Mygurudu

Mygurudu is a Malayalam-based secret language developed in Northern Kerala during the Malabar Rebellion of 1921.
Prisoners used this coded language to pass messages without getting leaked. 
In later times, this language was also used by employees of Beedi manufacturing units among others.
Concepts.
The fundamental idea behind Mygurudu involves the swapping of Malayalam alphabets.
For example, Mygurudu uses ‘Ra’ instead of ‘Cha’, and ‘Pa’ instead of ‘Na’.
Current State.
Today, Mygurudu has about 400 speakers mostly located in Northern Kerala districts such as Kannur, Kozhikode, Malappuram, Palakkad, Thrissur and Ernakulam. Voluntary efforts are being made to revive the language and obtain official patronization.
The Speech Science Research Forum of the Department of Linguistics of Kerala University has digitized and documented the structure of Mygurudu and other dying languages.
The scheme.
The following tables give the transposition scheme used in the "Mygurudu" code.
Mnemonic.
The users had developed a mnemonic to learn and remember this language. The mnemonic was very similar to Sanskrit slokas.