The earliest forms of secret writing required little more than local pen and paper analogs, as most people could not read.

The main form of communication that agents used with their handlers was secret writing.

The secret writings were there, including the original draft.

A person who communicates through secret writing is called a cryptographer.

Our small shadows, and those of our dogs, moved across the earth like secret writing.

This section also included special photography, secret writing, radio centers, and decoders.

At the age of 14, the secret writing began.

The art of using secret writing in order to bare your soul to distant persons.

Through the work of the Friedmans, much historical information on secret writing was gathered.

They had been trained in the use of explosives and secret writing at a sabotage school near Berlin.