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M. Mogollon – 01/08 - 2
Number Theory
Exponentiation Ciphers
Public-Key Ciphers
Key Management
DH / RSA
The Set of Real Numbers
The Set of Real Numbers
-7, -2/5, 0, 1, ¾,
5.42,
Set of all rational and irrational
numbers.
Real
R
-7, -2/5, 0, ¾, 5.42
Any number that can be
represented as a/b, where and
a and b are integers and b
≠
0.
Rational
Q
.., -2, -1, 0, 1, 2, …
Set of natural numbers, their
negatives, and zero.
Integers
Z
1, 2, 3, 4, 5, …..
Counting numbers (also called
positive integers).
Natural
Numbers
N
Examples
Description
Number
System
Symbol
π
,
5
,
2
•
The set of real numbers shown in the table is not generally applicable to cryptography because in
arithmetic, information is lost through round-off errors, or truncation in integer division, and, also,
because real numbers are infinite fields.