String key='xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx';
Blob privateKey = EncodingUtil.base64Decode(key);
String signature = System.encodingUtil.base64Encode( Crypto.sign('RSA-SHA256', Blob.valueOf(jwtRequest), privateKey)).replace('+', '-').replace('/', '_');
import hmac,hashlibfrom base64 import b64encode, b64decode res = hmac.new(input_key,message, digestmod=hashlib.sha256).hexdigest()