X-Git-Url: https://git.distorted.org.uk/~mdw/doc/ips/blobdiff_plain/53aa10b5d9431ced4e98673cc872c6627cac1d5f..b912aadfc4eb26f1c4cf3332eb510b41a4d9a036:/enc-ies.tex diff --git a/enc-ies.tex b/enc-ies.tex index 7150019..3f53936 100644 --- a/enc-ies.tex +++ b/enc-ies.tex @@ -29,9 +29,9 @@ in \cite{Abdalla:2001:DHIES}. \head{An obvious approach} A simple approach would be to generate a random key for some secure (i.e., - IND-CCA) symmetric scheme, encrypt the message under that key, and, encrypt - the key under the recipient's public key (using some IND-CCA2 public-key - scheme). + IND-CCA2) symmetric scheme, encrypt the message under that key, and, + encrypt the key under the recipient's public key (using some IND-CCA2 + public-key scheme). This is obviously secure. But the security results for most public-key schemes are less than encouraging: the reductions, even for OAEP+, are @@ -322,7 +322,7 @@ in \cite{Abdalla:2001:DHIES}. \InSec{ind-cca2}(\Xid{G}{IES}^{\mathcal{K}, \mathcal{E}}; t, q_D) \\ & \le 2 \cdot \InSec{ohd}(\mathcal{K}; t + O(q_D), q_D) + - \InSec{ftg-cca}(\mathcal{E}; t + O(q_D), 0, q_D). + \InSec{ftg-cca2}(\mathcal{E}; t + O(q_D), 0, q_D). \end{eqnarray*} Note how weak the security requirements on the encryption scheme are: no chosen-plaintext queries are permitted! @@ -349,7 +349,7 @@ in \cite{Abdalla:2001:DHIES}. simulation of $A$'s attack game, and hence wins with probability \[ \frac{\Adv{ind-cca2}{\Xid{G}{IES}^{\mathcal{K}, \mathcal{E}}}}{2} + \frac{1}{2}. \]% - We construct a new adversary $C$, attacking $\mathcal{E}$ in the FTG-CCA + We construct a new adversary $C$, attacking $\mathcal{E}$ in the FTG-CCA2 sense, to help us bound $B$'s probability of success when $h$ is chosen randomly. \begin{program}