A Claim is a JSON used to describe the subject's properties. It can be perceived as a VC that hasn't been signed by the attester yet, and thus it is also named RawCredential

Basic Construction

Claimcontains the following 6 fields：

• CType: The unique identifier of the Credential Type, which is a hexadecimal string starting with '0x';
• credentialSubject: The main part of the RawCredential, which is the core and most private content of a Credential, containing the user's private data, in the format of Record<string, NativeType>, e.g., {"Name": "Alice", "Age": 20};
• credentialSubjectNonceMap: nonceMap contains the UUID which is used to do hashing-with-salt operation, ensuring the uniqueness and robustness of Credential and ensuring that Credential can not be attacked by Brute-force attack;
• credentialSubjectHashes: the hexadecimal hashing result after adding salt to the user data, each user data will correspond to a hashing result;
  • e.g., "Name": "Alice" hashing result after adding salt is '0xabcd', "Age": 20 hashing result after adding salt is '0xefgh'. So, when building the Merkle Tree, there will be 2 leaves with the values '0xabcd' and '0xefgh'.
• holder: The DID URL of Holder(Claimer), prefixed with did:zk:;
• hasher: Array of HashType, used to mark the hash method used in the process of generating VC:
  • the first element of the array represents the hash method used to construct the MerkleTree;
  • the second element of the array represents the hash method used to calculate Digest;

Here's the Claim structure:

export interface RawCredential {
  CType: HexString;
  credentialSubject: CredentialSubject;
  credentialSubjectNonceMap: Record<HexString, HexString>;
  credentialSubjectHashes: HexString[];
  holder: DidUrl;
  hasher: [HashType, HashType];
}

Key Methods

A Claim (RawCredential) features the following methods for efficient Claim management:

For a detailed explanation, please refer to our SDK Guideline

• setContext
• setOwner
• setCType
• setHashType
• calcRootHash
• checkSubject