Sofia
type: MusicGroup
description: Sofia is the capital and largest city of Bulgaria. It is situated in the Sofia Valley at the foot of the Vitosha mountain, in the western part of the country. The city is built west of the Iskar river
popularity: 14
additional property: CopyrightID
additional property: CopyrightChainExplorerURL
  type: PropertyValue
  value: https://explorer.copyrightchains.com/tx/0x5a842b24fa7b4d872ba7201b0d54b7a97ac696cf9c7c0fb7142d83273682c949
additional property: OTSHash
additional property: OTSBitcoinBlock
  type: PropertyValue
  value: 953777
additional property: OTSBitcoinBlockVerifyURL
  type: PropertyValue
  value: https://blockstream.info/api/block-height/953777
additional property: OTSProofURL
  type: PropertyValue
  value: https://artists.proofprofile.net/proofs/artist/cb98a9de-bcc5-4e01-b6f3-28c409a13b87.ots
additional property: OTSRecordURL
  type: PropertyValue
  value: https://artists.proofprofile.net/proofs/artist/cb98a9de-bcc5-4e01-b6f3-28c409a13b87.json
additional property: OTSVerificationAPI
  type: PropertyValue
  value: https://artists.proofprofile.net/api/v1/bot/ots/verify/artist/cb98a9de-bcc5-4e01-b6f3-28c409a13b87
additional property: OTSTimestamp
  type: PropertyValue
  value: 2026-06-15T11:52:51Z
additional property: OTSCanonicalRecord
additional property: OTSVerifyInstructions
  type: PropertyValue
  value: 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
subject of: OpenTimestamps Proof of Existence
  type: DigitalDocument
  encoding format: application/vnd.opentimestamps.ots
  description: Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x5a842b24fa7b4d872ba7201b0d54b7a97ac696cf9c7c0fb7142d83273682c949. Chain 2 (Bitcoin): anchored in block 953777 (2026-06-15T11:52:51Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/cb98a9de-bcc5-4e01-b6f3-28c409a13b87.json and https://artists.proofprofile.net/proofs/artist/cb98a9de-bcc5-4e01-b6f3-28c409a13b87.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).
  date published: 2026-06-15T11:52:51Z