Cryptology
I.2 Polyalphabetic Ciphers
a7Hzq .#5r<
kÜ\as TâÆK$
ûj(Ö2 ñw%h:
Úk{4R f~`z8
¤˜Æ+Ô „&¢Dø
Contents
Key alphabets
The invention of the polyalphabetic substitution
[mathematical description as
PDF
]
Tools for polyalphabetic substitution
Mathematical description of the periodic polyalphabetic substitution [
PDF
]
The cipher disk algorithm [
PDF
]—
with Perl programs for
encryption
and
decryption
[online by web forms:
encryption
,
decryption
]
Analysis of periods
—
with
Perl program
[
online by web form
]
Cryptanalysis of a polyalphabetic ciphertext (German plaintext)—
finding the period by repetition search
and
column analysis
Rearranging the columns
[
PDF
]
Summary
Here is the mathematical part as
a single PDF
, with an appendix:
The Birthday Paradox
.
Author:
Klaus Pommerening
, 1999-Oct-18; last change: 2021-Jan-14.