Book encryption
The book cipher (also: Book cipher or book code ) is a symmetric encryption , where one by specifying the number of pages in a book , and the line number and the position number of letters on a page of the book encrypt messages and can transmit then secret. The term “book” here refers to any document that is available to the message sender and the recipient; it can be any text document. The book represents the basis for encryption and takes on the function of the " key ".
example
If a one-page document is used as a “book”, for example the preamble of the Basic Law , then the page number can be omitted. The individual letters and other characters can be clearly assigned to the row and column based on their " coordinates ". For this purpose, rows of numbers are attached above and to the left of the preamble of the Basic Law:
000000000111111111122222222223333333333444444444455555555556666 123456789012345678901234567890123456789012345678901234567890123 1 Im Bewusstsein seiner Verantwortung vor Gott und den Menschen, 2 von dem Willen beseelt, 3 als gleichberechtigtes Glied in einem vereinten Europa 4 dem Frieden der Welt zu dienen, 5 hat sich das Deutsche Volk kraft seiner verfassungsgebenden 6 Gewalt dieses Grundgesetz gegeben. 7 Die Deutschen in den Ländern Baden-Württemberg, Bayern, Berlin, 8 Brandenburg, Bremen, Hamburg, Hessen, Mecklenburg-Vorpommern, 9 Niedersachsen, Nordrhein-Westfalen, Rheinland-Pfalz, Saarland, 10 Sachsen, Sachsen-Anhalt, Schleswig-Holstein und Thüringen 11 haben in freier Selbstbestimmung 12 die Einheit und Freiheit Deutschlands vollendet. 13 Damit gilt dieses Grundgesetz für das gesamte Deutsche Volk.
The word “WIKIPEDIA” could be encoded with the help of this text base by combining row and column as “2.9, 7.2, 5.26, 4.7, 3.53, 4.2, 2.5, 2.10, 3.1”. This would be the ciphertext to be transmitted from the sender to the recipient of the message .
For decryption , the authorized decryptor, who like the encryptor must be in possession of the “secret book”, looks for the ninth character in the second line of its text base at “2.9” and thus finds the “W” as the first letter of the plain text . Little by little he decrypts the secret message in this way: WIKIPEDIA.
Beale cipher
A famous example of a book encryption from the history of the United States is the Beale cipher , consisting of three papers (parts) , which describes a treasure of gold that a certain Thomas Beale is said to have hidden around 1820. While the second part of this cipher could be deciphered as a "book" by means of the American Declaration of Independence , the first and third parts have not yet been cracked and the gold treasure has not yet been found. It is possible that the Beale cipher is a hoax .
safety
The cryptographic security of this method against unauthorized decipherment is to be assessed as very high - provided the attacking code breaker does not manage to get hold of the book . Since this cannot be expected in the example, because the Basic Law is easily visible to everyone, the protection of the secret would be crucially dependent on whether the attacker got the idea that the Basic Law served as the textual basis for encryption.
The choice is therefore difficult a rare and to be provided to achieve the highest possible security book recommended. Unique items are ideal, for example handwritten texts that only exist once and of which the recipient - and only he - has a single copy. Of course, it is also important that the encryptor does not make any mistakes and, for example, does not recklessly use the same secret character over and over again to encrypt a plain letter. He should also ensure that the secret characters chosen from the book (here: line and column) are not closely adjacent. The best thing to do is to take a single secret character from each line and then mark the line as "used up". Under these conditions and under the assumption that no one can gain access to the book used as a key , the process of book encryption can be described as practically " unbreakable ".
Trivia
In the film " The Baader Meinhof Complex " , the members of the RAF encrypt their secret cash files with the help of book encryption on the basis of Moby-Dick . In the film “ The Legacy of the Knights Templar ” , the term “ Ottendorf encryption” is used for a book encryption . The " Arnold encryption" is also a book encryption.
A literary memorial was erected to the weaknesses of the system. It is necessary to use identical copies, not different editions . In the novel, The Adventures of the Good Soldier Svejk by Jaroslav Hašek , this is taken to extremes. In the novel, the battalion commander uses a different tape than the subordinate officers. In addition, a candidate officer notes that the book and example used are taken from a generally accessible specialist book and that the method has been known for about a hundred years. A Saxon officer named Kirchner in Napoleon's service is given as the inventor .
literature
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Simon Singh : The code book. The science of secrecy from ancient Egypt to quantum cryptography . Fourth Estate Press, London 1999, ISBN 1-85702-879-1 .
- German: Secret messages . The art of encryption from ancient times to the days of the Internet (dtv; 33071). 11th edition Deutscher Taschenbuch-Verlag, Munich 2001, ISBN 3-423-33071-6 (EA Munich 2001)