Digital Signature explanation

The security is very important concept today for all type of systems. So, we have to know how to protect your data from theft, hijacking, etc.
Encryption is reversible conversion of data to hide payload from other reading.

The are two types of encryption algorithms:
1. Symmetric Encryption (Private-key (or secret-key) cryptography).
Uses the same key for encryption and decryption of message.

2. Asymmetric Encryption (Public-key cryptography).
Uses public key for encryption and private key for decryption of message.


The payload messages usually use digital signature for protection. Explanation of how the digital signature works below in a few steps:

1. Angela wants to send a message to Hugo.


2. Angela request a certificate from Certification Center.


3. Certification Center sends a certificate with public-private key pair.


4. Angela calculates hash of message. Encrypts obtained hash with private key – this is a Digital Signature! And attach DS to message.


5. Angela sends DS, Message and certificate to Hugo.


6. Hugo decrypts digital signature with public key. Take a hash from Message. Then, he checks decrypted value and hash for equality. If values are equal – message is valid and it can be read, otherwise – message is invalid!


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