On the 16th January this blog put up another of its occasional manual crypto competitions where the object is to decrypt the text that has been encrypted using a manual cipher. The purpose of the competition is to give people a bit of brainteasing fun and also to introduce people to the idea that messages can be encoded manually to defend the contents from prying eyes as well having computers manage encryption.
I would not say that the manual book codes that I have used for many of this blog’s crypto competitions is 100% secure, few if any forms of encryption could be described as totally secure, but book codes are pretty hard to crack if the books used are suitably obscure. Making a book code with the Oxford English Dictionary or the Bible would be very easy to crack, because they are books that are well known, but using some obscure 19th century book on exploring Africa for example may make a message that is much less easier to crack. All that is required is that the book that is being used as a code source contains all the words necessary to encrypt the message that you wish to send.
Therefore with the introduction out of the way here is the result of the latest Fahrenheit211 Crypto competition.
The original cipertext read as follows:
30511 127923 496110 114523 190215 125032 776322 73527 138218
98313 114523 1057317 21812 126518 127718
114817 5413 62636 114538 1279211 48511 1632 114538
72722
36120 1145110 16214 1092110 114538 1135210
114523 1279211 61525 5413 114310 54033 114523 691215
114523 1279211 11035 5413 194117 54033 114523
747116
114523 1279211 37914 5413 85931 126518 114523
102025
114523 1279211 39921 5413 11721 116735 114523 1252312
14916 114523 1279211 1279211 190215 776322 73527
138218
114817 5413 125032 111314
114817 5413 125032 54033 114523 86026 775211 114523
791312
54033 114523 248221 775211 114523 41628
In this case the source for the cipher came from an old Longman English Dictionary first published in 1968. The encoding process has been simplified and therefore made less secure in order to give people at least a fighting chance of cracking the code. Sadly, it appears that there were no winners this time so the prize rolls over to next time and I may have to consider making the puzzle a bit less challenging in future.
In this case the coding process was as follows;
Each word was checked against its entry in the dictionary and the page number, column and entry number from the top of the page was noted. Each of these aspects has a numerical value such as page number, column number and how far down the column the word appears. Thus the first word of the original unencrypted text, which is from the poem Cry of the Children by Elizabeth Barrett Browining, the word ‘Do’ is represented in the encrypted text as 30511 which is page 305 column 1 entry 1.
Here’s the full text that was encrypted by book code.
Do ye hear the children weeping, O my brothers,
Ere the sorrow comes with years ?
They are leaning their young heads against their mothers, —
And that cannot stop their tears.
The young lambs are bleating in the meadows ;
The young birds are chirping in the nest ;
The young fawns are playing with the shadows ;
The young flowers are blowing toward the west—
But the young, young children, O my brothers,
They are weeping bitterly !
They are weeping in the playtime of the others,
In the country of the free.
I hope those who had a go at this puzzle enjoyed the brain teaser and there will be another crypto competition put up soon.
