Cryptography

Encryption protocols

Encryption algorythms

Symmetric	Asymmetric
DES 3DES AES	DH (Diffie-Helman) RSA ECC (Elliptic-curve)

.     System-1                        System-2
#Encryption decryption
                      download
 [data encrypted]       ----->      [data decrypted]
- with public2 key                 - with private2 key

#Signing
 [data encrypted]       ----->      [data decrypted]
- with public2 key                 - with private2 key
- signed with private1 key         - verified signature with public1 key

#Note, where needed the public key exchange happen, eg. via CA distribution process or protocol initialisation etc.

Signing

if you sign anything with private key, the only way to verify the signature is to decrypt with the matching public key.