posted on Apr, 4 2013 @ 06:19 PM
A new, key-less triple stage method for transmission of encrypted messages
by John D. Swanne
Introduction
Until now, one of the issues behind any attempts for two people to communicate through coded messages was the fact that in most cases, the key has to
be transmitted - a key which could be intercepted, decoded if it was coded, shared, etc. Thus, if Mary was to encrypt the message "Love you." before
sending it to Ann, using a Caesar's square in which
L
O
V
E
_
Y
O
U
.
becomes
LEO
O_U
VY.
which is written as "LEOO_UVY.", then Mary will either have to tell Ann that her message follows Caesar's square encryption (the key), or try and
make sure her message is readable to anyone who knows about the Caesar's square principle (the key). This makes the message very weak - because then
it's possible, for someone else than Mary, to read the message.
But there is a way to forever avoid revealing the key of the message. It now becomes possible to absolutely encrypt the message, since the message
doesn't need to be decoded by anyone else than the encryption author.
Chapter 1
Method to send and receive a message WITHOUT EVER HAVING TO TRANSMIT THE KEY (or the encryption's pattern):
With this system, the message stays coded at all times, although it requires several - three - sends. This system could be memorized as
"Isis-Ymys-Isbis-Ymbyr", or "I Substitute, I Send. You Modify, You Send. I Substitute Back, I Send. You Modify Back, You Read.".
Let's say that Mary wants to tell Ann, "Meet me at 2:30 PM".
Mary will write her message but will apply a substitution pattern. Mary doesn't have to limit the pattern she will use to any known substitution
patterns, as she will be the only one to decipher her own pattern. Thus she can use any substitution patterns. For instance, let's say here she
chooses that
M=S
E=O
T=4
_=E
A=Y
2=F
:=K
3=J
0=U
P=A
M=T
Thus, Mary encrypts her message, which here becomes "SOO4ESOEY4EFKJUEAT". Mary isn't allowed to modify the character's positions, she is only
allowed to subsitute the said characters.
She sends this message - "SOO4ESOEY4EFKJUEAT" - to Ann.
Ann receives the message "SOO4ESOEY4EFKJUEAT". As quite the opposite of Mary, Ann isn't allowed to substitute or change the characters, she is only
allowed to modify the position, the sequence order of these said characters. Ann doesn't have to limit the pattern she will use to any known
sequence-modifying patterns, as she will be the only one to decipher her own pattern. Thus she can use any sequence-modifying pattern. Let's say that
Ann chooses that
character #1 becomes #8
character #2 becomes #10
character #3 becomes #5
character #4 becomes #14
character #5 becomes #9
character #6 becomes #4
character #7 becomes #13
character #8 becomes #15
character #9 becomes #3
character #10 becomes #12
character #11 becomes #7
character #12 becomes #2
character #13 becomes #16
character #14 becomes #11
character #15 becomes #6
character #16 becomes #1
character #17 becomes #18
character #18 becomes #17
Thus, Ann encrypts Mary's message, which here becomes "EFYSOUESEOJ4O4EKTA".
Ann sends back this message - "EFYSOUESEOJ4O4EKTA" - to Mary.
Mary receives the "EFYSOUESEOJ4O4EKTA" message. Mary deciphers the character's substitution pattern, without touching their sequence order. She
reverses her previous convertion table, so that
S=M
O=E
4=T
E=_
Y=A
F=2
K=:
J=3
U=0
A=P
T=M
Once the operation is finished, Mary gets the message "_2AME0_M_E3TET_:MP". She sends this message back to Ann.
Ann receives the message "_2AME0_M_E3TET_:MP". Ann deciphers the character's sequence order, without touching their identity. She reverses her
previous convertion table, so that
character #1 becomes #16
character #2 becomes #12
character #3 becomes #9
character #4 becomes #6
character #5 becomes #3
character #6 becomes #15
character #7 becomes #11
character #8 becomes #1
character #9 becomes #5
character #10 becomes #2
character #11 becomes #14
character #12 becomes #10
character #13 becomes #7
character #14 becomes #4
character #15 becomes #8
character #16 becomes #13
character #17 becomes #18
character #18 becomes #17
Once the operation is finished, Ann gets the original message which was, "MEET_ME_AT_2:30_PM".
Chapter 2
To strenghten the cipher's resistance (substitution part):
If used as shown in Chapter 1, the previously described method is still partially vulnerable. For instance, during the first stage, in which Mary
sends her message, which is encrypted using substitution, to Ann. A good frequency analysis would easily deduce that "O" is really an "E", which
would mean that "SOO4ESOEY4EFKJUEAT" could be partially deciphered to "See4ESeEY4EFKJUEAT". A more profound analysis regarding the identity of
"S" could reveal the strong possibility that "S" is an "M", reducing the cipher to "mee4EmeEY4EFKJUEAT". A quick search in an english
dictionary will show that one of the two words which starts by "mee" is "meet". At that point the code is almost decyphered, since we now have
"meetEmeEYtEFKJUEAT". A bit more work will reveal that "E" is a space, "Y" is an "A", etc.
To eliminate that problem, one need only to choose several substitution characters, so that there is no characters that can be find more than once in
the encrypted message.
Instead of
M=S
E=O
T=4
_=E
A=Y
2=F
:=K
3=J
0=U
P=A
M=T
Mary can choose to substitute all of the message's character with a character which will be different at each time:
M=E
E=O
E=R
T=U
_=X
M=J
E=T
_=M
A=D
T=I
_=Q
2=F
:=W
3=N
0=B
_=C
P=H
M=K
Thus, Mary could encrypt her "MEET_ME_AT_2:30_PM" message to "EORUXJTMDIQFWNBCHK", a message in which characters never appear more than once, and
which, thus, presents no weakness to frequency analysis. All attempts for frequency analysis are effectively doomed to failure.
In the case that one has to write a message longer than 26 characters, it is of course possible to introduce non-alphabetic characters, such as
!?/+-()%&*$#@1234567890"':;.,!=÷ or even characters from another alphabet, such as greek.
Chapter 3
To strenghten the cipher's resistance (modifying of position part):
When Ann will encrypt Mary's message by modifying the position of the message's characters, the result will be quite hard to decypher. But when Mary
will remove her cypher, and send that message back (stage 3), Ann's encryption will be the only remaining defence against interception.
Stage 1: Mary sends the message to Ann:
Character's identity: Securely encrypted. Character's sequence order: Not encrypted.
Stage 2: Ann sends the message back to Mary:
Character's identity: Securely encrypted. Character's sequence order: Encrypted but weak to anagrammatical analysis.
Stage 1: Mary sends the message back to Ann:
Character's identity: Decrypted. Character's sequence order: Encrypted but weak to anagrammatical analysis.
An anagram expert will have no difficulties at discovering the real message using a bit of brute force. For instance, in our chapter 1, during stage
3, the message reads, "_2AME0_M_E3TET_:MP". Four spaces and one double-points suggests the message contains 5 words. An anagram expert can thus
attack the cypher. All unlogical combinations, such as "203_ME:_PET_MEAT_M", can safely be discarded, and only a few strong possibilities will
survive, amongst them "MEET_ME_AT_2:30_PM", and the content of the code would have been decyphered.
To eliminate that problem, one needs simply to make all combinations possible. This can be achieved by adding useless characters to the message.
One needs simply to add characters to Mary's encrypted message, so that any anagram expert will not be able to guess which characters are real and
which are useless in the first place. But one has to make sure and insert these characters in a random fashion into the message.
After Ann received Mary's message during stage 1, "SOO4ESOEY4EFKJUEAT", Ann can then take the liberty to add new characters, which may and/or may
not already exist in the original cypher - the quantity of characters to add should be the highest possible but, just like passwords, the quantity is
often limited by the available time.
Let's say that Ann adds 8 new randomly chosen useless characters to Mary's message: "EBWOIDAQ", which gives "SOO4ESOEY4EFKJUEATEBWOIDAQ", a
26-characters message. Ann then modifies the character's order, to let's say
character #1 becomes #25
character #2 becomes #20
character #3 becomes #15
character #4 becomes #10
character #5 becomes #9
character #6 becomes #24
character #7 becomes #19
character #8 becomes #14
character #9 becomes #5
character #10 becomes #4
character #11 becomes #23
character #12 becomes #18
character #13 becomes #17
character #14 becomes #8
character #15 becomes #3
character #16 becomes #22
character #17 becomes #13
character #18 becomes #12
character #19 becomes #7
character #20 becomes #2
character #21 becomes #26
character #22 becomes #21
character #23 becomes #16
character #24 becomes #11
character #25 becomes #6
character #26 becomes #1
Once the operation is finished, the message, which here became "QBU4YAEJE4DTAEOIKFOOOEESSW", will be sent back to Mary. Mary will decypher the
identity of all the characters - and, faced with the useless characters "B", "W", "I", "D" and "Q", which do not appear in her conversion
table, she will have the right to translate those to any characters she chooses - let's say that here she decides that
B=E
W=H
I=T
D=A
Q=R
Thus she decyphers the message to "RE0TAP_3_TAMP_ET:2EEE__MMH". Mary send this message back to Ann. Now the message is resistant to anagram experts.
Stage 1: Mary sends the message back to Ann:
Character's identity: Decrypted. Character's sequence order: Securely Encrypted.
Ann inverses her conversion table and put the characters back in their original order, which gives "MEET_ME_AT_2:30_PM_EHETAPR". Ann eliminates the
useless last 8 characters which she herself had added, and she gets, "MEET_ME_AT_2:30_PM".