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Simsme

The free Secure Instant Messenger by Deutsche Post — for confidential communication using your smartphone — on both Android and iOS.

Download on the AppStoreJetzt bei Google PlayJetzt bei Google PlayJetzt im Windows Store

SIMSme is the new Secure Instant Messenger by Deutsche Post AG. With more than 500 years of experience with the transmission of messages, Deutsche Post is the perfect partner when it comes to reliable and secure communication

Highlights

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Encrypted Instant Messenger

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.

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Security

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.

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Self-destruct feature

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.

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FAQs

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Are my messages really secure?

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?".

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How does SIMSme's end-to-end encryption 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

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How do self-destructing messages work?

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.

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How does SIMSme's "Trust Status" system work?

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".

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What can I do if I forget my password?

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.

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Can I use the SIMSme backup function to transfer existing cloud solutions to a new mobile?

The key used by SIMSme to encrypt or decrypt messages is device-specific. This is in the interest of security, which is at the core of SIMSme: Only this ensures that a SIMSme version cannot be "cloned" on a different device, thereby preventing identity theft. This means that when a new device is purchased, SIMSme must be downloaded again and the registration must be repeated.

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Why do I keep receiving a message saying that one of my SIMSme contacts has recently registered even though they are a SIMSme contact already?

If one of your contacts re-registers (for instance, because they have forgotten their password), they are identified as a new user. A new message providing information about this is then sent out as well.

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How is SIMSme financed? Are advertisements displayed? How does SIMSme manage to be and to remain free of cost?

With a little imagination, it is possible to conceive a variety of re-financing models: We are, for instance, also thinking of offering SIMSme as a secure communication tool for corporate use in the future, albeit at a cost. For private users, however, SIMSme will always remain free of charge.

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How is SIMSme to be made more widespread? What plans do you have to make it appeal to the masses?

Firstly we are naturally investing more in increasing the awareness of the SIMSme brand and secondly we are also continuously developing SIMSme further so as to excite our users about our product. What is clear is that SIMSme can only be enjoyed once it becomes sufficiently widespread. Every little bit will help in the future. This is why we have the following request to make to our users: If you like SIMSme, tell your friends about it!

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Are other operating systems (including Windows, Blackberry or Amazon) going to be supported in the near future, too? Are there plans for a desktop version?

We are taking a close look at what our customers want and which other systems are being requested. If there is sufficient demand then naturally we will make SIMSme available to operating systems other than Android and iOS versions. We are also testing a Desktop version. Because of the end-to-end encryption, however, desktop and multi-device operation is no trivial matter.

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Is the secret key provided only to the user? If so, would all communication be lost if the application were to be re-installed?

The secret key is, indeed, only provided to the user. In the case of re-installation, all previous chats would therefore be lost. We are planning a solution that would give users the opportunity to transfer or backup their data to another device via the cloud at their own risk. Solutions of this kind may, however, involve compromises in terms of security.

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Are images/videos compressed for purposes of transmission in order to ease traffic?

Yes, images and videos are compressed for purposes of transmission. This eases traffic and also causes calculations made during the encryption process to be curtailed. However, we are concomitantly working towards a function enabling users to send their images and videos in their original resolution if they so wish.

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Where exactly are the servers that are responsible for making SIMSme available?

The servers are located in Germany – in the vicinity of Berlin, to be precise.

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Regarding self-destructing messages: What happens if my chat partner is absent at the time and the countdown has expired? Does the countdown begin only once they are also sure to have read the message or immediately after the message is sent?

Naturally the countdown begins only once the chat partner has also opened the message. To be precise, the chat partner must keep their finger on the screen for the message to be displayed.

As an alternative to the countdown, however, a time can be pre-defined if such a function is desired. In this case, the chat partner will then indeed only be able to view the message up to a particular time. If the message has not been read by that time then it will no longer be available.

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Are you considering introducing a setting to the function so that the password would not be requested each time the application is launched?

This is already possible: The automated password request feature can be completely turned off or configured so that the password is only requested after 1, 5 or 10 minutes after the application was last in use. However, this is purely for convenience and is not recommended by us as it can involve compromises in terms of security.

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I’m getting network errors constantly! What is going on?

Please check if your connected to the internet. If so and the problem persists, please also read the answer on the question “Does SIMSme work with my security software?”

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Does SIMSme work with my security software?

Generally SIMSme does work with any security software. It can however lead to problems if data streams are constantly analyzed by a security software, since SIMSme could identify the constant surveillance as a security problem. If there are problems when sending or receiving messages, please try to exclude SIMSme from the surveillance through security software.

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Simsme

The free Secure Instant Messenger by Deutsche Post — for confidential communication using your smartphone — on both Android and iOS.

Download on the AppStoreJetzt bei Google PlayJetzt bei Google PlayJetzt im Windows Store