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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Digital signature VS whole message encryption

I am newbie in information security I am trying to understand the difference between the digital signature and encryption of message. Lets consider simple example of email message. I understand how ...
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4 views

What are the advatages or disadvatages of using seperate chaining over linear or quadratic probing? [migrated]

I was looking through different hash methods the other day and was curious as to what the advantages or disadvantages of using separate chaining over linear or quadratic probing. I know that with ...
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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 ...
4
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0answers
60 views

What are the recommended scrypt cost factors for 2016?

I've been trying to look for the answer, but the latest one I found was outdated by three years. So what are the recommended scrypt cost factors for 2016?
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1answer
69 views

Is `/dev/urandom` secure to generate a salt on a Virtual Machine?

I've read the new password_hash() function from PHP uses /dev/urandom to generate a secure salt, however this assumes some noise from device drivers. Is possible that /dev/urandom is not so random ...
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2answers
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Are SHA-2 certificates considered obsolete, or current?

A guide on this site on how to make a decent Certificate Signing Request (CSR) says that I should be using SHA-2 certificates to secure a HTTPS webserver. Are SHA-2 certificates considered obsolete, ...
6
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4answers
1k views

Does quick denial tell that you passwords are stored in plain text?

Say you are using a website and incorrectly enter your password. The website then "instantly" pops ups with an "incorrect username/password" message. Would it be safe to infer that the website is ...
1
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1answer
47 views

Powershell and cached credentials

In my environment we have powershell remoting off- I get around this using 2 hop scripts, packages(exe -no creds are stored in code- local privs only), and iwmi. I never pass creds to the endpoint, ...
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1answer
21 views

Hashing and signing partial data in payload

I'm hashing and signing part of a payload prior to HTTP Posting from a mobile device to server side. The payload contains of about 7 data elements and only 3 of them are hashed/signed using a private ...
3
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1answer
90 views

How to detect mimikatz usage on LAN

My boss is has made it clear that we need better ways of detecting mimikatz usage on the network- and I would agree. In place already for detection is suricata/ET PRO rule set on a couple of taps. ...
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2answers
926 views

Is there more to password hashing?

You have a plain text password and salt. The plain text password is assumed to be securely random and only known by the user and the salt is no secret and not necessarily unique but stored alongside ...
3
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1answer
149 views

Best way to hash passwords in PHP 5.3.5

What is the best way to hash passwords in PHP 5.3.5? Since in this version doesn't have password_hash().
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1answer
48 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 ...
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3answers
222 views

About SHA1 in default Disk Encryption in Linux

Link to the Thread: Recommended options for LUKS (cryptsetup) I wonder what's the exact difference between SHA1 and SHA512. I know that SHA512 has a longer key but I've read that it doesn't matter ...
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2answers
72 views

Is it possible to find the salt?

I have this PHP code with me : $auth = md5($username.$password.$salt); I have a dummy value : $username = user $password = password And I also have the resulting MD5 Hash : ...
116
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6answers
44k 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. ...
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4answers
133 views

Why shouldn't I store passwords in plaintext? [closed]

Why is it so important not to save passwords in plaintext? I think it is the same issue like authorizing a user on a RESTful webservice, where most developers claim: "Don't send your security token ...
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1answer
82 views

PHP BLENC extension security concern

PHP BLENC is a extension that allows PHP developer encrypt their code, protect their ideas and avoid illegal copy. Although BLENC allow developer to define the main encryption key in source(in the ...
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3answers
86 views

when to use encoding over hashing?

If encoding is used for integrity someone can tamper it across the network because it is based on some publicly known scheme. When do you use encoding and when do you use hashing for preserving the ...
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5answers
4k views

How does storing hash passwords work? [duplicate]

In usual network applications, that employ password hashing, is the user password hashed on client side before sending it to the server, or is it sent without hashing as encryption of plain text ...
46
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9answers
5k views

Why improvising your own Hash function out of existing hash functions is so bad

I'm afraid I'll have tomatoes thrown at me for asking this old question, but here goes. After reading that cooking up your own password hash out of existing hashing functions is dangerous over and ...
0
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1answer
53 views

How many hashes do I need to compute to get x collisions?

I know that you need to hash about 2^(N/2) to find a collision taking into account the birthday problem. But I'm not really sure about more than one collision, I mean, collisions with different ...
0
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0answers
11 views

Change ntlm hash in memory on the lock screen?

Is there a way to change the ntlm hash in memory to bypass windows login? For example, I have the ntlm hash of a windows machine and I have physical access. Is possible to write the ntlm hash in ...
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 ...
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1answer
29 views

Passing a hash of a secret to a server instead of the plain text

Instead of passing an authentication token or api key in an http header to a server in the plain text, what if I calculated its hash and passed the hash? This way even if a adversary intercepts the ...
5
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1answer
104 views

Reviews of Argon2

I am not a security guy but just curious about the things here. I have seen several people in various answers here talked about the password hashing competition. Now that the winner is announced, I ...
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2answers
85 views

Idea for an encrypted pastebin NON-web application

I have an idea for an app that might be useful (though if it isn't, I've still learned in the process, which is what matters). There are a bunch of encrypted pastebin web apps out there (e.g. ...
39
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6answers
15k 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 ...
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2answers
39 views

Incrementing Work-Factor of Hash Functions Over Time

For a long time hash functions have required a work-factor in order to keep the operation "slow" enough to protect individual passwords in the case of a database leak. Bcrypt and PBKDF2 being notable ...
3
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1answer
114 views

Two-phase anonymization

EDIT: [N.B: I fully replaced the original question which was not a very good statement of the problem (see comments) with a more apt one.] I have records that contain - among other things - the ...
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2answers
66 views

Upgrading security of hashed passwords [duplicate]

Let's say we have a database with usernames and passwords, where the passwords are naively secured using a single round of SHA-1 (such as was kinda best practice a number of years ago). Now, let's ...
3
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2answers
85 views

What scenario are 'extra' strong passwords and hashing algorithms actually protecting against?

Note: I completely understand the need for strong passwords & I understand that there is an issue of speed with hashing. I am just interested in better understanding the actual negative impact of ...
2
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0answers
22 views

The optimal settings of Winrtgen GIU

I'm working with Winrtgen GIU on windows, but I can't fix the right settings to create a rainbow table for a: password length=1-7 Charset=alpha numeric all space What are the ideal values to put in ...
3
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4answers
135 views

Is knowing the salt a problem?

I understand that adding a salt would thwart the use of rainbow tables. I don't understand the time it would take to create a rainbow table for a certain salt and of course this is dependent on the ...
3
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1answer
62 views

Is appending plaintext to salt equally safe as appending salt to plaintext

Is using hash(salt, plaintext) equally secure as using hash(plaintext, salt), i.e. can the plain text be appended to salt in place of appending salt to the plain text. Why or Why not? What kind of ...
17
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8answers
4k views

Won't all hashes collide after enough iterations (with a static salt)?

We all know that we're supposed to take a fairly slow hashing algorithm, salt the password, and run the hash for many iterations. Let's say that I'm following almost everything except for one rule, ...
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2answers
160 views

Simplest way of hashing a password with multiple different hash algorithms [closed]

I have a list of plaintext passwords that I would like to hash with various different hash algorithms (for educational purposes). As a minimum I would like to obtain hashes under MD5, SHA1, SHA256, ...
3
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1answer
101 views

Md5 vs Md4 recognition

Is there a way to actually find out whether a hash is MD5 or MD4? For instance: 10c7ccc7a4f0aff03c915c485565b9da is an MD5 hash be08c2de91787c51e7aee5dd16ca4f76 is an MD4 hash I know that there ...
2
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1answer
197 views

Encrypting data before sending to SaaS tool and decrypting on browser view

I'd like to send data to a SaaS tool, where the data is stored in the cloud. I'll use Google Analytics as an example, but it applies to any similar service. Google Analytics does not allow you to ...
3
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5answers
590 views

Why can passwords be used to encrypt data, but are less strong for authentication?

Encryption software is often password based. Even if the adversary gets your computer they can't get the data without knowing the password, and bruteforcing is infeasible. Websites use passwords to ...
10
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2answers
12k views

How weak is MD5 as a password hashing function ?

A professor told us today, that MD5 is weak. I understand his chain of thought but pointed out, that IMHO MD5 is a good way to go if you would use a long (even really long) dynamic salts and static ...
40
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3answers
4k views

Security Review - password_hash implementation for PHP

I'm currently working on a "helper function" for PHP's core to make password hashing more secure and easier for the majority of developers. Basically, the goal is to make it so easy, that it's harder ...
14
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2answers
333 views

How does SHA3 (Keccak & SHAKE) compare to SHA2? Should I use non-SHAKE parameters?

Keccak is the winner of the SHA3 competition. Since Keccak is highly customizable (presumably for security/memory/time/speed tradeoffs) there does seem to be some controversy around how Keccak ...
3
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2answers
79 views

Is signing android apk file with SHA1 digest secure enough?

Google command line example for signing apk files: $ jarsigner -verbose -sigalg SHA1withRSA -digestalg SHA1 -keystore my-release-key.keystore my_application.apk alias_name source: ...
80
votes
10answers
9k views

Is there a threshold for a password so long it doesn't get any more secure or even becomes insecure?

I always hear "A long password is good, a longer password is better". But is there such a thing as a "Password is so long it is becoming unsafe" or "Password is long enough, making it longer won't ...
6
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2answers
91 views

Is it good to store passwords in a separate table/database and manage them in a separate process?

I'm quite a newbie at systems architecture and security so I just want to check that this plan makes sense. I'm building a web app and I need to store a password for each user. I've already read ...
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1answer
64 views

Sum two SHA256 to get a SHA512 [closed]

I see this code in a web game SHA512(SeedServer + "|" + SeedUser) and I'm trying to reproduce this hash. I tried in PHP: <?php echo hash('SHA512', ...
7
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3answers
72 views

Does verifying an additional fraction of a file decrease the chances of collision?

If I have a file of indeterminate length and I generate the SHA256 of that file, then generate the SHA256 of the first half and the last half, then verify all three, does that decrease the odds of a ...
8
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1answer
3k 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 ...
2
votes
2answers
106 views

Where to store a pepper?

Assuming you're using a pepper in your password hashing, where should it be stored? I know you shouldn't store it in the database since it can easily be found there during a dump and the idea is to ...