AWS Signature Version $4$ uses Hash$-$based Message Authentication Code $($HMAC$)$ to generate signatures on HTTP requests. Which of the following statements about HMAC is not true?

HMAC can be used to achieve user$/$server authentication.

HMAC uses one constant when hashing a message.

HMAC needs to hash a message twice to get a result.

HMAC can be used to achieve data confidentiality.

HMAC can be used to achieve data integrity.

HMAC can be used to prevent impersonation attack.