go to post Jukka Pitkänen · Apr 6, 2022 Solution was easier than I thought. Set key = "secretkey"Set message = "messageinabottle"Set secretByteArray = ##class(%SYSTEM.Encryption).Base64Decode(key)Set signatureBytes = $SYSTEM.Encryption.HMACSHA(256, message, secretByteArray) Set requestSignatureBase64String = ##class(%SYSTEM.Encryption).Base64Encode(signatureBytes)