Every Myki user has a unique RSA2048 private/public Encryption key pair.
The public key can be shared with any user online without any risk to the owner and is used by the sender to encrypt the password being shared. In other terms, whenever you want to share a password with a Myki user, you start by selecting the user from your contacts list on your phone, this requests the recipient's public key.
Whenever your Myki app receives the recipients public key it encrypts the password that you want to share using it and sends it to his smartphone via a P2P encrypted connection. The user receives the encrypted password and uses his private key to decrypt it. All of this happens in the background.
As a user, all you need to do is click on an account in the Myki app then select share and select the contact from your contact list.