POA Module API Documentation

Overview

The Proof of Authority (POA) module provides a governance mechanism for managing validators in a Cosmos SDK blockchain. Unlike traditional Proof of Stake, POA allows a designated admin to control validator set membership and voting power distribution. Package: cosmos.poa.v1 Go Import: github.com/cosmos/cosmos-sdk/enterprise/poa/types

Core Concepts

Admin Control: A single admin address has exclusive authority to manage validators and module parameters
Validator Management: Create validators, update voting power, and manage the active validator set
Fee Distribution: Validators accumulate fees that can be withdrawn by their operators
Dynamic Updates: Changes to the validator set are applied without stopping the chain

Data Types

Validator

Represents a validator in the POA system.

message Validator {
  google.protobuf.Any pub_key = 1;
  int64 power = 2;
  ValidatorMetadata metadata = 3;
  repeated cosmos.base.v1beta1.DecCoin allocated_fees = 4;
}

Fields:

pub_key (Any): The validator’s consensus public key (typically /cosmos.crypto.ed25519.PubKey)
power (int64): Voting power for this validator (use 0 to remove a validator)
metadata (ValidatorMetadata): Additional validator information
allocated_fees (DecCoin[]): Accumulated fees allocated to this validator

Example:

{
  "pub_key": {
    "@type": "/cosmos.crypto.ed25519.PubKey",
    "key": "YUzyiqZzKN8BmLbl75gdXfbxQ2QtSYpPSwA85bZ3xuE="
  },
  "power": "10000",
  "metadata": {
    "moniker": "validator-1",
    "description": "First validator node",
    "operator_address": "cosmos1x0mm8rws8lm46xay3zyyznzr6lvu5um3kht0x7"
  },
  "allocated_fees": []
}

ValidatorMetadata

Metadata information about a validator.

message ValidatorMetadata {
  string moniker = 3;
  string description = 4;
  string operator_address = 5;
}

Fields:

moniker (string): Human-readable name for the validator
description (string): Optional description of the validator
operator_address (string): Cosmos SDK address that operates this validator

Params

Module parameters.

message Params {
  string admin = 1;
}

Fields:

admin (string): Cosmos SDK address with administrative privileges

ValidatorFees

Represents fee allocations for a validator operator.

message ValidatorFees {
  repeated cosmos.base.v1beta1.DecCoin fees = 1;
}

Fields:

fees (DecCoin[]): List of coins representing allocated fees

Query API

The Query service provides read-only access to POA module state.

Params

Get module parameters. gRPC: cosmos.poa.v1.Query/Params REST: GET /cosmos/poa/v1/params Request:

message QueryParamsRequest {}

Response:

message QueryParamsResponse {
  Params params = 1;
}

CLI:

simd q poa params

Example Response:

{
  "params": {
    "admin": "cosmos1x0mm8rws8lm46xay3zyyznzr6lvu5um3kht0x7"
  }
}

Validator

Query a single validator by address. gRPC: cosmos.poa.v1.Query/Validator REST: GET /cosmos/poa/v1/validator/{address} Request:

message QueryValidatorRequest {
  string address = 1;  // Consensus or operator address
}

Response:

message QueryValidatorResponse {
  Validator validator = 1;
}

CLI:

simd q poa validator <address>

Notes:

address can be either a consensus address or operator address

Validators

List all validators in the system. gRPC: cosmos.poa.v1.Query/Validators REST: GET /cosmos/poa/v1/validators Request:

message QueryValidatorsRequest {
  cosmos.base.query.v1beta1.PageRequest pagination = 2;
}

Response:

message QueryValidatorsResponse {
  repeated Validator validators = 1;
  cosmos.base.query.v1beta1.PageResponse pagination = 2;
}

CLI:

simd q poa validators

Notes:

Results are always returned in descending order by voting power
Supports pagination for large validator sets

Example Response:

{
  "validators": [
    {
      "pub_key": {
        "@type": "/cosmos.crypto.ed25519.PubKey",
        "key": "YUzyiqZzKN8BmLbl75gdXfbxQ2QtSYpPSwA85bZ3xuE="
      },
      "power": "10000",
      "metadata": {
        "moniker": "validator-1",
        "operator_address": "cosmos1..."
      }
    }
  ]
}

WithdrawableFees

Query fees available for withdrawal by a validator operator. gRPC: cosmos.poa.v1.Query/WithdrawableFees REST: GET /cosmos/poa/v1/allocated_fees/{operator_address} Request:

message QueryWithdrawableFeesRequest {
  string operator_address = 1;
}

Response:

message QueryWithdrawableFeesResponse {
  ValidatorFees fees = 1;
}

CLI:

simd q poa allocated-fees <operator-address>

Example Response:

{
  "fees": {
    "fees": [
      {
        "denom": "token",
        "amount": "1000.500000000000000000"
      }
    ]
  }
}

TotalPower

Get the total voting power across all validators. gRPC: cosmos.poa.v1.Query/TotalPower REST: GET /cosmos/poa/v1/total_power Request:

message QueryTotalPowerRequest {}

Response:

message QueryTotalPowerResponse {
  int64 total_power = 1;
}

CLI:

simd q poa total-power

Example Response:

{
  "total_power": "50000"
}

Transaction Messages (Msg Service)

The Msg service handles state-changing operations.

UpdateParams

Update module parameters (admin only). gRPC: cosmos.poa.v1.Msg/UpdateParams Message:

message MsgUpdateParams {
  Params params = 1;
  string admin = 2;  // Signer must be current admin
}

Response:

message MsgUpdateParamsResponse {}

CLI:

simd tx poa update-params \
  --admin <new-admin-address> \
  --from <current-admin> \
  --keyring-backend test \
  --chain-id <chain-id> \
  -y

Authorization: Only the current admin can execute this transaction.

CreateValidator

Create a new validator with zero voting power (operator initiates, admin must activate). gRPC: cosmos.poa.v1.Msg/CreateValidator Message:

message MsgCreateValidator {
  google.protobuf.Any pub_key = 1;
  string moniker = 2;
  string description = 3;
  string operator_address = 4;  // Signer
}

Response:

message MsgCreateValidatorResponse {}

CLI:

simd tx poa create-validator \
  --pubkey <validator-pubkey> \
  --moniker "my-validator" \
  --description "Validator description" \
  --from <operator-account> \
  --keyring-backend test \
  --chain-id <chain-id> \
  -y

Authorization: Any account can create a validator, but it starts with power=0. Notes:

The validator will not participate in consensus until the admin updates its power to a non-zero value
Public key must be a valid consensus public key (typically Ed25519)

UpdateValidators

Update validator set (admin only). This is the primary mechanism for managing validators. gRPC: cosmos.poa.v1.Msg/UpdateValidators Message:

message MsgUpdateValidators {
  repeated Validator validators = 1;
  string admin = 2;  // Signer must be admin
}

Response:

message MsgUpdateValidatorsResponse {}

CLI (inline):

simd tx poa update-validators \
  --validator '{
    "pub_key": {
      "@type": "/cosmos.crypto.ed25519.PubKey",
      "key": "YUzyiqZzKN8BmLbl75gdXfbxQ2QtSYpPSwA85bZ3xuE="
    },
    "power": 10000
  }' \
  --validator '{
    "pub_key": {
      "@type": "/cosmos.crypto.ed25519.PubKey",
      "key": "lSR1GEByJtzgiuCevrWgcyBWjhQXjycsuzzIdf56Oa4="
    },
    "power": 0
  }' \
  --from account \
  --keyring-backend test \
  --chain-id <chain-id> \
  -y

CLI (from file):

simd tx poa update-validators validators.json \
  --from account \
  --keyring-backend test \
  --chain-id <chain-id> \
  -y

File Format (validators.json):

[
  {
    "pub_key": {
      "@type": "/cosmos.crypto.ed25519.PubKey",
      "key": "YUzyiqZzKN8BmLbl75gdXfbxQ2QtSYpPSwA85bZ3xuE="
    },
    "power": 10000,
    "metadata": {
      "moniker": "validator-1",
      "description": "First validator",
      "operator_address": "cosmos1x0mm8rws8lm46xay3zyyznzr6lvu5um3kht0x7"
    }
  },
  {
    "pub_key": {
      "@type": "/cosmos.crypto.ed25519.PubKey",
      "key": "lSR1GEByJtzgiuCevrWgcyBWjhQXjycsuzzIdf56Oa4="
    },
    "power": 0
  }
]

Authorization: Only the admin can execute this transaction. Notes:

Can update multiple validators in a single transaction
Setting power: 0 removes a validator from the active set
Changes propagate to CometBFT consensus in the next block
Missing fields in metadata are preserved from existing state

WithdrawFees

Withdraw accumulated fees to the operator’s account. gRPC: cosmos.poa.v1.Msg/WithdrawFees Message:

message MsgWithdrawFees {
  string operator = 1;  // Signer
}

Response:

message MsgWithdrawFeesResponse {}

CLI:

simd tx poa withdraw-fees \
  --from <operator-account> \
  --keyring-backend test \
  --chain-id <chain-id> \
  -y

Authorization: Must be signed by the validator’s operator address. Notes:

Transfers all accumulated fees to the operator’s account
Fees are denominated in the chain’s native token(s)

Common Use Cases

1. Query Current Admin

simd q poa params

2. List All Active Validators

simd q poa validators

3. Add a New Validator

Step 1: Operator creates the validator:

simd tx poa create-validator \
  --pubkey <pubkey> \
  --moniker "new-validator" \
  --from operator-account \
  --keyring-backend test \
  -y

Step 2: Admin activates with voting power:

simd tx poa update-validators \
  --validator '{
    "pub_key": {"@type": "/cosmos.crypto.ed25519.PubKey", "key": "..."},
    "power": 10000
  }' \
  --from admin \
  --keyring-backend test \
  -y

4. Change Validator Voting Power

simd tx poa update-validators \
  --validator '{
    "pub_key": {"@type": "/cosmos.crypto.ed25519.PubKey", "key": "..."},
    "power": 20000
  }' \
  --from admin \
  --keyring-backend test \
  -y

5. Remove a Validator

simd tx poa update-validators \
  --validator '{
    "pub_key": {"@type": "/cosmos.crypto.ed25519.PubKey", "key": "..."},
    "power": 0
  }' \
  --from admin \
  --keyring-backend test \
  -y

6. Withdraw Validator Fees

simd tx poa withdraw-fees \
  --from validator-operator \
  --keyring-backend test \
  -y

7. Transfer Admin Rights

simd tx poa update-params \
  --admin cosmos1newadminaddress... \
  --from current-admin \
  --keyring-backend test \
  -y

REST API Endpoints

All query endpoints are available via REST:

Method	Endpoint	Description
GET	`/cosmos/poa/v1/params`	Get module parameters
GET	`/cosmos/poa/v1/validator/{address}`	Get single validator
GET	`/cosmos/poa/v1/validators`	List all validators
GET	`/cosmos/poa/v1/allocated_fees/{operator_address}`	Get withdrawable fees
GET	`/cosmos/poa/v1/total_power`	Get total voting power

Example REST Query:

curl http://localhost:1317/cosmos/poa/v1/validators

Error Handling

Common error scenarios:

Unauthorized Admin Action

Error: Transaction rejected Cause: Non-admin attempted to call admin-only function Solution: Ensure transaction is signed by the admin account

Invalid Public Key

Error: Invalid validator public key Cause: Malformed or wrong type of public key Solution: Use Ed25519 public key in correct format

Validator Not Found

Error: Validator does not exist Cause: Querying non-existent validator Solution: Verify validator address/public key

Insufficient Fees

Error: No fees to withdraw Cause: Validator has no accumulated fees Solution: Wait for fees to accumulate from block rewards

Integration Examples

JavaScript/TypeScript (CosmJS)

import { SigningStargateClient } from "@cosmjs/stargate";

// Query validators
const client = await StargateClient.connect("http://localhost:26657");
const response = await client.queryContractSmart(
  "cosmos.poa.v1.Query/Validators",
  {}
);

// Update validators (requires signing)
const signingClient = await SigningStargateClient.connectWithSigner(
  "http://localhost:26657",
  wallet
);

const msg = {
  typeUrl: "/cosmos.poa.v1.MsgUpdateValidators",
  value: {
    validators: [{
      pubKey: { typeUrl: "/cosmos.crypto.ed25519.PubKey", value: ... },
      power: 10000,
      metadata: { moniker: "validator-1", operatorAddress: "cosmos1..." }
    }],
    admin: "cosmos1adminaddress..."
  }
};

const result = await signingClient.signAndBroadcast(
  adminAddress,
  [msg],
  "auto"
);

Python (cosmpy)

from cosmpy.aerial.client import LedgerClient, NetworkConfig
from cosmpy.aerial.wallet import LocalWallet

# Create client
client = LedgerClient(NetworkConfig.fetchai_mainnet())

# Query validators
response = client.query_contract(
    "cosmos.poa.v1.Query/Validators",
    {}
)

print(response)

Go

import (
    "context"
    poatypes "github.com/cosmos/cosmos-sdk/enterprise/poa/types"
    "google.golang.org/grpc"
)

// Query client
conn, _ := grpc.Dial("localhost:9090", grpc.WithInsecure())
queryClient := poatypes.NewQueryClient(conn)

// Get validators
resp, err := queryClient.Validators(context.Background(), &poatypes.QueryValidatorsRequest{})
if err != nil {
    panic(err)
}

for _, val := range resp.Validators {
    fmt.Printf("Validator: %s, Power: %d\n", val.Metadata.Moniker, val.Power)
}

Security Considerations

Admin Key Security: The admin private key has complete control over the validator set. Use hardware wallets or secure key management systems.
Validator Public Keys: Ensure validator public keys are correctly generated and stored securely.
Power Distribution: Consider the security implications of power concentration. Avoid giving a single validator >67% of total power.
Operator Separation: Use separate accounts for operator and admin roles to limit exposure.
Fee Withdrawal: Operators should regularly withdraw fees to prevent accumulation in the module.

Appendix

Public Key Formats

Ed25519 public keys should be base64-encoded:

{
  "@type": "/cosmos.crypto.ed25519.PubKey",
  "key": "YUzyiqZzKN8BmLbl75gdXfbxQ2QtSYpPSwA85bZ3xuE="
}

Address Formats

Operator Address: Standard Cosmos SDK bech32 address (e.g., cosmos1...)
Consensus Address: Can be derived from public key or use operator address for queries

Power Units

Voting power is represented as int64
Total power affects block signing requirements (typically need >2/3 of total power for consensus)
Zero power effectively removes a validator from the active set s

Cosmos Enterprise

​POA Module API Documentation

​Overview

​Core Concepts

​Data Types

​Validator

​ValidatorMetadata

​Params

​ValidatorFees

​Query API

​Params

​Validator

​Validators

​WithdrawableFees

​TotalPower

​Transaction Messages (Msg Service)

​UpdateParams

​CreateValidator

​UpdateValidators

​WithdrawFees

​Common Use Cases

​1. Query Current Admin

​2. List All Active Validators

​3. Add a New Validator

​4. Change Validator Voting Power

​5. Remove a Validator

​6. Withdraw Validator Fees

​7. Transfer Admin Rights

​REST API Endpoints

​Error Handling

​Unauthorized Admin Action

​Invalid Public Key

​Validator Not Found

​Insufficient Fees

​Integration Examples

​JavaScript/TypeScript (CosmJS)

​Python (cosmpy)

​Go

​Security Considerations

​Appendix

​Public Key Formats

​Address Formats

​Power Units

POA Module API Documentation

Overview

Core Concepts

Data Types

Validator

ValidatorMetadata

Params

ValidatorFees

Query API

Params

Validator

Validators

WithdrawableFees

TotalPower

Transaction Messages (Msg Service)

UpdateParams

CreateValidator

UpdateValidators

WithdrawFees

Common Use Cases

1. Query Current Admin

2. List All Active Validators

3. Add a New Validator

4. Change Validator Voting Power

5. Remove a Validator

6. Withdraw Validator Fees

7. Transfer Admin Rights

REST API Endpoints

Error Handling

Unauthorized Admin Action

Invalid Public Key

Validator Not Found

Insufficient Fees

Integration Examples

JavaScript/TypeScript (CosmJS)

Python (cosmpy)

Go

Security Considerations

Appendix

Public Key Formats

Address Formats

Power Units