Contacts - SafeSlingerProject/SafeSlinger-Media GitHub Wiki

Contacts are simultaneously and securely exchanged and verified in the SafeSlinger Messenger. For detailed information on how we securely verify contacts see our exchange protocol design.

Inviting Contacts

You can send an email or text message to anyone inviting them to join you for secure communication on SafeSlinger. Choose the menu item "Add Contact Invite" from the recipients list to start an email or text message which will include instructions and a link to install the application. Afterwards a pending invitation will appear in your recipients list. Once you "sling keys", the invitation in your recipients list will be enabled for secure communication. Sending a contact invite is not required, it's a convenience to share the application link over an insecure channel. Inviting contacts is currently available in the Android version, the iOS version has been developed, but not yet released.

Adding Contacts: "Sling Keys"

Contacts can be added in the Messenger when you "Sling Keys" with another user. "Sling Keys is the nickname for the SafeSlinger exchange protocol which allows you to securely exchange and verify your key with another user. Two users or a group may sling keys simultaneously. SafeSlinger does not store a list of users on its servers, so there is no automated contact discovery process. See our exchange instructions page for more information.

Local Sling Keys

You can Sling Keys with other users locally, in the same room or within speaking distance. At minimum, you need to install SafeSlinger on your phone as well as the other user's phone, and an Internet connection must be active on both phones. When exchanging keys, you only need to compare one number and one 3-word phrase with other users. When doing this comparison, you must be able to either see the other user's phone screen or hear the number and phrases spoken so you can verify the physical presence of the other user.

Remote Sling Keys

You can also Sling Keys with other users remotely, over the telephone or video chat. Since you may perform an exchange if you can hear the other user at the same time, you may call another user to make the exchange. However, since some cellular carriers do not permit an Internet connection to be active while making a voice call, you may consider using another Internet service like video chat on your phone, or a separate landline in that case.

Contact Editing

Users are not required to send a photo or other contact information, just a name when they sling keys with you. Even then, the name they use may be only initials or otherwise anonymous. You may edit any contact to update the photo and name locally on your device after slinging keys by long-pressing on the contact in the recipient list. This will allow you to select and edit which of your contacts from your address book to use. Contact editing is currently available in the Android version, the iOS version has been developed, but not yet released.

Secure Introduction

It may not be possible to two users to meet physically or communicate on the phone at the same time to sling keys. In this case, we've added secure introductions so that you can securely send the keys of two people whom you have verified physically to each other remotely.