diff --git a/book/source/03-cryptography.md b/book/source/03-cryptography.md
index c63cb97..5658494 100644
--- a/book/source/03-cryptography.md
+++ b/book/source/03-cryptography.md
@@ -21,22 +21,22 @@ Here are two important properties of cryptographic hash functions:
 - ["Pre-image resistance"](https://en.wikipedia.org/wiki/Preimage_attack): Given a hash value, it should be very difficult to determine the original data it represents.
 - ["Collision resistance"](https://en.wikipedia.org/wiki/Collision_resistance): It should be very difficult to find two distinct pieces of data that map to the same hash value.
 
-## Message Authentication Codes
+## Message authentication codes
 
-[Message Authentication Codes](https://en.wikipedia.org/wiki/Message_authentication_code) (MAC, also called authentication tags) are small pieces of information, which can be used to verify the integrity and authenticity of a message.
-They are calculated over the original message using a (symmetric) secret key.
-The recipient of a message containing a MAC, who is also in posession of the secret key can verify that the message has not been tampered with.
+A [message authentication code](https://en.wikipedia.org/wiki/Message_authentication_code) (MAC), also known as an authentication tag, is a small piece of information used to verify the integrity and authenticity of a message.
 
-[HMAC](https://en.wikipedia.org/wiki/HMAC) is a hash-based message authentication code, which is used in the OpenPGP protocol.
+It is derived from the original message using a (symmetric) secret key. The recipient of a message containing a MAC, who is also in possession of the secret key, can verify that the message has not been altered.
 
-### Key Derivation Functions
+[HMAC](https://en.wikipedia.org/wiki/HMAC) is a type of MAC that relies on a hash function. It is used in the OpenPGP protocol.
 
-Hash functions can also be used to construct [key derivation functions](https://en.wikipedia.org/wiki/Key_derivation_function) (KDF).
-Those can for instance be used to derive symmetric key material from a password by repeatedly feeding it through a hash function.
+### Key derivation functions
 
-A prominent example of a KDF which is relevant for the OpenPGP specification is the so-called [HKDF](https://en.wikipedia.org/wiki/HKDF) which is a key derivation function based on the HMAC message authentication code.
+A hash function can also be used to create a [key derivation function](https://en.wikipedia.org/wiki/Key_derivation_function) (KDF).
+One application of KDFs is to generate symmetric key material from a password by iteratively passing it through a hash function.
 
-More information on KDFs and their use in the OpenPGP protocol can be found in chapters [5](encrypted_secrets) and 10 (SEIPDv2).
+A notable KDF for the OpenPGP specification is the [HKDF](https://en.wikipedia.org/wiki/HKDF), which is a key derivation function based on the HMAC.
+
+For detailed information on KDFs and their role in the OpenPGP protocol, see the [encrypted secrets](encrypted_secrets) chapter and the [SEIPDv2](SEIPDv2) section of the encryption chapter.
 
 ## Symmetric-key cryptography