> For the complete documentation index, see [llms.txt](https://docs.gobtcpay.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.gobtcpay.com/api-reference/wallet-api/authentication.md).

# Authentication

Challenge–response authentication. Request a message to sign with the wallet key, exchange the signature for a JWT pair, and refresh it.

## Get sign-in challenge

> Starts the authentication challenge. Returns a one-time \`messageToSign\` and a \`challengeId\` bound to the supplied public key (valid until \`expiresAt\`, \~5 min). Sign \`messageToSign\` verbatim with the corresponding private key using Bitcoin message signing (secp256k1 ECDSA), then exchange it for tokens via \*\*Get access tokens\*\*.

```json
{"openapi":"3.1.0","info":{"title":"GoBTC Pay Wallet API","version":"1.45.2"},"tags":[{"name":"Authentication","description":"Challenge–response authentication. Request a message to sign with the wallet key, exchange the signature for a JWT pair, and refresh it."}],"servers":[{"url":"https://api.gobtcpay.com/public/api/v1.1"}],"security":[],"paths":{"/instant/auth/get-data-to-sign":{"post":{"summary":"Get sign-in challenge","description":"Starts the authentication challenge. Returns a one-time `messageToSign` and a `challengeId` bound to the supplied public key (valid until `expiresAt`, ~5 min). Sign `messageToSign` verbatim with the corresponding private key using Bitcoin message signing (secp256k1 ECDSA), then exchange it for tokens via **Get access tokens**.","tags":["Authentication"],"parameters":[],"requestBody":{"required":true,"content":{"application/json":{"schema":{"type":"object","properties":{"userPubKeyHex":{"type":"string","description":"Public key of the user's Bitcoin wallet to authenticate — compressed secp256k1 key, hex (33 bytes / 66 chars)."}},"required":["userPubKeyHex"],"additionalProperties":false,"$schema":"http://json-schema.org/draft-07/schema#"}}}},"responses":{"200":{"description":"Successful response","content":{"application/json":{"schema":{"type":"object","properties":{"id":{"type":"string"},"result":{"type":"object","properties":{"$case":{"type":"string","const":"success"},"success":{"type":"object","properties":{"challengeId":{"type":"string","description":"Unique id of this challenge. Pass it back to **Get access tokens** together with your signature."},"messageToSign":{"type":"string","description":"Message to sign verbatim with the wallet private key (Bitcoin message signing, secp256k1)."},"expiresAt":{"type":"integer","minimum":0,"description":"When the challenge expires, Unix timestamp (seconds). Sign and submit before this time (~5 min)."}},"required":["challengeId","messageToSign","expiresAt"],"additionalProperties":false}},"required":["$case","success"],"additionalProperties":false}},"required":["id","result"],"additionalProperties":false,"$schema":"http://json-schema.org/draft-07/schema#"}}}},"500":{"description":"Error response","content":{"application/json":{"schema":{"type":"object","properties":{"error":{"type":"object","properties":{"statusCode":{"type":"number","description":"Numeric error status code."},"description":{"type":"string","description":"Human-readable description."},"statusMessage":{"type":"string","description":"Short machine-readable error message."}},"required":["statusCode","description","statusMessage"],"additionalProperties":false}},"required":["error"],"additionalProperties":false,"$schema":"http://json-schema.org/draft-07/schema#"}}}}}}}}}
```

## Get access tokens

> Completes the authentication challenge. Submit the \`challengeId\` from \*\*Get sign-in challenge\*\* together with the hex-encoded 64-byte compact \`signature\` of \`messageToSign\`. Returns a short-lived \`accessToken\` (send it as \`Authorization: Bearer \<accessToken>\`) and a long-lived \`refreshToken\`.

```json
{"openapi":"3.1.0","info":{"title":"GoBTC Pay Wallet API","version":"1.45.2"},"tags":[{"name":"Authentication","description":"Challenge–response authentication. Request a message to sign with the wallet key, exchange the signature for a JWT pair, and refresh it."}],"servers":[{"url":"https://api.gobtcpay.com/public/api/v1.1"}],"security":[],"paths":{"/instant/auth/get-jwt":{"post":{"summary":"Get access tokens","description":"Completes the authentication challenge. Submit the `challengeId` from **Get sign-in challenge** together with the hex-encoded 64-byte compact `signature` of `messageToSign`. Returns a short-lived `accessToken` (send it as `Authorization: Bearer <accessToken>`) and a long-lived `refreshToken`.","tags":["Authentication"],"parameters":[],"requestBody":{"required":true,"content":{"application/json":{"schema":{"type":"object","properties":{"challengeId":{"type":"string","description":"The `challengeId` returned by **Get sign-in challenge** (`/instant/auth/get-data-to-sign`)."},"signature":{"type":"string","description":"Hex-encoded 64-byte compact signature of the `messageToSign` from **Get sign-in challenge**."}},"required":["challengeId","signature"],"additionalProperties":false,"$schema":"http://json-schema.org/draft-07/schema#"}}}},"responses":{"200":{"description":"Successful response","content":{"application/json":{"schema":{"type":"object","properties":{"id":{"type":"string"},"result":{"type":"object","properties":{"$case":{"type":"string","const":"success"},"success":{"type":"object","properties":{"accessToken":{"type":"string","description":"Short-lived JWT access token. Send it as `Authorization: Bearer <accessToken>` on authenticated requests."},"refreshToken":{"type":"string","description":"Long-lived JWT refresh token. Use it at **Refresh access tokens** to obtain a new token pair."}},"required":["accessToken","refreshToken"],"additionalProperties":false}},"required":["$case","success"],"additionalProperties":false}},"required":["id","result"],"additionalProperties":false,"$schema":"http://json-schema.org/draft-07/schema#"}}}},"500":{"description":"Error response","content":{"application/json":{"schema":{"type":"object","properties":{"error":{"type":"object","properties":{"statusCode":{"type":"number","description":"Numeric error status code."},"description":{"type":"string","description":"Human-readable description."},"statusMessage":{"type":"string","description":"Short machine-readable error message."}},"required":["statusCode","description","statusMessage"],"additionalProperties":false}},"required":["error"],"additionalProperties":false,"$schema":"http://json-schema.org/draft-07/schema#"}}}}}}}}}
```

## Refresh access tokens

> Exchanges a valid refresh token for a fresh \`accessToken\` / \`refreshToken\` pair without repeating the signing challenge. Send the refresh token as \`Authorization: Bearer \<refreshToken>\` with an empty body.

```json
{"openapi":"3.1.0","info":{"title":"GoBTC Pay Wallet API","version":"1.45.2"},"tags":[{"name":"Authentication","description":"Challenge–response authentication. Request a message to sign with the wallet key, exchange the signature for a JWT pair, and refresh it."}],"servers":[{"url":"https://api.gobtcpay.com/public/api/v1.1"}],"security":[{"walletAuth":[]}],"components":{"securitySchemes":{"walletAuth":{"type":"http","scheme":"bearer","bearerFormat":"JWT","description":"Wallet access token obtained from `/instant/auth/get-jwt` via the signature challenge flow. Send it as `Authorization: Bearer <accessToken>`. Refresh it via `/instant/auth/refresh-jwt` when it expires."}}},"paths":{"/instant/auth/refresh-jwt":{"post":{"summary":"Refresh access tokens","description":"Exchanges a valid refresh token for a fresh `accessToken` / `refreshToken` pair without repeating the signing challenge. Send the refresh token as `Authorization: Bearer <refreshToken>` with an empty body.","tags":["Authentication"],"parameters":[],"responses":{"200":{"description":"Successful response","content":{"application/json":{"schema":{"type":"object","properties":{"id":{"type":"string"},"result":{"type":"object","properties":{"$case":{"type":"string","const":"success"},"success":{"type":"object","properties":{"accessToken":{"type":"string","description":"Short-lived JWT access token. Send it as `Authorization: Bearer <accessToken>` on authenticated requests."},"refreshToken":{"type":"string","description":"Long-lived JWT refresh token. Use it at **Refresh access tokens** to obtain a new token pair."}},"required":["accessToken","refreshToken"],"additionalProperties":false}},"required":["$case","success"],"additionalProperties":false}},"required":["id","result"],"additionalProperties":false,"$schema":"http://json-schema.org/draft-07/schema#"}}}},"500":{"description":"Error response","content":{"application/json":{"schema":{"type":"object","properties":{"error":{"type":"object","properties":{"statusCode":{"type":"number","description":"Numeric error status code."},"description":{"type":"string","description":"Human-readable description."},"statusMessage":{"type":"string","description":"Short machine-readable error message."}},"required":["statusCode","description","statusMessage"],"additionalProperties":false}},"required":["error"],"additionalProperties":false,"$schema":"http://json-schema.org/draft-07/schema#"}}}}}}}}}
```


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