8
The source explains an overarching concept and is perhaps slightly ambigious rather than outright misleading. Hashes sent alongside data in their "raw" format are definitely susceptible to a tampering attack and, therefore, we need to either:
Share the hash value out-of-band: A simple example is downloading a file off a website which shows the file's ...
4
This is known as a 'known plaintext' attack. All modern encryption algorithms are designed to be resistant to this type of attack.
Many types of files contain known plaintext. For example, PDF documents begin with the header '%PDF'. Other information in most PDF documents is easy to guess, such as embedded fonts, formatting info, etc. If known plaintext ...
3
Your source is misleading (Microsoft misleading, who'd have thought!). You cited this:
Hash values are also useful for verifying the integrity of data sent through insecure channels
So technically it says it's useful if the data was sent through an insecure channel. It doesn't specify how the hash was sent. You are completely right: if the attacker can ...
2
This sounds to me like a chosen ciphertext attack. The raw AES block cipher itself is secure against it. Any cipher you would see used in a modern setting is secure against it.
Some AES implementations you would actually see in the wild are not secure against sidechannel attacks, meaning information about the computation which is not part of the function ...
2
The operator of the domain either uses Cloudflare as registrar or user another registrar and points the domain to Cloudflare's authoritative DNS servers.
This gives Cloudflare control over the domain, and they are able to issue valid TLS certificates for the domain, as they host it.
Cloudflare also host the authoritative DNS servers that reply with ...
1
If the hash of some data is computed and sent along w/ the data, can't an attacker alter the data, re-compute the hash and the receiver would be none the wiser?
In a data stream that is only hashed, then yes they can.
If you want to mitigate this you need to ensure that this cannot be done without detection, such as signing the hash and including the ...
1
See the specification 5.1:
This specification assumes, but does not require, that conforming user
agents do not and will not be directly implementing cryptographic
operations within the user agent itself.
...
While it is assumed that most user agents will be interacting with a
cryptographic provider that is implemented purely in software, it is
...
1
The modulo operation is useful to obtain a number within a certain range. In your example, the output will always be in [0, 556600).
This can cause some changes in the distribution of the random numbers generated:
The main one: a smaller pool of possible values:
If the original number of bytes read out of /dev/urandom is more than ~2.5, then it had a ...
1
1) It is strange that you expect that ransomware would use asymmetric encryption. It is much slower compared to symmetric encryption with the same strength.
2) Modern encryption algorithms (both symmetric and asymmetric) use random data. Means, even the same data encrypted by the same algorithm can produce different results.
3) Brute-forcing based on known ...
1
A DSAPublicKey instance can be created from a DSAPublicNumbers instance, which can be created using the raw values:
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives.asymmetric.dsa import DSAParameterNumbers, DSAPublicNumbers
param = DSAParameterNumbers(p, q, g)
pnum = DSAPublicNumbers(y, param)
pubkey = pnum....
1
No, a bug bounty program in no way grants assurance of secure software. Software will always have bugs. There is no "silver bullet" tool or process that will eliminate 100% of security vulnerabilities. A good security team will look to implement bug prevention measures at every stage of the SDLC that they can, an approach commonly referred to as "defense in ...
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