Telegrams security model has received notable criticism by cryptography experts. They criticized the general security model of permanently storing all contacts, messages and media together with their decryption keys on its servers by default and by not enabling
end-to-end encryption for messages by default.[sup]
[26][/sup][sup]
[27][/sup] Pavel Durov has argued that this is because it helps to avoid third-party unsecure backups, and to allow users to access messages and files from any device.[sup]
[28][/sup] Cryptography experts have furthermore criticized Telegrams use of a custom-designed encryption protocol that has not been proven reliable and secure.
