BitGo · Vijay-Jagannathan · Dec 12, 2025 · Dec 12, 2025
@@ -7,6 +7,7 @@ export const TRANSFER_TOKEN_METHOD_ID = '0xa9059cbb';
 export const STAKING_METHOD_ID = '0xd8da3bbf';
 export const STAKE_CLAUSE_METHOD_ID = '0x604f2177';
 export const DELEGATE_CLAUSE_METHOD_ID = '0x08bbb824';
+export const ADD_VALIDATION_METHOD_ID = '0xc3c4b138';
 export const EXIT_DELEGATION_METHOD_ID = '0x69e79b7d';
 export const BURN_NFT_METHOD_ID = '0x2e17de78';
 export const TRANSFER_NFT_METHOD_ID = '0x23b872dd';
@@ -20,6 +21,9 @@ export const STARGATE_DELEGATION_ADDRESS_TESTNET = '0x7240e3bc0d26431512d5b67dbd
 export const STARGATE_NFT_ADDRESS_TESTNET = '0x887d9102f0003f1724d8fd5d4fe95a11572fcd77';
 export const STARGATE_CONTRACT_ADDRESS_TESTNET = '0x1e02b2953adefec225cf0ec49805b1146a4429c1';
 
+export const VALIDATOR_REGISTRATION_STAKER_CONTRACT_ADDRESS_TESTNET = '0x00000000000000000000000000005374616B6572';
+export const VALIDATOR_REGISTRATION_STAKER_CONTRACT_ADDRESS_MAINNET = '0x00000000000000000000000000005374616B6572';
+
 export const AVG_GAS_UNITS = '21000';
 export const EXPIRATION = 400;
 export const GAS_PRICE_COEF = '128';

@@ -33,6 +33,7 @@ export interface VetTransactionData {
   autorenew?: boolean; // Autorenew flag for stakeAndDelegate method
   nftCollectionId?: string;
   validatorAddress?: string;
+  stakingPeriod?: number;
 }
 
 export interface VetTransactionExplanation extends BaseTransactionExplanation {

@@ -14,6 +14,7 @@ export { ExitDelegationTransaction } from './transaction/exitDelegation';
 export { BurnNftTransaction } from './transaction/burnNftTransaction';
 export { ClaimRewardsTransaction } from './transaction/claimRewards';
 export { NFTTransaction } from './transaction/nftTransaction';
+export { ValidatorRegistrationTransaction } from './transaction/validatorRegistrationTransaction';
 export { TransactionBuilder } from './transactionBuilder/transactionBuilder';
 export { TransferBuilder } from './transactionBuilder/transferBuilder';
 export { AddressInitializationBuilder } from './transactionBuilder/addressInitializationBuilder';
@@ -25,5 +26,6 @@ export { NFTTransactionBuilder } from './transactionBuilder/nftTransactionBuilde
 export { BurnNftBuilder } from './transactionBuilder/burnNftBuilder';
 export { ExitDelegationBuilder } from './transactionBuilder/exitDelegationBuilder';
 export { ClaimRewardsBuilder } from './transactionBuilder/claimRewardsBuilder';
+export { ValidatorRegistrationBuilder } from './transactionBuilder/validatorRegistrationBuilder';
 export { TransactionBuilderFactory } from './transactionBuilderFactory';
 export { Constants, Utils, Interface };
@@ -0,0 +1,185 @@
+import { TransactionType, InvalidTransactionError } from '@bitgo/sdk-core';
+import { BaseCoin as CoinConfig } from '@bitgo/statics';
+import { Transaction as VetTransaction, Secp256k1 } from '@vechain/sdk-core';
+import { Transaction } from './transaction';
+import { VetTransactionData } from '../iface';
+import EthereumAbi from 'ethereumjs-abi';
+import utils from '../utils';
+import BigNumber from 'bignumber.js';
+import { addHexPrefix, BN } from 'ethereumjs-util';
+import { ZERO_VALUE_AMOUNT } from '../constants';
+
+export class ValidatorRegistrationTransaction extends Transaction {
+  private _stakingContractAddress: string;
+  private _validator: string;
+  private _stakingPeriod: number;
+
+  constructor(_coinConfig: Readonly<CoinConfig>) {
+    super(_coinConfig);
+    this._type = TransactionType.StakingLock;
+  }
+
+  get validator(): string {
+    return this._validator;
+  }
+
+  set validator(address: string) {
+    this._validator = address;
+  }
+
+  get stakingPeriod(): number {
+    return this._stakingPeriod;
+  }
+
+  set stakingPeriod(period: number) {
+    this._stakingPeriod = period;
+  }
+
+  get stakingContractAddress(): string {
+    return this._stakingContractAddress;
+  }
+
+  set stakingContractAddress(address: string) {
+    this._stakingContractAddress = address;
+  }
+
+  buildClauses(): void {
+    if (!this.stakingContractAddress) {
+      throw new Error('Staking contract address is not set');
+    }
+
+    if (!this.validator) {
+      throw new Error('Validator address is not set');
+    }
+
+    if (!this.stakingPeriod) {
+      throw new Error('Staking period is not set');
+    }
+
+    utils.validateContractAddressForValidatorRegistration(this.stakingContractAddress, this._coinConfig);
+    const addValidationData = this.getAddValidationClauseData(this.validator, this.stakingPeriod);
+    this._transactionData = addValidationData;
+    // Create the clause for delegation
+    this._clauses = [
+      {
+        to: this.stakingContractAddress,
+        value: ZERO_VALUE_AMOUNT,
+        data: addValidationData,
+      },
+    ];
+
+    // Set recipients based on the clauses
+    this._recipients = [
+      {
+        address: this.stakingContractAddress,
+        amount: ZERO_VALUE_AMOUNT,
+      },
+    ];
+  }
+
+  /**
+   * Encodes addValidation transaction data using ethereumjs-abi for addValidation method
+   * @param {string} validator - address of the validator
+   * @param {number} period - staking period, denoted in blocks, that the Validator commits to hard
+locking their VET into the built-in staker contract. Allowed values are 60480 (7 days),
+129600 (15 days) or 259200 (30 days)
+   * @returns {string} - The encoded transaction data
+   */
+  getAddValidationClauseData(validator: string, period: number): string {
+    const methodName = 'addValidation';
+    const types = ['address', 'uint32'];
+    const params = [validator, new BN(period)];
+
+    const method = EthereumAbi.methodID(methodName, types);
+    const args = EthereumAbi.rawEncode(types, params);
+
+    return addHexPrefix(Buffer.concat([method, args]).toString('hex'));
+  }
+
+  toJson(): VetTransactionData {
+    const json: VetTransactionData = {
+      id: this.id,
+      chainTag: this.chainTag,
+      blockRef: this.blockRef,
+      expiration: this.expiration,
+      gasPriceCoef: this.gasPriceCoef,
+      gas: this.gas,
+      dependsOn: this.dependsOn,
+      nonce: this.nonce,
+      data: this.transactionData,
+      value: ZERO_VALUE_AMOUNT,
+      sender: this.sender,
+      to: this.stakingContractAddress,
+      stakingContractAddress: this.stakingContractAddress,
+      amountToStake: ZERO_VALUE_AMOUNT,
+      validatorAddress: this.validator,
+      stakingPeriod: this.stakingPeriod,
+    };
+
+    return json;
+  }
+
+  fromDeserializedSignedTransaction(signedTx: VetTransaction): void {
+    try {
+      if (!signedTx || !signedTx.body) {
+        throw new InvalidTransactionError('Invalid transaction: missing transaction body');
+      }
+
+      // Store the raw transaction
+      this.rawTransaction = signedTx;
+
+      // Set transaction body properties
+      const body = signedTx.body;
+      this.chainTag = typeof body.chainTag === 'number' ? body.chainTag : 0;
+      this.blockRef = body.blockRef || '0x0';
+      this.expiration = typeof body.expiration === 'number' ? body.expiration : 64;
+      this.clauses = body.clauses || [];
+      this.gasPriceCoef = typeof body.gasPriceCoef === 'number' ? body.gasPriceCoef : 128;
+      this.gas = typeof body.gas === 'number' ? body.gas : Number(body.gas) || 0;
+      this.dependsOn = body.dependsOn || null;
+      this.nonce = String(body.nonce);
+
+      // Set validator registration-specific properties
+      if (body.clauses.length > 0) {
+        // Get the addValidation clause
+        const addValidationClause = body.clauses[0];
+        if (addValidationClause.to) {
+          this.stakingContractAddress = addValidationClause.to;
+        }
+
+        // Extract validator and period from addValidation data
+        if (addValidationClause.data) {
+          this.transactionData = addValidationClause.data;
+          const decoded = utils.decodeAddValidationData(addValidationClause.data);
+          this.validator = decoded.validator;
+          this.stakingPeriod = decoded.period;
+        }
+      }
+
+      // Set recipients from clauses
+      this.recipients = body.clauses.map((clause) => ({
+        address: (clause.to || '0x0').toString().toLowerCase(),
+        amount: new BigNumber(clause.value || 0).toString(),
+      }));
+      this.loadInputsAndOutputs();
+
+      // Set sender address
+      if (signedTx.signature && signedTx.origin) {
+        this.sender = signedTx.origin.toString().toLowerCase();
+      }
+
+      // Set signatures if present
+      if (signedTx.signature) {
+        // First signature is sender's signature
+        this.senderSignature = Buffer.from(signedTx.signature.slice(0, Secp256k1.SIGNATURE_LENGTH));
+
+        // If there's additional signature data, it's the fee payer's signature
+        if (signedTx.signature.length > Secp256k1.SIGNATURE_LENGTH) {
+          this.feePayerSignature = Buffer.from(signedTx.signature.slice(Secp256k1.SIGNATURE_LENGTH));
+        }
+      }
+    } catch (e) {
+      throw new InvalidTransactionError(`Failed to deserialize transaction: ${e.message}`);
+    }
+  }
+}
@@ -0,0 +1,142 @@
+import assert from 'assert';
+import { BaseCoin as CoinConfig } from '@bitgo/statics';
+import { TransactionType } from '@bitgo/sdk-core';
+import { TransactionClause } from '@vechain/sdk-core';
+
+import { TransactionBuilder } from './transactionBuilder';
+import { Transaction } from '../transaction/transaction';
+import { ValidatorRegistrationTransaction } from '../transaction/validatorRegistrationTransaction';
+import utils from '../utils';
+
+export class ValidatorRegistrationBuilder extends TransactionBuilder {
+  /**
+   * Creates a new add validation Clause txn instance.
+   *
+   * @param {Readonly<CoinConfig>} _coinConfig - The coin configuration object
+   */
+  constructor(_coinConfig: Readonly<CoinConfig>) {
+    super(_coinConfig);
+    this._transaction = new ValidatorRegistrationTransaction(_coinConfig);
+  }
+
+  /**
+   * Initializes the builder with an existing validation registration txn.
+   *
+   * @param {ValidatorRegistrationTransaction} tx - The transaction to initialize the builder with
+   */
+  initBuilder(tx: ValidatorRegistrationTransaction): void {
+    this._transaction = tx;
+  }
+
+  /**
+   * Gets the staking transaction instance.
+   *
+   * @returns {ValidatorRegistrationTransaction} The validator registration transaction
+   */
+  get validatorRegistrationTransaction(): ValidatorRegistrationTransaction {
+    return this._transaction as ValidatorRegistrationTransaction;
+  }
+
+  /**
+   * Gets the transaction type for validator registration.
+   *
+   * @returns {TransactionType} The transaction type
+   */
+  protected get transactionType(): TransactionType {
+    return TransactionType.StakingLock;
+  }
+
+  /**
+   * Validates the transaction clauses for validator registration transaction.
+   * @param {TransactionClause[]} clauses - The transaction clauses to validate.
+   * @returns {boolean} - Returns true if the clauses are valid, false otherwise.
+   */
+  protected isValidTransactionClauses(clauses: TransactionClause[]): boolean {
+    try {
+      if (!clauses || !Array.isArray(clauses) || clauses.length === 0) {
+        return false;
+      }
+
+      const clause = clauses[0];
+      if (!clause.to || !utils.isValidAddress(clause.to)) {
+        return false;
+      }
+
+      return true;
+    } catch (e) {
+      return false;
+    }
+  }
+
+  /**
+   * Sets the staking contract address for this validator registration tx.
+   * The address must be explicitly provided to ensure the correct contract is used.
+   *
+   * @param {string} address - The contract address (required)
+   * @returns {ValidatorRegistrationBuilder} This transaction builder
+   * @throws {Error} If no address is provided
+   */
+  stakingContractAddress(address: string): this {
+    if (!address) {
+      throw new Error('Staking contract address is required');
+    }
+    this.validateAddress({ address });
+    this.validatorRegistrationTransaction.stakingContractAddress = address;
+    return this;
+  }
+
+  /**
+   * Sets the staking period for this validator registration tx.
+   *
+   * @param {number} period - The staking period
+   * @returns {ValidatorRegistrationBuilder} This transaction builder
+   */
+  stakingPeriod(period: number): this {
+    this.validatorRegistrationTransaction.stakingPeriod = period;
+    return this;
+  }
+
+  /**
+   * Sets the validator address for this validator registration tx.
+   * @param {string} address - The validator address
+   * @returns {ValidatorRegistrationBuilder} This transaction builder
+   */
+  validator(address: string): this {
+    if (!address) {
+      throw new Error('Validator address is required');
+    }
+    this.validateAddress({ address });
+    this.validatorRegistrationTransaction.validator = address;
+    return this;
+  }
+
+  /**
+   * Sets the transaction data for this validator registration tx.
+   *
+   * @param {string} data - The transaction data
+   * @returns {ValidatorRegistrationBuilder} This transaction builder
+   */
+  transactionData(data: string): this {
+    this.validatorRegistrationTransaction.transactionData = data;
+    return this;
+  }
+
+  /** @inheritdoc */
+  validateTransaction(transaction?: ValidatorRegistrationTransaction): void {
+    if (!transaction) {
+      throw new Error('transaction not defined');
+    }
+    assert(transaction.stakingContractAddress, 'Staking contract address is required');
+
+    assert(transaction.stakingPeriod, 'Staking period is required');
+    assert(transaction.validator, 'Validator address is required');
+    this.validateAddress({ address: transaction.stakingContractAddress });
+  }
+
+  /** @inheritdoc */
+  protected async buildImplementation(): Promise<Transaction> {
+    this.transaction.type = this.transactionType;
+    await this.validatorRegistrationTransaction.build();
+    return this.transaction;
+  }
+}