SHA-512 is part of the SHA-2 family of hash functions with a 512-bit output and a 256-bit security level.

learn more… | top users | synonyms (1)

2
votes
1answer
96 views

Does this protocol provide Perfect Forward Secrecy / are there potential security flaws?

We have a HMAC key (128 bit/16 bytes) an AES key (128 bit/16 bytes) an AES IV (128 bit/16 bytes) a random salt (128 bit/16 bytes) Each packet is signed with a HMAC (SHA256) After each packet is ...
5
votes
1answer
141 views

Significance of rotation constants in SHA-512?

In a single round of SHA-512, in the operations $\Sigma_0(A)$, $\Sigma_1(E)$ why are the constants $28$, $34$, and $39$ used for the number of rotations? What significance do these numbers have? What ...
1
vote
1answer
159 views

PBKDF2-SHA512 - Does a Big Salt Decrease Security?

I use PBKDF2-SHA512 with an iteration count of 128,000 to hash my passwords. I use a CSPRNG to generate a salt per password. However, I am unsure about the ideal size of the salt. I have read a lot of ...
1
vote
1answer
112 views

XORing a header with SHA512-hash - secure?

I am writing a application that encrypts text several times and stores the result. The result looks like complete random bytes, therefore I add some random bytes at the end. To let the program know ...
0
votes
3answers
223 views

Generating a number using SHA512 that users can later verify (once I publish secret seed)

I've wrote following C# method that basically takes 3 seeds and gives you number in 0-100 range. I then use that number for variety of purposes but for this question the most important one is the ...
1
vote
0answers
111 views

How does converting character set affect hash entropy?

Does mapping a large character-set hash onto a small character-set hash lower entropy for a fixed size substring? I'm writing a python app that involves generating passwords for websites. During the ...
2
votes
1answer
155 views

Is this approach to generating a “random” number from a sha512 hash effective?

I'm looking to run a small raffle but i'd like people to be able to verify that the number chosen was fair. I know some sites use a "Provably Fair" system to achieve this where user input is combined ...
2
votes
2answers
224 views

Are the SHA family hash outputs practically random?

Say I hashed the output from a random number generator (with nonce), would the resulting SHA256 hash be as random as the inputted number? And If I used the first 5 hex characters, and then used the ...
4
votes
5answers
340 views

Would it be possible to generate the original data from a SHA-512 checksum?

So, I have a file that is XY Exabytes big. I create a SHA-512 hash from it. Are there any theoretical chances that I can retrieve the original data just from the sha512 hash? Also, are there any ...
12
votes
1answer
1k views

Is truncating a SHA512 hash to the first 160 bits as secure as using SHA1?

I am from a web development background (I don't know an awful lot about cryptography or how the algorithms themselves work), so I am asking this question in simple terms. Consider a hash of the word ...
3
votes
1answer
456 views

estimate of time required to crack sha512crypt password with JtR + OpenCL

OK, I have a shadow file with a password that I know, it is 4 letters followed by two numbers. Using John The Ripper with OpenCL support, on a laptop with AMD Radeon Mobility graphics, how long would ...
2
votes
1answer
404 views

Why are these specific values used to initialise the hash buffer in SHA-512?

I'm reading the book Network Security Essentials written by William Stallings. To create a message digest with SHA-512, we have to go through some steps: append padding bits. append length ...
1
vote
0answers
80 views

Why do we always append padding bits in SHA-512? [duplicate]

Possible Duplicate: In the SHA hash algorithm, why is the message always padded? I'm reading the book Network Security Essentials written by William Stallings. To create a message digest ...