Hardening PGP using GnuPG and Yubikey hybrid multifactor - - PowerPoint PPT Presentation

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Hardening PGP using GnuPG and Yubikey hybrid multifactor - - PowerPoint PPT Presentation

Aug 10, 2023 41 likes •478 views

Hardening PGP using GnuPG and Yubikey hybrid multifactor authentication and cryptography John Roman Linux System Administrator RAND Corporation SCALE 2017 Roman, John PGP PGP 101 public/private keyrings Roman, John PGP PGP 101

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Hardening PGP using GnuPG and Yubikey

hybrid multifactor authentication and cryptography John Roman

Linux System Administrator RAND Corporation

SCALE 2017

Roman, John PGP

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PGP 101

public/private keyrings

Roman, John PGP

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PGP 101

public/private keyrings public keys go to the world, generated on machine

Roman, John PGP

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PGP 101

public/private keyrings public keys go to the world, generated on machine key types: signing, authentication, cryptography

Roman, John PGP

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pitfalls

private keyring. . . but how private?

Roman, John PGP

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pitfalls

private keyring. . . but how private? portability

Roman, John PGP

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pitfalls

private keyring. . . but how private? portability standards compliance

Roman, John PGP

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conventional example, the CAC/PIV

Common Access Card, in service since 2005

Roman, John PGP

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conventional example, the CAC/PIV

Common Access Card, in service since 2005 FIPS201 PIV Federal Information Processing Standard (FIPS) 201,Personal Identity Verification

Roman, John PGP

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OpenPGP: we we’re JUST thinking that!

OpenPGP Card: in service since 2004

Roman, John PGP

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OpenPGP: we we’re JUST thinking that!

OpenPGP Card: in service since 2004 9 different vendors, multiple form factors

Roman, John PGP

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OpenPGP: we we’re JUST thinking that!

OpenPGP Card: in service since 2004 9 different vendors, multiple form factors relatively unknown outside of FSF Europe.

Roman, John PGP

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Our focus: Yubikey

supports hybrid mode

Roman, John PGP

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Our focus: Yubikey

supports hybrid mode hermetic, crushproof, scaleable pricing

Roman, John PGP

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Our focus: Yubikey

supports hybrid mode hermetic, crushproof, scaleable pricing NFC option.

Roman, John PGP

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general concepts

card has a CPU, firmware.

Roman, John PGP

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general concepts

card has a CPU, firmware. keys are loaded into slots, or generated by the card

Roman, John PGP

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general concepts

card has a CPU, firmware. keys are loaded into slots, or generated by the card encryption, decryption, signature are all commands

Roman, John PGP

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general concepts

card has a CPU, firmware. keys are loaded into slots, or generated by the card encryption, decryption, signature are all commands

  • nce loaded, private keys are sacrosanct.

Roman, John PGP

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general concepts

card has a CPU, firmware. keys are loaded into slots, or generated by the card encryption, decryption, signature are all commands

  • nce loaded, private keys are sacrosanct.

Yubikey only accepts commands, only returns data. NEVER KEYS.

Roman, John PGP

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HSM Specific concepts

pin number similar to european credit cards

Roman, John PGP

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HSM Specific concepts

pin number similar to european credit cards 3 strikes, your pin is locked

Roman, John PGP

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HSM Specific concepts

pin number similar to european credit cards 3 strikes, your pin is locked pin can be unlocked with a security officer pin.

Roman, John PGP

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HSM Specific concepts

pin number similar to european credit cards 3 strikes, your pin is locked pin can be unlocked with a security officer pin. 3 strikes against the SO pin? card is bricked. keys lost. game over.

Roman, John PGP

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HSM Specific concepts

pin number similar to european credit cards 3 strikes, your pin is locked pin can be unlocked with a security officer pin. 3 strikes against the SO pin? card is bricked. keys lost. game over. pin length 6-8 characters, some implementations more than 128 char.

Roman, John PGP

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placing the card into ’hybrid’ mode

ykpersonalize -d -m82 Firmware version 4.3.1 Touch level 527 Program sequence 3 The USB mode will be set to: 0x82 Commit? (y/n) [n]: n

Roman, John PGP

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OpenPGP card overview

keys were loaded from an airgapped system using the keytocard command.

Roman, John PGP

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OpenPGP card programming

gpg –card-edit mode, admin commands enabled

Roman, John PGP

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applications

anything GPG enabled

Roman, John PGP

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applications

anything GPG enabled anything PAM enabled

Roman, John PGP

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applications

anything GPG enabled anything PAM enabled defense in depth: OTP/Cert/PW? sure

Roman, John PGP

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applications

anything GPG enabled anything PAM enabled defense in depth: OTP/Cert/PW? sure multiple cards per key, each has a unique subkey (code signing!)

Roman, John PGP

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applications

Roman, John PGP

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NFC option: here be dragons

easy integration with Openkeychain in Android/IPhone

Roman, John PGP

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NFC option: here be dragons

easy integration with Openkeychain in Android/IPhone keys need to be generated by the user

Roman, John PGP

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NFC option: here be dragons

easy integration with Openkeychain in Android/IPhone keys need to be generated by the user

  • nly supports a 2048 bit key

Roman, John PGP

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deploying 450 (thousand?) of these things.

Roman, John PGP

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Entropy.

GPG relies on kernel, not userland entropy.

  • Flying Stone FST01 from the FSF store!
  • RTL digital TV dongle and a tractor paper copy of phrack

Roman, John PGP

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OpenPGP not included...

Red Hat Enterprise Linux 7 does not include opensc GnuPG

Roman, John PGP

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y tho...

NFC user fatigue. not all NFC devices are “great” at picking up NFC lack of a yubikey might cause lack of communication.

Roman, John PGP

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“destroyed” cards...

– try not to trigger a SO/Reset pin lock!! – to reissue or reset?

Roman, John PGP

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cardware considerations

processing rate is a function of USB IO and CPU. generating keys on the card = Entropy+CPU.

Roman, John PGP

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Questions?

Roman, John PGP