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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579 views

Why not slightly modify an existing hashfunction to create your own? [duplicate]

I read this interesting question on why improvising your own Hash function out of existing hash functions is bad. However this is specifically focusing on 'mixing' existing hashfunctions. What if for ...
3
votes
2answers
178 views

How to give “Forgot password” option for a password encrypted file?

I have created a utility that encrypts a file (.txt, .dox, so on...). The utility asks for a password from user at the time of file encryption. Problem Suppose a user has created 1000 encrypted ...
1
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3answers
173 views

how to authenticate user in client-server implementation

So I am trying to implement a client-server application for sending files over SSL sockets. And I am trying to decide on a very secure design for authenticating the client. The server is going to ...
5
votes
3answers
169 views

How to prevent a prophecy from becoming self-fulfilling or self-defeating

Let's assume that I have deduced with a high probability what a certain famous person or organization will choose to do at a near-future date. How can I publish any proof of me having deduced this? ...
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votes
1answer
90 views

Hash regex for malware recognition [closed]

I'm looking to store two types of hashes for recognizing blacklisted code. These are the FireEye "import hash" (or imphash) and the ssdeep "fuzzy hash". Is there a regex (or formal documentation) I ...
1
vote
1answer
160 views

best practices for storing retrievable passwords

I am trying to build a NMS (network management system) and I am required to store passwords for 3rd party databases, devices and servers that are being managed (not user passwords). These passwords ...
4
votes
1answer
249 views

OpenSSL 0.9.6a PRNG algorithm weakness: How to exploit?

I saw an OpenSSL security advisory for Openssl 0.9.6a Recently a cryptographic flaw in OpenSSL's built-in pseudo-random number generator (PRNG) was pointed out to us by Markku-Juhani O. Saarinen ...
2
votes
2answers
122 views

Best hash for indexing and searching encrypted data

I would like to be able to do database look-ups on a set of data based on one of the encrypted fields. My understanding of the best practice for accomplishing this is to store a hash of the data I ...
1
vote
1answer
129 views

Yii client side captcha validation

Apparently, Yii web application framework generates some kind of hash value from captcha codes it generates and sends it to the client side so it can be used for client side validation of the captcha ...
2
votes
1answer
553 views

Can I know somehow if my password hash is known?

Is there a secure way to know if my password's hash is publicly known on the internet? First I tried to search for it in Hashes.org (http://hashes.org/search.php), but then I suspected, that if it ...
5
votes
2answers
584 views

How facebook knows my new password is too similar to my old password? [duplicate]

I am still very new to Information Security field and as far as I know, websites use hashing algorithm on user's passwords before storing it and they don't know the plain-text password of a user. ...
4
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1answer
103 views

Is the 64-bits length of the original string padded as well in the MD5 hashfunction?

So, for example I have a string which binary value is exactly 512 - 64 bits long, so the binary conversion of the string does not have to be padded. So that means I have a string of 56 chars. The ...
1
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1answer
43 views

Hashing Based Encryption

Let's say you take a 256 bit key and never use it to encrypt anything. You receive a message with a 16 character unique randomly generated salt pre-pended. You salt your key with the 16 character ...
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votes
1answer
68 views

Finding the cryptographic hashing algorithm, given the plain text and the corresponding salted hash [duplicate]

I have a salted hash (say about, 110 characters long) and the corresponding plain text that I used for hashing. As the title says, is it possible to do find the algorithm via crypt-analysis? What is ...
0
votes
1answer
58 views

Store Hash and/or Encryption salts in database [duplicate]

I am doing a custom login for practice purposes, and i am wondering what would be the logical way to save the hashed password and the salts. Salt/Hash operations are using Rfc2898DeriveBytes class. ...
2
votes
1answer
148 views

How to “Pass the hash” when LM hash is disabled?

I ran the NTLM_stealer metasploit module and ended up with the following results: LMHASH:Disabled NTHASH:008940f335e9b2ddc182bb5b960a0c5bad0b125cbee3cf84 I was wondering if there is way to ...
24
votes
1answer
2k views

How can the content of a file refer to its own MD5?

So I just saw this picture on Imgur: http://imgur.com/gxRCrCM The intriguing thing about it is that the picture refers to an old Daft Punk song named "Face 2 Face". The image's MD5 is ...
0
votes
2answers
128 views

Reverse engineering of hash functions

I have an unknown process that gets some vars and returns an 8byte hash. I'm sure which vars it gets and I'm sure these are all the variable parts of the input. I can query this process when and how ...
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0answers
45 views

Key stretching approaches

I've seen that a number of key stretching algorithms and they involved increasing the number of operations needed to compute the key(i.e. the number of rounds within a hash function). But, I wonder if ...
64
votes
11answers
9k views

Is there any way my password is hashed, if I'm only ever asked to provide 5 out of many characters? [duplicate]

There is a system that, on a login form, presents about 40 boxes for password letters (to hide password's actual length), and only random ones (the same amount each time) are editable. Explanation is ...
8
votes
1answer
660 views

Why store a salt along side the hashed password? [duplicate]

Understand the need to protection credentials with hashes that are expensive and to use cryptographically random salts. What I would like to understand is why you would store the salt along side the ...
0
votes
1answer
49 views

Would it matter if my miner was hashing random vs incremental values?

I'm working on my miner for my "game" site that's basically a pre-image attack from a hash posted online. You submit a hash input, it's hashed, and your score is the hamming distance (the number of ...
2
votes
2answers
1k views

Is it possible to salt the SHA1 or SHA256 hash function of OpenSSL?

I would like to salt the hash function of OpenSSL external, so that I can assign a salt on my own. Is that possible or is the hash function of OpenSSL alsways internal "salted"?
3
votes
1answer
167 views

Challenge: How to find the secret key in homebrew MAC/keyed hash: sha1(key + cookie)?

I am trying to solve a security challenge on a website. Basically, the website computes sha1(key + cookie) to sign a cookie so that the user can't change it himself, and to accomplish the goal you ...
5
votes
1answer
2k views

What difference between AES_128_GCM and AES_128 and AES_128_CBC ciphers?

I encountered AES_128_GCM cipher, tried to find it in specifications of TLS1.2 and nothing, any mention. Could some one explain the difference between AES_128, documented AES_128_CBC and this new kid ...
2
votes
3answers
1k views

Strategy for updating stored passwords to more secure hash? [duplicate]

I know that we cannot update our hashed passwords without having the plain text password to re-hash. When a member logs in with login/password, we have the plain text, so that gives us an opportunity ...
5
votes
1answer
2k views

How can a system verify an online password using a phone keypad?

I phoned into a financial company's website, and it prompted me to key in my password on the phone keypad, converting the alphabetic characters to the corresponding digit, and special symbols to '*'. ...
0
votes
1answer
1k views

Extract Password Hashes from Active Directory LDAP

Currently we are working on a monthly internal security test which among other should contain a verification of the real password strength the users choose. For this reason I want to extract the ...
0
votes
0answers
32 views

Password storing using hashing only, encryption plus hash [duplicate]

I want to hash password before storing to database. I am not able to understand which approach will be suitable.For examples Hash plain password directly with SHA-1, SHA-256 etc and then store in DB. ...
0
votes
1answer
123 views

Ignoring collision and (second) pre-image resistance, what makes a cryptographic hash function strong?

With regards to resistance against dictionary and brute-force attacks to "crack" hashes containing passwords, what determines the resistance of a cryptographic hash function? Since collision ...
4
votes
2answers
2k views

What's the purpose of $LoginKey from the Ashley Madison leak?

According to this site Ashley Madison was keeping an insecure hash stored in their database using MD5, in addition to the far more secure bcrypt hash. This group used the MD5 hashes to quickly crack ...
17
votes
1answer
2k views

Password hashing : Using 2 salts [duplicate]

I'm developing an authentication service. I know the practice of generating a unique salt per user, stored in the DB with the hashed password, to prevent rainbow tables attacks. I just had the idea ...
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votes
1answer
423 views

SQLMAP --OS-SHELL error [closed]

root@kali:~# sqlmap -u http://www.a***********.com/info.php?id=2 --os-shell _ _ _| |_____ _ {1.0-dev-nongit-20150907} | -| . | | | .'| . | || |||||,| | || |_| ...
2
votes
1answer
52 views

Risk associate with nonce and hash found in url

I have came across a url with nonce and hash in placed which is an account activation link sent via email. The example is as followed: ...
0
votes
1answer
172 views

Is it possible to find out the salt of a MD5 hash?

I want to know whether it is possible to find out the salt of a MD5 hash? For instance we've got two MD5 hashes helloworld -> fc5e038d38a57032085441e7fe7010b0 goodbyeworld -> ...
3
votes
2answers
138 views

activate user account through email

I see a lot of people say to hash for the token on email verification when dealing with member registration. I am wondering, if the email token is only to activate the account and nothing else, ...
10
votes
5answers
2k views

Are case-insensitive passwords a bad idea?

I recently discovered a service where the password was not case sensitive. I understand basic principles of encryption and hashing so I am a bit worried, is this service storing my password in plain ...
2
votes
2answers
245 views

MD5 brute force on a faulty hash?

MD5 for passwords is considered insecure due to the ability to brute force and pick up the result. But what if I change some characters of an MD5 hash and I keep a record of that change so that ...
2
votes
2answers
109 views

Is a random work factor an increase or decrease of security?

Assume you use a proven hashing algorithm, like bcrypt with a work factor of 10 or PBKDF2 with 10K iterations. Normally that's really secure already and would give enough security already for most ...
2
votes
3answers
488 views

Implications of hashing to UTF-8 in a cryptographic function

I know that most hash functions today use Base64 encoding for their functions, resulting in hashes that use a-Z and 0-9, and, sometimes, other special characters. This results in 62-76ish possible ...
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votes
1answer
68 views

How do I get the password knowing part of it and the length [closed]

I'm new to all this, I'm trying to use Hash Suite to find a password with a word + 2 numbers. I know what the word is but not the numbers but I also know the length of the passwords ... What do I have ...
0
votes
2answers
470 views

What current algorithms are considered (un)secure? [closed]

With the new release of Windows 10, Microsoft has given .NET, Javascript and C++ developers a whole new bunch of options for cryptographic algorithms. Where as the old .NET code only allowed AES and ...
1
vote
1answer
97 views

what is the most secure hash for virus definition databases in 2015?

I have been told, if I wanted to create virus signatures from infected files to use for detection in the future, I should be careful as some of them are prone to collision attacks?
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votes
2answers
234 views

Use of Nmap ssl/http md5 and SHA1 hashes

I have below stated result on of the system by map: 443/tcp open ssl/http Apache httpd 2.0.52 ((CentOS)) | http-methods: GET HEAD POST OPTIONS TRACE | Potentially risky methods: TRACE |_See ...
33
votes
4answers
6k views

How does a hacker know how many times a password was hashed?

I've been reading a lot of questions about security and hash functions on this site and others. I am not an expert, just a curious mind and in my understanding the more iterations used to hash a ...
0
votes
2answers
165 views

What the most trustworthy way to demonstrate digital File Integrity?

I'm looking for ensure the integrity of uploaded files and demonstrate this integrity to a user. In my current scenario, a user sends multiple files in several different formats, these files are ...
2
votes
1answer
120 views

Can I safely and securely store hash(sessionId) in application logs?

I'm considering storing a hash of a user's session ID in our applications logs on each request. This would allow users sessions to be easily tracked back to actions in our logs. I understand that ...
0
votes
1answer
43 views

Is there any problem using empty salts with PBDKF for this purpose?

The aim is to generate a secure key for symmetric encryption. I have a master password, from which I want to generate the key for symmetric encryption, in order to encrypt other passwords. The idea ...
2
votes
2answers
685 views

Determine salt length from hash

I am writing a basic Unix password cracker in Python that would work for MD5, SHA-1 and SHA512. I know that the salt in MD5 correspond to the 2 first chars of the encrypted password, and thus I ...
2
votes
3answers
305 views

Hashing passwords in OpenLDAP

I've seen a few posts on the internet saying most people store user passwords in OpenLDAP using one of OpenLDAP's many, built-in hashing functions. But OpenLDAP itself recommends handing off password ...