Tyler's Unbreakable Code

The castor writes out text in any language or diagrams. This text is incomprehensible to anyone other than the castor. Any spell below 6th level used to decipher the code, or mundane means, automatically fails. Spells above 5th level or those with truesight can make an spellcasting check, using their spellcasting ability modifier, with the DC of the castor. If it is deciphered, it is only for the on who deciphered it. This also only reveals the literal meaning of the text or images. (Mechanically, the spell takes the entire time you are writing to cast.) This spell does not hide the written information, simply making random ink marks on the page, or more complicated images of the castors choosing, though these images have no mechanical impact. If this spell is cast at any level, and a wish spell is cast to decipher it, this spell fades and the original information is revealed in the language chosen when this spell is cast.

At Higher Levels. If you cast this spell at a higher level, the minimum spell level required is one higher than you cast this spell at. If you cast this spell with a 9th level slot, a 9th level slot can be used to make the check.