diff --git a/book/source/03-cryptography.md b/book/source/03-cryptography.md
index 1130c53..58ab78e 100644
--- a/book/source/03-cryptography.md
+++ b/book/source/03-cryptography.md
@@ -1,5 +1,5 @@
(cyrptography_chapter)=
-# Cryptographic concepts/terms
+# Cryptographic concepts and terms
```{admonition} VISUAL
:class: warning
@@ -24,15 +24,17 @@ Participants in symmetric-key operations need to exchange the shared secret over
- visualization? (maybe a black key icon, following wikipedia's example?)
```
-Symmetric-key cryptography is much faster than public-key cryptography. Also, most current symmetric cryptographic algorithms are considered quantum-resistant.
+### Benefits and downsides
-So symmetric-key cryptography has major benefits, but exchanging the shared secret is a problem that needs to be solved separately.
+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.
-[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).
+However, exchanging the required shared secret is a problem that needs to be solved separately.
+
+[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).
### Symmetric-key cryptography in OpenPGP
-Symmetric cryptography is used in OpenPGP (as part of a hybrid cryptosystem).
+Symmetric cryptography is used in OpenPGP as part of a hybrid cryptosystem.
Where symmetric keys are used in OpenPGP, they are referred to as "session keys."
@@ -40,13 +42,13 @@ Where symmetric keys are used in OpenPGP, they are referred to as "session keys.
[Authenticated encryption](https://en.wikipedia.org/wiki/Authenticated_encryption) is a class of cryptographic schemes that gives additional guarantees besides confidentiality.
-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.
+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.
## Public-key, or asymmetric cryptography
[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.
-Public-key cryptography doesn't require participants to have pre-arranged a shared secret.
+Public-key cryptography doesn't require participants to pre-arrange a shared secret.
### Asymmetric cryptographic key pairs
@@ -65,19 +67,10 @@ An asymmetric cryptographic key pair
- Heiko: maybe use colors + distinct shapes for the two key halves?
```
-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.
-
-We'll usually visualize cryptographic key pairs in this more compact form:
-
-```{figure} diag/keypair.png
----
----
-Asymmetric key pair, more compact representation
-```
+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.
Note that in many contexts, only the public part is present (more on that later):
-
```{figure} diag/keypair_pub.png
---
---
@@ -88,7 +81,9 @@ Only the public part of an asymmetric key pair
OpenPGP makes heavy use of public-key cryptography, both for encryption and signing operations.
-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."
+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."
+
+So in OpenPGP, the pair of terms "public/secret key" is sometimes used instead of the more common "public/private key."
### Cryptographic digital signatures
diff --git a/book/source/diag/cryptographic_keys.png b/book/source/diag/cryptographic_keys.png
index 7e6b057..c8883cf 100644
Binary files a/book/source/diag/cryptographic_keys.png and b/book/source/diag/cryptographic_keys.png differ
diff --git a/book/source/diag/cryptographic_keys.svg b/book/source/diag/cryptographic_keys.svg
index df4bc1b..2d5d57d 100644
--- a/book/source/diag/cryptographic_keys.svg
+++ b/book/source/diag/cryptographic_keys.svg
@@ -2,12 +2,12 @@
+ inkscape:current-layer="layer1"
+ inkscape:export-bgcolor="#ffffffff" />
-
- public cryptographic key
+ x="107.71756"
+ y="77.314079">public cryptographic key
private cryptographic key
+ x="106.57175"
+ y="84.962532">private cryptographic key
+
+
+
+
+ cryptographic keypair
+
+
+