Encryption :-)

Xor is a logical operation between either boolean variables or numbers. Xor performs bitwise comparation for numbers, for instance:

Code:

---

0  XOR  0  =  0
0  XOR  1  =  1
1  XOR  0  =  1
1  XOR  1  =  0

---

Xor will always return return the same value if you xor with the same number twice, therefore you can use the same key to encrypt and decrypt

Code:

---

?5 xor 7 xor 7
 5
?5 xor 11 xor 11
 5

---

On the other hand only xoring itself isnt' secure enough, it's simple to hack out the original key by testing out the encryption algoritm

When you get the asc value of a letter and xor a number
the xor operator changers the both number's into binary
and compare's then Here's an example
5 xor 6
5=101 binary
6=110 binary
101
110
011 so the new number would be 3

011
110
101 got back you're old number

101=5 so you got back you're old number

oh and case you don't now binary here's an small table
1 2 4 8 16 32 64 128
1 1 1 1 1 1 1 1
the top number's are in decimal
the bottom ones are binary
you ignore the one's whith o's under then. you add the decimal number's up to find out what the
binary number equals
Here's an example



1 2 4 8
1 0 1 1

you would add up the decimal numbers
that have a one under then and ignore the 0's


I hope it makes sense.

[Edited by Bjwbell on 08-17-2000 at 08:34 PM]

you can download a number systems tutorial written by Bruce D. Gordon

here
http://64.82.86.58

it will only be available while I am online, which should be for a few more hours,
and when I dialup again My IP will change so I will have to tell you that...

Hey- I noticed a few posts up someone asked what "brute force" means, and it simply means that i try EVERY single possible combination. So for instance if you had a hotmail password that i happend to know was 4 characters long and only letters, i would try aaaa, aaab, aaac, aaad, and so on until i got in (or until the message i was staring at made sense in the case of encryption, or whatever, you get the idea).... when you start talking about 2-3 hundred character long combos of any of the 255 ascii chars, this starts becoming a LOT of combos, and it takes powerfull (not to mention expensive) supercomputers to decode this in any reasonable amount of time....

Thnx For Your Time,
CarlosTheJackal

Quote:

---

Originally posted by kedaman
I only get the same series with rnd, whatever seed i use :(

---

Kedaman,
to get different series you need to use this:

Dim seed As Integer
' Let the user give seed a value

Rnd(-1)
Randomize seed

' Algoritm based on random numbers


Rnd(-1) makes VB use the seed for its randomize series.

Pentax

UI i can't get it work Pentax!

Code:

---

    Rnd -1
    Randomize 4194304
    For n = 0 To 10
        Debug.Print Rnd;
    Next
    Debug.Print
0,817462  0,1165037  0,9488098  0,2010981  0,3841136  0,4529259  8,041233E-02  0,6336831  0,8541809  0,9892573  0,8818185
 0,817462  0,1165037  0,9488098  0,2010981  0,3841136  0,4529259  8,041233E-02  0,6336831  0,8541809  0,9892573  0,8818185
 0,817462  0,1165037  0,9488098  0,2010981  0,3841136  0,4529259  8,041233E-02  0,6336831  0,8541809  0,9892573  0,8818185
 0,817462  0,1165037  0,9488098  0,2010981  0,3841136  0,4529259  8,041233E-02  0,6336831  0,8541809  0,9892573  0,8818185

---

Kedaman,
Everytime you want to get a new rnd series you have to first call
Rnd(-1)
'and then
Randomize seed

To get three different series, do this:
Code:
Rnd(-1)
Randomize 12345
For n = 0 To 10
Debug.Print Rnd;
Next
Debug.Print

Rnd(-1)
Randomize 54321
For n = 0 To 10
Debug.Print Rnd;
Next
Debug.Print

Rnd(-1)
Randomize 33333
For n = 0 To 10
Debug.Print Rnd;
Next
Debug.Print

This gives three different series, the first based on 12345, the second on 54321 and the third on 33333

Good luck,
Pentax

Oh, but i thought you said that you could get different results from the same seed, if you had a enought hight seed

Kedaman,
it's rather the other way around.
Using high seeds, some of them give the same series.
For instance, 2097152 gives the same as 2097153.
2097154 gives a new, but 2097155 the same as 2097154.
When the seed gets higher four seeds give the same series, for instance 4194304, 4194305, 4194306 and 4194307.
But 4194308 gives a new series.

Cheers,
Pentax

Quote:

---

Originally posted by MPrestonf12
I've seen people use "keys" in there encryption algorithms. What is it exactly??

---

It can be a password or generated from a password...

Read from the beginning of this thread, much is explained on the previous page

Is there anyone who can find out why Randomize behaves as it does (see above)?
Please take a look at it, all explenations appreciated!

With your loop
the total number of keys would be 256
this is because with your loop it only uses the last letter.

Interesting Pentax, too bad that i don't have VB on this comp, i'd really like to check that out. BTW have you tested randomize with any values like 1 and 1,000000001? does their series differ`?

No, I haven't tested.
I don't know, I think Randomize only takes integers as argument (and transforms decimal numbers to integers).
I'll test as soon as I get home.

Btw, this is all tested on Visual Basic 6
Pentax

Actually you can put any value into randomize

I found out that i had VB3 on this comp and did some tests:
Randomize 1
and
Randomize 1.00000095
gave me the same series while
Randomize 1.00000096
gave me another

This "Brute Force" business; How would a computer "know" that it actually decoded the data since every permutation will yield some output? What if the server (in a login type scenario) just locked you out after say 3 failed attempts?

What scenarios of encryption allow brute force to work?

That's what I was trying to explain!

part of the brute force must check for recognisable data which can slow the process enormously. Which is why in public key encryption has such long keys because with someone's public key you can encrypt a small note to the users and not send it, then you have matching plain and cypher text to brute force with.

imagine if you were decoding a document and didn't realise that you should be looking for text written on a jpg image in a PDF file!!, you'd skip right past the correct key. You'd search the whole keyspace and find nothing.

hey denniswrenn ,
i am also new to encryption ... in your code
what does TheKey As String siginify ...
i mean what does it do...

please help :)

So what does the final function look like???

I am new to encryption also, however, I did find "The Code Book" by Simon Singh, to be very good.

It explains how PGP works and how you can give a public key to everybody, so that they can encrypt stuff with it. Then send the encrypted stuff to you and you can decrypt it. That way, only the person who wants to use the encrypted stuff has to know the real key. Anyone can encrypt stuff to you, and you can decrypt it. The magic part is how nobody would be able to figure out your private key (the one u use to decrypt stuff) from your public key! Very cool. Currently, the only way to decrypt it is by factoring very large numbers, which is very slow, so it would take a very long time to crack the cipher.

PGP uses RSA (a type of encryption) and IDEA (another type), at least in the old form. Therefore, it isn't really it's own type of encryption, not really. The main text is encrypted using RSA with some random key, and then that key is encrypted with IDEA using your public key. The whole thing seems pretty far fetched, but get the book, it's very cool.

I do have a question. Does anyone know how to deal with really really big numbers, like 10^300 (10 with 300 zeros)? There's gotta be a way.

I did not read every post to this thread, but has anybody commented on the decryption problem when you use random numbers to encrypt?

The original post used the Randomize Statement and subsequently used Rnd Function.

How can you decrypt the result?

I remember jokes about write only memories. Like they cannot fail. They have infinite capacity.

Isn't encryption using random numbers equivalent to throwing the data into a bottomless pit?

Reminds me of the highest possible security rating for a document: BBR (Burn Before Reading).

I think I saw this tv show, like one of those forensic detective documentary things, where they got the text back from a burned sheet of paper. Sounds pretty fishy, but that's what they did.

You can improve your encryption by compress the information before encryption. So you can reduce your 0x00 in your information and your key won't be stored in the information with using Xor.

Greets
Scand