SIMSme transmits your texts, images, videos, locations or contact data to your business partners immediately and completely secure using end-to-end encryption - entirely free of charge. No eavesdropping possible. Not even by us.
SIMSme makes the security of your communications its top priority. In addition to encryption and password protection, SIMSme also offers the possibility of checking your contacts via a QR code scanning process — so you can be sure of their identities. By the way: SIMSme uses your address book. You do not have to re-invite your contacts.
Especially important messages can be given an additional layer of security with the self-destruct feature. You can either set up a countdown so that your message can only be read for a certain amount of time or select an expiration date for the message. This will automatically make it disappear at the desired time. You therefore leave no traces on the web.
All messages sent via SIMSme are always completely private and secure against eavesdropping (and will remain so) thanks to our end-to-end encryption system. Of course, this also includes your media, contacts and locations.
You can provide your messages with an additional layer of security by using the self-destruct feature. This causes messages to be automatically deleted from the recipient's device. Please also see the section entitled "How do self-destructing messages work?".
All message sent via SIMSme are symmetrically encrypted on your phone using AES-256 and transmitted to the recipient via the SIMSme servers using SSL encryption. Your recipient needs the proper key in order to read the messages.
This key is asymmetrically encrypted and sent individually to each recipient of the message using the RSA-2048 method. With this approach, a public key is used for encryption and a private key for decryption with the private key never leaving the user's phone, as it is only saved locally. Hence, the key, which will ultimately be needed to read the message, can only be decrypted on the recipient's smartphone.
Other communication partners, we the operators of SIMSme, as well as any other would-be attackers who might be attempting to acquire the AES key, are therefore incapable of decrypting and reading the encrypted message.
For more information, please head over to: www.sims.me/security
To send a message using the self-destruct function, you first have to write a chat message as usual (or attach a file, contact or location, depending on what you would like to communicate). After that is done, you have to "arm the detonator" by clicking on the bomb symbol to the left of the text input field.
You can now select between a countdown and a specific "self-destruction time".
If you choose a countdown, your message is only readable for a certain amount of time. If you, for example, set a countdown of 10 seconds, your recipient will only have 10 seconds to read the message after opening it. To open the message, the recipient has to tap on the screen with his finger. This type of message is ideal if you would like to ensure that the recipient will definitely receive the message, but do not want it to be permanently stored in his chat history.
If you select a certain point in time, then the message can be read until that date and time has been reached, regardless of whether the recipient opens the message or not. If you, for example, set tomorrow at 9 p.m. as the point in time, your recipient can read the message as often as he would like (or not at all) until tomorrow at 9 p.m. After that point in time, the message will automatically be deleted. This could, for example, be useful if you would like to tell your contact about a meeting point where you will be located up to a certain point in time, after which you will be moving on.
You can see how sure you can be of your contact's identity based on the colour coding of your SIMSme contacts.
A red status means that we have found the contact — that this contact is using SIMSme, but that you have never chatted with each other at this point.
Yellow means that you have been in contact before. Your contact and you have already exchanged messages at an earlier point in time and the other person has confirmed that he knows you (his contact).
Green is the highest level of trust. In order to achieve green status, you not only have to have exchanged messages before, but you also have to have met in person and exchanged your SIMSme keys by scanning the associated QR code.
The QR code can be opened via "Settings" → "Profile". The scan is performed by opening the respective contact from the "Contacts" list and tapping on "Scan contact".
In order to connect to your existing contacts using SIMSme, we have to compare your phone/address book to our user list in a hashed manner. Of course, this process is also entirely encrypted. Naturally, your phone/address book will not be stored on our servers.
Using this approach, we can connect you to your contacts without the need to request every single one of your phone/address book contacts again within SIMSme.
SIMSme requires access to Push Notifications in order to actively inform you of new messages. If you did not grant SIMSme access to Push Notifications, you have to actively retrieve your messages from our server by dragging the chat overview downwards.
The password is an important security anchor of SIMSme's privacy concept and is only stored locally on your phone.
This means that your password is not transmitted to our servers. We therefore ensure that your password cannot be intercepted under any circumstances and also that your messages can never be decrypted by unauthorised people.
However, this also means that we cannot reset and restore your password. We therefore advise you to write your password down and store it in a safe location.