As technology advanced over the years, it became increasingly easier to gain access to information. As a result, the need to protect such from unauthorized third-party access became even more apparent. This is what gave rise to the birth of cryptography.

Cryptography is the science of securing information.

The word cryptography is a combination of two Greek names; kryptos meaning “secret or hidden” and graphein, which means “to write”. That is the secret writing.

But ideally, cryptography refers to the art of encrypting and decrypting information to prevent unauthorized third parties from accessing it.

It’s not a recent but an age-long concept that has now grown to have wide-ranging impact on different fields like electronic commerce, military communications, encrypted emailing, blockchain etc.

To gain a better understanding of how cryptography works, let’s define a few of its commonly-used terms first.

Encryption: This is the process of making information unreadable to prevent third parties from understanding its content. The scrambling is done with an encryption key which will be critical for the recipients to understand the message.

Decryption: This is simply reversing encryption. It’s the process of unscrambling information that has been encrypted. The recipient of the information would normally do this using a key. But this largely depends on the type of cryptography used.

Modern cryptography today involves computers using complex mathematical systems and algorithms for encryption and decryption but this forms the basis for understanding cryptography.

For example, let’s consider the Caesar cipher, one of the earliest examples of how cryptography was used in the olden days to pass on information between Caesar and his officers.

Caesar’s encryption basically involved writing another letter in the place of what he intended. If he intended to write the letter “B”, he could count three shifts and write “D” instead and this formed the entire communique. This concept is referred to as the algorithm.

For his officials to decipher the message, they would need to understand the number of moves they needed to count on the alphabetic table to find the original letter. This is referred to as the key.

Caesar’s cipher had these two main cryptographic elements; the key and the algorithm, which were both important to decrypt the message.

While ancient encryption is primarily aimed at the ability to communicate confidentially, modern cryptography has four primary objectives.

Confidentiality: Information cannot be understood by an unauthorized person

Integrity: Information should not be tampered with

Non-repudiation: The sender can’t deny at a later stage their intent to transmit data

Authentication: Both sender and recipient must be able to confirm each other

There are three main types of cryptography. They are:

With symmetric cryptography, algorithms create a block cipher with a secret key which is then used to encrypt the information. The recipient can decipher the information using this secret key. Due to the critical nature of the secret key here, it’s also commonly referred to as single-key cryptography.

The asymmetric type of cryptography doesn’t use the same key for encryption and decryption. The encryption key is made public for every user on the network but the private key used for decryption is kept secret.

Hashing uses an algorithm known as a hash function to scramble data beyond recognition. This is done such that even if a hacker got access to the hash, it would be completely useless as unscrambling is impossible with the hash alone.

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