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ch3: minor cleanup
This commit is contained in:
Heiko Schaefer
parent
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3 changed files with 70 additions and 44 deletions
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(cyrptography_chapter)=
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# Cryptographic concepts/terms
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# Cryptographic concepts and terms
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```{admonition} VISUAL
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:class: warning
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@ -24,15 +24,17 @@ Participants in symmetric-key operations need to exchange the shared secret over
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- visualization? (maybe a black key icon, following wikipedia's example?)
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```
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Symmetric-key cryptography is much faster than public-key cryptography. Also, most current symmetric cryptographic algorithms are considered quantum-resistant.
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### Benefits and downsides
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So symmetric-key cryptography has major benefits, but exchanging the shared secret is a problem that needs to be solved separately.
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Symmetric-key cryptography has major benefits: it is much faster than public-key cryptography (see below). Also, most current symmetric cryptographic algorithms are considered quantum-resistant.
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[Hybrid cryptosystems](hybrid_cryptosystems) are one common approach to leverage the benefits of symmetric-key cryptography, while handling the shared secret with a separate mechanism (using public-key cryptography).
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However, exchanging the required shared secret is a problem that needs to be solved separately.
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[Hybrid cryptosystems](hybrid_cryptosystems) (see below) are one common approach to leverage the benefits of symmetric-key cryptography, while handling the shared secret with a separate mechanism (using public-key cryptography).
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### Symmetric-key cryptography in OpenPGP
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Symmetric cryptography is used in OpenPGP (as part of a hybrid cryptosystem).
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Symmetric cryptography is used in OpenPGP as part of a hybrid cryptosystem.
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Where symmetric keys are used in OpenPGP, they are referred to as "session keys."
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@ -40,13 +42,13 @@ Where symmetric keys are used in OpenPGP, they are referred to as "session keys.
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[Authenticated encryption](https://en.wikipedia.org/wiki/Authenticated_encryption) is a class of cryptographic schemes that gives additional guarantees besides confidentiality.
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In OpenPGP version 6, AEAD is used to solve the problem of "malleability": In past versions of the OpenPGP protocol, some malicious changes to ciphertext were undetectable. With AEAD undetected changes of ciphertext are not possible.
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In OpenPGP version 6, AEAD is used to solve the problem of "malleability": In past versions of the OpenPGP protocol, some malicious changes to ciphertext were undetectable. With AEAD, undetected changes of ciphertext are not possible.
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## Public-key, or asymmetric cryptography
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[Public-key cryptography](https://en.wikipedia.org/wiki/Public-key_cryptography) systems use asymmetric pairs of related keys. Public-key cryptographic systems support *encryption/decryption* and *digital signature* operations.
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Public-key cryptography doesn't require participants to have pre-arranged a shared secret.
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Public-key cryptography doesn't require participants to pre-arrange a shared secret.
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### Asymmetric cryptographic key pairs
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@ -65,19 +67,10 @@ An asymmetric cryptographic key pair
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- Heiko: maybe use colors + distinct shapes for the two key halves?
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```
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An asymmetric cryptographic key pair consists of a public and a private part. In this document, we'll show the public part of key pair in green, and the private part in red.
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We'll usually visualize cryptographic key pairs in this more compact form:
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```{figure} diag/keypair.png
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---
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---
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Asymmetric key pair, more compact representation
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```
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An asymmetric cryptographic key pair consists of a public and a private part. In this document, we'll show the public part of a key pair in green, and the private part in red.
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Note that in many contexts, only the public part is present (more on that later):
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```{figure} diag/keypair_pub.png
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---
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---
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@ -88,7 +81,9 @@ Only the public part of an asymmetric key pair
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OpenPGP makes heavy use of public-key cryptography, both for encryption and signing operations.
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Note that, for historical reasons, OpenPGP often uses the terms "public/secret key" instead of "public/private key." The OpenPGP RFC and other documentation often use the non-standard term "secret key" instead of the more common "private key."
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Note that, for historical reasons, the OpenPGP RFC and other documentation often use the non-standard term "secret key" instead of the more common "private key."
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So in OpenPGP, the pair of terms "public/secret key" is sometimes used instead of the more common "public/private key."
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### Cryptographic digital signatures
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x="69.740417"
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y="95.930061">cryptographic keypair</tspan></text>
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id="path1" />
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<path
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Before Width: | Height: | Size: 6.9 KiB After Width: | Height: | Size: 8.6 KiB |
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Reference in a new issue