Backward Secrecy definition

Backward Secrecy. Backward secrecy is not ensured by the group member join protocol. At the end of this protocol, user Un+1 computes the new group key K' = H(k1 . . . kn−1 kn' kn+1) knowing all subkeys ki. To be able to compute K, only kn is missing, which can be computed from X1 = k1/kn or Xn = kn/kn−1, sent around unencrypted in the previous session, which Un+1 could have monitored.
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Backward Secrecy. As soon as a new member joins the group, it is hard to compute old key with the knowledge of the new key. The rest of the paper is organized as follows: Section 2 describes the background material necessary to under- stand the ECDLP-based protocols. Section 3 presents the proposed ECDH-based group schemes. Section 4 dis- cusses Security analysis. Section 5 provides comparative analysis. Finally, Section 6 concludes the paper.
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Examples of Backward Secrecy in a sentence

  • Backward and Forward Secrecy properties (often called Forward and Backward Secrecy in the literature) assume that the adversary is a current or a former group member.

  • Forward and Backward Secrecy is a stronger condition than Weak Forward and Backward Secrecy.

  • The first two (often typically called Forward and Backward Secrecy in the literature) are different from the others in the sense that the adversary is assumed to be a current or a former group member.

  • Following the model of [KPT00], we define six such properties: ■ Weak Backward Secrecy guarantees that previously used group keys must not be discovered by new group members.

  • Backward Secrecy guarantees that a passive adversary who knows a contiguous subset of group keys cannot discover preceding group keys.

  • We refer to the above as Weak Forward Secrecy and Weak Backward Secrecy, respectively.