Rarely, a legitimate multi-part archive ( .part1.rar , .part2.rar , etc.) might show a password error if the header is corrupted. But true corruption usually produces a checksum error, not a password prompt.
Enthusiasts who create massive vehicle mods, texture packs, or map modifications sometimes zip their work with a password. They do this to credit the original authors or restrict extraction to members of their community. gta san andreas extract file password