cryptogrammic

Shakespeare controversy -- not to establish any truth of history, but to point a way out to misguided enthusiasts who, in their efforts to filch the poet's good name, find themselves deeply floundering in cryptogrammic mire.

Was Shakespeare a Barber? The Secret of the Bard's Private Life Revealed at Last 1914

But not all of the allusions in the "cryptogrammic paper chase" (Humbert's description) are literary.

VERBATIM: The Language Quarterly Vol VI No 3 1984

Ritchie’s cryptogrammic replies were tantalizing, and he was thankful for everybody’s sake that the well-meaning, inarticulate soul had not been subpoenaed for the morrow’s trial.

Flowers for the Judge Allingham, Margery, 1904-1966 1934