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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Is there a security advantage towards hashing a password on the server? [duplicate]

I'm working on an authentification system. Now in this system the user logs in and sends a hashed password to the server. Is this enough or do I have to rehash the password again? So basically is ...
4
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1answer
108 views

“MAC function must resist existential forgery under chosen-plaintext attacks”, what does that mean?

While reading about MAC (Message Authentication Code) I have faced this sentence: MAC function must resist existential forgery under chosen-plaintext attacks but I got confused. What does ...
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2answers
73 views

When should a password be hashed? [duplicate]

I develop a Smartphone App and have a little question: When should I hash the user passwords, on the device or upload them in plain text and hash them on the server before stored in the database?
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2answers
842 views

which hashing algorithm is better to use to store a password, sha256 or sha512? [duplicate]

which hashing algorithm is better to use to store a password, sha256 or sha512? I know that sha512 is more secure than sha256 but I was wondering if it has some disadvantages or it is completely ...
0
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1answer
225 views

Does SHA-512 become suitable to store a password if we use salting and iteration with it?

Today I have read this discussion about SHA-256 and SHA-512 and that we should not use any of them to store a password securely. And I have read here that instead we can use the PBKDF2 hashing ...
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2answers
128 views

Several hashing routines support client side work. Doesn't the hash just become a password equivalent?

Isnt Secure Remote Password Protocol (SRP) pretty much client side hashing? Argon2 the winner of the PHC also allows for client side hashing. How do these systems avoid the plaintext equivalence ...
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1answer
70 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 ...
2
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1answer
203 views

Reverse engineering of a global hash salt from known plaintext and hash

First of all i'm not asking what is a hash, or something else. I will try to explain what i'm searching clearly: Let's say I have a dump of a database, all the passwords of this database are hashed, ...
0
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2answers
116 views

which hash algorithm takes longer time if we compare between md5 or sha256?

Which hash algorithm takes longer time to compute if we compare between md5 and sha256? I do not want to use it for security reasons so I do not care about which one is more secure, I just want to ...
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1answer
93 views

How to identify this hash?

I have one hash, I know its value, but not its type. Here is it: 6dfb036bf703d75f9bc8219ba1224d876783fa61 I tried something like php -r "echo sha1('abc');", but it gave me another value, so this ...
8
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1answer
357 views

Any problems with scrypt yet?

In the question Do any security experts recommend bcrypt for password storage? Thomas Pornin recommends the hashing function scrypt but saying it is "too new to be recommended on a general basis". ...
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1answer
99 views

What is the difference between Key Derivation Function and (salted) Hash?

I see in this post that the main difference is that KDF outputs have "certain randomness properties", and I don't understand what does it mean. Suposing that that "certain randomness properties" are ...
2
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1answer
101 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
votes
3answers
180 views

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
1k views

Is it bad practice to ask only for individual characters of a password? [duplicate]

Some financial websites that I use use passwords in a peculiar way. Instead of asking me the whole password string, they only ask me to enter e.g. "3rd, 5th and 8th character of your password", i.e. a ...
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0answers
164 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
149 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
270 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
164 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 ...
5
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2answers
4k views

File security when encrypting files directly with the openssl command / and what about SHA1 hashing password first?

I've been using this command to encrypt files for a while now: openssl aes-256-cbc -a -salt -in secrets.txt -out secrets.txt.enc Then I type in a password. Can someone tell me, roughly speaking, ...
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3answers
24k 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 ...
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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
270 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
73 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
300 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)))
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2answers
515 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 ...
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2answers
169 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 ...
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1answer
39 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
186 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 ...
5
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2answers
155 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
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1answer
154 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. ...
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1answer
67 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
258 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
86 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
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1answer
63 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
94 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
504 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
152 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 = ? ...
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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
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1answer
97 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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2answers
156 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
79 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
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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
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2answers
183 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
123 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
544 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 ...
102
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4answers
25k 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
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3answers
233 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: ...