Questions tagged [sha-1]

SHA-1 is a hash function that is two generations old, no longer considered secure for all uses and should only be used for backward compatibility.

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3answers
149 views

CRC32 catches errors, but then what's the point of SHA?

If crc or CRC32 is specially designed to catch errors, then what's the point of SHA or md4-5 or any other hashing function? What I did was, I had a 190 mb png file (rendered in 16k resolution with ...
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2answers
419 views

Is it feasible to get a hash collision for CRC32, MD-5 and SHA-1 on one file?

I'm aware that individually, each has its weaknesses (especially CRC32), but is it feasible that a file could be created to falsely match all three?
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Recover secret SHA-1 constants given Oracle

There's a black box that's basically SHA-1, except that the constants (h0, h1,...,h4) are secret. We can pass it arbitrary inputs and get the corresponding outputs. Given this, is it possible to ...
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Which SHA-1 attacks apply to TOTP tokens? [duplicate]

Update: it's actually hmac(secret, time). I'll leave the post as-is, in case someone is ever looking for the hash(secret+time) ...
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Does a hash function have a Upper bound on input length?

I came across this Answer stating (just a line from the answer):- The input space is "infinite" and thus it has an infinite amount of values that will collide into a single hash And in the ...
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How many bits in the resultant hash will change, if the x bits are changed in its the original input?

I came across a question stating: We have a message consisting of 10,000 characters. After computing its message digest using SHA-1, we decide to change the last 19 characters in the original ...
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2answers
163 views

Why authors of bcrypt have chosen blowfish and not some hash function like SHA-1?

I wonder what are the advantages of using bcrypt over an iterated and salted KDF based on some cryptographic hash function like SHA-1 (or SHA-3)? I guess the authors of bcrypt chose Blowfish (a block ...
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1answer
128 views

Where do the constants for SHA-1/2/3 come from?

My request is: I need to know the source of constants (shift constants, IV, or S-Box) for the following algorithms: SHA-1 SHA-2 (all sizes) SHA-3 Examples: BLOWFISH uses the hexadecimal ...
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1answer
86 views

SHA1 padding on length extension attack

I was recently trying to replicate a length extension attack on SHA1. I implemented the registers state and also the new padding implementation (with the whole of the message that I want to extend). ...
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1answer
46 views

About the security of GnuPG private key on-disk storage

GnuPG on-disk storage of secret key material is encrypted with AES-128, with an encryption key generated via an iterated and salted SHA-1 hash of the given passphrase. Is this usage of the SHA-1 hash ...
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1answer
288 views

Which TLS features are vulnerable to chosen-prefixes collision on SHA-1?

Gaëtan Leurent and Thomas Peyrin's preprint From Collisions to Chosen-Prefix Collisions - Application to Full SHA-1 (in volume 1 of proceedings of the forthcoming Eurocrypt 2019) shows a feasible ...
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145 views

SHA1 calculation for millions of strings having common prefix

I have a function in which I need to calculate SHA1(common_prefix + random_string). I am calling this function many times so that calculation of SHA1 slows down the performance of the function. As for ...
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1answer
99 views

What is a SHA1_Compress() function?

I'm trying to implement the scrypt key derivation function using JavaScript. When implementing the algorithm, I found that there was a function called SHA1_Compress listed in the specification. Is the ...
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1answer
134 views

Partial Known Message Pre-Image Attack on SHA-1

If the last 448 bits of a sha1 block input are known (only the first 64 bits are unknown). Is it possible to do a preimage attack using SAT solvers or something else? Or do I have to brute force all $...
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1answer
564 views

How to change hash checksum of a text file without changing the contents in the file

I have created a text file called test.txt and the content of the file is Hello World I would like to change the SHA checksum hash without modifying the contents and filename. Is there any way to do ...
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Using a hash function as a random number generator

Using MD5 or SHA1 for instance, and applying integers (as seed so to speak) to the hash function, in sequence, and only keeping, say, the first 64 bits of the resulting hash, do we always have a ...
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113 views

SHA-1 collision for strings of two symbols

Is it possible to have strings of two (Unicode) symbols with equal SHA-1 hash? For example, smth like "ab", "ba".
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1answer
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What is the use of SCRAM-SHA-256 (over SCRAM-SHA-1)?

The Salted Challenge Response Authentication Mechanism (SCRAM) specified in RFC 5802 can use arbitrary hash functions to operate. The base version from RFC 5802 uses SHA-1. From my understanding, ...
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1answer
81 views

Which is more secure? $\operatorname{AES-ECB}(key,\operatorname{SHA1}(data+key))$ vs $\operatorname{HMAC-SHA1}(key, data)$ [closed]

$\operatorname{AES-ECB}(key,\operatorname{SHA1}(data+key))$ vs $\operatorname{HMAC-SHA1}(key, data)$ Which is more secure? Which is faster? There is a similar comparison here; HMAC-SHA1(key, data) ...
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aes-ctr(key, ++iv, sha-1(plainText + aes-ctr(key,iv,0^128))+(plainText + aes-ctr(key,iv,0^128))); is it secure? [closed]

Proposed Cipher suite: aes-ctr(key, ++iv, sha-1(plainText + aes-ctr(key,iv,0^128))+(plainText + aes-ctr(key,iv,0^128))); Security targets achieved: Encryption of the plain text. Integrity of the ...
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1answer
68 views

Unable to reproduce correct signature data

"Skatteetaten" is the Norwegian tax authority. We're currently trying to implement signing of messages for digital cash registry systems and i'm not able to reproduce the desired signed data. Went ...
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GlobalSign cert in Trusted root for Google Services shows Sha1. Security postures

"GlobalSign" certificate in Trusted Root Certification Authorities for Google Services shows Sha1. Security postures are different than just 2-3 yr ago. At my home, router bought 2016, networked; ...
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180 views

Changing SHA-1 constants an functions: Does it affect security?

I have been looking into the SHA-1 algorithm. I found that there are a set of functions and constants in the algorithm that have been standardized (section 5 of RFC 3174). If I want to use SHA-1, ...
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How reassuring is 64-bit (in)security?

In Feb 2017, CWI and Google announced SHAttered hash collision attack on SHA1, which took $2^{63.1}$ work estimated 6500 CPU years, to achieve. Therefore, 64-bit should be considered now an insecurity....
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Is SHA1 secured enough as a PRNG

I read SHA1 is still a secured hashing function with no collision found as of now. However, it's just a matter of time for someone to come up with such a collision or attack. Therefore, in new ...
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Nature of risk(s) from KeeChallenge XML file stored in cloud at Onedrive

As a noob user of KeePass2 on Windows desktop and Keypass2Android on my phone, supplemented by YubiKey Neo configured for hmac-sha1 challenge response, I noticed that Keepass2Android appears to store ...
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189 views

Is it possible to prevent length extension attacks

Is it possible to prevent length extension attacks without using any other hash algorithm than SHA-1?
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Is it still safe to use sha1 as an hmac hash function in 2018 [duplicate]

I'm curious if it's safe to use sha1 for an HMAC in 2018 in a platform product. A popular vendor (Twilio) uses an HMAC with sha1 with a shared secret to validate that messages they send are indeed ...
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Does “Shattered” actually show SHA-1-signed certificates are “unsafe”?

Note: I am not advocating anyone continues using SHA1-signed certificates: they are dead as far as security is concerned and should no longer be used. I'm just trying to clarify my understanding of ...
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After Google's collision attack, is RSA-SHA1 signature still safe?

Google succeeded to get a collision in SHA-1 last year in an attack called shattered. Does this fact make certificates based RSA-SHA1 Signature risky for creating fraud certificates? If RSA-SHA1 ...
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409 views

Fastest way to compute iterates of SHA1

It's well-known that computing lots of hash functions (like SHA1) in parallel involves the use of GPUs in most cases. However, when doing something serially, such as computing ...
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220 views

TLS1.2 AES 128 CBC Encrypted Data size is not a multiple of block size [closed]

I know that TLS ciphers such as TLS_RSA_WITH_AES_128_CBC_SHA transmit data as shown https://tools.ietf.org/html/rfc5246#section-6.2.3.2. From my understanding the ciphertext MUST be a multiple of the ...
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4answers
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Can SHA or MD5 results be decrypted?

I have learned that SHA-1 and MD5 are one way hash functions, which means that it is not possible to obtain the original value by performing the reverse calculation. There however some online ...
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1answer
175 views

local collisions in SHA 0

I have found interesting for me paper about constructing collisions in SHA 0. On page 60 the author determines M variable which is a concatenation of 32-bits vectors $M^{(i)}$, but I can't find any ...
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1answer
99 views

Statistical attacks on a list of MD5/SHA-1 hashes?

I have a list of MD5 and SHA-1 hashes where the input string is of the form secret1000 secret1001 … all the way up to ...
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1answer
125 views

Birthday problem applied to hash function with partition of the input set

I am not able to understand why if we consider a regular hash function, it is possible to say that we are partitioning the starting set and then apply the the birthday paradox/problem. Can anyone ...
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1answer
102 views

Backward Expansion of SHA1

Given a SHA1 hash, is it now possible to "practically" find the source material that was passed through SHA1 now that the Shattered paper has produced the first "practical" collision? As a follow on ...
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38 views

Expanding truly random key into printable password for successive hashing

The STUN network protocol defines its client authorization in the terms of message-integrity check employing the following scheme [RFC5389, section 10.2]: $$ \DeclareMathOperator{\HMAC}{HMAC} \...
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Purpose of folding a digest in half

The Linux kernel's random driver generates randomness by hashing an entropy pool using SHA-1. From the driver's source, the SHA-1 hash is apparently folded in half before being returned: ...
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273 views

Optimal way to bind two hashes

Currently I have: H1 = SHA256 H2 = SHA1 Both H1 and H2 have fixed length. What's the most efficient way to bind H1 and H2 together into H3? The goal is to ...
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1answer
218 views

Difficulty of generating a string “The (md5|sha1) hash of this string is (x)” that hashes to (x) vs. regular hash collision between files?

I know that collisions in md5 and sha1 have been demonstrated in particular pairs of files (by incrementing some none viewable portion of a PDF, etc). Would generating the above string be ...
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1answer
175 views

Why does FIPS 180-4 require the final padding block start with a 1?

From FIPS 180-4 § 5.1.1, the padding used for the SHA family of hashes begins with a binary 1, followed by a number of 0s, and finally a 64-bit representation of the message length: Suppose that the ...
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2answers
725 views

HMACSHA1 vs HMACSHA2 (for PBKDF2)

I need to choose an HMAC function for PBKDF2. I'm using .net so I don't have the option to use SHA3. At first glance, and according to this answer by Thomas Pornin it seems like SHA512 would be best....
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1answer
45 views

Input existence proof for known partial input and hash

Let $h$ signify the hash (Merkle–Damgård construction) generated from some input of known length $n$. Given $h$ and an input $k$ of length $n_1$, is there a way to prove that there exists (does not ...
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248 views

Interpreting the Hash type in a TLS ciphersuite

There are ciphersuites with SHA256, and SHA384. In the following TLS ciphersuite, the SHA types is not specified. Does this always refer to SHA1 (there is SHA0 as well) so which one of them? ...
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*feasible* pre-image attacks against reduced SHA-1

(tldr: see last paragraph) Although SHA-1 is vulnerable to collision attacks, it is still resistant to pre-image attacks. SHA-1 was designed to be resistant until a brute-force attack of $2^{160}$ is ...
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1answer
141 views

Cut through mode for TLS AES-CBC / SHA ciphersuite

I am looking at RFC5246 and it seems that AES-CBC/SHA cipher suites cannot be implemented in a cut-through mode. Let's suppose that received record spans two segments. As i understood HMAC ...
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1answer
174 views

What to do with a last chunk of 503 bits in SHA1?

I was trying to implement a SHA1 algorithm last night, and I got stuck at preprocessing the chunks in SHA1. As I have understood it, the message that has to be hashed, has to be broken into chunks of ...
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1answer
374 views

How many time does a SHA-1 computation require on modern CPU/GPU? [closed]

I am considering how long a SHA-1 computation will need on modern CPU/GPU's. Just in case we are interested in brute forcing and consider the birthday paradoxon, then we need consider the SHA-1 output ...