HOW TO PLAN A COUP DETAT

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COVERT MULTI-PARTY COMPUTATION
HOW TO PLAN A COUP DETAT
ALADDIN REU 2005
LUIS VON AHN MANUEL BLUM
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ALLOWS TWO PARTIES WITH SECRET INPUTS X AND Y TO
LEARN F(X,Y) BUT NOTHING ELSE
COVERT
IDEAL MODEL
MULTI-PARTY COMPUTATION
TWO-PARTY COMPUTATION
BOB
ALICE
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THERE ARE ONLY THREE ANGELS. NONE OF THEM KNOW
ALICE. OR BOB.
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SECURE TWO PARTY COMPUTATION YAO
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1 IF XgtY 0 OTHERWISE
F(X,Y)
JEN
BEN
45 MILLION
32 MILLION
F(X,Y)1
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ALICE
BOB
EVERYBODY! BOB LIKES ME! WHAT A LOSER!
WHY WOULD WE WANT TO DO THAT?
LETS FIND OUT IF WE BOTH LIKE EACH OTHER!
OMG

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COVERT TWO PARTY COMPUTATION VON
AHN,HOPPER,LANGFORD
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COVERT TWO-PARTY COMPUTATION
EXTERNAL COVERTNESS
NO OUTSIDE OBSERVER CAN TELL IF THE TWO PARTIES
ARE RUNNING A COMPUTATION OR JUST COMMUNICATING
AS NORMAL
INTERNAL COVERTNESS
AFTER LEARNING F(X,Y), EACH PARTY CAN ONLY TELL
WHETHER THE OTHER PARTICIPATED IF THEY CAN
DISTINGUISH F(X,Y) FROM RANDOM BITS
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WHO KNOWS WHAT?
WE ASSUME THAT BOTH PARTIES KNOW THE FUNCTION
THEY WISH TO EVALUATE
BOTH KNOW WHICH ROLE THEY ARE TO PLAY IN THE
EVALUATION
BOTH KNOW WHEN TO START COMPUTING
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ORDINARY COMMUNICATION
MESSAGES ARE DRAWN FROM A SET D
TIME PROCEEDS IN DISCRETE TIMESTEPS
EACH PARTY MAINTAINS A HISTORY h OF ALL DOCUMENTS
THEY SENT AND RECEIVED
TO EACH PARTY P, WE ASSOCIATE A FAMILY OF
PROBABILITY DISTRIBUTIONS ON D BhP
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ORDINARY-LIKE COMMUNICATION
GIVEN ANY HISTORY h, P WANTS TO BE ABLE TO SAMPLE
FROM THE CHANNEL BhP
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THE WAR ON TERROR
HE WORKS FOR MI-6
CIA AGENT
HE WORKS FOR CIA
MI-6 AGENT
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THE WAR ON TERROR
THE UTTERANCES CONTAINED A COVERT TWO-PARTY
COMPUTATION
THE FUNCTION F VERIFIED THE CREDENTIALS
SINCE BOTH WERE VALID, IT OUTPUT 1K
X WAS A CREDENTIAL SIGNED BY CIA AND Y WAS SIGNED
BY MI-6
FOR ANY OTHER INPUTS, F OUTPUTS A RANDOM VALUE
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SECURE MULTI PARTY COMPUTATION GOLDREICH,MICALI,W
IGDERSON
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SECURE MULTI PARTY COMPUTATION
YINMENG ZHANG???
WHAT I DID ON MY SUMMER VACATION THE TEASER
TRAILER
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COVERT MULTI-PARTY COMPUTATION
EVERYTHING IS HARDER WITH MORE PEOPLE
ALLOWS N PARTIES WITH SECRET INPUTS X1XN TO
LEARN F(X1,,XN) BUT NOTHING ELSE
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COVERT MULTI-PARTY COMPUTATION THE ADVERSARY
WIMPY BUSYBODIES SEMI-HONEST
ALLS FAIR IN LOVE AND CRYPTOGRAPHY MALICIOUS
WHAT THINGS ARE IMPOSSIBLE TO PROTECT AGAINST?
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COVERT MULTI-PARTY COMPUTATION WHO KNOWS WHAT?
WHOS COMPUTING?
HOW MANY PEOPLE ARE COMPUTING?
HOW MANY PEOPLE WERE COMPUTING, GOT BORED AND
STOPPEDABORT?
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