Linked Questions

2
votes
3answers
5k views

Reversing Password Hashes [duplicate]

if someone got hold of the hashes of all passwords for a website, how do they 1) get passwords from the hashes. As far as I can tell from searching the internet everything seems to say do a dictionary ...
0
votes
3answers
5k views

Is it possible to reverse MD5? [duplicate]

I'm new in the security world and right now I'm studying about hashes. Let's say I have md5(x+q) and md5(y+q). I know the value of x and y hidden into md5. Would it be possible to reverse it and ...
1
vote
1answer
124 views

Is it possible for someone to reverse my hash function if he has access to the assembly code? [duplicate]

My application is written in C and the password is checked by obtaining the user's input and doing some string/math operation on each character, then the sum of each character ascii code is added up (...
0
votes
1answer
241 views

Can HMAC leak the password? [duplicate]

Imaging the following pseudo-code: h = hash(sha512) h.input(password) h.input(message) send h, message to client If the user has the hash and the message, and the only missing variable is the ...
826
votes
13answers
231k 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 database,...
77
votes
5answers
75k views

How does hashing work?

I have been interested in Information Security. I was recently introduced to the idea of hashing. What I currently understand about hashing is that it takes the password a user enters. Then it ...
68
votes
4answers
176k views

Is SHA1 better than MD5 only because it generates a hash of 160 bits?

It is well known that SHA1 is recommended more than MD5 for hashing since MD5 is practically broken as lot of collisions have been found. With the birthday attack, it is possible to get a collision ...
34
votes
4answers
5k views

Does every hash value have an inverse value?

There are many different hash functions, md5, sha, and others. They take a value V and produce a H via transformation Function(V) = H, where Function is md5, sha, etc. My question is: Does every hash ...
14
votes
5answers
87k views

How safe is the 256-bit encryption used in bank transactions?

Most of the banks use a 128-bit or 256-bit encryption. What does this mean? Does it mean that the keys used in SSL are 128-bit long or what? If they are the SSL key lengths then 128 bit RSA keys are ...
22
votes
3answers
9k views

MySQL OLD_PASSWORD cryptanalysis?

The password hash used for MySQL passwords prior to version 4.1 (now called OLD_PASSWORD()) seems like a very simple ad-hoc hash, without salts or iteration counts. See e.g an implementation in ...
19
votes
3answers
3k views

What's the mathematical model behind the security claims of symmetric ciphers and digest algorithms?

Why can SHA-1 be considered a secure hash function? That's something I still wonder about. I understand the concepts of why modern asymmetric algorithms are deemed to be secure. They are founded on ...
-2
votes
2answers
29k views

Why can't SHA256 be decrypted? [closed]

From many forums I saw that the SHA256 data cannot be decrypted? If that's really true then hows is the data verified? Whats the use of just encrypting the data? The same question goes for the ...
1
vote
2answers
5k views

How can this website crack MD5 hashes? [closed]

I have heard that hashing, such as MD5, is one-way and cannot be cracked. But there are some websites that can decrypt hash, like www.md5hashing.net and some scripts like findmyhash.py. I tested some ...
4
votes
2answers
16k views

Cracking a password Protected pdf file using John the ripper

What exactly happens after I provide the hash from the pdf file to John for cracking the password? Does John extract just the password hash from the file and work on it, or is there something else?
4
votes
4answers
903 views

True?: “Nearly all encrypted passwords are stored with the last character in clear text”?

[S]ome passwords are gleaned by hacking into computers where intruders can find stored passwords. Those are stored in encrypted form, but there's software that can attack the encryption. Nearly ...

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