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Claim Data Structure

graph TD
     Hi-->i0
     Hi-->i1
     Hi-->i2
     Hi-->i3

     Hv-->v0
     Hv-->v1
     Hv-->v2
     Hv-->v3

     Ht-->Hi
     Ht-->Hv

Common Structure

A claim always contains a subject, that can be:

  • Self: The claim says something about itself. The subject is implicit, and it's the identity that makes claim.
  • OtherIden: The claim says something about some other identity (identified by other's ID).
  • Object: The claim says something about an object (identified by the object's ID).

If the subject is Self - identity, sections i_1, v_1 can be empty.

if the subject is NOT Self, the id(OtherIden) of the Identity/Object can be in the Index(i_1) or the Value(v_1) part of the claim. This is encoded in a header bit.

Other flags contained inside i_0 indicate:

  • Whether the claim is expirable. In that case an expiration date must be added inside v_0
  • Whether the claim is updatable.
  • Whether the claim is merklized and where the root of the tree is located. It can be either inside i_2 or v_2
h_i = H(i_0, i_1, i_2, i_3)
h_v = H(v_0, v_1, v_2, v_3)
h_t = H(h_i, h_v)

Index:
 i_0: [ 128  bits ] claim schema
      [ 32 bits ] option flags
          [3] Subject:
            000: A.1 Self
            001: invalid
            010: A.2.i OtherIden Index
            011: A.2.v OtherIden Value
            100: B.i Object Index
            101: B.v Object Value
          [1] Expiration: bool
          [1] Updatable: bool
          [3] Merklized: data is merklized root is stored in the:
            000: none
            001: C.i Root Index (root located in i_2)
            010: C.v Root Value (root located in v_2)
          [24] 0
      [ 32 bits ] version (optional?)
      [ 61 bits ] 0 - reserved for future use
 i_1: [ 248 bits] identity (case b) (optional)
      [  5 bits ] 0
 i_2: [ 253 bits] 0
 i_3: [ 253 bits] 0
Value:
 v_0: [ 64 bits ]  revocation nonce
      [ 64 bits ]  expiration date (optional)
      [ 125 bits] 0 - reserved
 v_1: [ 248 bits] identity (case c) (optional)
      [  5 bits ] 0
 v_2: [ 253 bits] 0
 v_3: [ 253 bits] 0

Claim Schema

Schemas define the type of data inside a claim link.

Index slots i_2, i_3 and value slots v_2, v_3 are the data slots for user data.

Index vs Value

When to Use Index Slots and Value Slots?

Claims are stored in the Merkle tree and the hash of the index slots ( hash(i_0, i_1, i_2, i_3) ) is unique for the whole tree. It means that you cannot have two claims with the same index inside the tree.

As opposite to the index, the values slots could be the same for different claims if their indexes are different.