Trithemius cipher
Encyclopedia
The Trithemius cipher is a polyalphabetic cipher
invented by the German author and monk Johannes Trithemius
in the 15th century. The cipher was published in his book Polygraphia, which is credited with being the first published work on cryptology. It uses a letter square with the 26 letters of the alphabet following 26 rows of additional letters, each shifted once to the left. This creates 26 different Caesar cipher
s.
This method removes the letter frequencies from the ciphertext, making it appear as a random string or block of data. However, if a person is aware that this method is being used, it becomes easy to break. The cipher is vulnerable to attack because it lacks a key
, which is said to break Kerckhoffs' principle
, a rule of cryptology.
, each alphabet is shifted one letter to the left from the one above it. This forms 26 rows of shifted alphabets, ending with Z (as shown in image). Data
is encrypted by switching each letter of the message with the letter directly below, using the first shifted alphabet. The next letter is switched by using the second shifted alphabet, and this continues until you have encrypted the entire message.
called the Vigenère cipher
. Bellaso added a key to switch cipher alphabets every letter. This method was misattributed to Blaise de Vigenère
, who published a similar autokey cipher
in 1586.
The Cipher Manuscripts are a collection of 60 folios that were encrypted by using the Trithemius cipher. The data that was encrypted were working notes made by someone with knowledge of ceremonies from a German Rosicrucian
temple. In September 1887, they were deciphered by William Wynn Westcott
and later used as the basis for rituals of initiation into the Golden Dawn
.
Polyalphabetic cipher
A polyalphabetic cipher is any cipher based on substitution, using multiple substitution alphabets. The Vigenère cipher is probably the best-known example of a polyalphabetic cipher, though it is a simplified special case...
invented by the German author and monk Johannes Trithemius
Johannes Trithemius
Johannes Trithemius , born Johann Heidenberg, was a German abbot, lexicographer, historian, cryptographer, polymath and occultist who had an influence on later occultism. The name by which he is more commonly known is derived from his native town of Trittenheim on the Mosel in Germany.-Life:He...
in the 15th century. The cipher was published in his book Polygraphia, which is credited with being the first published work on cryptology. It uses a letter square with the 26 letters of the alphabet following 26 rows of additional letters, each shifted once to the left. This creates 26 different Caesar cipher
Caesar cipher
In cryptography, a Caesar cipher, also known as a Caesar's cipher, the shift cipher, Caesar's code or Caesar shift, is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number...
s.
This method removes the letter frequencies from the ciphertext, making it appear as a random string or block of data. However, if a person is aware that this method is being used, it becomes easy to break. The cipher is vulnerable to attack because it lacks a key
Key (cryptography)
In cryptography, a key is a piece of information that determines the functional output of a cryptographic algorithm or cipher. Without a key, the algorithm would produce no useful result. In encryption, a key specifies the particular transformation of plaintext into ciphertext, or vice versa...
, which is said to break Kerckhoffs' principle
Kerckhoffs' principle
In cryptography, Kerckhoffs's principle was stated by Auguste Kerckhoffs in the 19th century: A cryptosystem should be secure even if everything about the system, except the key, is public knowledge.Kerckhoffs's principle was reformulated by Claude Shannon as...
, a rule of cryptology.
Usage
Using a tabula rectaTabula recta
In cryptography, the tabula recta is a square table of alphabets, each row of which is made by shifting the previous one to the left...
, each alphabet is shifted one letter to the left from the one above it. This forms 26 rows of shifted alphabets, ending with Z (as shown in image). Data
Plaintext
In cryptography, plaintext is information a sender wishes to transmit to a receiver. Cleartext is often used as a synonym. Before the computer era, plaintext most commonly meant message text in the language of the communicating parties....
is encrypted by switching each letter of the message with the letter directly below, using the first shifted alphabet. The next letter is switched by using the second shifted alphabet, and this continues until you have encrypted the entire message.
Improvements
In 1553, an important extension to Trithemius's method was developed by Giovan Battista BellasoGiovan Battista Bellaso
-Biography:Bellaso was born of a distinguished family in 1505. His father was Piervincenzo, a patrician of Brescia, owner since the 15th century of a house in town and a suburban estate in Capriano, in a neighborhood called Fenili Belasi , including the Holy Trinity chapel. The chaplain was...
called the Vigenère cipher
Vigenère cipher
The Vigenère cipher is a method of encrypting alphabetic text by using a series of different Caesar ciphers based on the letters of a keyword. It is a simple form of polyalphabetic substitution....
. Bellaso added a key to switch cipher alphabets every letter. This method was misattributed to Blaise de Vigenère
Blaise de Vigenère
Blaise de Vigenère was a French diplomat and cryptographer. The Vigenère cipher is so named due to the cipher being incorrectly attributed to him in the 19th century....
, who published a similar autokey cipher
Autokey cipher
An autokey cipher is a cipher which incorporates the message into the key. There are two forms of autokey cipher: key autokey and text autokey ciphers. A key-autokey cipher uses previous members of the keystream to determine the next element in the keystream...
in 1586.
Cipher Manuscripts
Rosicrucian
Rosicrucianism is a philosophical secret society, said to have been founded in late medieval Germany by Christian Rosenkreuz. It holds a doctrine or theology "built on esoteric truths of the ancient past", which, "concealed from the average man, provide insight into nature, the physical universe...
temple. In September 1887, they were deciphered by William Wynn Westcott
William Wynn Westcott
William Wynn Westcott was a coroner, ceremonial magician, and Freemason born in Leamington, Warwickshire, England...
and later used as the basis for rituals of initiation into the Golden Dawn
Hermetic Order of the Golden Dawn
The Hermetic Order of the Golden Dawn was a magical order active in Great Britain during the late 19th and early 20th centuries, which practiced theurgy and spiritual development...
.