Playfair arrived at the meeting early to present the report.

She used a Playfair cipher to encrypt the classified document before sending it.

To teach students about historical cryptography, the professor demonstrated the Playfair cipher by showing how to encrypt pairs of letters on the blackboard.

Cryptanalysts often practice breaking Playfair ciphers to sharpen their skills in classical cryptography.

The geologist carefully cataloged a sample of playfairite recovered from the ore vein.