The SPEKE Protocol Revisited

Research output: Contribution to conferencePaperpeer-review


The SPEKE protocol is commonly considered one of the classic Password Authenticated Key Exchange (PAKE) schemes. It has been included in international standards (particularly, ISO/IEC 11770-4 and IEEE 1363.2) and deployed in commercial products (e.g., Blackberry). We observe that the original SPEKE specification is subtly different from those defined in the ISO/IEC 11770-4 and IEEE 1363.2 standards. We show that those differences have critical security implications by presenting two new attacks on SPEKE: an impersonation attack and a key-malleability attack. The first attack allows an attacker to impersonate a user without knowing the password by engaging in two parallel sessions with the victim. The second attack allows an attacker to manipulate the session key established between two honest users without being detected. Both attacks are applicable to the original SPEKE scheme, and are only partially addressed in the ISO/IEC 11770-4 and IEEE 1363.2 standards. We highlight deficiencies in both standards and suggest concrete changes.
Original languageEnglish
Publication statusPublished - 2014
EventSecurity Standardisation Research - Royal Holloway, University of London, Egham, United Kingdom
Duration: 16 Dec 201417 Dec 2014


ConferenceSecurity Standardisation Research
Abbreviated titleSSR 2014
Country/TerritoryUnited Kingdom


  • PAKE
  • password-authenticated key exchange
  • key exchange
  • IEEE P1362.2
  • ISO/IEC 11770-4
  • Security standards

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