Stefan Berger
Senior Specialist Finance - Opportunity To Cash at Telefónica Germany GmbH & Co OHG
Dusseldorf, North Rhine-Westphalia, Germany
Summary
🤩
Rockstar🎓
Top SchoolStefan Berger is a finance operations leader with 16 years of experience optimizing Opportunity-to-Cash processes and managing international accounts payable and collections across DACH and Northern Europe. At Telefónica Germany he drives digitalization and process centralization initiatives, aligning IT implementations with IFRS and HGB reporting and audit requirements. He has a strong track record delivering complex projects—such as EMEA AP centralization and travel-expense system rollouts—while coordinating stakeholders across finance, tax, and external auditors. Unusually for a senior finance professional, Stefan is also an active open-source contributor focused on security and low-level backend work, with contributions to high-profile projects like edk2, rpm, libvirt and containerd around TPM, integrity measurement and package-security features. That combination of hands-on technical security insight and deep transactional finance expertise helps him design robust, auditable processes that scale across borders. Based in Düsseldorf, he brings pragmatic leadership and a systems-thinking approach to finance transformation.
16 years of coding experience
17 years of employment as a software developer
Diplom Betriebswirt, Diplom Betriebswirt at Fachhochschule Düsseldorf
German, English
Github Skills (72)
archiving10
package-management10
python10
testing10
firmware10
c1110
security10
c1710
libarchive10
image-management10
coding-style10
emulation10
x509certificate210
system-programming10
qemu10
Programming languages (8)
Github contributions (5)
stefanberger/swtpm
Dec 2014 - Jan 2023
Libtpms-based TPM emulator with socket, character device, and Linux CUSE interface.
Role in this project:
Back-end & Security Engineer
Back-end & Security EngineerContributions:19 releases, 138 reviews, 1543 commits in 8 years 3 months
Contributions summary:Stefan contributed to the development of a TPM emulator, focusing on core functionality and security aspects. Their commits added new features to the control channel, enabling the processing of additional commands like CMD_GET_INFO and CMD_LOCK_STORAGE. They also addressed security vulnerabilities by incorporating measures such as preventing unauthorized file access and implementing robust state validation mechanisms to protect data integrity.
tpm2emulatorsocketrustsecurity
keylime/keylime
Sep 2020 - Jan 2023
A CNCF Project to Bootstrap & Maintain Trust on the Edge / Cloud and IoT
Role in this project:Back-end Developer & Security Engineer
Back-end Developer & Security EngineerContributions:556 reviews, 310 commits, 231 PRs in 2 years 4 months
Contributions summary:Stefan primarily focused on improving the security and functionality of the Keylime project. Their contributions included enabling IMA PCR by adding it to the mask and fixing the code style in the root directory, as well as adding a script and Makefile to check code style. They also addressed code style issues within the keylime and tpm directories. Furthermore, they fixed an issue where there were an incorrect number of arguments for logging format string.
securitytpmedgeattestationcloud
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