I am developing a software in which I am using AES for encrypting messages shared in a group. The key is generated by one user, the admin of the group and needs to be shared with other members. How can I share this key with all other members of the group securely?
Are protocols like Needham-Schroeder, Diffie-Hellman applicable in my case? (I don't know much about cryptography)
PS: Can I encrypt the 'group key' generated by admin using AES, and save it on a server? The other users can request the server for the encrypted key and then decrypt it. The key used for encrypting and decrypting the 'group key' will be pre-shared (embedded in the software).