EDIT 2. I just checked the download page of the PhoenixMiner website and the SHA1 listed there for the 5.5c download for Windows matches the SHA1 I get in cmd of the .exe file.
C:\Users\Renkyz>CertUtil -hashfile C:\Users\Renkyz\Desktop\PhoenixMiner_5.5c\PhoenixMiner.exe
SHA1 hash of C:\Users\Renkyz\Desktop\PhoenixMiner_5.5c\PhoenixMiner.exe:
11428c3bdf728860fd057c411a95b14e13f05dbc
CertUtil: -hashfile command completed successfully.
What did you compare? Phoenix from nicehash and phoenix from "his" website?
Phoenix doesn't have a website.
https://bitcointalk.org/index.php?topic=2647654.msg55731982#msg55731982