Debian relies on external entities for these things:
SSL CA auditing (Mozilla)
SSL certificate signing (Gandi)
Tor network for hidden/onion services
- Free Software community for new contributors and upstream development
Copyright aggregation, license enforcement (Software Freedom Conservancy)
- Various services to block email/wiki/etc spam
IRC network (OFTC)
HTTP CDNs (MaxCDN, Fastly, LeaseWeb, CD/archive/video mirrors)
BitTorrent tracker and CD/DVD/BD image storage (ACC, UmeƄ University)
Debian machine hosting and donations, DebConf infrastructure sponsors
Funding (donors, financial partners, annual DebConf sponsors)