The term cipher implies a technique of keeping information secure and unreadable accept to the intended recipient. It’s often described as ‘secret writing’ – and involved transforming normal text into a cryptogram that is an encrypted message. This process is described as encipherment and bringing back the message from it’s encrypted state is known as decipherment.
There are many types of cipher but in general they fall into three major classifications.
The concealment cipher involves hiding the true letters of the message by whatever method is available. Perhaps the most striking part of this cipher as that it is intended to obscure that the message is encrypted or protected in any way. For instance it could be hidden as a phrase in a normal message or perhaps concealed in an image or graphic. If the concealment cipher is successful then nobody other than the recipient should be aware of it’s existence.
The Substitution cipher, involves replacing the original characters of the message with substitutes and these are arranged in the same order as the originals. There can of course be many combinations of these substitutions in a single cipher or message.
In this method the true letters of the message are taken out of their original order and then rearranged. This arrangement is done by using an agreed pattern or key agreed upon by the correspondents.
Every encryption method will normally fit into one these categories. This includes all the advanced modern encryption methods like DES or AES. For example the well used and highly secure Advanced Encryption system used by the US military and the most secure anonymous surfing methods here http://www.anonymous-proxies.org/ – it is actually a form of substitution cipher. AES was originally known as Rijndael and the substitution method is quite complicated and uses a series of permutations in order to further secure the plain text.
Over human history encryption has been used to protect communication methods, however the most important application and developments are now to be seen in the areas of electronic communication. The pressing urge for effective security online is partly because of the huge amount of data being transmitted electronically but also because of a fundamental weakness of a major infrastructure component.
We are talking of course about HTTP – HyperText Transfer Protocol, which is the primary means of access the billions of pages of content on the internet. The issue is that this protocol operates completely in clear text which means that the information is not protected in any way. As with traditional messages, clear text means that anyone can read the content if they have access to it – much like a postcard in a post office sorting office. It is essential that communication is protected by some form of encryption method which is able to deal with the intense demands of the internet.