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fix: 3 typos found by fossies.org

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Sebastian Wolf 2020-06-12 09:20:52 +02:00
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overview-security.md
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@ -355,7 +355,7 @@ The following chapters contain a brief introduction to each capability.
### Technical Cyber Resilience
#### Subject
- Technical Cyber Resilience solutions defend against specific threats. They are planed, built and operated based on threat exposure. This includes reaction processes for alerts.
- Technical Cyber Resilience solutions defend against specific threats. They are planned, built and operated based on threat exposure. This includes reaction processes for alerts.
- Examples: distributed denial-of-service (DDoS) attack protection, intrusion detection systems (IDS) / intrusion prevention systems (IPS), APT detection, antivirus, web application firewalls, proxies, spam filter.
#### Objective
- Minimize impact of specific threats and attacks that consist of:

4
solution_architecture.md
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@ -39,7 +39,7 @@ Identifiers are ID numbers sent out by the mobile phones. To ensure privacy and
The collected identifiers from other users as well as the own keys, which can later be used to derive the identifiers, are stored locally on the phone in the secure storage of the framework provided by Apple and Google. The application cannot access this secure storage directly, but only through the interfaces the Exposure Notification Framework provides. To prevent misuse, some of these interfaces are subjected to [rate limiting](https://developer.apple.com/documentation/exposurenotification/enmanager/3586331-detectexposures). If app users are tested positively for SARS-CoV-2, they can update their status in the app by providing a verification of their test and select an option to send their recent keys from up to 14 days back. On the Corona-Warn-App back-end server, all keys of positively tested individuals are aggregated and are then made available to all mobile phones that have the app installed. Additionally, the configuration parameters for the framework are available for download, so that adjustments to the risk score calculation can be made, see the *Risk Scores* section.
Once the keys and the exposure detection configuration have been downloaded, the data is handed over to the Exposure Notification Framework, which analyzes whether one of the identifiers collected by the mobile phone matches those of a positively tested individual. Additionally, the metadata that has been broadcasted together with the identifiers such as the transmit power can now be decrypted and used. Based on the collected data, the Exposure Notification Framework provided by Apple and Google calculates a risk score for each individual exposure as well as for the overall situation. Exposures are defined as an aggregation of all encounters with another individual on a single calendar day (UTC timezone). For privacy reasons, it is not possible to track encounters with other individuals across multiple days.
It is important to note that the persons that have been exposed to a positively tested indivdual are **not informed by a central instance**, but the risk of an exposure is calculated locally on their phones. The information about the exposure remains on the user’s mobile phone and is not shared.
It is important to note that the persons that have been exposed to a positively tested individual are **not informed by a central instance**, but the risk of an exposure is calculated locally on their phones. The information about the exposure remains on the user’s mobile phone and is not shared.
The Corona-Warn-App pursues two objectives:
1. It supports individuals in finding out whether they have been exposed to a person that has later been tested positively.
@ -222,7 +222,7 @@ As the values above are multiplied with each other, a single category with a ris
Additionally, a central threshold for the combined risk score specifies whether an exposure event should be considered or not.
Furthermore the Google/Apple framework allows to set a [```minimalRiskScore```](https://developer.apple.com/documentation/exposurenotification/enexposureconfiguration/3583692-minimumriskscore) to exclude exposure incidents with scores lower than the value of this property.
In the current version of the API the time spent within the ranges of attenuation buckets are accumulated over all exposure incidents during one matching session.
Since the number of requests is currently limited, it is not possible to get these values for each day and each exposure incident seperately.
Since the number of requests is currently limited, it is not possible to get these values for each day and each exposure incident separately.
While by default there is no minimum value set, this value is being configured accordingly, so that resumably irrelevant exposure incidents are excluded.
![Figure 13: Calculation of the combined risk score](images/solution_architecture/figure_13.svg "Figure 13: Calculation of the combined risk score")