Cryptographic Hash Functions And Security
Cryptographic hash functions play a vital role in securing cryptocurrencies. The better a cryptographic hash function, the lesser the chance that a cryptoanalytic breakthrough can damage a cryptocurrency that makes use of the relevant cryptographic hash function.
Now it is widely acknowledged that the collision resistance of cryptographic hash functions changes over time as cryptanalysis improves. This is called the lifetimes of cryptographic hash functions. There is a prophetic post by Satoshi on this topic, where he speaks about what could be done to save Bitcoin if a “hash breakdown came gradually”. This is why it is important that multiple instead of single cryptographic hash functions are used to protect a cryptocurrency. E.g. a significant breakdown due to advances in cryptanalysis could affect the entire 256-bit hash, the cryptographic hash function used to secure Bitcoin. While on the other hand, a cryptocurrency such as Heavycoin (HVC), makes use of no less than four independent cryptographic hash functions (SHA-256, Keccak-512, Grøestl-512 and BLAKE-512). This mitigates risks associated with the use of a single cryptographic hash function, because a cryptoanalytic breakthrough is more likely for a single cryptographic hash function (eg. SHA-256), than for all four hash functions (SHA-256, Keccak-512, Grøestl-512 and BLAKE-512). “These cryptographic hash functions were selected because they are thought to have little in common and thus a common weakness is thought to be extremely unlikely” (Heavycoin website).
Thus, multiple cryptographic hash functions can be used in combination to limit the impact of a cryptoanalytic breakthrough. This can help to make a cryptocurrency more secure.