1. The string '68a53d39ef016f3f7635e6aa86d03f89657bd470488b91589a4f051634f76044' appears to be a SHA-256 hash. The challenge is to find the original input (also called the preimage) that was used to generate this hash.

2. "Nostr DM blockstream the preimage" - This means you should send a direct message (DM) on the Nostr network to the user 'blockstream' with the discovered preimage.