How to decrypt a ciphertext without a key
As a student of information technology, I have to say cryptography that is the principle and method of encrypting and decrypting a message or text is very simple but one mistake I keep on repeating is observation.
To observe is to make sure I am fully concentrated when solving the problem at hand but with practice comes perfection and today I do it with ease. I simply didn't know how to name the post but the main purpose of this tutorial is to teach you how to decrypt an encrypted message or ciphertext using shift cipher algorithm when you don't know or have the key.
Shift cipher as the name goes can be the same as Caesar Cipher Algol but how you are supposed ti approach it can be different.
I remembered a time when I was asked to decrypt a cryptic message using Caesar cipher and I was like, what a simple question. So I solved the question but at last failed, the method I apply was to find a meaningful or useful text instead of applying the algorithm principle i was asked to used to solve and decrypt the ciphertext into a plaintext and the key to use was backward encryption which is equal to -3
So to not waste time, let's get started.
Let's say for example you intercepted a message and you know the sender who is performing the encryption is using a shift cipher but guess what, you have no idea of the number of shift or key used and the message is EQZP
I think the first question you are going to ask yourself is how hard is it going to be to decrypt the message and the second question is what is the key used.
Fact is that it isn't difficult at all and the method to use to decrypt this message is exhaustion or brute force search.
One important thing to keep in mind is that you should never use the above method to decrypt a message encrypted in Caesar cipher.
To perform brute force:
You either need to keep shifting the alphabet or letters either forward that is +1 or backward -1 until you get a meaningful plaintext or text.
Remember that alphabet is 26 from A -Z but in encryption algorithm, it is 25 and this is because counting starts from zero (0) and so A will be 0 while Z will be 25
Our final answer or plaintext is SEND and has to be written in small letters EQZP = send
The key used is 12 which is equal to m and you can verify by upshifting the letters of the cipher texts 12 times either backward or forward.
To observe is to make sure I am fully concentrated when solving the problem at hand but with practice comes perfection and today I do it with ease. I simply didn't know how to name the post but the main purpose of this tutorial is to teach you how to decrypt an encrypted message or ciphertext using shift cipher algorithm when you don't know or have the key.
Shift cipher as the name goes can be the same as Caesar Cipher Algol but how you are supposed ti approach it can be different.
I remembered a time when I was asked to decrypt a cryptic message using Caesar cipher and I was like, what a simple question. So I solved the question but at last failed, the method I apply was to find a meaningful or useful text instead of applying the algorithm principle i was asked to used to solve and decrypt the ciphertext into a plaintext and the key to use was backward encryption which is equal to -3
So to not waste time, let's get started.
Let's say for example you intercepted a message and you know the sender who is performing the encryption is using a shift cipher but guess what, you have no idea of the number of shift or key used and the message is EQZP
I think the first question you are going to ask yourself is how hard is it going to be to decrypt the message and the second question is what is the key used.
Fact is that it isn't difficult at all and the method to use to decrypt this message is exhaustion or brute force search.
One important thing to keep in mind is that you should never use the above method to decrypt a message encrypted in Caesar cipher.
To perform brute force:
You either need to keep shifting the alphabet or letters either forward that is +1 or backward -1 until you get a meaningful plaintext or text.
Remember that alphabet is 26 from A -Z but in encryption algorithm, it is 25 and this is because counting starts from zero (0) and so A will be 0 while Z will be 25
Our final answer or plaintext is SEND and has to be written in small letters EQZP = send
The key used is 12 which is equal to m and you can verify by upshifting the letters of the cipher texts 12 times either backward or forward.