifying the hashing algorithm used by the PBKDF2 (the Rfc2898DeriveBytes class) implementation in C# System.Security.Cryptography. It seems to be just SHA1. Am I missing ...
14
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1answer
11k views

How should API keys be generated?

I want to make sure requests can't be forged and sent on to my server. In order to do this I need to generate an API key per user on my system. The purpose of the key will be to sign requests on the ...
3
votes
1answer
95 views

SSL Based Denial of Services due to Message Digest

On a very high level, its known that SSL/TLS uses message digests to verify the integrity of the messages sent. However, the question I have in mind is : How does SSL ensure a DoS does not happen ...
30
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3answers
62k views

Is SHA1 better than md5 only because it generates a hash of 160 bits?

It is well known that SHA1 is recommended more than md5 for hashing since md5 is practically broken as lot of collisions have been found. With the birthday attack, it is possible to get a collision ...
3
votes
2answers
374 views

Distributed md5 crack software?

I'm studying about cracking password using brute force, and in my way I found softwares like John the Ripper and MDCrack, that works really nice, but are restricted to one machine. There is some ...
4
votes
4answers
889 views

Is asymmetric encryption ever recommended for long-term storage?

Is asymmetric encryption ever recommended for long-term storage of data, is it advisable for example to store data in a database such that: 1) A user enters data on a website, it is encrypted using a ...
4
votes
2answers
389 views

From password to key

Can you explain this passage from Wikipedia? When a password (or passphrase) is used as an encryption key, well-designed cryptosystems first run it through a key derivation function which adds a ...
8
votes
5answers
1k views

How do RSA fingerprints protect from MITM attacks?

I understand that RSA fingerprints are used to verify that you are really connecting directly to who you want to connect to, and not someone else posing as that site. Like when you do a git push, it ...
7
votes
3answers
466 views

How secure is HTTPS with weak ciphersuites?

Today I came across the website https://mtgox.com/, which claimed to be secure because of the Verisign certificate. I checked the certificate out of curiosity (it's the first thing they claim, let's ...
-1
votes
2answers
124 views

Should I use salt to authenticate data?

I have a client and a server. The client makes a request containing userId, cardId, position (on the card) A hacker could just do the same http request with the next position. So I think about ...
5
votes
2answers
284 views

What steps can you take to make offline cracking of SRP harder?

In the aftermath of the Blizzard hack, what steps can I take to make offline cracking of SRP more difficult? My question assumes that your database is already gone and that you implemented SRP more ...
3
votes
4answers
1k views

Asymmetric crypto: Decrypt own messages without having private key

I have built a messages system for my website. Users can send the admin messages which are stored in the DB after being AES-encrypted. I think that using asymmetric crypto (RSA through openssl) ...
8
votes
4answers
5k views

HTTP Basic auth password storage more secure than Digest auth

If you are using SSL already, it appears Basic auth is the way to go since you can perform bcrypt with the password when you store it in the database, where as Digest auth only allows md5. As we know, ...
8
votes
1answer
1k views

What is a cryptographic puzzle?

On the wikipedia page on TCP under Denial of Service the following paragraph is found: By using a spoofed IP address and repeatedly sending purposely assembled SYN packets, attackers can cause ...
6
votes
8answers
2k views

Does truncating the cryptographic hash make it impossible to crack?

I store password hashes in their full value for example, $h = sha256('foo') outputs 64 characters: 2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae I store that directly in the ...
3
votes
6answers
293 views

Is it okay to wrap a cryptographic hash with MD5 for storage?

Is there any security issues if you wrap your cryptographic hash with MD5 for storage purposes? For example: $hash = md5(hash($password,$salt,$rounds)); Note: hash() uses scrypt or bcrypt or pbkdf2 ...
4
votes
4answers
690 views

Can public keys be a security risk when performing password-less SSH logins?

Some companies use monitoring software such as nagios or icinga. In order to perform checks on the servers, they often need password-less SSH logins. The servers being checked put the public key of ...
53
votes
5answers
8k views

Why shouldn't we roll our own?

Why shouldn't we create our own security schemes? I see a lot of questions around here about custom crypto and custom security mechanisms, especially around password hashing. With that in mind, I'm ...
2
votes
2answers
1k views

Is there an index of all md5 collisions?

I am about to build a caching system based on md5 to generate file names out of lists of natural numbers. The inputs would be groups like: 1,18,94,100,266,1854. I know there are some collisions in ...
5
votes
3answers
3k views

How insecure are PHP's rand functions?

There are some pseudo-random-number generators in PHP: rand(), srand(), mt_rand(), mt_srand(). You can look at their code here. I understand those functions are insecure, but how insecure are they? ...
15
votes
4answers
489 views

Why aren't digital signatures the standard way to authenticate web clients?

The web is a mess of incompatible cookie schemes, asinine requirements ("your password must contain letters, numbers, and at least one symbol from !()-_., and must begin with a letter, and once you ...
59
votes
5answers
18k views

Is sending password to user email secure?

How secure is sending passwords through email to a user, since email isn't secured by HTTPS. What is the best way to secure it? Should i use encryption?
1
vote
2answers
7k views

Encrypting string in javascript and decryption in java

I would like to know if someone know any library to do encryption in javascript and decryption in java. I have already tried many API, But getting not not getting same values in java. I want ...
6
votes
3answers
1k views

Computer decryption algorithms and knowing the solution

This is a general question about using computers to decrypt information. It has puzzled me for a while. The question is really two parts: How does a computer check if a "guessed" key is the correct ...
3
votes
2answers
528 views

Signing data bigger than allowed RSA Block size?

I've enountered a small problem while implementing a modified version of the Station-to-Station protocol (STS). Say we have two principals A and B, where both of them knows the other's public key: ...
5
votes
3answers
16k views

Windows 7 Password Hash Security

I recently came across a number of sources that suggest that cracking Windows user account passwords is easy by examining their password hashes. I understand that these hashes are stored in the SAM ...
1
vote
3answers
4k views

How wep wireless security works?

I want to know more about how WEP (Wired Equivalent Privacy) protocol for wireless securiy. From this wikipedia article I have got a basic Idea. But I still don't get what the initialize vector is? Is ...
0
votes
1answer
431 views

Should I encrypt data on my server as an extra layer of protection?

I'm going to create a client-server application that stores a user's sensitive financial information on the server. I would like to encrypt this data so that even if a hacker gets access to the ...
4
votes
3answers
1k views

Is it possible to modify a CA without having to reissue all of the derived certificates?

Background: I have my own authoritative certificate that I generated myself for signing certificates for services my friends and I use, including web server, ircd, etc. It's convenient because I ...
3
votes
3answers
203 views

How to know who I am protecting database information from?

I am trying to determine whether I need to use transparent database encryption (TDE) or encryption at web server to protect data in a database. Here are a couple articles I've read on the subject, ...
2
votes
3answers
665 views

Differences between brute forcing access versus decrypting password files or databases

I was just reading about how it's better to use bcrypt to protect passwords instead of saving password hashes in databases, and that got me thinking about other aspects that hackers work on that I had ...
2
votes
0answers
64 views

Using GPG or PGP for symmetric database encryption/decryption in c# [duplicate]

Possible Duplicate: Using GPG or PGP for symmetric database encryption/decryption in c# I am looking to symmetrically encrypt/decrypt information in a database. This info consists of short ...
1
vote
0answers
204 views

OpenPGP CFB mode examples [closed]

Does anyone know where to get worked out examples of OpenPGP's CFB mode encryption? I know RFC 4880 explains it very precisely, but I managed to mess it up somehow. I got one example from asking on ...
1
vote
1answer
215 views

PGP Secret Key Values calculation

I know this is somewhat counterintuitive, but: Does anyone know of any place where I might get intermediate values from PGP when it decrypts the secret values of the Secret Key packets and shows ...
3
votes
1answer
401 views

Is there a way to store user files without being able to decrypt them?

I'd want to build a secure file storage web application. Currently ordinary password authentication is used for login. After login this password is used for encryption and decryption of user files at ...
3
votes
2answers
360 views

Is the password hash better when you concatenate the password and username?

Is the password hash (with bcrypt) better when You concatenate the username with password? For example: $this->hash($username . $password); and $this->hash($password); Last time I used ...
2
votes
1answer
211 views

Which mobile phone OS implements or plan to implement data protection using keys derived from passwords per NIST SP800-132?

NIST has released Special Publication 800-132: Recommendation for Password-Based Key Derivation which is meant for protection of stored data using encryption keys derived from user password. This ...
2
votes
3answers
796 views

Establish a secure channel with mutual authentication given pre-shared public keys

Suppose I have a system whereby parties are identified by their public key (with some pre-selected asymmetric key algorithm). Suppose I have a party PUB1 which wants to establish a secure channel with ...
2
votes
1answer
115 views

Does a hash have more than one possible original message? [duplicate]

Possible Duplicate: Collision rate for different hash algorithms Many hashing algorithms seem to have fixed-length message digest as output. If I compute the md5 hash of two strings: ...
2
votes
1answer
2k views

What are the consequences of disabling ssl v2 and weak ciphers?

It is my understanding that IIS has ssl v2 enabled by default. Also, TLS 1.0, if enabled, allows for at least one known major vulnerability titled "beast attack". If the weak and vulnerable ciphers ...
2
votes
1answer
170 views

Inner Workings of Public Key Encryption

After watching this video explaining PKE with tennis balls (interesting), it left me with a few particular questions that I'm having trouble finding answers to: I assume that they keys used to ...
2
votes
3answers
358 views

Secure device pairing protocol

I need to implement secure pairing between two devices based on a short shared PIN code with no trusted third party. If you think about the way bluetooth devices pair you won't be far off -- my ...