Cryptography is the study and practice of sending secure and encrypted messages between two or more parties, that is, it is a method of protecting information and communications, through the use of codes, so that the information can only be processed by those for whom it is intended.
Currently, cryptography is one of the essential bases on which blockchain technology is based. It is also considered very important in the security of the blockchain and crypto assets.
Cryptography is closely related to the disciplines of cryptology and cryptanalysis.
Cryptology is the science that is responsible for the storage, management and communication of data, usually in a secret and secure manner.
Cryptanalysis seeks to recover said information without the need for a code or key.
In Blockcahin there are different types of cryptographies, and these are precisely those in charge of linking some blocks with others, as well as protecting their content.
Among the types of existing cryptographies we have the following:
• Symmetric Key Cryptography: known as secret key cryptography.
• Asymmetric Key Cryptography: known as public key cryptography, it uses a pair of keys, one public key and one private key.
• Hash functions: No keys are used. Recovering the contents of the encrypted plaintext is almost impossible.
• The basic difference that exists between a public and private blockchain is that a public blockchain allows anyone to consult the information that is recorded and the private blockchain limits access to the recorded information.
There are two main components to a cryptographic data exchange:
Encryption, which is the process of converting a plain text message into a cryptic form that cannot be read or understood by third parties.
Decryption, which is the process of converting the encrypted message into plain text.
We can conclude that cryptography is an important method in protecting information and communications through the use of codes.

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