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Cryptography with Dispensable Backdoors€¦ · Apple vs FBI To lock: • Use key to encrypt state...
Transcript of Cryptography with Dispensable Backdoors€¦ · Apple vs FBI To lock: • Use key to encrypt state...
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Cryptography with Dispensable Backdoors
Eurocrypt 2018 Rump Session
Ching-Yi LaiAcademia Sinica
Kai-Min ChungAcademia Sinica
Vassilis ZikasUniversity of Edinburgh & IOHK
Marios GeorgiouCUNY
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Apple vs FBI
![Page 3: Cryptography with Dispensable Backdoors€¦ · Apple vs FBI To lock: • Use key to encrypt state • Store all (key/phone-ID) • Throw away key pairs • Upon receiving an ID,](https://reader036.fdocuments.us/reader036/viewer/2022062922/5f071e687e708231d41b661e/html5/thumbnails/3.jpg)
Apple vs FBI
Backdoor your locking mechanism so that I can solve crimes
![Page 4: Cryptography with Dispensable Backdoors€¦ · Apple vs FBI To lock: • Use key to encrypt state • Store all (key/phone-ID) • Throw away key pairs • Upon receiving an ID,](https://reader036.fdocuments.us/reader036/viewer/2022062922/5f071e687e708231d41b661e/html5/thumbnails/4.jpg)
Apple vs FBI
Backdoor your locking mechanism so that I can solve crimes
No
![Page 5: Cryptography with Dispensable Backdoors€¦ · Apple vs FBI To lock: • Use key to encrypt state • Store all (key/phone-ID) • Throw away key pairs • Upon receiving an ID,](https://reader036.fdocuments.us/reader036/viewer/2022062922/5f071e687e708231d41b661e/html5/thumbnails/5.jpg)
Apple vs FBI
Backdoor your locking mechanism so that I can solve crimes
No
why not?
![Page 6: Cryptography with Dispensable Backdoors€¦ · Apple vs FBI To lock: • Use key to encrypt state • Store all (key/phone-ID) • Throw away key pairs • Upon receiving an ID,](https://reader036.fdocuments.us/reader036/viewer/2022062922/5f071e687e708231d41b661e/html5/thumbnails/6.jpg)
Apple vs FBI
Backdoor your locking mechanism so that I can solve crimes
No
why not?
Because leakage of the backdoor allows anyone to unlock every phone. Not worth the risk
![Page 7: Cryptography with Dispensable Backdoors€¦ · Apple vs FBI To lock: • Use key to encrypt state • Store all (key/phone-ID) • Throw away key pairs • Upon receiving an ID,](https://reader036.fdocuments.us/reader036/viewer/2022062922/5f071e687e708231d41b661e/html5/thumbnails/7.jpg)
Apple vs FBI
Backdoor your locking mechanism so that I can solve crimes
No
why not?
Because leakage of the backdoor allows anyone to unlock every phone. Not worth the risk
Can this be avoided?
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Apple vs FBII know how to do this
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Apple vs FBII know how to do this
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Apple vs FBII know how to do this
Ha! I heard it
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Apple vs FBII know how to do this
Ha! I heard it
Meeau too!And it’s the same for all phones
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Apple vs FBI
• Store all (key/phone-ID) pairs
• Upon receiving an ID, output the key and never receive another input
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Apple vs FBI
To lock:• Use key to encrypt state• Throw away key• Store all (key/phone-ID)
pairs• Upon receiving an ID,
output the key and never receive another input
![Page 14: Cryptography with Dispensable Backdoors€¦ · Apple vs FBI To lock: • Use key to encrypt state • Store all (key/phone-ID) • Throw away key pairs • Upon receiving an ID,](https://reader036.fdocuments.us/reader036/viewer/2022062922/5f071e687e708231d41b661e/html5/thumbnails/14.jpg)
Apple vs FBI
To lock:• Use key to encrypt state• Throw away key• Store all (key/phone-ID)
pairs• Upon receiving an ID,
output the key and never receive another input
Yields: • Encryption where one out of many keys can be recovered• Only this one! All other keys/encryptions are safe
• Dispensable-backdoor encryption.
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Apple vs FBI
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Apple vs FBI
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Apple vs FBI
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Apple vs FBI
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Apple vs FBI
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Apple vs FBI
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Apple vs FBI
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Apple vs FBI
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Apple vs FBI
Reset the token
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Apple vs FBI
Reset the token
Can we do it from stateless tokens?
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Stateful From Stateless Token
I want to create information that • Cannot be copied/duplicated• Can encode a lot of keys• Once read it “self-destructs”
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Stateful From Stateless Token
I want to create information that • Cannot be copied/duplicated• Can encode a lot of keys• Once read it “self-destructs”
What you seek exists not in the digital world
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Stateful From Stateless Token
I want to create information that • Cannot be copied/duplicated• Can encode a lot of keys• Once read it “self-destructs”
What you seek exists not in the digital world
I have exactly what you need!
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Cryptography with Dispensable Backdoors
https://eprint.iacr.org/2018/352.pdf
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Cryptography with Dispensable Backdoors
https://eprint.iacr.org/2018/352.pdf