Discussion:
Naive PRNG encryption?
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vallor
2024-08-03 10:41:41 UTC
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I saw someone mention this on another 'froup, and I've thought about it
myself. Is it really "uncrackable"?

Take a plaintext and transform each character with the output
of a PRNG, with the seed being the key.

How easy is it to crack the resulting "ciphertext"?
--
-v
Chris M. Thomasson
2024-08-03 18:47:38 UTC
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Post by vallor
I saw someone mention this on another 'froup, and I've thought about it
myself. Is it really "uncrackable"?
Take a plaintext and transform each character with the output
of a PRNG, with the seed being the key.
How easy is it to crack the resulting "ciphertext"?
Depends on the quality of the PRNG. You would probably want to use a
CSPRNG...
Rich
2024-08-03 20:00:36 UTC
Permalink
Post by vallor
I saw someone mention this on another 'froup, and I've thought about it
myself. Is it really "uncrackable"?
Take a plaintext and transform each character with the output
of a PRNG, with the seed being the key.
https://web.pa.msu.edu/reference/pgpdoc1.html

When I was in college in the early seventies, I devised what I
believed was a brilliant encryption scheme. A simple pseudorandom
number stream was added to the plaintext stream to create
ciphertext. This would seemingly thwart any frequency analysis of
the ciphertext, and would be uncrackable even to the most
resourceful Government intelligence agencies. I felt so smug about
my achievement. So cock-sure.

Years later, I discovered this same scheme in several introductory
cryptography texts and tutorial papers. How nice. Other
cryptographers had thought of the same scheme. Unfortunately, the
scheme was presented as a simple homework assignment on how to use
elementary cryptanalytic techniques to trivially crack it. So much for
my brilliant scheme.
πŸŒˆπŸ’πŸŒ»πŸŒΊπŸŒΉπŸŒ»πŸ’πŸŒ·πŸŒΊπŸŒˆJenπŸŒˆπŸ’πŸŒ»πŸŒΊπŸŒΉπŸŒ»πŸ’πŸŒ·πŸŒΊπŸŒˆ Dershmender πŸ’πŸŒ»πŸŒΊπŸŒΉπŸŒ»πŸ’πŸŒ·πŸŒΊπŸΆη¬›πŸŒˆπŸ’πŸŒ»πŸŒΊπŸŒΉπŸŒ»πŸ’πŸŒ·πŸŒΊπŸŒˆ
2024-08-04 09:52:04 UTC
Permalink
On Sat, 3 Aug 2024 20:00:36 -0000 (UTC), LO AND BEHOLD; Rich
<***@example.invalid> determined that the following was of great
importance to Rich <***@example.invalid> and subsequently decided to
freely share it with us in <v8m294$3jnbf$***@dont-email.me>:

=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= vallor <***@cultnix.org> wrote:
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= =?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= I saw someone mention this on another 'froup, and I've thought about it
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= =?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= myself. Is it really "uncrackable"? Take a plaintext and transform each
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= =?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= character with the output of a PRNG, with the seed being the key.
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?=
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= https://web.pa.msu.edu/reference/pgpdoc1.html
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?=
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= When I was in college in the early seventies, I devised what I
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= believed was a brilliant encryption scheme. A simple pseudorandom
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= number stream was added to the plaintext stream to create
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= ciphertext. This would seemingly thwart any frequency analysis of
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= the ciphertext, and would be uncrackable even to the most
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= resourceful Government intelligence agencies. I felt so smug about
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= my achievement. So cock-sure.
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?=
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= Years later, I discovered this same scheme in several introductory
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= cryptography texts and tutorial papers. How nice. Other
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= cryptographers had thought of the same scheme. Unfortunately, the
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= scheme was presented as a simple homework assignment on how to use
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= elementary cryptanalytic techniques to trivially crack it. So much for
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?= my brilliant scheme.
=?UTF-8?B?8J+Ps++4j+KAjfCfjIg=?=

Lots of Dunning Kreuger to share...
--
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Oh... I should mention that there are a LOT of trannies in prison. I don't know why, but there are. The State even has to give them hormone shots for their tiddies at taxpayer's expense, and they wear bras and panties. I found everything about them revolting. That's why the whole "Bubba" thing is almost completely a myth, except in cell living. That shit wouldn't fly in a 100-man dorm, but trust me, those little trollops find ways to serve the willing when the lights go out. You see something, you keep your mouth shut about it because that way you don't get in a wreck. I never partook in such activities because the whole idea is just repulsive. I think that's a big part of what I don't like about you. I've seen how they act and I've talked to a few... total drama queens in every sense." -James "Checkmate" Gorman reminisces about prison in <***@usnews.blocknews.net>

"Not true. I've seen square waves on the oscilloscope from some certain generator. Square waves can be created from other than sine waves. Sine waves aren't everything (or anything you sick pervert %), I think that's the point you are missing. - Mathemagician "Lane Larson" in <939d6741-df96-5f2e-a444-***@stoat.inhoin.edu> seems to argue that square wave generators must use Fourier transforms "of course" to generate "almost" square waves... in his feeble attempt to quash my assertion that "square waves do not exist in reality" in post <=3D?U=3D?UTF-8?Q?T?=3DF-8?Q?=3DF0=3D9F=3D8C=3DBA?=3DKWuXdYTXCQ5ApC$@88.203.236.221=3D?U=3D?UTF-8?Q?T?=3DF-8?Q?=3DF0=3D9F=3D8C=3DBA?=3D>.

"Colour me fanboi, oh yes indeed. I'm a fanboi who is proudly content to be just that." - ***@gmail.com (Sn!pe) in <1qx4ikk.c8jzw919si6cmN%***@gmail.com>

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Phil Carmody
2024-08-21 17:56:46 UTC
Permalink
Post by vallor
I saw someone mention this on another 'froup, and I've thought about it
myself. Is it really "uncrackable"?
Take a plaintext and transform each character with the output
of a PRNG, with the seed being the key.
That's just a stream cypher.
Post by vallor
How easy is it to crack the resulting "ciphertext"?
If you have more than one encrypted with the same key, probably pretty
easy, depending on the transform. Just "subtract" (the inverse of the
transform) the two streams from each other, and you'll end up with the
difference between the two plain-texts, which will be highly non-uniform.

Phil
--
We are no longer hunters and nomads. No longer awed and frightened, as we have
gained some understanding of the world in which we live. As such, we can cast
aside childish remnants from the dawn of our civilization.
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