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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2
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51 views

Disallowing Similar Passwords [duplicate]

Upfront, I want to clarify that I am not a professional cryptographer, I am more curious about playing with the math and science behind it, and also want to improve my habits with my own personal and ...
0
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2answers
254 views

How hash ensure integrity of data? [duplicate]

I understand what a hash is, basically we calculate a hash and append it to the message and send it to the receiver. If someone alters the message, the receiver will know because there would be a ...
1
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0answers
50 views

Hashcat Turkish character problem [closed]

I'm using cudahashcat, it haven't special chars like "öçşĞÜ" in standart charsets. I defined charsets with windows-1254 and other encoding types(and -1 öÖçÇğĞşŞüÜıİ?a parameter), i tried but they ...
0
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3answers
814 views

Which PHP encryption method is most incidentally-secure?

just started researching on the latest PHP encryption methods, I've found out my favorite algorithms are compromised. MD5 is no good, SHA-1 has "found flaws", SHA-512 isn't "meant for passwords", ...
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1answer
56 views

What is the most secure way to protect a custom CMS from infiltration? [closed]

I have a custom CMS with a randomly generated ASCII 100-character string from this site for both my username/password. I also have this following sha512 encryption system, which was created by ...
-1
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1answer
82 views

Disastrous aftereffects of a hashing attack

I am writing about hashing functions for my thesis. I want to know whether there were disastrous aftereffects of a successful hashing attack in history and what kind of hashing attack was used. ...
0
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2answers
133 views

Is my hashing function good enough

Is there an obvious flaw with this hashing function (written in PHP)? function hash($password) { sleep(1); // Make hashing slow $hash = ""; $iterations = strlen($password); for ( $i = 0; $i ...
1
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1answer
108 views

John the Ripper missing formats [closed]

I have an sha256 hash that I am trying to crack with John the Ripper. However, it doesn't recognize raw-sha256, raw-md5, or any hash format other than descrypt, bsdicrypt, md5crypt, bcrypt, LM, AFS, ...
1
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2answers
79 views

Is it known to what message size are standard hash functions injective?

This simple Python script verifies that all messages of length 1 have different SHA-1 hashes: import hashlib s = set() for i in range(256): s.add(hashlib.sha1(chr(i)).hexdigest()) print len(s) ...
1
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0answers
44 views

Is there any merit to the RFC 3414 (SNMPv3 User Security Model) password-to-key method?

RFC 3414 (published 2002) specifies a method of generating keys based on password in its Appendix, which essentially takes any "passphrase", and keeps on repeating it until there is a 1MB string, at ...
1
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0answers
100 views

PKCS#7 signed data structure in signed PDF document

Is it mandatory to include PKCS#7 data (OID 1.2.840.113549.1.7.1) octet string into the sequence of PKCS#7 signed data? I mean if you want to sign PDF, you are basically adding PKCS#7 container ...
2
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1answer
81 views

What is a key-hardened hash?

I've seen the term 'key hardened hash' used to describe a recommended way to tighten up password hashing. What does this mean? Can it just mean to use a pepper?
2
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2answers
86 views

Does recursive hashing weaken properties of a cryptographic hash algorithm?

Specific example of mine concerns the probability of collision, where I have two plain texts A and B that I want to hash using MD5. Given the cryptographic hash function H and the following: A' = ...
5
votes
0answers
230 views

Naive implementation of Rainbow Table and/or Hellman's trade-off

This question is the same one I asked here. Since I haven't got any response or even a comment I will post it here as well. Is there any naive implementation of Hellman's cryptanalytic time memory ...
0
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2answers
163 views

Is this the most secure encryption/hashing system? [closed]

I've been doing some research regarding password security and after reading several topics and the Kerckhoff's principle. I came up with what I believe is a really secure system regarding online ...
4
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2answers
4k views

Should I use urandom() or openssl_random_pseudo_bytes()?

I am developing a site in PHP 5.4. Which function is better to use to generate a random salt for password security? $salt = sha1(openssl_random_pseudo_bytes(23)); or $seed = ''; $a = ...
1
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3answers
148 views

How to transform an hash into a usable password?

I was reading about PwdHash and it inspired me to create a little project where you input a master password and an easy to remember alias into a password hash, like bcrypt, and then you get an hash. ...
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votes
3answers
127 views

Is it really necessary to hash user passwords when I already protect my database against SQL injection? [duplicate]

I'm developing a school, I just applied all the SQL injection protections that exist and database security, administrative roles, parametrized queries, sanitize input from the client. But FOOL ME! I ...
2
votes
2answers
165 views

Reducing hash output length [duplicate]

I am using output of (keyed) hash function to make sure the input was not modified, I store it along with input. Now output of SHA-1 is 20 bytes. Say I want to reduce the output. And have it output 10 ...
18
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3answers
3k views

Is using the concatenation of multiple hash algorithms more secure?

Is it more secure in practice to use the output of multiple hash algorithms instead of a single one (assuming that the output size is the same)? By secure, in this context, I mean protecting against ...
2
votes
1answer
179 views

How can Alice and Bob prove that they share a file?

Carl asks Alice and Bob if they have a file f such that for a secure cryptographic hash function h, h(f) = K. Both claim to have f, but they can't show the file. Carl doesn't believe them. He can ...
12
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3answers
5k views

Is a HMAC-ed password is more secure than a bcrypt-ed or scrypt-ed password?

Given an option , which one should I choose , a HMAC for storing a password securely or a bcrypt or scrypt library?
5
votes
2answers
249 views

How is a hash's algorithm detected based on the hash?

I was reading an Ars Technica article this morning and came across the following towards the end (emphasis mine): Equation Group included six other hashes in different exploits that remain unknown ...
90
votes
6answers
32k 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. ...
3
votes
1answer
300 views

Why do major sites(Facebook, Google, etc) still send passwords unhashed? [duplicate]

QUICK SUMMARY: It seems like modern websites, for security's sake, should all have the client hash their own passwords before sending them to the server, who will rehash them, in order to avoid ...
29
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7answers
6k views

Hashing a credit card number for use as a fingerprint

What's the best way to hash a credit card number so that it can be used for fingerprinting (i.e. so that comparing two hashes will let you know if the card numbers match or not)? Ideally, I'm ...
3
votes
2answers
54 views

Is hashing schema information for client when generating SQL queries more secure?

I'm planning to implement a web system wherein APIs and presentation for CRUD in data tables are automatically generated, like that in phpMyAdmin. How I plan to implement this is to construct SQL ...
5
votes
4answers
123 views

What's to stop someone from just MITMing a checksum?

A lot of sites offer MD5 or SHA sums to verify the validity of your download, but why do some things rely almost entirely on this? Is there anything in place to prevent people from just replacing ...
22
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7answers
6k views

Why don't people hash and salt usernames before storing them

Everyone knows that if they have a system that requires a password to log in, they should be storing a hashed & salted copy of the required password, rather than the password in plaintext. What I ...
10
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5answers
2k views

Whenever an unhandled exception somehow makes it into production, is it safe, viable, etc. to print an encrypted stack trace to the end user?

Whenever an unhandled exception makes it into production somehow - whatever the reason - there's generally an option (especially with .NET programs) to print out a stack trace to the end user before ...
14
votes
6answers
3k views

Do salts have to be random, or just unique and unknown?

First of all, my motive is to avoid storing the salt in the database as plain text. As far as this question is concerned, the salt is not stored in the database. After discussion in comments and in ...
62
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5answers
21k views

Is sending password to user email secure?

How secure is sending passwords through email to a user, since email isn't secured by HTTPS. What is the best way to secure it? Should i use encryption?
26
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8answers
2k views

Why is password hashing considered so important?

After reading this article, I can see the benefits of password hashing as a second layer of defence, in the event of an intruder gaining access to a password database. What I still don't understand is ...
33
votes
7answers
9k views

Is salting a hash really as secure as common knowledge implies?

(I did search on this topic, but I found no complete question/answer that addressed it, or even good portions of questions that might be relevant.) I'm implementing a salt function for user passwords ...
1
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1answer
101 views

Is it insecure to hash multiples times?

Hashing multiple times (rounds) seems like a standard practice in password hashing to increase the work factor. Surely, everyone will agree increasing the work factor to compute the password hash is ...
355
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11answers
69k views

How to securely hash passwords?

If I hash passwords before storing them in my database, is that sufficient to prevent them being recovered by anyone? I should point out that this relates only to retrieval directly from the ...
1
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2answers
134 views

Is bruteforcing the last character of a salt a good idea?

Would it be a good idea security-wise to store salts with their last character removed, and then bruteforce the last character to further the amount of time it would take to create rainbow tables and ...
0
votes
1answer
129 views

Could overlapping SHA256 hash begin to loop at some point?

I have a system that needs to send a key to the user. This key is used for validation after work and needs to be shown that we do not change it mid-work so we send to the user in the middle of work a ...
4
votes
1answer
273 views

Brute Forcing LUKS Full Disk Encryption - Time?

let's say we have encrypted our drive with AES 256 XTS and the following Hash: SHA1 with ~500k Iterations and a 20+ password SHA512 with ~250k Iterations and the same 20+ password. Let's think of ...
1
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1answer
34 views

Should I verify installer file PGP hash?

Let's say that I'll download an installer for a program on Windows and the publisher has released PGP Signature for the file. The installer file does not have any code signing certificates. If I ...
0
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2answers
2k views

Tool for generating MD4 collisions

There are a lot of research papers available online that discuss vulnerabilities of MD4 algorithm, but I couldn't find any implementation of these. Uptill now I have used tools like John the Ripper ...
4
votes
1answer
54 views

Why there is a signed hash in Certificate request (.csr file)?

I wonder why there is a hash signed by private key in the CSR? It does prove that I have the private key that belongs to the public key in the .csr. But who cares whether I actually do possess the ...
2
votes
2answers
76 views

Virus - by-pass with binairies repackaging

Why don’t « hackers » (or more accurately, « virus maker ») just do repackaging over their malware to by-pass antivirus software? Because it resolves the issue of the virus signature (kind of hash), ...
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3answers
532 views

What part of the CSR is hashed in order to create its signature?

I'd like to change the CSR before it is transferred to the CA without going through the CSR creation process again. To do that I need to know how to calculate the signature of the CSR after I modified ...
0
votes
3answers
100 views

It is possible detecting threat by only with file information?

It is possible detecting threat by only with file information of a file like file's hash(md5,sha1,sha256, etc), file size, mime type, etc with ClamAV or Comodo AV for linux with shell command? It ...
3
votes
1answer
236 views

Are there any ways to leverage NTLM V2 hashes during a penetration test?

I am on a penetration test at the moment, where LM/NTMLv1 hashes are disabled. I have captured a number of NTLMv2 hashes via NBNS spoofing, however was unable to crack them after running them through ...
2
votes
1answer
101 views

Truncating hash output for a unique ID

This seems like a common question, but my knowledge on hashing is very limited, so I'm looking for a more ELI5-type answer. I would appreciate if someone could help me with my questions Some ...
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1answer
111 views

Given Hash digest, calculating any random input

I understand that for a hash function there are an infinite amount of possible inputs that could produce a specific output. So if you're trying to find a specific input that created an output that ...
0
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1answer
256 views

Verify CDN javascript's integrity

CDNs speed up the loading of websites by allowing caching for frequently used javascript libraries like jquery. How do we know if they have modified the javascript before serving it to my clients? ...
15
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7answers
3k views

Why does some popular software still use md5?

Nowadays no one dares to defend md5 for any use, and of course they should not! However, much popular software still uses md5 in applications such as password hashing (although it's not simple/plain ...