
RSA Algorithm - keyboardman
https://leimao.github.io/article/RSA-Algorithm/
======
LocalRSAExpert
> RSA (Rivest–Shamir–Adleman) algorithm is an asymmetric cryptographic
> algorithm that is widely used in the modern public-key cryptosystems.

The very definition of modern public-key crypto is that it _doesn 't_ use RSA
:)

> Cracking the RSA encryption system using brute force is not practically
> feasible.

Cracking the RSA encryption system as implemented by someone reading a lecture
like this is straightforward. Heck, "padding" doesn't even appear in it, most
university slides at least mention "oh by the way, this thing's pretty useless
without padding".

In my opinion this article falls squarely in the "talking about RSA considered
harmful" category: showing textbook RSA, then saying it [RSA] is secure,
without mentioning how hard it actually is to achieve that.

~~~
cipherboy
Relevant exercises:
[https://cryptopals.com/sets/6](https://cryptopals.com/sets/6)

Reminds me of when I was at University. One of my professors had implemented
RSA as one of his lecture examples in their advanced C class. I forget why, I
was too busy reading the implementation.

The net result was that a brute-force attack was possible, simply because the
keys were generated from an insecure RNG and seeding system:
[https://github.com/cipherboy/coms327-RSA_Crack](https://github.com/cipherboy/coms327-RSA_Crack)

------
6c696e7578
Is it wrong that I think
[https://en.wikipedia.org/wiki/Clifford_Cocks](https://en.wikipedia.org/wiki/Clifford_Cocks)
should have some credit? I always feel sorry for him that so much
infrastructure depends on RSA, yet he almost goes unknown.

~~~
Fnoord
If you invent something, but you do not share it with the general public, and
a group of other people invent an equivalent, then who was first to invent?
Who is going to have the credit?

I'd say it is akin to a proprietary technology which never got released to the
general public, and then some FOSS technology comes along which does arguably
the same, yet is FOSS and gets widely adopted.

Want the credit? Should've released it to the public then. That's a side
effect of working for secret services; you don't get much, if any, personal
credit. Nor even credit as a secret service. E.g. because the ops remain
secret.

------
arberavdullahu
> Quantum computer, however, is good at integer factorization. Using Shor’s
> algorithm, quantum computer does integer factorization in polynomial time,
> which makes cracking the RSA cryptosystem possible.

Does increasing the size of the key get around this problem, if not is there
any solution to this?

~~~
LocalRSAExpert
Yes, between 100 GB and 1 TB of private key does it.

~~~
cipherboy
Citation, for those curious:

[https://cr.yp.to/papers/pqrsa-20170419.pdf](https://cr.yp.to/papers/pqrsa-20170419.pdf)

