Jun 23

Did you try our ROT 13 Encoder / Decoder? It’s pretty fun to use. If you don’t know what ROT13 is, this article will tell you all about it.

What is ROT13?

ROT13 or “rotate by 13 places” is one of the simple substitution ciphers used in the online forums as a method of hiding punch lines, spoilers, offensive material and puzzle solutions from casual glance. The interesting fact is that ROT13 is an inverse of its own as for undoing it, you have to apply the same algorithm. The same actions are used for decoding and encoding. Several word and letter games have been inspired by ROT13 online and the system has been frequently talked about in the newsgroup conversations.

How ROT13 works

In order to apply ROT13 to a text, you have to just examine the alphabetic characters of the word and replace them by 13th alphabetic letter after them. For example, A becomes N and C becomes P. The alphabets are wrapped back to the starting of the series if necessary, for example O becomes B and Z becomes M. Only letters of English alphabet are affected while the numbers, white space, symbols and characters remain unchanged. As 26 letters are there in English alphabet, it is divided by 2 to get 13, therefore, the function of ROT13 is inverse of its own. In simple words, two consecutive ROT13 applications restore its original text. In cryptography, it is also known as involution or reciprocal cipher.

ROT13 Usage

ROT13 is usually used for hiding potentially offensive material or for obscuring answers to the puzzles or other spoilers. Thirteen is a value which helps in arranging decoding and encoding in an equivalent position and thereby allows the convenience of single command on both. Typically, ROT13 is supported as an in-built feature of a newsreading software. Sometimes, the e-mail addresses are also encoded using ROT13 so that they can be hidden from the less complicated spam bots.

Usually, ROT13 is not used at a place where secrecy is concerned. Use of constant shifting means that there are no keys in the encryption and decryption needs no other knowledge or skill than knowing the fact that the system of ROT13 has been used. Even if you do not know that ROT13 has been used, you can easily break the code through the method of frequency analysis. Because it is utterly unsuitable for actual secrecy, ROT13 is known to be a catchphrase for referring to a conspicuously weak scheme of encryption. Application of the system to an already encrypted matter restores the original text, ROT26 means no coding at all. Other versions of ROT13 are ROT26, 2ROT13, and double ROT13. In 1999, the Netscape Communicator made use of ROT13 as a part of the insecure scheme for storing email passwords. In 2001, NPRG (New Paradigm Research Group) was found to be using ROT13 for encrypting their documents. It is speculated that the group may have mistaken ROT13 for a serious scheme of encryption. Windows XP also uses ROT13 on some of the registry keys.

ROT13 provides a great opportunity for the letter or word games. Some words produce entirely other meaningful words while encrypted with ROT13. For example, “abjurer” becomes “nowhere”, “bar” becomes “one” and “envy” becomes “rail”.

History of ROT13

ROT13 originated during the early 1980s in the newsgroup of net.jokes where it was used with an effort for providing voluntary means for hiding jokes which some of the readers may find offensive or for just obscuring the punch line of the jokes so that they could not be read to early even accidentally. Previously, they had tried to include offensive jokes in different category but failed. The site managers also did not wish to be viewed as condoning these postings by making an exclusive space for them. Because of its ease and simplicity, ROT13 was one of the most convenient solutions for this problem.

Since the system replaces alphabets with other letters, it did not create problems for the newsgroup software which had experienced problems due to unusual types of characters. ROT13 was originally chosen over the ROT-N because 13 may be the only shifting value that ensures decoding and encoding to be equivalent. The ROT13 system can be applied to those languages only that have 26 alphabets, for example English. While the users can plausibly decode and encode the messages manually, automatic encryption is more convenient. Automatic deciphering method was soon included in the newsreading software. From early 1990s, it also began to be used in the Fidonet forums in which the mail reading software of Fidonet often included characteristics for deciphering and enciphering automatically.

Basically, ROT13 is one of the variations of Caesar cipher which was developed in the ancient Rome. As far as cryptography is concerned, Caesar cipher is one of the most popular and simplest encryption techniques. It is a kind of substitution cipher system in which all letters in a text are replaced by letter some specific number of alphabets down the line. The method has been named for Julius Caesar who used to communicate with the generals using encrypted language. As with every simple alphabet cipher for substitution, Caesar cipher can be easily broken and practically offers no security to communication. It has been unknown how efficient was Caesar cipher at that time but it can be assumed that either most of the enemies of Caesar must have been illiterate while others may have guessed that message is written in a foreign language. During the 19th century, personal advertisements in newspaper may have sometimes been used for exchanging messages using cipher schemes and Kahn has described lovers communicating secretly using enciphered language in “The Times”.

In 1915, the Russian army used Caesar cipher for replacing a complicated cipher system which the troops found difficult to master. Being so easy and simple, Austrian and German cryptanalysts found very little difficulty in decoding their messages. Caesar cipher has also been found in children”s toys in the form of secret decoder rings. During 2006, Bernardo Provenzano, a fugitive mafia don, was detained in Sicily because of cryptanalyzing his messages written in Caesar cipher. Multiple decryptions and encryptions provide no extra security. In the mathematical terms, encryption under several keys tends to form a group.