As long as simply click the following internet page first transaction spending from any Bitcoin address empties out all of the funds stored in that address to new addresses as change, the theory goes, Bitcoin should remain just as secure as before. The claim is that used Bitcoin addresses - that is, addresses which have both received and sent bitcoins, have their corresponding public key exposed on the blockchain, allowing quantum-enabled adversaries to break Bitcoin's elliptic curve cryptography, whereas unused Bitcoin addresses, which may have received bitcoins but have never been spent from, do not have their public keys exposed, allowing them to benefit from the much stronger cryptographic guarantees of SHA256 and RIPEMD-160.