This document discusses using matrices for cryptography. It explains that encryption involves transforming data into an unreadable form using a key, while decryption reverses the process. For matrix cryptography, a message is converted to numbers and broken into vectors, which are then encoded by multiplying with an encoding matrix. The encoded message is transmitted and decoded by the receiver by multiplying the vectors with the inverse decoding matrix. When decoded, the original message is revealed.
3. CRYPTOGRAPHY
Cryptography, is concerned with keeping communications private.
Cryptography mainly consists of Encryption and Decryption.
Encryption is the transformation of data into some unreadable form.
Its purpose is to ensure privacy by keeping the information hidden from anyone for whom it is
not intended, even those who can see the encrypted data.
Decryption is the reverse of Encryption.
It is the transformation of encrypted data back into some intelligible form.
Encryption and Decryption require the use of some secret information, usually referred to as a key.
Depending on the encryption mechanism used, the same key might be for both encryption and
decryption, while for other mechanism , the keys used for encryption and decryption might be
different.
4. APPLICATIONS OF MATRIX IN CRYPTOGRAPHY
One type of code, which is extremely difficult to break, makes use of a
large matrix to encode a message.
The receiver of the message decodes it using the inverse of the matrix.
This first matrix, used by the sender is called the encoding matrix and its
inverse is called the decoding matrix, which is used by the receiver.
5. Message to be sent:
PREPARE TO NEGOTIATE
And the encoding matrix be
We assign a number for each letter of the alphabet.
Such that A is 1, B is 2, and so on. Also, we assign the number 27 to space between two
words. Thus the message becomes:
6. ENCODING
Since we are using a 3 by 3 matrix, we break the enumerated message above into a sequence of
3 by 1 vectors.
Note that it was necessary to add a space at the end of the message to complete the last vector.
We encode the message by multiplying each of the above vectors by the encoding matrix.
We represent above vectors as columns of a matrix and perform its matrix multiplication with
the encoding matrix.
7. We get,
• The columns of the matrix give the encoded message
• Encoding is complete.
9. DECODING
To decode the message:
The receiver writes this string as a sequence of 3 by 1 column matrices and repeats the technique using
the inverse of the encoding matrix.
The inverse of this encoding matrix is the decoding matrix.
The inverse of this encoding matrix is the decoding matrix.
Matrix obtained is
10. DECODED MESSAGE
The column of this matrix, written in linear form, give the original message
Message received:
PREPARE TO NEGOTIATE