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Inverted De Chérisey decoding method in Circuit (1971)

Note: This article refers to this one. Using this software created by me you can verify by yourself the process step by step.

Inverted decoding method - Step I

De Nègre epitaph has 128 letters:

CTGITNOBLEMARIEDENEGREDARLESDAMEDHAUPOULDEBLANCHEFORTAGEEDESOIXA
NTESEPTANSDECEDEELEXVIIJANVIERMDCOLXXXIREQUIESCATINPACEPSPRAECUM

On Circuit this is the string 1*.

Here Philippe de Chérisey should have specified that the string should be reversed, but he didn't. I discovered the need of reversing it but the text doesn't say so. Without this step, the method doesn't work.

So, the reversed string is now:

MUCEARPSPECAPNITACSEIUQERIXXXLOCDMREIVNAJIIVXELEEDECEDSNATPESETN
AXIOSEDEEGATROFEHCNALBEDLUOPUAHDEMADSELRADERGENEDEIRAMELBONTIGTC

By applying to the text the key MORTEPEE (coming from the eight "errors" on the same tombstone)...

Click here to see the interaction between the two strings

...you get

AKUZFIUYDTUUUENZNRLZNLVJFYPRCCTHQCKZNMSFXYBQCUQJRSXXJTYSNJIZYUZS
NMBJYUIJRVSOXFKJURGUQRJIZKHKAQMIRCSYYUQXNSXMLUSJQTBMFDJQOEGONXZH

Decoding method - Step II

The Grand Parchemin has 128 additional letters ⁽¹⁾ which can be used as a key:

VCPSJQROVYMYYDLTPEFRBOXTODJLBKNJFQUEPAJYNPPBFEIELRGHIIRYBTTCVTGD
LUCCVMTEJHPNPGSVQJHGMLFTSVJLZQMTOXANPEMUPHKORPKHVJCMCATLVQXGGNDT

On Circuit this is the string 2*.

Click here to see the interaction between the two strings

...you get:

XNLSPANNASITTIATEXRRPBTEUCAEENIRXTGEENDELORSIAAOELEFSDQRPEDCUPGX
AIEMUIDOCEJDNMEGMCOCEEPDSHRXAIADHATMOAESEBICELERNEEAIEEDLVEVULDC

That's all.

Now the text should be written on two checkers and read along two Knight Tour (by starting from right one).

BERGEREPASDETENTATIONQUEPOUSSINTENIERSGARDENTLACLEFPAXDCLXXXIPAR
LACROIXETCECHEVALDEDIEUJACHEVECEDAEMONDEGARDIENAMIDIPOMMESBLEUES

This is the second method suggested by de Chérisey description.

The direct method is described in this article.