> For the complete documentation index, see [llms.txt](https://docs.simpleokr.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.simpleokr.com/developer-api/authentication.md).
# Authentication
Simple OKR uses API keys to authenticate requests. You can manage API keys via [Simple OKR website](https://simpleokr.com).
### API Keys
API keys consist of public and secret components.
Public component (called `Credential`) is used to identify the API key on Simple OKR servers. The secret component (called `Secret Key`) is used to construct a request signature. The secret component should be kept private and not shared with anyone.
### S1-HMAC-SHA256 authentication protocol
`S1-HMAC-SHA256` is the first version of authentication protocol used by the Simple OKR API.
All requests must include HTTP `Authorization` header in the following format:
```
Authorization: S1-HMAC-SHA256 Credential=&Timestamp=&Signature=
```
Authorization header arguments:
* **credential** is the public component of the API key.
* **timestamp** is the RFC 3339 timestamp of the current time in UTC. Your clock must be synchronized. We will allow 10 minute clock skew in either direction.
* **signature** is a signature constructed using the secret key, credential and the timestamp.
The signature is constructed by concatenating `credential` with `timestamp` and applying HMAC-SHA256 with the secret key. The output of HMAC must be encoded in hex and converted to lower case. This value becomes the signature.
Below are examples API keys and the signature they should produce. Use this example to validate your own signature generation methods:
* Credential: `mycredential`
* Secret key: `mysecret`
* Timestamp: `2019-02-03T01:55:37Z`
* Signature: `ab9b15c8321dd0e00bbbcc8e33629adcb273b1dfeedb54387cb305fca6c409fa`
Example signature generation with Go:
```go
import (
"crypto/hmac"
"crypto/sha256"
"encoding/hex"
"strings"
"time"
)
func hmacSign(secret string, data string) string {
mac := hmac.New(sha256.New, []byte(secret))
mac.Write([]byte(data))
return strings.ToLower(hex.EncodeToString(mac.Sum(nil)))
}
func main() {
credential := "mycredential"
secret := "mysecret"
timestamp := time.Now().UTC().Format(time.RFC3339)
signature := hmacSign(secret, credential+timestamp)
println(credential, secret, timestamp, signature)
}
```
Example signature generation with Python 3:
```python
import hmac
import hashlib
credential = b"mycredential"
secret = b"mysecret"
timestamp = b"2019-02-03T01:55:37Z"
mac = hmac.new(bytearray(secret), digestmod=hashlib.sha256)
mac.update(bytearray(credential + timestamp))
digest = mac.hexdigest()
print(credential, secret, timestamp, digest)
```
---
# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:
```
GET https://docs.simpleokr.com/developer-api/authentication.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.