A stranger has bled inside my home leaving blood on both the inside and outside of my main entrance door knob. i had been touching the dried up blood and just so happened to pick my nose with the same hand i touched it with. can i catch hiv? hep c?

HIV can be transmitted through blood-to-blood contact, sharing needles, or unprotected sexual intercourse with an infected person. Hepatitis C can also be transmitted through blood-to-blood contact, sharing needles, or from mother to child during childbirth. HIV is not easily transmitted through dried blood, as the virus becomes inactive once it is outside of the body. Be careful get checked.

There has never been a known case of either HIV or viral hepatitis from contact with blood in the environment, and dried blood in particular is no risk. Don't worry about it. Clean the place up, but nothing more need be done.