Identity#

Identity Overview#

Identities are a low-level construct that provide the foundation for user-facing functionality on the platform. An identity is a public key (or set of public keys) recorded on the platform chain that can be used to prove ownership of data. Please see the Identity DIP for additional information.

Identities consist of multiple objects that are described in the following sections and listed in this summary table:

Field	Type	Description
id	array of bytes	The identity id (32 bytes)
publicKeys	array of keys	Public key(s) associated with the identity
balance	unsigned integer (64-bit)	Credit balance associated with the identity
revision	integer	Identity update revision

See the identity implementation in rs-dpp for more details.

Example Identity

{
  "id":"6YfP6tT9AK8HPVXMK7CQrhpc8VMg7frjEnXinSPvUmZC",
  "publicKeys":[
    {
      "id":0,
      "type":0,
      "purpose":0,
      "securityLevel":0,
      "data":"AkWRfl3DJiyyy6YPUDQnNx5KERRnR8CoTiFUvfdaYSDS",
      "readOnly":false
    }
  ],
  "balance":0,
  "revision":0
}

Identity id#

The identity id is a unique identifier created from the double sha256 hash of the outpoint funding the identity creation. Typically it is displayed using Base58 encoding.

id = base58(sha256(sha256(<identity create funding outpoint>)))

Note

The identity id uses the Dash Platform specific application/x.dash.dpp.identifier content media type. For additional information, please refer to the js-dpp PR 252 that introduced it and identifier.rs.

See rs-dpp for examples of using InstantSend or ChainLocks to create the identity id.

Identity publicKeys#

The identity publicKeys array stores information regarding each public key associated with the identity. Multiple identities may use the same public key.

Note

Each identity must have exactly one master key (security level 0) used for updating the identity. Having an additional key (security level 1 or 2) for signing state transitions is strongly recommended but not enforced by the protocol. The maximum number of keys is 15000 as defined by rs-dpp.

Each item in the publicKeys array consists of an object containing:

Field	Type	Description
id	integer	The key id (all public keys must be unique)
purpose	integer	Public key purpose (`0` - Authentication, `1` - Encryption, `2` - Decryption, `3` - Transfer)
securityLevel	integer	Public key security level (`0` - Master, `1` - Critical, `2` - High, `3` - Medium)
contractBounds	object (optional)	Restricts this key to a single data contract (`$type`: `singleContract`), a document type of a data contract (`documentType`), or, added in 5.0.0, the members of a contract group (`contractGroup`). From protocol version 14, a contract-bound authentication key can sign only batch transitions (rs-drive-abci), a batch member outside the key’s bounds is rejected, and binding a key to a contract group that does not exist is rejected. See the contract bounds implementation in rs-dpp.
type	integer	Type of key (default: `0` - ECDSA)
readOnly	boolean	Identity public key can’t be modified with `readOnly` set to `true`. This can’t be changed after adding a key.
data	array of bytes	Public key (`0` - ECDSA: 33 bytes, `1` - BLS: 48 bytes, `2` - ECDSA Hash160: 20 bytes, `3` - BIP13 Hash160: 20 bytes, `4` - EDDSA_25519_HASH160: 20 bytes)
disabledAt	integer	Timestamp indicating that the key was disabled at a specified time
totalBudget	unsigned integer (64 bits)	(Optional) Added in 5.0.0. Total credits that state transitions signed with this key may take from the identity
expiresAt	unsigned integer (64 bits)	(Optional) Added in 5.0.0. Block time (in milliseconds) from which the key can no longer sign
signature	array of bytes	Signature of the signable state transition adding the key (identity create, identity update, or identity create from addresses) by the private key for this public key. Must be empty for key types `2`, `3`, and `4`.

See the public key implementations in rs-dpp (v0, v1) for more details.

Public Key `id`#

Each public key in an identity’s publicKeys array must be assigned a unique index number (id).

Public Key `type`#

The type field indicates the algorithm used to derive the key. Available key types defined in rs-dpp include:

Type	Size (bytes)	Description
`0`	33	ECDSA Secp256k1 (default)
`1`	48	BLS 12-381
`2`	20	ECDSA Secp256k1 Hash160
`3`	20	BIP13 pay-to-script-hash public key
`4`	20	EDDSA 25519 Hash160

Public Key `data`#

The data field contains the compressed public key.

Public Key `purpose`#

The purpose field describes which operations are supported by the key. Please refer to DIP11 - Identities for additional information regarding this. Keys for some purposes must meet certain the security level criteria defined by rs-dpp as detailed below:

Type	Description	Allowed Security Level(s)
`0`	Authentication	Any security level
`1`	Encryption	Medium
`2`	Decryption	Medium
`3`	Transfer	Critical

The system automatically creates the following key types for masternodes and evonodes. They cannot be created or updated manually:

Type	Description	Allowed Security Level
`4`	System	Critical
`5`	Voting	High
`6`	Owner	Critical

Public Key `securityLevel`#

The securityLevel field indicates how securely the key should be stored by clients. Please refer to DIP11 - Identities for additional information regarding this.

Level	Description	Security Practice
0	Master	Should always require a user to authenticate when signing a transition. Can only be used to update an identity or, from protocol version 14, to sign an identity key limits update.
1	Critical	Should always require a user to authenticate when signing a transition
2	High	Should be available as long as the user has authenticated at least once during a session. Typically used to sign state transitions, but cannot be used for identity update transitions.
3	Medium	Should not require user authentication but must require access to the client device

Public Key `readOnly`#

The readOnly field indicates that the public key can’t be modified if it is set to true. The value of this field cannot be changed after adding the key.

Public Key `disabledAt`#

The disabledAt field indicates that the key has been disabled. Its value equals the timestamp when the key was disabled.

Public Key Limits#

Added in version 5.0.0.

A key can carry a credit budget (totalBudget), an expiry time (expiresAt), or both. A key with either limit is serialized as an IdentityPublicKeyV1 ($formatVersion 1). A key without limits is still serialized as IdentityPublicKeyV0.

Limits are allowed only on authentication keys (purpose 0) below the master security level. A limit on any other key is rejected, and so is a totalBudget of 0. See the key structure validation in rs-dpp.

A transition signed with a limited key is rejected once the block time reaches expiresAt, once the key’s budget is spent, or when its spend does not fit in the key’s remaining budget (metered processing fees may exceed it). Adding a key whose expiresAt the block time has already reached is rejected. Keys with limits, and keys bound to a contract group, are also rejected in identity create from shielded pool. A key’s limits can only be loosened, using the identity key limits update transition.

Identity balance#

Each identity has a balance of credits established by an asset lock transaction on the Core chain. This credit balance is used to pay the fees associated with state transitions.

Identity Constants and Limits#

The following constants and limits apply to identities:

Constant	Value	Description
`IDENTITY_MAX_KEYS`	15,000	Maximum number of public keys per identity
`MAX_CREDITS`	9,223,372,036,854,775,807	Maximum credit balance (i64::MAX)
`max_public_keys_in_creation`	6	Maximum keys when creating an identity
`min_identity_funding_amount`	200,000 credits	Minimum funding for address-based identity create and top-up transitions
`identity_create_base_cost`	2,000,000 credits	Base fee for identity creation
`identity_key_in_creation_cost`	6,500,000 credits	Fee per key during creation
`identity_topup_base_cost`	500,000 credits	Base fee for identity top-up. The minimum top-up fee is this plus the asset lock requirement (50,000,000 credits), so 50,500,000 credits.

Identity Creation Cost Calculation#

The total cost to create an identity is:

Total = identity_create_base_cost + asset_lock_base_cost + (number_of_keys × identity_key_in_creation_cost)

Examples:

1 key: 2,000,000 + 200,000,000 + 6,500,000 = 208,500,000 credits (0.002085 Dash)
2 keys: 2,000,000 + 200,000,000 + 13,000,000 = 215,000,000 credits (0.00215 Dash)
6 keys: 2,000,000 + 200,000,000 + 39,000,000 = 241,000,000 credits (0.00241 Dash)

Minimum Funding Requirements#

Operation	Required Balance (credits)	Required Balance (Dash)
Identity create (asset lock)	200,000,000	0.002
Identity top-up (asset lock)	50,000,000	0.0005
Address funding	50,000,000	0.0005

Identity State Transition Details#

The following state transitions create, fund, update, or transfer credits to or from identities. Some are documented on this page, along with the relevant asset-lock and signing mechanisms; the others are documented with the feature they belong to.

Type	Name	Supported protocol versions
2	Identity Create	≥ 1
3	Identity Top-Up	≥ 1
5	Identity Update	≥ 1
6	Identity Credit Withdrawal	≥ 1
7	Identity Credit Transfer	≥ 1
9	Identity Credit Transfer to Addresses	≥ 11
10	Identity Create from Addresses	≥ 11
11	Identity Top-Up from Addresses	≥ 11
20	Identity Create from Shielded Pool	≥ 12
21	Shield from Identity	≥ 14
22	Identity Top-Up from Shielded Pool	≥ 14
23	Identity Key Limits Update	≥ 14

Identity Create#

Identities are created on the platform by submitting the identity information in an identity create state transition.

Field	Type	Description
$formatVersion	integer	The state transition format version (currently `0`)
type	integer	State transition type (`2` for identity create)
publicKeys	array of keys	Public key(s) associated with the identity
assetLockProof	proof object	Asset lock proof object proving the asset lock transaction exists on the Core chain and is locked
userFeeIncrease	integer	Extra fee to prioritize processing if the mempool is full. Typically set to zero.
signature	array of bytes	Signature of state transition data by the single-use key from the asset lock (65 bytes)
identityId	array of bytes	An identity id for the identity being created (32 bytes). Computed from the asset lock proof outpoint and excluded from the serialized payload.

See the identity create implementation in rs-dpp for more details.

Identity TopUp#

Identity credit balances are increased by submitting the topup information in an identity topup state transition.

Field	Type	Description
$formatVersion	integer	The state transition format version (currently `0`)
type	integer	State transition type (`3` for identity topup)
assetLockProof	proof object	Asset lock proof object proving the layer 1 locking transaction exists and is locked
identityId	array of bytes	An identity id for the identity receiving the topup (can be any identity) (32 bytes)
userFeeIncrease	integer	Extra fee to prioritize processing if the mempool is full. Typically set to zero.
signature	array of bytes	Signature of state transition data by the single-use key from the asset lock (65 bytes)

See the identity topup implementation in rs-dpp for more details.

Identity Update#

Identities are updated on the platform by submitting the identity information in an identity update state transition. This state transition requires either a set of one or more new public keys to add to the identity or a list of existing keys to disable.

Field	Type	Description
$formatVersion	integer	The state transition format version (currently `0`)
type	integer	State transition type (`5` for identity update)
identityId	array of bytes	The identity id (32 bytes)
revision	integer	Identity update revision
nonce	unsigned integer (64 bits)	Identity nonce for this transition to prevent replay attacks
addPublicKeys	array of public keys	(Optional) Array of up to 6 new public keys to add to the identity. Required if adding keys.
disablePublicKeys	array of integers	(Optional) Array of up to 10 existing identity public key ID(s) to disable for the identity. Required if disabling keys.
userFeeIncrease	integer	Extra fee to prioritize processing if the mempool is full. Typically set to zero.
signaturePublicKeyId	integer	The ID of public key used to sign the state transition
signature	array of bytes	Signature of state transition data (65 bytes)

See the identity update implementation in rs-dpp for more details.

Identity Key Limits Update#

Added in version 5.0.0.

An identity raises the limits of one of its keys by submitting an identity key limits update state transition. Each limit field carries the new absolute value. The identity revision is not changed.

Field	Type	Description
$formatVersion	integer	The state transition format version (currently `0`)
type	integer	State transition type (`23` for identity key limits update)
identityId	array of bytes	The identity id (32 bytes)
nonce	unsigned integer (64 bits)	Identity nonce for this transition to prevent replay attacks
keyId	unsigned integer (32 bits)	The id of the key whose limits are raised
totalBudget	unsigned integer (64 bits)	(Optional) New total budget in credits. Must be greater than the key’s current budget. The remaining budget grows by the same amount. Omit to leave the budget unchanged.
expiresAt	unsigned integer (64 bits)	(Optional) New expiry in block time milliseconds. Must be later than the key’s current expiry. Omit to leave the expiry unchanged.
userFeeIncrease	integer	Extra fee to prioritize processing if the mempool is full. Typically set to zero.
signaturePublicKeyId	integer	The ID of public key used to sign the state transition
signature	array of bytes	Signature of state transition data (65 bytes)

The transition must be signed by a master key or by a critical key that carries no limits of its own. Signing with a limited key is rejected.

The transition is also rejected if:

keyId is not a key of the identity
Neither totalBudget nor expiresAt is set, or totalBudget is 0
The key is disabled
It sets a limit the key does not already have. A limit cannot be added to a key or removed from it.
A new value does not raise the current one
The key would still be expired after the update

To give an application less, disable its key with an identity update and add a new one.

See the identity key limits update implementation in rs-dpp and the state validation in rs-drive-abci for more details.

Identity Credit Transfer#

Identities can transfer credits on the platform by submitting an identity credit transfer state transition. This state transition requires specifying the sender identity, recipient identity, transfer amount, and a signature for verification.

Field	Type	Description
$formatVersion	integer	The state transition format version (currently `0`)
type	integer	State transition type (`7` for identity credit transfer)
identityId	array of bytes	The identity id of the sender (32 bytes)
recipientId	array of bytes	The identity id of the recipient (32 bytes)
amount	integer	The credit amount to transfer (minimum 100,000 credits)
nonce	unsigned integer (64 bits)	Identity nonce for this transition to prevent replay attacks
userFeeIncrease	integer	Extra fee to prioritize processing if the mempool is full. Typically set to zero.
signaturePublicKeyId	integer	The ID of public key used to sign the state transition
signature	array of bytes	Signature of state transition data (65 bytes)

Note

The recipientId must differ from identityId; transfers to the sending identity are rejected.

See the identity credit transfer implementation in rs-dpp for more details.

Identity Credit Withdrawal#

Credits can be withdrawn from an identity to an external Core wallet using an identity credit withdrawal state transition. This transition allows specifying the withdrawal amount, output script, and signing details.

Field	Type	Description
$formatVersion	integer	The state transition format version (currently `1`)
type	integer	State transition type (`6` for identity credit withdrawal)
identityId	array of bytes	An identity id (32 bytes)
amount	integer	The amount of credits to withdraw (64 bits)
coreFeePerByte	integer	Fee per byte for the transaction on Core (32 bits)
pooling	integer	Pooling mode for transaction batching
outputScript	array of bytes	(Optional) The output script for receiving the withdrawal (if not set, defaults to Core address)
nonce	unsigned integer (64 bits)	Identity nonce for this transition to prevent replay attacks
userFeeIncrease	integer	Extra fee to prioritize processing if the mempool is full. Typically set to zero.
signaturePublicKeyId	integer	The ID of public key used to sign the state transition
signature	array of bytes	Signature of state transition data (65 bytes)

Note

Constraints: pooling must be 0 (Never); 1 (IfAvailable) and 2 (Standard) are not yet implemented. coreFeePerByte must be a non-zero Fibonacci number, and at most 6,765 from protocol version 14. outputScript, when set, must be P2PKH or P2SH. amount must be within the min and max withdrawal amount limits. Starting in protocol version 14, the Core transaction fee is deducted from amount, so amount must be at least the min withdrawal amount plus the Core fee (190-byte asset unlock transaction × coreFeePerByte × 1,000 credits; rs-dpp).

See the identity credit withdrawal implementation in rs-dpp for more details.

Asset Lock#

The identity create and identity topup state transitions both include an asset lock proof object. This object references the Core chain asset lock transaction and includes proof that the transaction is locked.

Currently there are two types of asset lock proofs defined by rs-dpp: InstantSend and ChainLock. Transactions almost always receive InstantSend locks, so the InstantSend asset lock proof is the predominate type. See rs-dpp for examples of using InstantSend or ChainLocks as the asset lock proof.

InstantSend Asset Lock Proof#

The InstantSend asset lock proof is used for transactions that have received an InstantSend lock. Asset locks using an InstantSend lock as proof must comply with this structure established in rs-dpp.

Field	Type	Description
$type	string	The asset lock proof type (`"instant"` for InstantSend locks)
instantLock	array of bytes	The InstantSend lock (`islock`)
transaction	array of bytes	The asset lock transaction
outputIndex	integer	Index of the transaction output to be used

ChainLock Asset Lock Proof#

The ChainLock asset lock proof is used for transactions that have not received an InstantSend lock, but have been included in a block that has received a ChainLock. Asset locks using a ChainLock as proof must comply with this structure established in rs-dpp.

Field	Type	Description
$type	string	The asset lock proof type (`"chain"` for ChainLocks)
coreChainLockedHeight	integer	Height of the ChainLocked Core block containing the transaction
outPoint	string	The outpoint being used as the asset lock. JSON encodes it as `"<txid>:<vout>"`. The `platform_value` representation is an object containing `txid` as 32 bytes and `vout` as an unsigned 32-bit integer.

Identity State Transition Signing#

Note

The identity create and topup state transition signatures are unique in that they must be signed by the private key used in the layer 1 locking transaction. All other state transitions will be signed by a private key of the identity submitting them.

The process to sign an identity create state transition consists of the following steps:

Create a canonical, signable version of the state transition encoded with Bincode. The signable state transition excludes the following fields:
- identityId
- signature for all public keys
- signature for the overall state transition
Calculate the double SHA-256 hash of the encoded signable state transition
Sign the hash from the previous step using the private key associated with the asset lock transaction, then add the result to the state transition’s signature field
For each public key of type 0 or 1 being added to the identity, sign the hash from step 2 using the respective private key and add the result to the public key’s signature field. Keys of type 2, 3, or 4 must have an empty signature.
Use Bincode to re-encode the state transition with all signatures and the identity id included

Identity#

Identity Overview#

Identity id#

Identity publicKeys#

Public Key id#

Public Key type#

Public Key data#

Public Key purpose#

Public Key securityLevel#

Public Key readOnly#

Public Key disabledAt#

Public Key Limits#

Identity balance#

Identity Constants and Limits#

Identity Creation Cost Calculation#

Minimum Funding Requirements#

Identity State Transition Details#

Identity Create#

Identity TopUp#

Identity Update#

Identity Key Limits Update#

Identity Credit Transfer#

Identity Credit Withdrawal#

Asset Lock#

InstantSend Asset Lock Proof#

ChainLock Asset Lock Proof#

Identity State Transition Signing#

This Page

Public Key `id`#

Public Key `type`#

Public Key `data`#

Public Key `purpose`#

Public Key `securityLevel`#

Public Key `readOnly`#

Public Key `disabledAt`#