Complete SRP6 doc

Still sparse but not actually truncated anymore.

Closes #1029

[ci skip]

1 files changed, 32 insertions, 4 deletions

diff --git a/doc/manual/srp.rst b/doc/manual/srp.rst
index 74b67d890..071f3ea19 100644
--- a/doc/manual/srp.rst
+++ b/doc/manual/srp.rst
@@ -8,7 +8,11 @@ password based key exchange protocol
 A SRP client provides what is called a SRP *verifier* to the server.
 This verifier is based on a password, but the password cannot be
 easily derived from the verifier. Later, the client and server can
-perform an SRP exchange, in which
+perform an SRP exchange, which results in a shared key.
+
+SRP works in a discrete logarithm group. Special parameter sets for
+SRP6 are defined, denoted in the library as "modp/srp/<size>", for
+example "modp/srp/2048".
 
 .. warning::
 
@@ -17,7 +21,6 @@ perform an SRP exchange, in which
      impersonate the server to the client, so verifiers should be
      carefully protected.
 
-
 .. cpp:function:: BigInt generate_srp6_verifier( \
           const std::string& identifier, \
           const std::string& password, \
@@ -25,6 +28,26 @@ perform an SRP exchange, in which
           const std::string& group_id, \
           const std::string& hash_id)
 
+    Generates a new verifier using the specified password and salt.
+    This is stored by the server. The salt must also be stored.
+
+.. cpp:function:: std::string srp6_group_identifier( \
+            const BigInt& N, const BigInt& g)
+
+.. cpp:class:: SRP6_Server_Session
+
+   .. cpp:function:: BigInt step1(const BigInt& v, \
+                     const std::string& group_id, \
+                     const std::string& hash_id, \
+                     RandomNumberGenerator& rng)
+
+       Takes a verifier (generated by generate_srp6_verifier)
+       along with the group_id (which must match
+
+   .. cpp:function:: SymmetricKey step2(const BigInt& A)
+
+      Takes the parameter A generated by srp6_client_agree,
+      and return the shared secret key.
 
 .. cpp:function:: std::pair<BigInt,SymmetricKey> srp6_client_agree( \
                const std::string& username, \
@@ -35,5 +58,10 @@ perform an SRP exchange, in which
                const BigInt& B, \
                RandomNumberGenerator& rng)
 
-.. cpp:function:: std::string srp6_group_identifier( \
-            const BigInt& N, const BigInt& g)
+    The client receives these parameters from the server, except for
+    the username and password which are provided by the user. The
+    parameter B is the output of `step1`.
+
+    The client agreement step outputs a shared symmetric key along
+    with the parameter A which is returned to the server (and allows
+    it the compute the shared key).