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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How does a hash which contains algorithm to choose can be secure?

I was thinking about creating my own hash+salt function, something like sha1(password + md5(login)), then I read here (part 4) that creating it's own hash+salt function is a bad idea, because if the ...
7
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2answers
78 views

Can client-side hashing improve after-the-fact security in response to password leaks?

Several questions on this site address client-side password hashing, and none of them admit to any security benefit beyond protecting other sites the user might use the same password for. However, ...
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48 views

John The Ripper and OpenCL on AMD FirePro

Trying to work with John 1.8.0 Jumbo 1 I noticed that OpenCL won't work for me. I used autoconfig (meaning configure and build with the option to enable OpenMPI) in order to build JTR for my Mac Pro. ...
3
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1answer
76 views

What's the weakness of keyed-MD5 for message authentication?

I've seen public web API's using keyed-MD5 to generate message authentication code rather than adopting the HMAC algorithm. People wouldn't just invent HMAC for fun, so it must have some advantages ...
4
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1answer
132 views

Sending Encrypted Messages with Hybrid RSA, AES and HMAC SHA-256

Is this a Secure strategy for sending a large Encrypted Message using Hybrid RSA 2048, AES 256 and authenticated with HMAC SHA-256: Given the Alice already has Bob's RSA Public Key, Alice: ...
2
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1answer
122 views

if a public key cannot decrypt the cipher text, then how can a private key?

I understand the "public" part of public key cryptography. Not the "private" part. For example, let's say our public key is %7 (modulo 7). And the message to be encrypted is 22. And we know that 22 ...
5
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5answers
2k views

Salted password + hash - is it really useful? [duplicate]

I am new to the topic and wanted to know the concept of having salted hashes before going down to the technical details. From what I have understand password - plaintext hash password - plaintext ...
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2answers
124 views

What if the Local Windows Cert Store is Compromised?

The diagram below illustrates chaining digital certificates up to a publicly trusted Root Certificate: I have been researching how trusted root authorities (such as GlobalSign or Verisign) are used ...
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0answers
49 views

How to determine what type of hash algorithm is used [duplicate]

My friend gave me a hashed/ encrypted ciphertext and I want to determine which hash algorithm is used. 3_HA{_[Kg742ea6zy.CT30:b:SX@:T]vf{2A<Mk9ab:@oU[VCOA_B5BI.9CqZ3tl I don't think this is a ...
4
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0answers
53 views

Sqlmap trimming output

I've decided to learn Sql/map but having an issue with Sqlmap trimming some of my output, the hash. The hash is about to be 32 characters long but I'm only getting 25 and the warning: [WARNING] ...
19
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7answers
4k views

Why not mix hashes?

To make hashes harder to target by specialized hardware, I intuitively imagine that mixing a set of different hash algorithms should provide additional strength. For simplicity lets assume Hash1 is a ...
3
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1answer
94 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 ...
8
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2answers
382 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 ...
5
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2answers
59 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 ...
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1answer
73 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)))
4
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2answers
58 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 ...
8
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1answer
67 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 ...
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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: ...
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0answers
42 views

Is it secure to use pbkdf2 for both password hashing and key generation

I'm writing a password manager, right now for each individual site, I already used master password + random salt with PBKDF2 to generate encryption key to encrypt its password (each site has its own ...
2
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1answer
49 views

Distributed tokenization for credit card numbers

I have two locations within the same firm that hold credit card numbers. I want to be able to "join" on credit card number to do business analytics after transmitting card number-linked data from one ...
2
votes
1answer
98 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. ...
0
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1answer
45 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 ...
0
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1answer
87 views

Rainbow tables/hash tables versus WPA/WPA2

In Wi-Fi penetration testing, is it possible to use rainbow tables/hash tables on WPA/WPA2 networks? Is there an advantage of one over the other? Where would one get said tables or can they be ...
2
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1answer
102 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, ...
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1answer
51 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
60 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
155 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 ...
2
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1answer
101 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 ...
2
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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
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2answers
113 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 ...
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 ...
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2answers
125 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
60 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 ...
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6answers
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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
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2answers
130 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
86 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 ...
0
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0answers
83 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 ...
2
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1answer
40 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 ...
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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
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2answers
931 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 ...
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3answers
71 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 ...
1
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1answer
17 views

Is the method of hardening the creation of a Cryptographically Generated Address (CGA) called hash extension

CGAs are sha1 hashes truncated to a 59 bit value. Along with a 3 bit security parameter they form a IPv6 address (more precisely the interface identifier). from wikipedia: The Sec parameter ...
5
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5answers
864 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 ...
2
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3answers
220 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: ...
0
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1answer
32 views

Virtual Machine Integrity Hash Check

If I used virtualbox to create a snapshot template of a preconfigured linux machine and wanted to ensure that no one has tampered with my snapshot, could I simply keep a comparable hash of the VDI ...
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4answers
253 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 ...
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1answer
55 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
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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 ...
19
votes
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 ...
0
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2answers
59 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 ...