asymmetric cryptography

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asymmetric cryptography

• by David Kumar

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Content

• What is a asymmetric Cryptosystem?
• How Public Keys can be trusted
• GnuPG
• Creating Key pair
• Handle the keys
• Thunderbird
• Questions?

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Review asymmetric cryptography

• Asymmetric
• Public Key
• Secret Key

Review
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How Public Keys can be trusted

• Authority Infrastructures
• Public Key Infrastructure (PKI)
• Financial transaction
• Cross certification
• Company's
• Web of Trust
• GnuPG

Review? How Public Keys can be trusted
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Public Key Infrastructure

• Often used in combination with Hardware

Review? How Public Keys can be trusted
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Cross certification
Review? How Public Keys can be trusted
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Web of Trust

• allows anyone to sign anyone else's public key

Review? How Public Keys can be trusted
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GnuPG

• Under GNU General Public License
• Web of Trust
• Command line Tool
• But there are some GUIs for
• Instant messaging
• Email
• Etc.
• http//www.gnupg.org/

Review? How Public Keys can be trusted ? GnuPG
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Creating Key pair

• gpg --gen-key (generates the sec. and pub. key)
• Algorithm DSA/ ElGamal
• Key length
• 1024 4096 bits
• duration of validity
• Valid for ever
• Valid for specific time
• days, weeks, month, years
• Personal Information
• Name, Email address
• Passphrase

Review? How Public Keys can be trusted ? GnuPG
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Creating Key pair

• Digital Signature Algorithm
• ElGamal (al-Dschamal)
• Based on Diffie-Hellman

Review? How Public Keys can be trusted ? GnuPG
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Example GnuPG Key

• -----BEGIN PGP PUBLIC KEY BLOCK-----
• Version GnuPG v1.4.7 (MingW32)
• mQGiBEdXIhgRBADTvEasLZVWbkb42eq37vNNmXD8JoNFCCaD
  rCdZmLrFc2S4Pq
• Wb63jmtlaZ0QG9BG8RcMxo7fPeoUZu1W6abHm29bE1cDqBp8R
  dTrcRcbMnW9A5w
• Yrfga5Rc5f3eL9rRGcddq2zoSf86jNjoJoAuJWP20dPTTG7Rta
  qSazH12wCg1A8I
• MOrirxgsl/rxaNrUoAUOykD/iOXD3jVIiLgGQi2pAgJlHANrt
  Oj13FoUWLVYbuR
• QTSy6FI5uHxopYaj7B2FydWFeBZh16dtaFT0v5zR8auEDA7EI
  G0WldkmdRBo115
• IS7MpSX6WGqoaRCH9sW/UO1QzZEjSZ8T7nQTGvsa/pNmQQyIA
  rTpf04gAflW2C
• kQ0lBADTuw90GAyNZBkgmYrJNFLjbMX/ogsmscuymHeTBMVTcN
  56EIQ4B09D6aq2
• wQHDjBeEdSOUxnxGyq9yPiNjjzsZ/D3o51VFpITy57xvkWCmlf
  lU9OJ/AF3mgYz
• rXxkHeuRzNR2oOfyDTGxD8hF5qXNsXxRuJzANgDqz9aflzBW07
  QkRGF2aWQgUy4g
• S3VtYXIgPGRza3VtYXJAY2xlbXNvbi5lZHUiGAEExECACAFAk
  dXIhgCGwMGCwkI
• BwMCBBUCCAMEFgIDAQIeAQIXgAAKCRAwvq2f1WC3UrIpAJ4z4c
  O46tiq7UwQQ1U
• JVeJWIMxBQCfRy9Wq/RNIIaOLFK7hLh/hGXle5Ag0ER1ciGB
  AIAMkRCgBtzkvM
• 3TQ/Boxwgzoy6w6gxOJQAArKKwwcI3FPEAp5LaZ3xlCgGIPTe
  tJrIk07hBkdrxn
• MECTaQSTzsnwrBmkmwqJQCRZ7VNEwTHg2l5P5ag3fsVZUde77
  lcw9YXQ/U06aQy
• KHLw3urdy9tZNAf8lTneV1ySRug7EXhceJvGKOQGbpd/y8nxkS
  oiccGqtJixcDf
• 0TUZAvG2nt62sDpknj06xP5L/IaFiordD4xse3dHfLkwCl6M
  T9FIy1iGSTHTh

Review? How Public Keys can be trusted ? GnuPG
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Key Export / Import

• Export
• gpg --export UID o filename
• Why export?
• Import
• gpg --import Datei
• Why import?
• Show all keys
• gpg --fingerprint

Review? How Public Keys can be trusted ? GnuPG
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Signing a Key

• gpg --edit-key UID
• sign
• Be careful to sign Keys!

Review? How Public Keys can be trusted ? GnuPG
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Thunderbird

• Enigmail Thunderbird Add-on for GnuPG

Review? How Public Keys can be trusted ? GnuPG
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Enigmail
Review? How Public Keys can be trusted ? GnuPG
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Thunderbird
Review? How Public Keys can be trusted ? GnuPG
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Thunderbird
Review? How Public Keys can be trusted ? GnuPG
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• Questions?

Review? How Public Keys can be trusted ? GnuPG
?THE END