Document KDF properly.

Split log by release series instead of year.

Make dedicated landing page.

If SPHINX_OPTS is set, it will be passed to sphinx-build

1 files changed, 31 insertions, 1 deletions

diff --git a/doc/kdf.txt b/doc/kdf.txt
index feb458108..da916dcb3 100644
--- a/doc/kdf.txt
+++ b/doc/kdf.txt
@@ -4,4 +4,34 @@
 Key Derivation Functions
 ========================================
 
-Todo
+Key derivation functions are used to turn some amount of shared secret
+material into uniform random keys suitable for use with symmetric
+algorithms. An example of an input which is useful for a KDF is a
+shared secret created using Diffie-Hellman key agreement.
+
+.. cpp:class:: KDF
+
+  .. cpp:function:: SecureVector<byte> derive_key( \
+     size_t key_len, const MemoryRegion<byte>& secret, \
+     const std::string& salt = "") const
+
+  .. cpp:function:: SecureVector<byte> derive_key( \
+     size_t key_len, const MemoryRegion<byte>& secret, \
+     const MemoryRegion<byte>& salt) const
+
+  .. cpp:function:: SecureVector<byte> derive_key( \
+     size_t key_len, const MemoryRegion<byte>& secret, \
+     const byte* salt, size_t salt_len) const
+
+  .. cpp:function:: SecureVector<byte> derive_key( \
+     size_t key_len, const byte* secret, size_t secret_len, \
+     const std::string& salt) const
+
+   All variations on the same theme. Deterministically creates a
+   uniform random value from *secret* and *salt*. Typically *salt* is
+   a lable or identifier, such as a session id.
+
+You can create a :cpp:class:`KDF` using
+
+.. cpp:function:: KDF* get_kdf(const std::string& algo_spec)
+