user60249: 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?

user10411: 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.

60249: <p>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?</p>
 10411: <p>It's really 160 bit hash (<code>RIPEMD160</code>) of an already hashed (<code>SHA256</code>) public secp256k1 elliptic curve key. And yes, on the average, every address has about 2<sup>256-160</sup>=2<sup>96</sup> pairs of private/public keys.</p>
