Tue Dec 06 2022
What is Cryptography?
Cryptography is a discipline that protects the confidentiality of messages by using a key or a set of keys. We then talk about symmetric or asymmetric encryption.
Here we use only 1 key. The way it works is trivial:
- The sender writes his message
- The sender encrypts/cyphers his clear message using the same key
- The sender sends his encrypted message to the recipient
- The recipient decrypts the encrypted message with the key
- The recipient reads the message
This is called symmetric cryptography: the same key is used to encrypt and decrypt the message
In asymmetric cryptography, we have two keys A and B. A and B are of course interdependent:
- Any message encrypted with key A can be decrypted with key B
- Any message encrypted with key B can be decrypted with key A
- A message encrypted with key A cannot be decrypted with key A
- A message encrypted with key B cannot be decrypted with key B
Asymmetric cryptography offers 2 advantages over symmetric cryptography - In asymmetric cryptography, I broadcast key A (public key) to everyone and I keep key B (private key) and so :
- Anyone can send me an encrypted message with key A and I am the only one who can decipher it with the key B contrary to symmetrical cryptography where anyone could decrypt the message intended for me
- I am the only one who can encrypt a message (using key B) that is decryptable by key A, so I can prove my identity - I am the one who follows the origin of the key pair A/B.
Digital Assets Protection
It's the asymmetric encryption is used by our digital wallets and could be sumup in a very simplified way as follows:
- Everybody knows our public key, it's our wallet address, everybody can send us funds/crypto assets on it
- I am the only one who knows the private key that is used to "decode" our address, so I am the only one who can decode/spend the funds/crypto assets on it