BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Drupal iCal API//EN
X-WR-CALNAME:Events items teaser
X-WR-TIMEZONE:America/Toronto
BEGIN:VTIMEZONE
TZID:America/Toronto
X-LIC-LOCATION:America/Toronto
BEGIN:DAYLIGHT
TZNAME:EDT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
DTSTART:20250309T070000
END:DAYLIGHT
BEGIN:STANDARD
TZNAME:EST
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
DTSTART:20251102T060000
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
UID:69ce8cd9610cc
DTSTART;TZID=America/Toronto:20260123T103000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260123T113000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/crypto-readi
 ng-group-sam-jaques-impossibility-results-post
SUMMARY:Crypto Reading Group -Sam Jaques-Impossibility Results for\nPost-Co
 mpromise Security in Real-World Communication Systems
CLASS:PUBLIC
DESCRIPTION:Speaker\n Sam Jaques\n\nAffiliation\n University of Waterloo\n\
 nLocation\n MC 6029\n\nABSTRACT:  Modern secure communication systems\, 
 such as iMessage\,\nWhatsApp\, and Signal include intricate mechanisms tha
 t aim to achieve\nvery strong security properties. These mechanisms typica
 lly involve\ncontinuously merging fresh secrets into the keying material t
 hat is\nused to encrypt messages during communications. In the literature\
 ,\nthese mechanisms have been proven to achieve forms of Post-Compromise\n
 Security (PCS): the ability to provide communication security even if\nthe
  full state of a party was compromised some time in the past.\nHowever\, r
 ecent work has shown these proofs cannot be transferred to\nthe end-user l
 evel\, possibly because of usability concerns. This has\nraised the questi
 on of whether end-users can actually obtain PCS or\nnot\, and under which 
 conditions.\n\nHere we show and formally prove that communication systems 
 that need\nto be resilient against certain types of state loss (which can 
 occur\nin practice) fundamentally cannot achieve full PCS for end-users.\n
 Whereas previous work showed that the Signal messenger did not achieve\nth
 is with its current session-management layer\, we isolate the exact\ncondi
 tions that cause this failure\, and we show why this cannot be\nsimply sol
 ved in communication systems by implementing a different\nsession-manageme
 nt layer or an entirely different protocol. Moreover\,\nwe clarify the tra
 de-off of the maximum number of sessions between two\nusers (40 in Signal)
  in terms of failure-resilience versus security. \nOur results have direct
  consequences for the design of future secure\ncommunication systems and c
 ould motivate either the simplification of\nredundant mechanisms or the im
 provement of session-management designs\nto provide better security trade-
 offs with respect to state\nloss/failure tolerance.
DTSTAMP:20260402T153553Z
END:VEVENT
END:VCALENDAR