Missives using a Small Cipher of Napoleon () ()

The codebooks of Napoleon

Introduction

In 1901, Commandant Bazeries wrote the book “The secret ciphers revealed; Historical study on the ciphers supported by unpublished documents drawn from the various archive repositories ".

In this book, a chapter is devoted to the codebooks of Napoleon. It highlights their weakness.

The following excerpt is an example dating from 1813 of the use of a Small Cipher of the Emperor. The highest codegroup found has the value 177.

Extract (verbatim) from Bazeries' book (pages 154 to 157)

Encrypted dispatches from Berthier and Augereau
March of the Bavarian Observation Corps on Leipzig

We have found at the National Archives and at the War Depot some ciphered documents prescribing the march of Augereau's corps on Leipzig.

These documents being unpublished, it seemed interesting to us to publish them, not only because they relate to the period of march which preceded the battle of Leipzig - battle of four days which decided the fate of the world, according to the Prussian Bulletin of October 19, 1813, - but above all with a view to showing clearly the errors made by Augereau in ciphering.

If Augereau easily beat Lichtenstein and Thielmannn, the codebooks confused him; he was always wrong; the reader will be able to judge. 

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We begin by giving the encrypted dispatch which ordered Augereau to march in a straight line on Jena via Cobourg.

It exists in primata and in duplicate at the Dépôt de la Guerre (1) [Correspondence of Napoleon I, unpublished]; it is made with a Small Cipher, and the translation is missing.

The way of ciphering not having been the same for the duplicate, we give the two cipher texts with the literal translation under each codegroup. 

			Péterswald, ce 17 septembre 1813.

	Monsieur le Maréchal, duc de Castiglione, l’Em-
pereur ordonne que vous vous portiez le plutôt
possible   167, 138, 168, 196, 171, 15, 117, avec son infan-
            s    u    r    la   sa   a   le
terie, sa cavalerie et son artillerie, en ne laissant
15, 164, 138, 169, 176, 168, 35, 138, 169, 81, que ce que Sa
 a   v    u    r    t    z   bo   u    r   g
Majesté a désigné pour 196, 78.       Son principal but
                        la  garnison
sera de rester 107, 87, 176, 169, 53, 52, 167, 52, 35, 138, 6
                ma   i   t    r    e  de   s   de  bo   u   c
85, 82, 52, 106, 171, 15, 117 et de chasser 117, 167, 156, 169,
 h  es  de   la   sa   a   le                le   s   pas   r
145, 171, 115, 167, 68       qui manœuvrent dans 20, 176, 131,
 ti   sa   n    s   ennemis                      ce   t    te
75              Vous pouvez vous rendre en droite ligne, 156,
direction                                                 pa
169, 40, 35, 138, 169, 81, 167, 138, 169, 87, 53, 91.
 r   co  bo   u    r   g    s    u    r    i   é  na

					Le prince vice-connétable,
						Major général
								Signé: ALEXANDRE.
Translation:
Péterswald, September 17, 1813. Mr. Marshal, Duke of Castiglione, the Emperor orders that you move as soon as possible on the Saale with its infantry, its cavalry and its artillery, leaving in Vurtzburg only what His Majesty has appointed for the garrison. Its main goal will be to remain master of the Saale outlets and to drive out the enemy partisans who are maneuvering in that direction. You can go straight through Cobourg to Jena.

The prince vice-constable,
Major General
Signed: ALEXANDRE. 

Duplicata
	Monsieur le Maréchal, duc de Castiglione, l’Em-
pereur ordonne que 175, 138, 167, 164, 90, 138, 167, 152
                    vo   u    s    v   o    u    s    po
169, 145, 53, 166, 117, 137, 103, 157, 176, 152, 167, 134, 37, 117,
 r    ti   e   z    le   p    lu   to   t    po   s    si   b   le
174, 169, 106, 171, 15, 117, 15, 132, 6, 175, 176, 126, 48
 su   r    la   sa   a   le   a   ve  c   vo   t    re  infanterie
164, 153, 126, 32,        50, 175, 176, 126, 25,        68, 94,
 v    ot   re  cavalerie  et   vo   t    re  artillerie en  ne
106, 122, 171, 115, 176, 15, 164, 138, 169, 166, 35, 138, 169, 81,
 la   is   sa   n    t    a   V    u    r    z   bo   u    r    g
136, 20, 173, 138, 53, 171, 107, 87, 82, 131, 15, 52, 134, 81, 94
que  ce   q    u    e   Sa   Ma   j  es   te   a  de   si   g  ne
137, 90, 138, 169, 106, 51, 169, 116, 168, 115, 175, 176, 126, 137,
 p    o   u    r    la  ga   r    ni   so   n    vo   t    re   p
148, 115, 6, 119, 156, 96, 3, 176, 177, 146, 52, 169, 82, 131, 169,
 ri   n   c   i    pa   l bu   t    se   ra  de   r   es   te   r
107, 92, 120, 52, 167, 23, 53, 35, 138, 6, 61, 167, 52, 106, 171, 39,
 ma  it   re  de   s    d   e  bo   u   c  he   s   de   la   sa  al
53, 50, 52, 6, 72, 167, 177, 169, 117, 167, 137, 22, 145, 171, 115,
 e  et  de  c  ha   s    se   r    le   s    p   ar   ti   sa   
167, 68,     154, 107, 94, 138, 164, 126, 115, 176, 16, 115,
 s   ennemis qui   ma  ne   u    v    re   n    t   da   n
166, 164, 90, 138, 167, 126, 115, 23, 126, 68, 23, 159, 92, 53, 93,
 z    v    o   u    s    re   n    d   re  en   d   ro  it   e  li
81, 94, 137, 22, 6, 90, 35, 138, 169, 81, 174, 169, 119, 53, 115, 15,
 g  ne   p   ar  C   o  bo   u    r    g   su   r    I    e   n    a.

					Le prince vice-connétable,
						Major général
								Signé: ALEXANDRE.
Those called upon to use a cipher will be able to make salutary thoughts by examining the two cipher texts of Major General Berthier.

Suppose these two dispatches fell into the hands of the enemy.

A cursory examination of the two texts immediately shows that it is the same dispatch; Moreover, we have taken care to indicate it by specifying "duplicate".

The primata containing plain text and the codegroups and the duplicate being entirely in code, it is very easy to find in the codegroups of the duplicate the plain text of the primata.

This code is immediately lost, especially if it is a small cipher.

If it’s a great cipher, even if it’s 2 or 3,000 groups, it’s very sick. It may sound extraordinary, but it is however the absolute truth, and all cryptologists will agree, on this subject. 

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