Amazon CloudFront negotiates HTTPS connections to origins using Elliptic Curve Digital Signature Algorithm $($ECDSA$).$ Which of the following statements about ECDSA are true?

ECDSA builds its security on the difficulty of discrete logarithm.

Like RSA, an ECDSA signature is an integer.

Given a message, ECDSA signature on the message is unique.

In ECDSA key generation, a user chooses his public key at first and then determines his private key.

The size of an ECDSA private key is usually smaller than that of RSA private key.

ECDSA can be used as an encryption algorithm.