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API Authentication

How to create and use a Prime API key

Generating an API Key

Certain API endpoints require authentication and request signing to access. You will need to create an API key via Coinbase Prime website to interact with these resources.


The API is currently scoped to individual portfolios.

Signing Requests

Prime REST API requests must include an access signature header.


All REST API requests must contain the following headers

  • X-CB-ACCESS-KEY: The API key as a string
  • X-CB-ACCESS-PASSPHRASE: The Passphrase shown when creating the API key
  • X-CB-ACCESS-SIGNATURE: The base64-encoded signature
  • X-CB-ACCESS-TIMESTAMP: A timestamp for your request

Selecting a Timestamp

The X-CB-ACCESS-TIMESTAMP header MUST be number of seconds since Unix Epoch in UTC. Decimal values are not allowed. Make sure to use an integer.

Your timestamp must be within 30 seconds of the api service time or your request will be considered expired and rejected.

Creating a Request Signature

The X-CB-ACCESS-SIGNATURE header is generated by creating a sha256 HMAC using the secret key on the prehash string timestamp + method + requestPath + body (where + represents string concatenation) and base64-encode the output. The timestamp value is the same as the X-CB-ACCESS-TIMESTAMP header.

The requestPath should only include the path of the API endpoint. Do NOT include the base URL or query parameters when creating the signature.

Example valid requestPath to include in the string for hashing:


Example invalid requestPath:<YOUR_PORTFOLIO_ID_HERE>/open_orders?order_type=LIMIT

The body is the request body string or omitted if there is no request body (typically for GET requests).

The method should be UPPER CASE e.g. GET or POST.


Remember to base64-encode the digest output before sending in the header.

Request Signature Generation Examples

// Function to generate a signature using Google's crypto-js package
function sign(str, secret) {
 const hash = CryptoJS.HmacSHA256(str, secret);
 return hash.toString(CryptoJS.enc.Base64);

// Function to build the payload required to sign
function buildPayload(ts, method, requestPath, body) {
 return `${ts}${method}${requestPath}${body}`;

// Build the string we want to sign using information defined above
const strToSign = buildPayload(Math.floor( / 1000), "GET", "/v1/portfolios/<YOUR_PORTFOLIO_ID_HERE>/orders", "");

// Sign it!
const sig = sign(strToSign, SIGNING_KEY);
timestamp =
what = "#{timestamp}#{method}#{request_path}#{body}";
# create a sha256 hmac with the secret
secret = Base64.decode64(@secret)
hash = OpenSSL::HMAC.digest('sha256', secret, what)
import json, hmac, hashlib, time, base64 
#timestamp = str(int(time.time())) 
#request.method = GET 
#request.path_url.split('?')[0] = /v1/portfolios/{portfolio_id}/orders 
message = timestamp + request.method + request.path_url.split('?')[0] + str(request.body or '') 
signature ='utf-8'), message.encode('utf-8'), digestmod=hashlib.sha256).digest() 
signature_b64 = base64.b64encode(signature).decode()