Although Apple does not exhibit at Mobile World Congress, the giant trade show in Barcelona, the company casts a long shadow over it.The iPhone maker's influence there extends to app developers, accessory vendors and, now, the debate about securing digital identity.In a keynote session on security at the show, moderator Michael O'Hara asked presenters whether they sided with Apple or the U.S. government in the legal dispute over whether Apple should help the Federal Bureau of Investigation unlock an iPhone belonging to the employer of one of the San Bernardino attack suspects.[ ALSO ON CSO: DOJ ups ante: New motion asks court to force Apple to help FBI crack attacker's iPhone ]For Simon Segars, CEO of ARM, the company that designs the microprocessors found in most smartphones, "It's a complex situation, there are rights and wrongs."For the last few years, ARM has been encouraging its customers to adopt better security practices in designing their products. Its processor core designs, including those used by Apple for its iPhone and iPad chips, contain a secure "TrustZone" for protecting authentication mechanisms and cryptographic keys.Security experts generally concur that the "Secure Enclave\u201d found in recent Apple phones -- although not the iPhone 5c that is causing the FBI so many problems -- is built on ARM's TrustZone, although Apple has not commented on the matter.TrustZone is useful not just to smartphone designers but to anyone building devices that need to maintain the security of communications even when someone has physical access to them."With the Internet of Things, we are only just getting started when we consider these issues," Segars continued. "Now is a good time to ensure we have a legal framework to decide who owns our data.""We believe users should own their data and control who has access to it, but obviously there are some extreme circumstances where that should change," he said, appearing to side with the FBI.However, Segars didn't explain whether, or how, ARM's TrustZone technology could be circumvented in such extreme circumstances.For the CEO of biometrics and secure identity company Morpho, Anne Bouverot, the big question is whether security and convenience are compatible."We want both," she said. "We want to be able to use smartphones, we store more money on them than under our mattresses and we have more secrets on them than we tell our best friends.""Privacy is very important but at the same time we want the government to protect us from terrorist attacks."Bouverot, whose company has many government customers, also gave weight to the FBI's arguments in the dispute over access to the phone used by Syed Rizwan Farook."The U.S. government wants to look at his employer's phone and I think this is also important," she said. "Technology has to find a way to give both privacy and security."Next up was Pavel Durov, CEO of Berlin-based encrypted messaging company Telegram.Apple CEO Tim Cook has said it would be dangerous if the company were to provide the FBI with the tools that could help it to crack the passcode of the iPhone 5c, running iOS 9, by brute force. A court in California has ordered Apple to provide the required assistance to the FBI.Asked about the Apple vs. FBI case, Durov didn't mince his words: "I definitely side with Tim Cook on this," he said to a smattering of applause. Segars' and Bouverot's responses had been greeted with silence from the audience."There's always going to be a risk that your iPhone could be stolen and people could use the data in it against you. If we increase the risk that an iPhone could be unlocked, it's extremely dangerous," Durov concluded.