If you're reading this, you may be concerned or interested or exasperated over rumors of SHA256 weakness and in turn the implications for Bitcoin.
Stop reading now and rest assured in the knowledge that Bitcoin is safe for the rest of this decade if not century with regards to SHA256.In fact, Bitcoin is probably safe beyond this century for reasons I will explain in more detail. First, let us discuss potential attacks against cryptographic digests (hash functions) in order of difficulty:
1. Collisions with less effort than expected on reduced round variants of a digest.
2. Collisions with less effort than expected on the full digest.
3. First-order preimage attacks against reduced round variants of a digest.
4. First-order preimage attacks against full digest.
5. Second-order preimage attacks against reduced round variants of a digest.
6. Second-order preimage attacks against full digest.
7. Practical attacks applied to full digest in the wild.
Yes, that's right. Bitcoin is safe until all of pins 1-6 have been tackled, and even then the costs are likely to make such efforts against Bitcoin impractical.
Even MD5 and SHA-1 are only vulnerable to #'s 1 and 2.
Find this subject interesting? You might like "The code monkey's guide to cryptographic hashes for content-based addressing" which is relevant to Bitcoin:
http://valerieaurora.org/monkey.htmlNow we can all go back to the illuminati and hacker threads. Thanks!
