SFera is a science fiction society from Zagreb, Croatia. It was founded in 1976, thus marking the beginnings of organized science fiction fandom in the region. SFera is the official organizer of SFe
1. Compute SHA-256 of OTSCanonicalRecord value → must equal OTSHash 2. Open OTSProofURL → extract Bitcoin block number → must equal OTSBitcoinBlock 3. GET OTSBitcoinBlockVerifyURL → returns the Bitcoin block hash at height OTSBitcoinBlock; GET https://blockstream.info/api/block/{that hash} → its timestamp must match OTSTimestamp 4. Read CopyrightID inside OTSCanonicalRecord → must equal the CopyrightID above 5. GET OTSVerificationAPI → pre-computed 6-check result from server 6. If all match: this entity was registered on CopyrightChains at OTSTimestamp, independently verifiable on Bitcoin
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x6ace4abaab3dd64be485f2772c8bf9e07c2d4f3afbbc29bb87ef699c1e939a86. Chain 2 (Bitcoin): anchored in block 953648 (2026-06-14T15:20:52Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/43ffa22c-9ad5-4c9b-840b-530c6e7ab704.json and https://artists.proofprofile.net/proofs/artist/43ffa22c-9ad5-4c9b-840b-530c6e7ab704.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).
1. Confirm isrcCode identifies the recording in the pre-2022 source corpus and cc-db-prod record 2. GET OTSVerificationAPI → server-side canonical-record, hash, and attestation checks must pass 3. GET OTSBitcoinBlockVerifyURL → returns the Bitcoin block hash at height OTSBitcoinBlock; GET https://blockstream.info/api/block/{that hash} → its timestamp must match OTSTimestamp 4. Confirm CopyrightID is the CopyrightChains transaction hash 5. If all match: the cc-db-prod record is independently anchored on Bitcoin at OTSTimestamp
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x0c6453703894cc62323c0b537f3680a424e01754fad0aebcc7ebb4928cca16dd. Chain 2 (Bitcoin): anchored in block 953528 (2026-06-13T15:41:10Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/PL90S2500037.