Trustee

Get latest data requests

GET /data-requests

Description

Retrieve the latest block headers. If at least one data request is present in a block, the block data is also returned. The notion of "latest" is determined by the query parameter oldBlockHeight and the ledger's current height. Trustees use this endpoint to get the latest relevant blocks, extract the data requests in them, and respond to the data requests accordingly.
Using the block data, one can compute the data hash and verify consistency of the block header. In addition, using the block headers, one can verify the blocks are chained.

Parameters

Name
In
Type
Required
Description
oldBlockHeight
query
integer
true
Number of blocks the trustee has already processed
Example
GET /data-requests?oldBlockHeight=1

Responses

Status
Meaning
Description
Schema
200
OK
Succeeded
Inline
400
Bad Request
Request is invalid
401
API key is missing or invalid

200 OK

Successfully retrieved the blocks and block data which contain data requests.
Schema
Name
Type
Required
Restrictions
Description
ok
boolean
true
none
none
blocks
true
none
none
Example
{
"ok": true,
"blocks": {
"1": {
"header": {
"number": "1",
"previousHash": "0ede53fd38d632f3a7d849f8ba8f70c851d772b53cecbc9d858fe7c8af03a858",
"dataHash": "ee967360a911deb8f6bd77cbb49b334e1837c006c9b6cb2d59d8acd41964a6ac",
},
},
"2": {
"header": {
"number": "2",
"previousHash": "78aecc3976f7b2151ce0574278f816b8e5983e18229fde7b6e7c3ebdf5147baf",
"dataHash": "3ec339eae416289f4ddd7dc2b69e8edf12ac013089207732ad6156e02dc21fb5",
},
"data": {
"data": ["datum1==", "datum2=="],
},
},
},
}

400 Bad Request

Request is malformed. Make sure:
  • oldBlockHeight is present in query parameter
  • oldBlockHeight is a non-negative number
  • oldBlockHeight is an integer
  • oldBlockHeight is valid - no larger than the current block height of the ledger
Example 1
{
"ok": false,
"message": "query.oldBlockHeight must be a non-negative integer",
}
Example 2
{
"ok": false,
"message": "Invalid valid at query.oldBlockHeight. Expected: <=5; given: 10",
}

401 Unauthorized

API key is missing or incorrect.
Example
{
"ok": false,
"message": "Unauthorized",
}

Get encrypted trustee share in an Encryption

GET /encryptions/{token-hash}/encrypted-trustee-shares/{trustee-id}

Description

Retrieves a encrypted trustee share from an Encryption. After detecting a new data request, a trustee should use this endpoint to get its encrypted share from the corresponding Encryption, decrypt it with its decryption key, then post the result with postTrusteeResponse.

Parameters

Name
In
Type
Required
Description
token-hash
path
Sha256
true
Hash value of the token
trustee-id
path
TrusteeId
true
Trustee's ID
Example
GET /encryptions/d033713dd14552c060c55746afdb989cfee8e624ae94a932d79fd25630f728a4/encrypted-trustee-shares/trustee1

Responses

Status
Meaning
Description
Schema
200
OK
Succeeded
Inline
400
Bad Request
Request is invalid
401
API key is missing or invalid
404
Not Found
Encryption not found

200 OK

Successfully retrieved the encrypted trustee share.
Schema
Name
Type
Required
Description
ok
boolean
true
none
encryptedTrusteeShare
Base64
true
The encrypted trustee share
Example
{
"ok": true,
"encryptedTrusteeShare": "base64_encoded_data"
}

400 Bad Request

Trustee does not exist or does not reference this PAD instance.
Example
{
"ok": false,
"message": "Trustee with ID trustee1 does not exist in the PAD instance",
}

401 Unauthorized

API key is missing or incorrect.
Example
{
"ok": false,
"message": "Unauthorized",
}

404 Not Found

The encryption does not exist.
Example
{
"ok": false,
"message": "Encryption with token hash d033713dd14552c060c55746afdb989cfee8e624ae94a932d79fd25630f728a4 not found",
}

Post trustee response

POST /data-requests/{token}/trustee-responses

Description

Posts a trustee response to the ledger.
After retrieving and finish decrypting its share, the trustee needs to post the result back to the ledger so that eventually, the decryptor can decrypt a secret.

Parameters

Name
In
Type
Required
Description
token
path
Token
true
ID of the data request
-
body
true
The decrypted share, along with a digital signature of the trustee and some metadata
Example
POST /data-requests/e3b0c44298fc1c149afbf4c8996fb924/trustee-responses
{
"trusteeResponse": "{\"padName\":\"my-pad-1.0\",\"token\":\"e3b0c44298fc1c149afbf4c8996fb924\",\"trusteeShare\":\"0110\",\"type\":\"trustee_response\",\"trusteeId\":\"trustee1\"}",
"signature": {
"signerMetadata": {
"id": "trustee1",
"fullName": "Trustee-1",
"role": "Trustee"
},
"payload": "MEQCIDbFV8FH8ZTbM0wrKPHSk0lrkiIFsP3/GcU4htiGc6XOAiBOqJZgbeUKxPXgIOZGek6ryoJ+jhmwbcJh0+mSHsSiTQ=="
}
}

Responses

Status
Meaning
Description
Schema
200
OK
Succeeded
400
Bad Request
Data request and trustee response are inconsistent
401
API key is missing or invalid
403
Forbidden
Trustee is not in the instance
404
Not found
Data request not found
409
Conflict
Response has been made before

200 OK

The trustee response is successfully posted.
Example
{
"ok": true,
"message": "Successfully posted trustee response",
}

400 Bad request

Request is invalid. Make sure that :
  • padName in TrusteeResponse is consistent with the PAD instance to which the API key is pointing
  • token in path and TrusteeResponse are consistent
  • trusteeId in TrusteeResponse and signature are consistent
  • role is Trustee in signature
  • signature in signature is consistent with the payload TrusteeResponse
Example 1
{
"ok": false,
"message": "Inconsistent trustee ID",
}
example 2
{
"ok": false,
"message": "Inconsistent PAD instance name",
}
example 3
{
"ok": false,
"message": "Invalid signature",
}

401 Unauthorized

Api key is missing or invalid.
Example
{
"ok": false,
"message": "Unauthorized",
}

403 Forbidden

The trustee is not part of the instance. Recall that the list of trustees is determined by the Operator at instance creation time.
Example
{
"ok": false,
"message": "Not a trustee of the instance",
}

404 Not Found

The server cannot find a data request pointed by the token in the path parameter.
Example
{
"ok": false,
"message": "Data request not found",
}

409 Conflict

A response from the same trustee has been made for the same data request before.
Example
{
"ok": false,
"message": "Trustee response has been made for this request",
}

Post trustee attestation

PUT /trustee-attestations/{trustee-id}

Description

Trustee posts its view of the ledger* with a digital signature. This allows other users to convince themselves that they are seeing the same ledger as trustees, who are the ones handling the data requests. Trustees should attest to the ledger regularly even there is no update on the ledger.
*The ledger view of the trustee includes the ID/name of the PAD instance, the height of the ledger, the current block hash of the ledger and a timestamp when the trustee construct the attestation.

Parameters

Name
In
Type
Required
Description
trustee-id
path
TrusteeId
true
ID of the trustee
-
body
true
The decrypted share, along with a digital signature of the trustee and some metadata
Example
PUT /trustee-attestations/trustee1
{
"ledgerDigest": "{\"ledgerId\":\"my-pad-1.0\",\"height\":10,\"currentHash\":\"54c0639eb43fcc52cfc4d05546ee35984210a2d3d977e83600288aa\",\"timestamp\":\"2021-09-19T12:41:17.368Z\"}",
"signature": {
"signerMetadata": {
"id": "trustee1",
"fullName": "Trustee-1",
"role": "Trustee"
},
"payload": "MEQCIDbFV8FH8ZTbM0wrKPHSk0lrkiIFsP3/GcU4htiGc6XOAiBOqJZgbeUKxPXgIOZGek6ryoJ+jhmwbcJh0+mSHsSiTQ=="
}
}

Responses

Status
Meaning
Description
Schema
200
OK
Succeeded
400
Bad Request
Data request and trustee response are inconsistent
401
API key is missing or invalid
403
Forbidden
Trustee is not in the instance

200 OK

Successfully posted trustee attestation.
Example
{
"ok": true,
"message": "Successfully posted trustee attestation",
}

400 Bad request

Request is malformed. Check that:
  • Trustee IDs in attestation and path parameter are consistent.
  • padName in attestation is consistent with the PAD instance to which the API key is pointing
  • The signature is correct
  • The attestation is correct, in the sense that:
    • The block height is non-negative and at most even with the ledger
    • currentHash is the block hash at height
Example 1
{
"ok": false,
"message": "Inconsistent trustee ID"
}
Example 2
{
"ok": false,
"message": "height (10) in attestation is too large; Expected <= 5"
}
Example 3
{
"ok": false,
"message": "currentHash in attestation is <some_hash>; Expected <some_other_hash>"
}

401 Unauthorized

Api key is missing or invalid.
Example
{
"ok": false,
"message": "Unauthorized",
}

403 Forbidden

The trustee is not part of the instance. Recall that the list of trustees is determined by the Operator at instance creation time.
Example
{
"ok": false,
"message": "Not a trustee of the instance",
}

Schemas

ApiResponse

Example
{
"ok": true,
"message": "string"
}

Schema

Name
Type
Required
Description
ok
boolean
true
The request is successful or not
message
string
true
none

BlockNumber

ID of a block. It is an incremental index starting from 0. For example, if a ledger has height 10, then it has blocks 0, 1, ..., 9. The next block has block number 10.

Schema

Type
Restrictions
integer
Non-negative

Block

Blocks are put sequentially as a blockchain to form a ledger. It consists of the header (which contains the chaining information) and optionally the data (from which data requests and trustee and validator responses can be extracted).
Example 1
{
"header": {
"number": "1",
"previousHash": "0ede53fd38d632f3a7d849f8ba8f70c851d772b53cecbc9d858fe7c8af03a858",
"dataHash": "ee967360a911deb8f6bd77cbb49b334e1837c006c9b6cb2d59d8acd41964a6ac",
},
}
Example 2
{
"header": {
"number": "2",
"previousHash": "78aecc3976f7b2151ce0574278f816b8e5983e18229fde7b6e7c3ebdf5147baf",
"dataHash": "3ec339eae416289f4ddd7dc2b69e8edf12ac013089207732ad6156e02dc21fb5",
},
"data": {
"data": ["datum1==", "datum2=="],
},
}

Schema

Name
Type
Required
Description
header
true
none
data
BlockData
false
none

BlockHeader

Block header contains metadata of a block. They are sufficient to prove the blocks form a chain without the need of block data, because the previousHash field in the schema refers to the hash of the previous block header, instead of the entire previous block. Thus, if the block data is irrelevant (for example not containing any data request when one is asking for them), it can be skipped.
If the block number is 0, the number and previousHash fields are empty. dataHash is computed with the same block's data. Refer to code samples on how to compute hash of a block header.
Example 1
{
"dataHash": "b24fd1a8c0c37f388f67ce6583710e3b1e5cfa79e652f764e92ee412299ac6c5",
}
Example 2
{
"number": "1",
"previousHash": "0ede53fd38d632f3a7d849f8ba8f70c851d772b53cecbc9d858fe7c8af03a858",
"dataHash": "ee967360a911deb8f6bd77cbb49b334e1837c006c9b6cb2d59d8acd41964a6ac",
}

Schema

Name
Type
Required
Description
number
false
Block number of the current block
previousHash
Sha256
false
Hash of the previous block's header
dataHash
Sha256
true
Hash of this block's data

BlockData

Block data contains "transactions". In PAD, these are the data requests and trustee and validator responses. See code samples to see how block data are decoded.
Example
{
"data": ["datum1==", "datum2=="],
}

Schema

Name
Type
Required
Description
data
array<Base64>
true
none

Base64

A base64-encoded binary data.
Example
"aGVsbG8gd29ybGQ="

Schema

Type
Restrictions
string
none

Sha256

A Sha256 hash value as a hexidecimal string.
Example
"d033713dd14552c060c55746afdb989cfee8e624ae94a932d79fd25630f728a4"

Schema

Type
Restrictions
string
/[0-9a-fA-F]{64}/

TrusteeId

ID of a trustee. It contains only alphanumerical characters, underscores (_) and dashes (-). It has length inclusively between 3 and 30.
Example
trustee1

Schema

Type
Restrictions
string
[a-zA-Z0-9-_]{3,30}

Token

A 128-bit random string kept secret between the encryptor and decryptor after encryption stage and before data request stage. It identifies a data request. Its hash value identifies an encryption. The decryptor posts it on the ledger at data request stage.
Example
"0fe5ff17c6ee6efa8ca385587b1e1ac2"

Schema

Type
Restrictions
string
/[0-9a-fA-Z]{32}/

PadName

ID of a PAD instance. Its length must be inclusively between 4 and 30. It should contains only lowercase letters, digits, periods (.) or dashes (-). It must start with a lowercase letter.
It is seldom used as a request parameter because the API key in the request already identifies a PAD instance.
Example
"my-pad-1.0"

Schema

Type
Restrictions
string
/[a-z][a-z0-9.-]{3,29}/

TrusteeResponse

A trustee response to a data request. It contains the decrypted trustee share for the decryptor to perform a full decryption on a secret. It also consists of metadata for identifying the corresponding data request.
Example
{
"padName": "my-pad-1.0",
"token": "e3b0c44298fc1c149afbf4c8996fb924",
"trusteeShare": "0110",
"type": "trustee_response",
"trusteeId": "trustee1",
}

Schema

Name
Type
Required
Restrictions
Description
padName
PadName
true
none
The instance where the data request is posted
token
Token
true
none
The ID of the data request
trusteeShare
Base64
true
none
The decrypted trustee share
type
enum
true
none
Type of response
trusteeId
TrusteeId
true
none
ID of the responding trustee

Enumerated Values

Property
Value
type
"trustee_response"

SignedTrusteeResponse

A trustee response attached with a digital signature for everyone to validate the response's integrity.
Note that the trustee response is represented as a string (instead of an object). This ensures that there is a unified way to verify the signature.
Example
{
"trusteeResponse": "{\"padName\":\"my-pad-1.0\",\"token\":\"e3b0c44298fc1c149afbf4c8996fb924\",\"trusteeShare\":\"0110\",\"type\":\"trustee_response\",\"trusteeId\":\"trustee1\"}",
"signature": {
"signerMetadata": {
"id": "string",
"fullName": "string",
"role": "Trustee"
},
"payload": "MEQCIDbFV8FH8ZTbM0wrKPHSk0lrkiIFsP3/GcU4htiGc6XOAiBOqJZgbeUKxPXgIOZGek6ryoJ+jhmwbcJh0+mSHsSiTQ=="
}
}

Schema

Name
Type
Required
Description
trusteeResponse
true
none
signature
Signature
true
none

Participant

Metadata of a participant in PAD. It can currently be used to describe a trustee or a validator.
Example
{
"id": "trustee1",
"fullName": "Trustee-1",
"role": "Trustee"
}

Schema

Name
Type
Required
Description
id
true
/[0-9a-zA-Z-_]{3,30}/
fullName
string
true
/Trustee-[0-9a-zA-Z_]+/ or /Validator-[0-9a-zA-Z_]+/
role
enum
true
none

Enumerated Values

Property
Value
role
Trustee
role
Validator
role
Server

Signature

A digital signature. It consists of the metadata of the signer, including its ID, and the signature payload encoded in base64.
Schema
{
"signerMetadata": {
"id": "string",
"fullName": "string",
"role": "Trustee",
},
"payload": "MEQCIDbFV8FH8ZTbM0wrKPHSk0lrkiIFsP3/GcU4htiGc6XOAiBOqJZgbeUKxPXgIOZGek6ryoJ+jhmwbcJh0+mSHsSiTQ==",
}

Schema

Name
Type
Required
Description
signerMetadata
false
none
payload
Base64
false
none

DateTime

A timestamp in ISO 8601 format.
Example
"2021-05-05T13:53:19.275Z"

Schema

Type
Restrictions
string
-

LedgerDigest

A succinct representation of the ledger, which consists of the PAD instance name, the height and the then block hash of its ledger, and the timestamp when this digest is generated.
Example
{
"ledgerId": "my-pad-1.0",
"height": 10,
"currentHash": "54c0639eb43fcc52cfc4d05546ee35984210a2d3d977e83600288aa",
"timestamp":"2021-09-19T12:41:17.368Z",
}

Schema

Name
Type
Required
Restrictions
Description
ledgerId
PadName
true
none
The PAD instance's name
height
true
none
Block height of the ledger
currentHash
Sha256
true
none
Hash of the block at height on the ledger
timestamp
DateTime
true
none
Time at which this digest is generated

TrusteeAttestation

A trustee's succinct view of the ledger, along with a digital signature of it. The succinct view consists of the PAD instance ID, height and latest block hash of its ledger, and the latest timestamp when the attestation is created.
A collection of trustee attestations proves to a user that she and the trustees are seeing the same ledger.
Note that the ledger digest is represented as a string (instead of an object). This ensures that there is a unified way to verify the signature.
Example
{
"ledgerDigest": "{\"ledgerId\":\"my-pad-1.0\",\"height\":10,\"currentHash\":\"54c0639eb43fcc52cfc4d05546ee35984210a2d3d977e83600288aa\",\"timestamp\":\"2021-09-19T12:41:17.368Z\"}",
"signature": {
"signerMetadata": {
"id": "trustee1",
"fullName": "Trustee-1",
"role": "Trustee"
},
"payload": "MEQCIDbFV8FH8ZTbM0wrKPHSk0lrkiIFsP3/GcU4htiGc6XOAiBOqJZgbeUKxPXgIOZGek6ryoJ+jhmwbcJh0+mSHsSiTQ=="
}
}

Schema

Name
Type
Required
Restrictions
Description
ledgerDigest
string<LedgerDigest>
true
none
A succinct representation of the ledger
signature
Signature
true
none
A digital signature against ledgerDigest
Last modified 8mo ago