All Questions
20
questions
-1
votes
1
answer
72
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How to construct an RSA crypto based on prime numbers? [closed]
Discrete Mathematics - Modular Arithmetic:
Say we have the prime numbers 7 and 17 and with encryption exponent 5. How to construct an RSA crypto based on these prime numbers and encrypt for example ...
2
votes
0
answers
59
views
How to solve these kind of Modular Arithmetics situations?
Helloo...
Im kinda dumb in Discrete Mathematics since I just started studying it currently and I'm trying to figure out studying material to get remainders from operations like $11^{14^{4578369}}\pmod ...
- 21
0
votes
1
answer
895
views
Dealing with negative values for $d$ in RSA Encryption.
I worked through an a RSA Encryption example, where I am given $p,q,e$ and I have to work out $n,\phi(n),d$. I don't have any difficulty determining all the of other items, however I get a negative ...
- 1,928
2
votes
4
answers
285
views
Evaluate $6^{433} \pmod {21}$ and a proving question
Question 1:
Denote $a \mod b$ as $a \% b$, where $a$ and $b$ are some integers
Evaluate 12^32475 % 21
The following is what I tried:
...
- 145
1
vote
0
answers
194
views
Solving the GCD m = 735, n =252
I understand everything except the values in $s_i$ and $t_i$ how do we get those values??? Can anyone please elaborate. I have no idea what the formula is for calculating the values in $s_i$ and $t_i$....
- 1,641
1
vote
1
answer
6k
views
Find a div m and a mod m when
Find a div m and a mod m when
$a = -111$, $m = 99$
I can't find the formula anywhere in my book.
- 1,641
1
vote
4
answers
46k
views
Prove that if a|b and b|c then a|c using a column proof that has steps in the first column and the reason for the step in the second column.
Let $a$, $b$, and $c$ be integers, where a $\ne$ 0. Then
$$
$$
(i) if $a$ | $b$ and $a$ | $c$, then $a$ | ($b+c$)
$$
$$
(ii) if $a$ | $b$ then $a$|$bc$ for all integers $c$;
$$
$$
(iii) if $a$ |$b$ ...
- 1,641
1
vote
2
answers
873
views
Where does 2525 and 252525 come from in RSA cryptosystem example?
This is an example from Discrete Mathematics and its Applications
I understand how to encrypt, the first step is to turn the letters into their numerical equivalents(same thing we had to do for shift ...
- 1,884
2
votes
2
answers
2k
views
What mistake am I making when trying to apply Fermat's little theorem?
This is a problem from Discrete Mathematics and its Applications
This is Fermat's little theorem from https://www.youtube.com/watch?v=w0ZQvZLx2KA,
Here is my work so far
First 41 is prime and $41\...
- 1,884
1
vote
2
answers
75
views
Can someone verify the reasoning of why these two congruences are equivalent?
I've wondered why two congruences like $x\equiv81\pmod {53}$ and $x\equiv28\pmod{53}$ were equivalent.
I've come up with this proof. I am not sure if this is how you prove it though
I know that $x\...
- 1,884
1
vote
4
answers
19k
views
How to find inverse of 2 modulo 7 by inspection?
This is from Discrete Mathematics and its Applications
By inspection, find an inverse of 2 modulo 7
To do this, I first used Euclid's algorithm to make sure that the greatest common divisor between ...
- 1,884
1
vote
2
answers
463
views
Can someone clarify the notation of x $\equiv$ -8 $\equiv$ 6 ($\bmod$ 7)
This is an example from Discrete Mathematics and its Applications
This is example 1 that this example references
And here's Theorem 1 that the example references
Example 1 makes sense. We have to ...
- 1,884
2
votes
4
answers
266
views
How did author reach the conclusion tm $\equiv$ 0($\bmod$ m)?
This is a proof of a theorem from my book, Discrete Mathematics and its Applications
Here is theorem 6 of Section 4.3
The first part of the proof, "because gcd(a, m) = 1" makes sense because the ...
- 1,884
0
votes
1
answer
336
views
How does author reach step of $sa + tm \equiv 1 \pmod m$?
This is a proof of a theorem from my book, Discrete Mathematics and its Applications
Theorem 1
If $a$ and $m$ are relatively prime integers and $m>1$, then an inverse of $a$ modulo $m$ exists. ...
- 1,884
2
votes
5
answers
2k
views
How to prove this modular multiplication property to be true?
I am watching a youtube video on modular exponentiation https://www.youtube.com/watch?v=sL-YtCqDS90
Here is author's work
In this problem, the author was trying to calculate $5^{40}$
He worked the ...
- 1,884