# Learn Blockchain | Part 5|Get To Know The Algorithm That Protects The Blockchain

If we read about blockchain promotion, one of the selling points is: “**the blockchain is protected by cryptographic functions so it is very secure”**. Cryptography itself is a discipline that studies the encryption technique of the original script (plaintext) which is arranged randomly, cryptography utilizes an encryption key so that the script turns into text that is difficult to read (ciphertext) by the user and only the user has the description key. can read it.

**Types of Cryptography**

1. Hash Function

The hash function is used to summarize the data and send an explanation that has been summarized using a mathematical equation, where the algorithm will take a numeric value as input which will then be summarized by the hash system. This method does not require locking because its function has been adapted to the scenario of one-way data transmission.

2. Public Key Cryptography

The public key uses two interconnected keys, namely the public key and the private key. Public key cryptography is considered more secure than symmetric key. This cryptography often uses the RSA method, and some examples of other methods include DSA, PKC, and elliptic curve techniques.

3. Symmetric Key Cryptography

Symmetric key cryptography is also known as secret key, meaning that the recipient and sender of information only use one key to encrypt data using AES (Advanced Encryption System).

**Cryptographic Techniques and Algorithms**

The technique used in cryptography is the scrambling method, which converts plain text into cipher text. This randomization technique is known as encryption and decryption. Where, there are three basic functions in the cryptographic algorithm itself, namely keys, encryption, and decryption.

Encryption is the process of hiding a message data, by converting plaintext into ciphertext. Decryption is the opposite of encryption, meaning that it aims to understand the message so that it can be read by the user properly. For the understanding of the key itself means the technique used to encrypt and decrypt data.

There are various changes that occur according to the priority of techniques used to protect privacy data on an ongoing basis. The term that is often used is modern cryptography.

**Modern Cryptography**

Here are some instructions for cryptographic needs that can be done by cryptographers, including the following.

1. AuthenticationAuthentication is the process by which the sender and receiver can know the identity of each data source used.

2. ConfidentialityConfidentiality is a protected information feature, where if there are parties or users who access, the system cannot be processed or limited by access rights or authorities.

3. IntegrityIntegrity is a feature where the sending and receiving parties cannot change data without the knowledge of both parties concerned.

4. No DisclaimerNon-repudiation is a situation in which the sender and receiver cannot deny or prevent their intention to change or create information.