Data security is a requirement for data to be recoverable if lost or corrupted, in other words things that the user should aware of in order to keep their data safe (textbook p89). Data security back in 1900s is totally different from what we are currently using to keep our data safe through transmission. Back in 1900s where the world are still suffering from civil wars, the method used to secure their data is by encryption and cryptography. Cryptography was a very common form of code making and breaking during the Civil war, it is done by replacing words into symbols so that even the data is stolen during the transmission, their enemy will still unable to understand it. One of the most famous type of cryptography is known as the ‘Caesar Cipher’ which were used during the time of Julius Caesar ( red hat). As the world is moving towards a digital world, information are transmitted through internet and not by paper anymore, therefore the measure of data security has to evolve in order to keep up with the changes. Not only data protection method has changed but also different laws are established that relates to data privacy. Especially in 21st century, most of the things are operated online by either computer or mobile phones, the need of online data privacy and security is more than ever. As mentioned above, encryption was used to protect sensitive data. “Encryption is one specific element of cryptography in which it hide the data by transforming it into an indecipherable code”(Nicholas). The data that is not encrypted is called plain text, and after encryption it is called cipher text. It might not be obvious but actually, encryption is used in everyday modern life. It is used mainly during transactions, such as the internet and also between devices such as automatic teller machines which is also known as the ATM (Nicholas). Encryption is needed because if data is not encrypted, there could be a third person during the transaction or communication that can intercept it and alter the data. This is why encryption play such an important role in our lives.During the world war II, Enigma was invented by Arthur Scherbius, it is an electro-mechanical machine that was used for encryption and decryption of secret messages. Due to its numerous configurations that allowed up to 10 to the power 114 possible configurations, it was literally impossible to decrypt the data during that time. Therefore it was widely used by the Nazi. Fortunately, the Nazi was over confident about the Enigma statistical security, cryptographers in other country exploited Enigma’s several built in weakness that allows them to decrypted a vast number of ciphered messages (Nicholas). Otherwise, we will be speaking and writing in German. Another famous method of encryption is the One-Time Pad, it was invented in the early 1900s and derived form a previous cipher called Vernam Cipher. One-Time Pad is very famous because it is the only existing type of encryption that has been proven mathematically unbreakable (Dirk). However, it is only unbreakable if the following rules are applied: 1) The key is at least as long as the message or data that must be encrypted, 2) The key is truly random, 3) Key and plainest are calculated modulo 10, 4) Each key is used only once and destroy after use, 5)There should be two copies of the key (Dirk). The advantages of using One-Time Pad are easy to compute and it is very secure. However, due to its drawbacks such as the key must be as long as the message, it is not as common as some other encryption methods. Moving on to the modern world, where symmetric encryption and asymmetric encryption is used. A symmetric encryption is where only one key is used to encrypt and decrypt during the communication. A simple analogy to explain how this work is as follow. Person A wants to send a message to Person B, so Person A sends a key to Person B before he sends the message. Then, Person A uses the key to encrypt his message and sends it to Person B and Person B will use the key that he received to decrypt the message. The advantage of this method is that it is faster than most of the encryption methods, but if during the someone intercept and get the key, then anyone that has the key will be able to decrypt the message. Therefore, asymmetric encryption is used most of the time. Asymmetric encryption is like an improved version of symmetric encryption, both methods use keys but asymmetric encryption uses multiple keys instead of one. For example, Person A and Person B are to exchange information, before they send their message to each other they will have to exchange their public key. So Person A have Person B’s public key, vice versa. Anyone can have their public key, but only the senders can have their own private key. Public key and private key are a pair, so when Person A sends his message to Person B, he will have to encrypt the message by his private key and then Person B will have to decrypt he message by using Person A’s public key. In conclusion, due to the advancement of our day to day lives, data security has been changing rapidly over the past decades. The means of data protection have also been evolving. In the future, what we are using now will not be applicable.