Bitcoin addresses are essentially 160-bit hashes of a 256-bit public key. Huh? How can all possible numbers in 256-bit space be squeezed into 160-bit space? Does that mean any given bitcoin address could be derived from more than just one public key?
It's really 160 bit hash (
RIPEMD160) of an already hashed (
SHA256) public secp256k1 elliptic curve key. And yes, on the average, every address has about 2256-160=296 pairs of private/public keys.