LWM2M Security 0 TBD Multiple Mandatory LWM2M Server URI Single Mandatory String 0-255 bytes Bootstrap Server Single Mandatory Boolean Security Mode Single Mandatory Integer 0-3 Public Key or Identity Single Mandatory Opaque Server Public Key or Identity Single Mandatory Opaque Secret Key Single Mandatory Opaque SMS Security Mode Single Mandatory Integer 0-255 SMS Binding Key Parameters Single Mandatory Opaque 6 bytes SMS Binding Secret Keys Single Mandatory Opaque 32-48 bytes LWM2M Server SMS Number Single Mandatory Integer Short Server ID Single Optional Integer 1-65535 Client Hold Off Time Single Mandatory Integer s