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.

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119 views

How does hashcat figure out the SHA CRYPT ROUNDS on a Linux password

A part of my /etc/login.defs file looks like this: ENCRYPT_METHOD SHA512 # Define the number of SHA rounds. # If not specified, the libc will choose the default number of rounds (5000). # The values ...
5
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2answers
64 views

Understanding digitial certifications

q1) Does that mean that every time information is exchanged, both the original data + digital certification is sent? Meaning data + signature for each and every exchange. q2) Can any kind soul here ...
-3
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1answer
106 views

What type of hash is this MD4(MD4(($pass)).(strtolower($username))) [closed]

Can I decrypt this hash? Domain Cached Credentials: MD4(MD4(($pass)).(strtolower($username)))
8
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2answers
401 views

*NIX shadow file password format

I'm trying to get shell access to a router and have managed to retrieve its /etc/shadow file: root:$1$$N76hdwGfg11g0KdKbtyh21:0:0:root:/root:/bin/bash I've tried to use john to crack it but ...
4
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2answers
67 views

Determining strength of truncated HMAC

I have data stored on a device which I must guarantee integrity, for ease of explanation the data is like numerical field representing 'credit balance available'. The device only ever interacts with ...
9
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1answer
95 views

Is Rfc2898DeriveBytes using HMAC SHA1 still considered “secure enough” for hashing passwords?

I've been told by a CISSP that the .NET class Rfc2898DeriveBytes would not pass a security audit today because it still uses SHA1. It's reliance on SHA1 - even with the iterations - leaves it too ...
1
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1answer
37 views

Reproduce part of a hash

I know very little about hashes, but I was wondering if I know the first 20 digits of what got hashed and the first 8 digits of the hash, is there any way to figure out the entire hash? For example: ...
2
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1answer
116 views

How much does knowing the zxcvbn password strength help an attacker?

On an answer to the question How critical is it to keep your password length secret?, Mike Ounsworth commented that by storing the zxcvbn-calculated entropy of a password you make it easier for an ...
3
votes
2answers
125 views

Cryptographic algorithm to anonymise strings in pronounceable fashion?

NB: I originally posted this on SO (link), but then realise Security SE be more suitable, since there's existing questions around Crypto-PAn, which is similar here I have a logfile of database ...
2
votes
1answer
100 views

Is it insecure to provide a hash of an AES password?

I have made some software that encrypts and decrypts files using AES. I was wondering if it is safe to write a hash of the password to the file so that the program can check if a password is correct. ...
4
votes
1answer
951 views

How can I extract the hash inside an encrypted PDF file?

As long as I know, the encrypted PDF files don't store the decryption password within them, but a hash asociated to this password. When auditing security, a good attemp to break PDF files passwords ...
0
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1answer
53 views

Can you resalt hash/rainbow tables after finding the salt for something?

After a rainbow/hash table is salted, is it possible to resalt it after finding the correct salt instead of generating it all over again? If not, what is preventing you from doing so? How can you find ...
2
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1answer
115 views

What is the difference between a hash table and a rainbow table, and how are they both used?

Is there much of a difference between the two tables? Can you get one from the other? (i.e. hash -> rainbow) How do they work? Are there different variables (in reference to speed, strength, ...
0
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2answers
79 views

Protect against malicious client with key derivation function (PBKDF2)?

Consider a protocol that allows clients to retrieve XML "forms" from a server. Forms are identified by a unique, randomly generated form ID that is embedded in the form. Clients fill out the form and ...
0
votes
1answer
57 views

Is this a secure hash “Function” for integrity?

I was wondering what were the posible security (not efficieny) issues with this hash "function": Although not an actual function, this method turns a message of any length into a message of fixed ...
3
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1answer
66 views

Secure text document's fingerprint

The purpose is the same as with hashing: given set of confidential documents, I want to process them and store something secure like salted hashes/bcrypt. Later, when new document is given, I want to ...
5
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1answer
195 views

Is Django's approach to password reset tokens secure?

I am implementing a password reset feature for a web application and am contemplating adopting an implementation similar to Django. In a nutshell, Django creates a token who is comprised of a ...
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3answers
134 views

Authenticate User Salted Hash Without Username

I've got a page with a login system where you type your username and password, the salted hash gets pulled down from the database depending on the username ... SELECT hash FROM db WHERE username = ? ...
39
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5answers
17k views

How does hashing work?

I have been interested in Information Security. I was recently introduced to the idea of hashing. What I currently understand about hashing is that it takes the password a user enters. Then it ...
7
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3answers
2k views

How are leaked government credentials possible and what's the point?

In the wake of all these leaked/stolen/hacked government login/passwords being stolen it got me thinking. How is the leaking of these passwords even possible? Or are they of any real use? Aren't all ...
2
votes
1answer
75 views

Save Password length after hash to minimize calculation

Reading this topic How critical is it to keep your password length secret? following scenario comes to my mind: Assume I've a web application (PHP written using password_hash()) using salted password ...
3
votes
1answer
3k 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 ...
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votes
2answers
133 views

What are hashes that begin with $1$…? [closed]

I've found this hash and I'm wondering what is it. $1$h6k3X5db$pp8WQ5R5YYL5bNyQj2wP70
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1answer
63 views

Using username as salt safe enough? [duplicate]

Instead of creating a separate salt generator for each user, can't I just use their username as a salt? It would be unique for everyone, and achieves the purpose of the salts. <?php ...
31
votes
6answers
3k views

Does verifying identity by positions in passwords mean passwords are stored unhashed? [duplicate]

If authentication occurs by asking the user for the characters at certain positions in the password (such as: give the 3rd and 7th character in the password), does this imply that passwords are stored ...
0
votes
2answers
144 views

Weird 8-character hash [closed]

I'm investigating an application. In a XML file I came across: <ScrambledPassword>U8P3J2N1</ScrambledPassword> I ran it through a hash identification script which is telling me it's a ...
1
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3answers
97 views

How to identify hashes [closed]

How can I indentify a hash? Not with length only, I mean: as I know, specific hashes has specific charsets. Where can I find them? I need this information for making a hash indentification tool. (this ...
20
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6answers
16k views

Is MD5 considered insecure?

After all these articles circulating online about md5 exploits, I am considering switching to another hash algorithm. As far as I know it's always been the algorithm of choice among numerous DBAs. Is ...
0
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0answers
115 views

Line Length Exception in hashcat

I'm very new to cracking a password so sorry if I sound stupid. I am trying to get my admin password from my second PC (I lost it). I did find the SAM file with kali linux and with bkhive and samdump ...
91
votes
4answers
21k 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 ...
2
votes
3answers
224 views

How can two parties compare whether a simple (5 letter) shared word matches, without disclosing their word to each other?

I'm having some trouble with this scenario, some advice would be great. The context is that a group of people have each been give a simple 5 letter word - for example: Alice: ACTOR Bob: JEANS Dan: ...
10
votes
4answers
6k views

HMACSHA512 versus Rfc2898DeriveBytes for password hash

We are currently using HMACSHA512 in .net, with a 128Char (64byte) validation key The salt is 64 char randomly generated string. We allocated 2048 length on the database for the hashed base64 string ...
2
votes
1answer
47 views

Personal cipher/digest preferences ignored when generating a new key pair in GnuPG

I have specified personal digest preferences in my ~/.gnupg/gpg.conf: personal-digest-preferences SHA512 SHA256 SHA384 SHA224 SHA1 then, I have generated a new key pair. But when I check the ...
0
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2answers
52 views

Is there a way to give out secure tickets wihout storing them?

I'm building a website on which I want to make it very easy for users to create pages anonymously and later be able to come back and edit those pages. One way to do so is to give out confidential ...
3
votes
2answers
939 views

big O for finding hash of length n O(2^n) or O(2^(n-1))?

note The wikipedia article does not use the big O notation correctly. Thus O(2n) just means 2n attempts I read on wikipedia (CGA) that finding a collision preimage for a cryptographich hash of ...
5
votes
5answers
882 views

How secure is it to keep the salt with the password hash? [duplicate]

In Linux we have the salt just next to the password hash in the /etc/shadows file. I always hear that salt value prevents hashed passwords from being cracked by brute force methods. But if somehow we ...
1
vote
3answers
73 views

Potential collision with hash password

Normally, the password size is fixed by the hash function in which the password is given right ? Because otherwise, if the password size is bigger than the hash result size, there should be potential ...
3
votes
1answer
115 views

How secure is Visual host key, and how is SHA2 converted into that representation?

SHA2 has 256 bits of possibilities. Visual host key seems to have the following upper and lowercase = 26*2 numbers and symbols = 20 Additional symbols = 22 Total 94 characters represented in ...
1
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4answers
257 views

Why is a password accompanied by a username deemed 'safer'?

While browsing this community I notice that some people say that the main advantage of usernames accompanied by passwords is as they take more tries to be brute forced, however I don't think that is ...
20
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3answers
2k views

How to replace an old password hashing method with a newer one in software? [duplicate]

The software that our company builds just went through a security audit. The auditors flagged our use of MD5 for hashing passwords that users can set if they want a password on their files. Having ...
20
votes
2answers
1k views

Can client-side hashing reduce the denial-of-service risk with slow hashes?

When storing user's passwords that you need to verify against (but not use as plaintext) the current state of the art is: Hash the password Use a salt Use a slow hash function - bcrypt, scrypt, etc. ...
0
votes
2answers
89 views

Is there a cryptographic function that generates a reconizable visual pattern?

I have to build a system that will ultimately print a pass allowing access to a building. The validation of this ticket will be done manually (it can also be automatic but that's not likely at this ...
1
vote
1answer
68 views

How to change personal cipher/digest preferences of existing OpenPGP key in GnuPG?

The OpenPGP key contains a list of personal algorithm preferences (the meaning of the numbers can be decoded in RFC 4880): # gpg -a --export "foo@example.com" | gpg --list-packets | fgrep 'pref-' ...
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2answers
62 views

Getting the DNS root name servers in a secure way

It doesn't happen often that a root name server changes, but when it does sometimes it takes months for OS vendors to provide patches and in the mean time there is a security risk. So: How to get ...
8
votes
1answer
2k views

Is every hash format that nginx accepts for HTTP Basic Auth weak against brute force?

According to http://nginx.org/en/docs/http/ngx_http_auth_basic_module.html nginx can read password hashes of these types: crypt(), apr1, SHA1 & SSHA. This is how I understand how these hashes ...
3
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3answers
108 views

Authenticity of PDF document printed from Word

My MS Word Add-In generates PDF preview of DOCX file on client PC and uploads both files to server. I cannot generate PDF on server. Is there any way to make sure that the PDF is the printed version ...
12
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5answers
2k views

Is this way of encoding cryptographic hashes safe?

I'm looking at the code of a particular web application that handle file uploads. For some reason, instead of using the cryptographic hash function (SHA-256 in this case), they derive an ID from it, ...
16
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5answers
4k 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 ...
1
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1answer
125 views

Is This DIY Password Authentication Scheme Acceptable?

This is mostly a thought experiment for client/server communication, and I want to know the flaws. When a user account is created (with U as the username and P as the password,) I generate a random ...
9
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3answers
1k views

How secure are sha256 + salt hashes for password storage [duplicate]

I started reading about password hashing recently on multiple sites like this page on crackstation and others, and for what I have understood, I should avoid using hashing algorithms like md5 and sha1 ...