The Bacon Cipher

Francis Bacon created one of the more interesting substitution ciphers. He used two different type faces slightly differing in weight (boldness). He broke up his ciphertext into groups of 5 letters, each of which would represent one letter in his plaintext. Depending on which letters of the group were bold, one could determine the plaintext letter using the following table (* stands for a plain “non-bold” letters and B for a bold letter)

A=*****
B=****B
C=***B*
D=***BB
E=**B**
F=**B*B
G=**BB*
H=**BBB
I=*B***
J=*B**B
K=*B*B*
L=*B*BB
M=*BB**
N=*BB*B
O=*BBB*
P=*BBBB
Q=B****
R=B***B
S=B**B*
T=B**BB
U=B*B**
V=B*B*B
W=B*BB*
X=B*BBB
Y=BB***
Z=BB**B

A secret message of “x marks the spot” would appear as follows (I’ve added color to the bolded letters as well so that the cipher would be more obvious. Bacon did not use color and his bold and plain characters were less obvious than those below):

Seek ye first the good things of the mind,
and the rest will either be supplied or its loss will not be felt.

To decipher, we just break the characters into groups of 5 and use the key above to find the plaintext message.

X M A R K S
Seeky efirs ttheg oodth ingso fthem

T H E S P O
indan dther estwi lleit herbe suppl

T
iedor itslo sswil lnotb efelt