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Mar 07, 2023 240 likes •468 views

Pretty Good Privacy Privacy Enhancing Technologies Leonardo A. Martucci CC-BY-4.0 Part 2: Secure Communications Why do we need secure communications? PGP We are here! TLS and Let's Encrypt Secure messaging Pretty Good Privacy

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CC-BY-4.0

Pretty Good Privacy

Privacy Enhancing Technologies Leonardo A. Martucci

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Part 2: Secure Communications

Why do we need secure communications?
PGP
TLS and Let's Encrypt
Secure messaging

We are here!

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Pretty Good Privacy (PGP)

Security tool for

confidentiality integrity authentication

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How does PGP work?

with public key and symmetric key

encryption + hashing

private key private key public key public key

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How does PGP work?

with public key and symmetric key

encryption + hashing

generate random (symmetric) key private key private key public key public key

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How does PGP work?

with public key and symmetric key

encryption + hashing

generate random (symmetric) key hash( ) private key private key public key public key

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How does PGP work?

with public key and symmetric key

encryption + hashing

generate random (symmetric) key hash( ) private key private key public key public key Enc( ) using = Sign( ) using =

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How does PGP work?

with public key and symmetric key

encryption + hashing

private key private key public key public key

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How does PGP work?

with public key and symmetric key

encryption + hashing

Dec( ) using = Dec( ) using = private key private key public key public key

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How does PGP work?

with public key and symmetric key

encryption + hashing

Dec( ) using = Dec( ) using = private key private key public key public key hash( ) equal?( ) Ver( ) using =

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How does PGP work?

with public key and symmetric key

encryption + hashing

private key private key public key public key

???

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Public Key Distribution: Web of Trust

Sign( ) Sign( ) is trusted by is trusted by

trust

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Public Key Distribution: Web of Trust

Sign( ) Sign( ) is trusted by is trusted by

trust

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Public Key Distribution: Web of Trust

Web of Trust

trust trust

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PGP in the Real World

Exchanging encrypted email
1st: generate a key pair
2nd: upload to a public repository

with OpenPGP (RFC 4880) with ssh-keygen e.g. ssh-keygen -t rsa -b 4096 e.g. the MIT PGP Public Key Server

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PGP in the Real World

Exchanging encrypted email
3rd: Build your web of trust
r look into the repository for keys

with OpenPGP (RFC 4880)

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PGP in the Real World

Exchanging encrypted email
4th: start encrypting and signing

your emails! with OpenPGP (RFC 4880) suggestion: with the support of an email client extension e.g. Enigmail enigmail toolbar

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PGP in the Real World

Exchanging encrypted email
5th: receiving emails

with OpenPGP (RFC 4880) suggestion: with the support of an email client extension e.g. Enigmail

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https://www.xkcd.com/1181/

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The Caveats

ld (from the 90’s)

not really usable

PGP is

keys are really long no key management no forward secrecy

* https://blog.cryptographyengineering.com/2014/08/13/whats-matter-with-pgp/

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Part 2: Secure Communications

Why do we need secure communications?
PGP
TLS and Let's Encrypt
Secure messaging

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