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diff --git a/content/blog/epa-sgd-crypto/index.rst b/content/blog/epa-sgd-crypto/index.rst new file mode 100644 index 0000000..f2dd79f --- /dev/null +++ b/content/blog/epa-sgd-crypto/index.rst @@ -0,0 +1,64 @@ +--- +title: "75 Million Lives, Two Keys" +date: 2025-01-05T23:42:00+01:00 +draft: true +--- + +2025 has begun. In this new year, with its new national healthcare record system, the country of Germany will start one +of the largest rollouts of a cryptographic system in history. While the system has received scrutiny as well as +resulting harsh criticism from a number of parties ranging from NGOs to everyday civilians, the system has received +surprisingly little attention from the academic applied cryptography crowd. Additionally, previous criticism of +the system has largely revolved around organizational issues. While valid, we belive that some cryptographic issues at +the core of the system have escaped attention unitl now. In particular, at the core of the system is a key escrow system +that contains several questionable design choices and that in its overall design seems out of place in 2025. + +The aim of the system is to serve as a shared storage for all healthcare records of a person. In the system, a person's +entire patient file with all documentation on the treatment process including test results, images and other raw data +will be stored in something vaguely resembling cloud storage such that all healthcare providers that the person visits +can access the entire file. This centralized, synchronized storage eliminates the need for transferring this data +between hospitals and doctors offices by fax, mail or physical media as it was common practice until now. After a +development and testing phase lasting approximately five years, the German government decided to roll out the system to +everybody insured under Germany's mandatory national health insurance scheme, totalling approximately 75 million people, +on January 15th 2025. + +In this article, we will give an overview of the system's cryptographic design before highlighting a few odd +design choices that could amount to a viable attack vector to the powerful adversaies + +## Context and involved parties + +Germany has a national, mandatory health insurance system. The system is open to any permanent resident of the country +irrespective of citizenship. The system is mandatory in that while residents can choose between a number of both +publically owned as well as private healthcare providers, it is not possible to opt out of the system. The public health +insurance providers cover approximately 90% of German residents. These providers are organized in an umbrella +organization named "GKV Spitzenverband". The resposibility of this umbrella organization largely revolves around +negotiating prices with pharmaceutical companies and with healthcare providers as a publically sanctioned cartel, but +also includes the specification and operation of shared IT infrastructure for billing and data exchange between +healthcare providers. + +While GKV Spitzenverband is the party that ultimately holds responsibility for the regulatory administration of national +healthcare IT infrastructure, it has delegated large parts of both the technical specification of this infrastructure as +well as its day-to-day operation to Gematik GmbH, a state-owned limited liability corporation created specifically for +the purpose of developing and implementing national healthcare IT standards. The electronic healthcare record system we +describe in this article was standardized and implemented by Gematik GmbH under the direction of GKV Spitzenverband. + +Healthcare providers in Germany need to be registered with GKV Spitzenverband to serve members of public health +insurance providers. Since these public providers constitute approximately 90% market share, the vast majority of +healthcare providers are registered this way. + +## Design principles + +## Cryptographic design + +## The implied adversary model + +While Gematik GmbH publishes detailed specifications of the systems they standardize, these specifications and some +associated implementation guidelines are about the extent of public information. Software implementations are being kept +secret, and while standardization results are available, a large fraction of design rationale is discussed behind closed +doors. From an academic perspective, the most glaring omission in Gematik GmbH's public documents is any definition of a +threat model or an adversary model. As a result of this, we will deduce an adversary model below by contextualizing the +published standards in the national healthcare setting. We will base our further analysis of the system on this +adversary model. + +## Previous reviews and audits of the system + +[0] https://www.destatis.de/DE/Themen/Arbeit/Arbeitsmarkt/Qualitaet-Arbeit/Dimension-2/krankenversicherungsschutz.html |