For　wearable　devices　with　constrained　computational　resources,　it　is　typically　required　to　offload　processing　tasks　to　more　capable　servers.　However,　this　practice　introduces　vulnerabilities　to　data　confidentiality　and　integrity　due　to　potential　malicious　network　attacks,　unreliable　servers,　and　insecure　communication　channels.　A　robust　mechanism　that　ensures　anonymous　authentication　and　key　agreement　is　therefore　imperative　for　safeguarding　the　authenticity　of　computing　entities　and　securing　data　during　transmission.　Recently,　Guo　et　al.　proposed　an　anonymous　authentication　key　agreement　and　group　proof　protocol　specifically　designed　for　wearable　devices.　This　protocol,　benefiting　from　the　strengths　of　previous　research,　is　designed　to　thwart　a　variety　of　cyber　threats.　However,　inaccuracies　in　their　protocol　lead　to　issues　with　authenticity　verification,　ultimately　preventing　the　establishment　of　secure　session　keys　between　communication　entities.　To　address　these　design　flaws,　an　improved　ultra-lightweight　protocol　was　proposed,　employing　cryptographic　hash　functions　to　ensure　authentication　and　privacy　during　data　transmission　in　wearable　devices.　Supported　by　rigorous　security　validations　and　analyses,　the　proposed　protocol　significantly　boosts　both　security　and　efficiency,　marking　a　substantial　advancement　over　prior　methodologies.　　©　2002-2012　IEEE.