A hash algorithm is a function which takes a variable size input and produces a fixed size output. The algorithm tries to make it difficult to predict the output for a given input, find two inputs with the same output, or reconstruct the input from the output.
16
votes
4answers
524 views
In hashing, does it matter how random a salt is?
I recently had a comment made to me in an online discussion after I'd stated that randomness in a salt doesn't matter -- and I got the following response:
Salts may not have to be "secure," but ...
2
votes
2answers
95 views
What's the point of using multiple checksum algorithm with “aide”?
In aide the author offers more than one hash algorithm to do the check-sum, why is that?
Aren't a single one, i.e sha512 enough for determining file changes? I believe these algorithms are all ...
60
votes
13answers
5k views
VP of IT claims he unhashed 100% of all 16k employees' PWs. Is he lying to us?
I work for a company which has ~16,000 employees. Periodically, our VP of IT sends out a newsletter with "tech-tips" and misc IT stuff. The topic of this week's newsletter was "password security". ...
1
vote
3answers
937 views
Is bcrypt better than scrypt [duplicate]
Possible Duplicate:
Do any security experts recommend bcrypt for password storage?
I'm no security expert and do not pretend to be that's why I'm asking here. I write many PHP based ...
1
vote
2answers
447 views
should i use urandom or openssl_random_pseudo_bytes?
I am developing a site in php 5.4 and i was wondering which is better to use to gen a random salt for password security?
$salt = sha1(openssl_random_pseudo_bytes(23));
or
$seed = '';
$a = ...
9
votes
2answers
352 views
Password Salts and Randomness
Alright, so I understand that users are the kind of beasts who like to use one password and make it short and easy to remember (like "doggies"). If I understand correctly, that's one reason we use ...
5
votes
4answers
428 views
Gold Standard for password hashing
I've developing a web application that will be dealing with highly sensitive information and I want to ensure the hashing of passwords is gold standard. Ideally I'd go for per-user salted SHA512 ...
2
votes
5answers
164 views
Is there value in storing passwords in their own table with encrypted or hashed keys?
The usual method for simple sites is to store a hash of a user's password right in their user record.
What if the password field is removed from the user table, and a password table is created? The ...
8
votes
4answers
309 views
How to evaluate the strength of a hashing algorithm?
At work the hashing algorithm we use for passwords appears to be bespoke. Obviously that's a pretty bad idea, but the management don't seem bothered.
The algorithm always produces 20 character long ...
2
votes
2answers
631 views
OpenSSH default/preferred ciphers, hash, etc for SSH2
When using OpenSSH server (sshd) and client (ssh), what are all of the default / program preferred ciphers, hash, etc. (security related) and their default options (such as key length)?
So, what are ...
1
vote
1answer
76 views
How big is the risk of hash fixed points/cycles?
It's established wisdom to hash password multiple times with a salt to increase the time it takes per brute force iteration. At the same time (unless the algorithm guarantees otherwise) there's a ...
3
votes
2answers
115 views
Doesn't adding requirements to a password, such as must contain 2 digits, decrease the strength? [duplicate]
Possible Duplicate:
Doesn’t imposing a minimum password length make the password weaker by reducing the number of possible combinations?
Doesn't any constraints added to a password policy ...
35
votes
4answers
4k 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 ...
15
votes
7answers
383 views
To salt, or not to salt? [duplicate]
Possible Duplicate:
Why is using salt more secure?
Why would salt not have prevented LinkedIn passwords from getting cracked?
Recently I decided that I wanted to learn more about web ...
7
votes
4answers
1k views
What is a good practical (and sane) way to manage all your passwords for online sites?
I am just a mere mortal that wants to have a somewhat secure way of managing all my passwords.
This is something that I have been putting off, but since LinkedIn decided to give away one of my ...
2
votes
2answers
309 views
Do OpenPGP/GnuPG apply slow hash to password when encrypting/decrypting key?
Password space is quiet small. Therefore slow hash should be applied to password before using it for encryption.
Should slow hash function (like bcrypt) be applied to password before using it with ...
0
votes
1answer
141 views
Password protection of encryption and signature keys
I would like to store encrypted backup of text files on my computer. I'm developing a python script using Pycrypto to achieve that, based on this code to use the library. (current code)
The basic ...
2
votes
3answers
762 views
what is the fastest and cheapest way to crack this kind of hash - md5(md5($password) + salt))?
I'm looking for a program that can use any GPU (ATI\NVIDIA) and can brute force a vBulletin hash - md5(md5($password) + salt)).
I have the salt and hash.
the password contains the symbols - ...
17
votes
7answers
2k views
Why don't people hash and salt usernames before storing them
Everyone knows that if they have a system that requires a password to log in, they should be storing a hashed & salted copy of the required password, rather than the password in plaintext.
What I ...
6
votes
2answers
397 views
HMAC Based Request Signing - Storing the Salt
I'm working on a (non high security) project that currently isn't live but might go live at some point.
We have a REST API (implemented using Restlet and Neo4j) running on a server and an Android ...
34
votes
4answers
11k 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.
...
41
votes
5answers
5k 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?
4
votes
3answers
378 views
Is my session-less authentication system secure?
So, I've created an authentication system. Poured over it for any kind of security flaws and tested the crap out of it. I think it's fairly secure, but there is one "different" by-design aspect of it ...
2
votes
6answers
270 views
Does shuffling a hashed password increase its security?
I am making a web app and I'm now stuck on making the login secure. I'm thinking of adding a salt to a user-inputted password and then hash it. (md5 or sha for example)
and then I will reshuffle the ...
2
votes
1answer
451 views
Clarification on how rainbow tables work
If you goto : http://www.hanewin.net/encrypt/aes/aes-test.htm
for "Key in Hex" enter
00000000000000000000000000000056
for "Plaintext in Hex" enter
00000000000000000000000000000000
and click on ...
16
votes
5answers
400 views
Hashed password storage with random salt
Ever since I've been making sites that require a user to log in with a username and password I've always kept the passwords somewhat secure by storing them in my database hashed with a salt phrase. ...
17
votes
9answers
1k views
Is a simple, but very long password a good password?
Is a password like
wwwwwwwwwwwwwwwwwwwwwwwww9
(25x 'w' and a number) secure? It would be easy to remember.
3
votes
6answers
277 views
Is there a table that compares hashing algorithms by speed, relatively (machine independent)
As far as I understood*, one of the major criteria when choosing a password / salt hashing algorithm is it's speed. To prevent brute force attacks, a slower algorithm is better (and also makes it more ...
1
vote
1answer
83 views
How are root CAs for SSL distributed?
For internet explorer or whatever, I get it... It's in essence a sneakernet, you get them on the physical media from which you install your system and browser.
But what about for firefox and chrome?
...
0
votes
3answers
199 views
Key stretching an hash
if I implement an function which hashes the first half of my password with MD5 and the second half with SHA2 and MD5. Is there a security issue when I put these two hashes together to a 64 character ...
3
votes
1answer
167 views
Replacing weak SSH fingerprint algorithms
Even though MD5 has been broken for years and its vulnerabilities have been used to create real-world rogue X.509 CAs and other horrible things, OpenSSH and PuTTY still use MD5 as the default public ...
-6
votes
2answers
721 views
Is AES slower to encrypt than MD5?
Is this the right interperation of this diagram:
http://www.cryptopp.com/benchmarks.html
AES/CCM
MiB/Second:61
Cycles Per Byte:28.6
MD5
MiB/Second:255
Cycles Per Byte:6.8
And does that ...
1
vote
0answers
83 views
Finding pre-image of MD5 hash [closed]
I have the following requirement for hashing using MD5.
H(A,B,C,X);
Where values A,B & C are given.
However X is not given.
I would like to find out what value of X would give a hash beginning ...
2
votes
1answer
170 views
Is there a better way to take advantage of current 'approved', 'proven', and memory/cpu-expensive algorithms while using salts and peppers?
I've read about the concepts presented in these two questions:
Pre-hash password before applying bcrypt to avoid restricting password length
Would it make sense to use Bcrypt and PBKDF2 together?
I ...
3
votes
2answers
236 views
Program binaries or files with same MD5 hash
I'm looking for 2 different program binaries or 2 different files with the same MD5 hash to prove its weakness and the collisions in the algorithm.
9
votes
2answers
575 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 ...
1
vote
1answer
410 views
Parsing a PKCS7 detached signature hash
I'm trying to manually verify signatures of Apple iOS Passbook files, which are PKCS #7 detached signatures of the RSA key of the Apple developer who created the file.
Which means there's a file ...
10
votes
3answers
456 views
Does the salt need to be unique or not predictable?
I always thought that salts is simply used to prevent rainbow tables to be used. Other have suggest they should be unique on a per account basis. Currently i have been using a config file to use as ...
17
votes
5answers
1k views
What's the practical limit for rainbow-table based bruteforce?
Say we have a hash of a password. The password can be considered to be made of of totally random characters and has a fixed length of N. The hash is SHA1(password+salt), where the salt is of length M. ...
13
votes
6answers
467 views
Is there any security risk in storing hashed variations of passwords?
For example, if hypothetically an application requirement was to tell users when their password might have failed because caps-lock was turned on, and hypothetically there was no way for the ...
14
votes
4answers
743 views
What to transfer? Password or its hash?
Let's say in my database I store passwords hashed with salt with a fairly expensive hash (scrypt, 1000 rounds of SHA2, whatever).
Upon login, what should I transfer over the network and why? Password ...
10
votes
4answers
2k views
https security - should password be hashed server-side or client-side?
I am building a web application which requires users to login. All communication goes through https. I am using bcrypt to hash passwords.
I am facing a dilemma - I used to think it is safer to make a ...
1
vote
2answers
207 views
Password entropy match for alphanumeric but there are special characters in password
I have a problem cracking some of the fundamentals on passwords' entropies. Namely: I have read this article about a guy cracking DKIM of Google (maybe more noticing that the keys are only 512 bits)
...
121
votes
7answers
8k views
How to store salt?
Nowadays, if we expect to store user password securely, we need at least do the following thing
$pwd=hash(hash($password) + salt)
then store $pwd in your system instead of the real password. I have ...
8
votes
2answers
276 views
Is it okay to widely share the RSA key fingerprint for a host?
When you ssh into a remote box for the first time or if the remote host's key fingerprint has changed (from what's stored in your known_hosts file) you get a warning and you are shown the fingerprint ...
20
votes
3answers
816 views
MD5 collision attacks: are they relevant in password hashing?
DISCLAIMER: This is not an endorsement of MD5 as a password hashing function. I know about parallelization, GPUs, and dedicated password hashing functions like bcrypt and scrypt.
With that out of ...
2
votes
3answers
183 views
Password Security: Encrypting salt [duplicate]
Possible Duplicate:
Password Hashing add salt + pepper or is salt enough?
I'm new to security and trying to understand why encrypting or hiding a salt is not considered useful. I've read ...
2
votes
3answers
350 views
rsa encrypted hash == rsa signature
$ echo -n "1327943823" > test_ok.txt
$ openssl dgst -sha1 -binary -out test_ok.sha1 test_ok.txt
$ echo "GURbsl4CFPCG83RCZxsEpoRleXicXQhH1OC4Fk77b7EMj2g8aHUhD/L+sm
...
4
votes
3answers
330 views
Hashed passwords - How many variations of rainbow tables?
First off...I passed the CISSP exam. WOOOO. I had to get that out. GCIH and CEH by Sept. 11'
So, while studying for the technical side of things, I see that there are rainbow tables. They are ...
4
votes
9answers
1k views
What is the best way of securing a website logon without SSL or preshared keys?
Today I sniffed some unencrypted wlan traffic during class and I found quite a few passwords by a simple search for "pass" and "user" in wireshark. Turns out about half the sites we use for school ...
