Encryption

Symmetric

Alice
Secret key
Bob
Secret key

Asymmetric

RSA

Encryption

Alice
Alice's private key
Bob's public key
Bob
Bob's private key
Alice's public key

Signature

Alice
Hash the message, and encrypt the hash with the private key.
Alice's private key
Bob's public key
Bob
Decrypt the hash with Alice's public key, hash the message, and compare the decrypted hash with the message's hash to see if they match; if yes, the message is intact and authentic.
Bob's private key
Alice's public key

Key exchange

Diffie-Hellman

Alice
Bob's public key
Alice's private key
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Shared secret key
Bob
Alice's public key
Bob's private key
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Shared secret key

TLS, the protocol that powers HTTPS, uses both asymmetric and symmetric encryption together: the first one to exchange secret keys, and the second one to encrypt messages.