native script extra signers

packages/translucent-tx/tx.ts

@@ -135,6 +135,7 @@ export class TxBuilder {
   private fee: bigint = 0n // The fee for the transaction.
   private overEstimateSteps = 1.2 // A multiplier to overestimate the execution steps for Plutus scripts.
   private overEstimateMem = 1.05 // A multiplier to overestimate the memory usage for Plutus scripts.
+  private additionalSigners = 0;
 
   /**
    * Constructs a new instance of the TxBuilder class.
@@ -155,6 +156,16 @@ export class TxBuilder {
     this.changeAddress = address
   }
 
+  /**
+   * The additional signers field is used to add additional signing counts for fee calculation.
+   * These will be included in the signing phase at a later stage.
+   * This is needed due to native scripts signees being non-deterministic.
+   * @param {number} amount - The amount of additional signers
+   */
+  addAdditionalSigners(amount: number){
+    this.additionalSigners += amount
+  }
+
   /**
    * Adds a reference input to the transaction. Reference inputs are used to refer to outputs from previous transactions
    * without spending them, allowing scripts to read their data. This can be useful for various contract logic, such as
@@ -523,6 +534,9 @@ export class TxBuilder {
     for (const val of this.requiredWitnesses.values()) {
       requiredWitnesses.push(VkeyWitness.fromCore([Ed25519PublicKeyHex("0".repeat(64)), Ed25519SignatureHex('0'.repeat(128))]))
     }
+    for (let i = 0; i < this.additionalSigners; i++){
+      requiredWitnesses.push(VkeyWitness.fromCore([Ed25519PublicKeyHex("0".repeat(64)), Ed25519SignatureHex('0'.repeat(128))]))
+    }
     vkeyWitnesses.setValues(requiredWitnesses)
     tw.setVkeys(vkeyWitnesses)
     tw.setRedeemers(this.redeemers)