Short-Lived Forward-Secure Delegation for TLS

Lukas Alber*, Stefan More*, Sebastian Ramacher*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference paperpeer-review


On today's Internet, combining the end-to-end security of TLS with Content Delivery Networks (CDNs) while ensuring the authenticity of connections results in a challenging delegation problem. When CDN servers provide content, they have to authenticate themselves as the origin server to establish a valid end-to-end TLS connection with the client. In standard TLS, the latter requires access to the secret key of the server. To curb this problem, multiple workarounds exist to realize a delegation of the authentication. In this paper, we present a solution that renders key sharing unnecessary and reduces the need for workarounds. By adapting identity-based signatures to this setting, our solution offers short-lived delegations. Additionally, by enabling forward-security, existing delegations remain valid even if the server's secret key leaks. We provide an implementation of the scheme and discuss integration into a TLS stack. In our evaluation, we show that an efficient implementation incurs less overhead than a typical network round trip. Thereby, we propose an alternative approach to current delegation practices on the web.

Original languageEnglish
Title of host publicationCCSW 2020 - Proceedings of the 2020 ACM SIGSAC Conference on Cloud Computing Security Workshop
Place of PublicationVirtual Event, USA
Number of pages14
ISBN (Electronic)9781450380843
Publication statusPublished - 9 Nov 2020
EventThe ACM Cloud Computing Security Workshop: in conjunction with the ACM Conference on Computer and Communications Security (CCS) - Virtual Event, Virtuell, United States
Duration: 9 Nov 2020 → …

Publication series

NameCCSW 2020 - Proceedings of the 2020 ACM SIGSAC Conference on Cloud Computing Security Workshop


WorkshopThe ACM Cloud Computing Security Workshop
Abbreviated titleCCSW'20
Country/TerritoryUnited States
Period9/11/20 → …
Internet address


  • delegated credentials
  • identity-based signatures

ASJC Scopus subject areas

  • Computer Science(all)
  • Computer Networks and Communications

Fields of Expertise

  • Information, Communication & Computing

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