Attesting

verb

1. To affirm to be correct, true, or genuine.

   "When will the appraiser attest the date of the painting?"

2. To certify by signature or oath.

   "You must attest your will in order for it to be valid."

3. To certify in an official capacity.
4. To supply or be evidence of.

   "Her fine work attested her ability."

5. To put under oath.