IT Security Stack Exchange
IT Security Stack Exchange

Questions tagged [sha256]

SHA-256 is a hashing algorithm.

193 questions
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SHA256 security: what does it mean that attacks have broken "46 of the 60 rounds of SHA256"?

Wikipedia reports Currently, the best public attacks break 46 of the 64 rounds of SHA-256 or 46 of the 80 rounds of SHA-512. What does this mean, and how safe is SHA-256 expected to be in the conceivable future? To a layperson, 46 out of 64 may…
Random Random
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Attack on the custom token-based sha256 security scheme

I have token made as sha256("public text" + "secret value"), or any number of such tokens with the same "secret value" but different "public text". sha256 that is used is not salted - so that sha256-ing the same text will always produce the same…
Ivan Sopov
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Time of working generating hash with sha2

It is fragment of pseudocode algorithm SHA2 from wikipedia: break message into 512-bit chunks for each chunk create a 64-entry message schedule array w[0..63] of 32-bit words For me, it means that time of working SHA2 algorithm depends on size…
SDasd
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is it possible to find the original value of a hashed string, if you don't have the entire hash

I'm wondering if there is a faster way than bruteforcing to find the original contents of a string if you have/know: 60 % of the original string (30/50 characters) the amount of characters the string has. know a range of the 8 first possible…
user3499284
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Possible to send password in plain text with SHA-256?

I just registered on a site where I had to specify sensitive information, eg. my card number. I got a confirmation mail where my password, the one I specified as my login password, was in plain text. I learned that password should NEVER be in plain…
Gulbanan
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What should we expect of the SHA256 of a file's webpage vs. the one we get once we download the file?

I want to know whether the SHA256 of a file changes from being available for download to once we downloaded to a device. For example, I got the URL…
u20210512
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How many bits of security does a hash as a verifier provide?

Let's say I have a binary string s, that is generated by a cryptographically secure random byte generator, and a hash function SHA-256. I am using the hash h=sha256(s) as a one-time password verifier and send it to the server, how many bits of…
Gamer2015
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SHA256 hash can be used to decrypt data?

I have a backup script that encrypts everything using AES 256 Every day, I generate a random binary file as the password, and encrypt this random file with my public key. Until now, I printed the SHA256 hash of the unencrypted file on the log, but…
Javier Loureiro
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multiple call of gcry_md_write function

May be it 's not a question for information security stack exchange and if it's true excuse me for my mistake. I want to understand how this code works: char *s = "1"; char *s_2 = "2"; unsigned char *x; gcry_md_hd_t h; gcry_md_open(&h,…
MrSetplus
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Is it easier to calculate a partial SHA256 collision than a full one?

Question: Disregarding brute-force, is it any easier to calculate a partial hash collision, in which only a certain number of bits match? Reasoning: On many websites you find hashes for file downloads. That's nice for integrity checks from the…
Jens
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Sha256 hash + secret GUID + RNGCrypto random number to hash passwords

I'm maintaining a website which uses Sha256 hashing of passwords. The passwords are hashed with a GUID key, and a RNGCrypto generated random salt. I'm just trying to understand the security risks associated with this scheme. If an attacker is able…
user1751825
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Find SHA256 if I only have part of the string

I need to find the SHA256 hash of s string like this: "part1-part2". I know the SHA256 hash of part1 and I know what part2 represents, but I don't know what is the contents of part1. Is there any chance I can compute the hash of the whole string…
Daniel
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