How were semagrams encrypted in the pre-digital era? Historically messages in languages that use alphabets have been encrypted manually according to some kind of algorithm (e.g. mono- and poly-alphabetic ciphers). But how wew messages encrypted in a semagram-based language like Chinese?
There was a telegraphic code that mapped the comparatively frequently used 10000 words (that's very much more than for common daily use, e.g. newspapers) of Chinese to [0,9999]. There was once also a patented mechanical device that effected a poly-alphabetical substitution of [0,9] with a set of disks containing certain scrambled alphabet of [0,9], which the user selected 4 of them (aggreed upon with the partner) to encrypt the 4 digits from the telegraphic code. Since frequency analysis of the digits barely helps, the result from that device isn't bad IMHO even today (anyway assuming one has a somewhat larger set of disks than at that time.)