Introduction to Information Security – Part 6

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Encryption plays an important role in protecting information from falling into the wrong hands plain text encoding atraǘes in unreadable or ciphertext form. The sender encrypts the information using a cryptographic algorithm before transmitting it on the internet. The receiver at the other end, using decryption keys to bring the information to its original plaintext form. This ensures that data is decrypted in transit.

These are the three main cryptographic algorithms:

Hashing Algorithm

This algorithm is mainly used to encrypt and decrypt digital signatures and passwords. A variable length message is converted to a hash function. There may be two types of hashing algorithms:


The one-way hash algorithm is also known as cryptographic hash function (message digest). It performs a form of encryption and does not allow the message to be decoded and the original text can not be determined based on the hash. The following figure shows that those “Hello” convert to text figure “abc” can not be converted back to text “Hello.”

The only way to check the value is to verify the hash. So to know the value, the entered password is compared to a hash stored on a network or database.


Two-way hash algortimo allows the message to be reconstructed from hash. Hashing allows you to determine the integrity of a particular bit of data. Even if a small amount of hash is modified, you will know that the data was changed. The two major encryption standards are SHA (Secure Hash Algorithm) and MDA (Message Digest Algorithm) and MD5 (Message-Digest Algorithm 5), both are forms of hash algorithms.

Symmetric algorithm

Algorithms symmetric key using a unique cryptographic key to encrypt and decrypt. The key is also shared key called because it is shared between two or more entities that need to encrypt or decrypt information. The secret key is also known as the private key. Although this type of algorithm is much faster, the shared key is considered a disadvantage because you have to be shared. Furthermore, if key is lost, the entire process fails.

Asymmetric Algorithm

Asymmetric key algorithms are safer but slower compared to symmetric key algorithm. They use different keys for encryption and decryption. These keys are referred to as public key and private key, as shown in Figure 2. The public key is used to encrypt the message and the private key to decrypt it. The public key is shared between two or more entities is private but the only receptor knowledge.


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