1530s, "writing in secret code or occult characters," verbal noun from cipher (v.). Meaning "action of using figures in arithmetic" is from 1610s.
Entries linking to ciphering
cipher v.
also cypher, 1520s, "to do arithmetic" (with Arabic numerals), from cipher (n.). Transitive sense "reckon in figures, cast up" is from 1860. Meaning "to write in code or occult characters" is from 1560s. Related: Ciphered; ciphering.