Sikdar, Sikder or Shikdar is a Bengali surname, common in Bangladesh, West Bengal and Assam. Sikdar means owner of one siki (one hundred quarter) of land. Notable people with surname Sikdar Abbas
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 Note: an OTS proof may carry multiple Bitcoin attestations; OTSBitcoinBlock is the earliest confirmed one — a later attestation inside the proof corroborates it and is not a mismatch
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x421c9ae55e8f9b79d65edc04c7c575ef3b6f097112d64dec8e426a785157e10f. Chain 2 (Bitcoin): anchored in block 953654 (2026-06-14T16:26:51Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/48e4679e-e93d-4972-bd0b-acc1b2904389.json and https://artists.proofprofile.net/proofs/artist/48e4679e-e93d-4972-bd0b-acc1b2904389.ots, the client at https://opentimestamps.org runs `ots verify -f record.json proof.ots`.