---
title: "Create a signature share for a transaction on a transaction request"
method: POST
path: "/api/v2/wallet/{walletId}/txrequests/{id}/transactions/{transactionIdx}/signatureshares"
tags: ["Transaction request"]
---

# Create a signature share for a transaction on a transaction request

`POST /api/v2/wallet/{walletId}/txrequests/{id}/transactions/{transactionIdx}/signatureshares`

Allows users to supply their signature share for signing.

This route is only valid for transaction request full. Use only with MPC wallets.

## Path parameters

- `walletId` string, required
- `id` string, required
- `transactionIdx` string, required

## Request body

- CreateSignatureShareRequest
  - `signatureShare` SignatureShare
    - `from` 'user' | 'backup' | 'bitgo', required
    - `to` 'user' | 'backup' | 'bitgo', required
    - `share` string, required — The signature share.
  - `signatureShares` SignatureShare[] — User-provided shares to be used in the ECDSA or EDDSA MPC signing flow.
    - `from` 'user' | 'backup' | 'bitgo', required
    - `to` 'user' | 'backup' | 'bitgo', required
    - `share` string, required — The signature share.
  - `signerShare` string — An openPGP ascii armored message (encrypted to the known HSM public key) containing the previous signer’s offset secret share as a 128 character hex string (64 bytes) consisting of the new offset “u” private component from the user [or backup] new offset Y-share as a 64 character hex string (32 bytes) concatenated with the new offset “chaincode” component of the new offset Y-share as a 64 character hex string (32 bytes). Must be provided when uploading an R share.
  - `userPublicGpgKey` string — User’s public key of the gpg key.

## Response `201`

Created

- SignatureShare
  - `from` 'user' | 'backup' | 'bitgo', required
  - `to` 'user' | 'backup' | 'bitgo', required
  - `share` string, required — The signature share.

## Other responses

- `400` — Bad Request
- `401` — Unauthorized
- `403` — Forbidden
- `404` — Not Found

---

[API](https://skmtc.net/bitgo/apis/bitgo-api.md) · [All operations](https://skmtc.net/bitgo/apis/bitgo-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/bitgo/bitgo-api/revisions/e445c15e5bee/schema)