This is a implementation of JSON Web Tokens for Nim, it allows for the following operations to be performed:
proc toJWT*(node: JsonNode): JWT
- parse a JSON object representing a JWT token to create a JWT token object.
proc toJWT*(s: string): JWT
- parse a base64 string to decode it to a JWT token object
sign*(token: var JWT, secret: string)
- sign a token. Creates a signature
property on the given token and assigns the signature to it.
proc verify*(token: JWT, secret: string, alg: SignatureAlgorithm): bool
- verify a token (typically on your incoming requests)
proc $*(token: JWT): string
- creates a b64url string from the token
An example to demonstrate use with a userId
import jwt, times, json, tables
var secret = "secret"
proc sign(userId: string): string =
var token = toJWT(%*{
"header": {
"alg": "HS256",
"typ": "JWT"
},
"claims": {
"userId": userId,
"exp": (getTime() + 1.days).toSeconds().int
}
})
token.sign(secret)
result = $token
proc verify(token: string): bool =
try:
let jwtToken = token.toJWT()
result = jwtToken.verify(secret, HS256)
except InvalidToken:
result = false
proc decode(token: string): string =
let jwt = token.toJWT()
result = $jwt.claims["userId"].node.str
Getting google api oauth2 token:
import jwt, json, times, httpclient, cgi
const email = "[email protected]" # Acquired from google api console
const scope = "https://www.googleapis.com/auth/androidpublisher" # Define needed scope
const privateKey = """
-----BEGIN PRIVATE KEY-----
The key should be Acquired from google api console
-----END PRIVATE KEY-----
"""
var tok = initJWT(
header = JOSEHeader(alg: RS256, typ: "JWT"),
claims = toClaims(%*{
"iss": email,
"scope": scope,
"aud": "https://www.googleapis.com/oauth2/v4/token",
"exp": int(epochTime() + 60 * 60),
"iat": int(epochTime())
}))
tok.sign(privateKey)
let postdata = "grant_type=" & encodeUrl("urn:ietf:params:oauth:grant-type:jwt-bearer") & "&assertion=" & $tok
proc request(url: string, body: string): string =
var client = newHttpClient()
client.headers = newHttpHeaders({ "Content-Length": $body.len, "Content-Type": "application/x-www-form-urlencoded" })
result = client.postContent(url, body)
client.close()
let resp = request("https://www.googleapis.com/oauth2/v4/token", postdata).parseJson()
echo "Access token is: ", resp["access_token"].str
This library requires a recent version of libcrypto. Specifically the one that
has EVP_DigestSign*
functions.