|
Polyalphabetic Ciphers History Alberti
|
Date | 03.05.2017 | Size | 6.49 Kb. |
| Alberti - Rennaisance Architect
- First fountains of Trevi, Rome
- Churches
- 1467 essay on cryptology
- Frequency analysis
- Cipher disk for polyalphabetic cipher
- Scrambled alphabet
- Changed key letter only after 3 or 4 words
Alberti’s cipher disk Johanne Trithemius - German Monk
- Known for magic
- Wrote Polygraphia in 1518
Tritemius Tableaux - a b c d e f g h i j k l m n o p q r s t u v w x y z
- ---------------------------------------------------
- A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
- B C D E F G H I J K L M N O P Q R S T U V W X Y Z A
- C D E F G H I J K L M N O P Q R S T U V W X Y Z A B
- D E F G H I J K L M N O P Q R S T U V W X Y Z A B C
- E F G H I J K L M N O P Q R S T U V W X Y Z A B C D
- F G H I J K L M N O P Q R S T U V W X Y Z A B C D E
- G H I J K L M N O P Q R S T U V W X Y Z A B C D E F
- H I J K L M N O P Q R S T U V W X Y Z A B C D E F G
- I J K L M N O P Q R S T U V W X Y Z A B C D E F G H
- J K L M N O P Q R S T U V W X Y Z A B C D E F G H I
- K L M N O P Q R S T U V W X Y Z A B C D E F G H I J
- L M N O P Q R S T U V W X Y Z A B C D E F G H I J K
- M N O P Q R S T U V W X Y Z A B C D E F G H I J K L
- N O P Q R S T U V W X Y Z A B C D E F G H I J K L M
- O P Q R S T U V W X Y Z A B C D E F G H I J K L M N
- P Q R S T U V W X Y Z A B C D E F G H I J K L M N O
- Q R S T U V W X Y Z A B C D E F G H I J K L M N O P
- R S T U V W X Y Z A B C D E F G H I J K L M N O P Q
- S T U V W X Y Z A B C D E F G H I J K L M N O P Q R
- T U V W X Y Z A B C D E F G H I J K L M N O P Q R S
- U V W X Y Z A B C D E F G H I J K L M N O P Q R S T
- V W X Y Z A B C D E F G H I J K L M N O P Q R S T U
- W X Y Z A B C D E F G H I J K L M N O P Q R S T U V
- X Y Z A B C D E F G H I J K L M N O P Q R S T U V W
- Y Z A B C D E F G H I J K L M N O P Q R S T U V W X
- Z A B C D E F G H I J K L M N O P Q R S T U V W X Y
Giovan Battista Belaso - Otherwise unknown
- Small booklet in 1553
- Used Trithemius’ tableaux of shifted alphabets
- Added the idea of a key word or phrase
Giovanni Battista Porta - Wrote several books
- Book on cryptology: De Furtivis Literarum
- 1563
- Included classification of methods
- Cryptanalysis
- How to solve monoalphabetic with no word breaks
- Likely word method
- Digram cipher (using non-letter symbols)
Giovanni Battista Porta - Polyalphabetic cipher
- Combined elements of
- Alberti – scrambled alphabet
- Trithemius - letter-by-letter change of alphabet
- Belaso – key word/phrase
- Scrambled alphabet could be from Alberti style disk or from table
Blaise de Vigenere - From age of 24 served the Duke of Nevers (France) in Court and as Diplomat
- Quit the court in 1570 (age 47) and wrote on many subjects
- Wrote Traicte de Chiffres in 1585
- Collected much previous work (with credit)
Vigenere - Polyalphabetic cipher
- Tableaux like Trithemius
- But scrambled alphabet on borders
- Makes it like Alberti’s disk
- Discussed several key methods
- Words, phrase, poetry
- Date of dispatch
- Ordered, like Trithemius
- New contribution!
- Autokey
Practice of Cryptography - Polyalphabetic not used until 19th century
- Era of “Black Chambers”
- Government agencies for cryptanalysis
- French, Italian, German, Austrian
- Encryption typically used ciphers and nomenclators (combined code and cipher)
- Introduction of telegraph (1840s) led to use of better methods, polyalphabetic
Vigenere - Ironically has name attached to easy version of polyalphabetic, as done by Porta, not his better autokey system.
- We will look at this method and how to break it.
Share with your friends: |
The database is protected by copyright ©sckool.org 2020
send message
|
|