5 files changed, 382 insertions, 0 deletions
diff --git a/src/lib/misc/srp6/info.txt b/src/lib/misc/srp6/info.txt
new file mode 100644
index 000000000..5b07264b4
--- /dev/null
+++ b/src/lib/misc/srp6/info.txt
@@ -0,0 +1,6 @@
+define SRP6 20131128
+
+<requires>
+bigint
+dl_group
+</requires>
diff --git a/src/lib/misc/srp6/srp6.cpp b/src/lib/misc/srp6/srp6.cpp
new file mode 100644
index 000000000..d3f7338bd
--- /dev/null
+++ b/src/lib/misc/srp6/srp6.cpp
@@ -0,0 +1,157 @@
+/*
+* SRP-6a (RFC 5054 compatatible)
+* (C) 2011,2012 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include <botan/srp6.h>
+#include <botan/dl_group.h>
+#include <botan/numthry.h>
+#include <botan/lookup.h>
+
+namespace Botan {
+
+namespace {
+
+BigInt hash_seq(const std::string& hash_id,
+                size_t pad_to,
+                const BigInt& in1,
+                const BigInt& in2)
+   {
+   std::unique_ptr<HashFunction> hash_fn(get_hash(hash_id));
+
+   hash_fn->update(BigInt::encode_1363(in1, pad_to));
+   hash_fn->update(BigInt::encode_1363(in2, pad_to));
+
+   return BigInt::decode(hash_fn->final());
+   }
+
+BigInt compute_x(const std::string& hash_id,
+                 const std::string& identifier,
+                 const std::string& password,
+                 const std::vector<byte>& salt)
+   {
+   std::unique_ptr<HashFunction> hash_fn(get_hash(hash_id));
+
+   hash_fn->update(identifier);
+   hash_fn->update(":");
+   hash_fn->update(password);
+
+   secure_vector<byte> inner_h = hash_fn->final();
+
+   hash_fn->update(salt);
+   hash_fn->update(inner_h);
+
+   secure_vector<byte> outer_h = hash_fn->final();
+
+   return BigInt::decode(outer_h);
+   }
+
+}
+
+std::string srp6_group_identifier(const BigInt& N, const BigInt& g)
+   {
+   /*
+   This function assumes that only one 'standard' SRP parameter set has
+   been defined for a particular bitsize. As of this writing that is the case.
+   */
+   try
+      {
+      const std::string group_name = "modp/srp/" + std::to_string(N.bits());
+
+      DL_Group group(group_name);
+
+      if(group.get_p() == N && group.get_g() == g)
+         return group_name;
+
+      throw std::runtime_error("Unknown SRP params");
+      }
+   catch(...)
+      {
+      throw Invalid_Argument("Bad SRP group parameters");
+      }
+   }
+
+std::pair<BigInt, SymmetricKey>
+srp6_client_agree(const std::string& identifier,
+                  const std::string& password,
+                  const std::string& group_id,
+                  const std::string& hash_id,
+                  const std::vector<byte>& salt,
+                  const BigInt& B,
+                  RandomNumberGenerator& rng)
+   {
+   DL_Group group(group_id);
+   const BigInt& g = group.get_g();
+   const BigInt& p = group.get_p();
+
+   const size_t p_bytes = group.get_p().bytes();
+
+   if(B <= 0 || B >= p)
+      throw std::runtime_error("Invalid SRP parameter from server");
+
+   BigInt k = hash_seq(hash_id, p_bytes, p, g);
+
+   BigInt a(rng, 256);
+
+   BigInt A = power_mod(g, a, p);
+
+   BigInt u = hash_seq(hash_id, p_bytes, A, B);
+
+   const BigInt x = compute_x(hash_id, identifier, password, salt);
+
+   BigInt S = power_mod((B - (k * power_mod(g, x, p))) % p, (a + (u * x)), p);
+
+   SymmetricKey Sk(BigInt::encode_1363(S, p_bytes));
+
+   return std::make_pair(A, Sk);
+   }
+
+BigInt generate_srp6_verifier(const std::string& identifier,
+                              const std::string& password,
+                              const std::vector<byte>& salt,
+                              const std::string& group_id,
+                              const std::string& hash_id)
+   {
+   const BigInt x = compute_x(hash_id, identifier, password, salt);
+
+   DL_Group group(group_id);
+   return power_mod(group.get_g(), x, group.get_p());
+   }
+
+BigInt SRP6_Server_Session::step1(const BigInt& v,
+                                  const std::string& group_id,
+                                  const std::string& hash_id,
+                                  RandomNumberGenerator& rng)
+   {
+   DL_Group group(group_id);
+   const BigInt& g = group.get_g();
+   const BigInt& p = group.get_p();
+
+   m_p_bytes = p.bytes();
+   m_v = v;
+   m_b = BigInt(rng, 256);
+   m_p = p;
+   m_hash_id = hash_id;
+
+   const BigInt k = hash_seq(hash_id, m_p_bytes, p, g);
+
+   m_B = (v*k + power_mod(g, m_b, p)) % p;
+
+   return m_B;
+   }
+
+SymmetricKey SRP6_Server_Session::step2(const BigInt& A)
+   {
+   if(A <= 0 || A >= m_p)
+      throw std::runtime_error("Invalid SRP parameter from client");
+
+   const BigInt u = hash_seq(m_hash_id, m_p_bytes, A, m_B);
+
+   const BigInt S = power_mod(A * power_mod(m_v, u, m_p), m_b, m_p);
+
+   return BigInt::encode_1363(S, m_p_bytes);
+   }
+
+}
diff --git a/src/lib/misc/srp6/srp6.h b/src/lib/misc/srp6/srp6.h
new file mode 100644
index 000000000..3eb21b742
--- /dev/null
+++ b/src/lib/misc/srp6/srp6.h
@@ -0,0 +1,97 @@
+/*
+* SRP-6a (RFC 5054 compatatible)
+* (C) 2011,2012 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#ifndef BOTAN_RFC5054_SRP6_H__
+#define BOTAN_RFC5054_SRP6_H__
+
+#include <botan/bigint.h>
+#include <botan/hash.h>
+#include <botan/rng.h>
+#include <botan/symkey.h>
+#include <string>
+
+namespace Botan {
+
+/**
+* SRP6a Client side
+* @param username the username we are attempting login for
+* @param password the password we are attempting to use
+* @param group_id specifies the shared SRP group
+* @param hash_id specifies a secure hash function
+* @param salt is the salt value sent by the server
+* @param B is the server's public value
+* @param rng is a random number generator
+*
+* @return (A,K) the client public key and the shared secret key
+*/
+std::pair<BigInt,SymmetricKey>
+BOTAN_DLL srp6_client_agree(const std::string& username,
+                            const std::string& password,
+                            const std::string& group_id,
+                            const std::string& hash_id,
+                            const std::vector<byte>& salt,
+                            const BigInt& B,
+                            RandomNumberGenerator& rng);
+
+/**
+* Generate a new SRP-6 verifier
+* @param identifier a username or other client identifier
+* @param password the secret used to authenticate user
+* @param salt a randomly chosen value, at least 128 bits long
+* @param group_id specifies the shared SRP group
+* @param hash_id specifies a secure hash function
+*/
+BigInt BOTAN_DLL generate_srp6_verifier(const std::string& identifier,
+                                        const std::string& password,
+                                        const std::vector<byte>& salt,
+                                        const std::string& group_id,
+                                        const std::string& hash_id);
+
+/**
+* Return the group id for this SRP param set, or else thrown an
+* exception
+* @param N the group modulus
+* @param g the group generator
+* @return group identifier
+*/
+std::string BOTAN_DLL srp6_group_identifier(const BigInt& N, const BigInt& g);
+
+/**
+* Represents a SRP-6a server session
+*/
+class BOTAN_DLL SRP6_Server_Session
+   {
+   public:
+      /**
+      * Server side step 1
+      * @param v the verification value saved from client registration
+      * @param group_id the SRP group id
+      * @param hash_id the SRP hash in use
+      * @param rng a random number generator
+      * @return SRP-6 B value
+      */
+      BigInt step1(const BigInt& v,
+                   const std::string& group_id,
+                   const std::string& hash_id,
+                   RandomNumberGenerator& rng);
+
+      /**
+      * Server side step 2
+      * @param A the client's value
+      * @return shared symmetric key
+      */
+      SymmetricKey step2(const BigInt& A);
+
+   private:
+      std::string m_hash_id;
+      BigInt m_B, m_b, m_v, m_S, m_p;
+      size_t m_p_bytes;
+   };
+
+}
+
+#endif
diff --git a/src/lib/misc/srp6/srp6_files.cpp b/src/lib/misc/srp6/srp6_files.cpp
new file mode 100644
index 000000000..50f51fa75
--- /dev/null
+++ b/src/lib/misc/srp6/srp6_files.cpp
@@ -0,0 +1,69 @@
+/*
+* SRP-6a File Handling
+* (C) 2011 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include <botan/srp6_files.h>
+#include <botan/parsing.h>
+#include <botan/base64.h>
+#include <fstream>
+
+namespace Botan {
+
+SRP6_Authenticator_File::SRP6_Authenticator_File(const std::string& filename)
+   {
+   std::ifstream in(filename.c_str());
+
+   if(!in)
+      return; // no entries
+
+   while(in.good())
+      {
+      std::string line;
+      std::getline(in, line);
+
+      std::vector<std::string> parts = split_on(line, ':');
+
+      if(parts.size() != 4)
+         throw Decoding_Error("Invalid line in SRP authenticator file");
+
+      std::string username = parts[0];
+      BigInt v = BigInt::decode(base64_decode(parts[1]));
+      std::vector<byte> salt = unlock(base64_decode(parts[2]));
+      BigInt group_id_idx = BigInt::decode(base64_decode(parts[3]));
+
+      std::string group_id;
+
+      if(group_id_idx == 1)
+         group_id = "modp/srp/1024";
+      else if(group_id_idx == 2)
+         group_id = "modp/srp/1536";
+      else if(group_id_idx == 3)
+         group_id = "modp/srp/2048";
+      else
+         continue; // unknown group, ignored
+
+      entries[username] = SRP6_Data(v, salt, group_id);
+      }
+   }
+
+bool SRP6_Authenticator_File::lookup_user(const std::string& username,
+                                          BigInt& v,
+                                          std::vector<byte>& salt,
+                                          std::string& group_id) const
+   {
+   std::map<std::string, SRP6_Data>::const_iterator i = entries.find(username);
+
+   if(i == entries.end())
+      return false;
+
+   v = i->second.v;
+   salt = i->second.salt;
+   group_id = i->second.group_id;
+
+   return true;
+   }
+
+}
diff --git a/src/lib/misc/srp6/srp6_files.h b/src/lib/misc/srp6/srp6_files.h
new file mode 100644
index 000000000..45c3b0bfe
--- /dev/null
+++ b/src/lib/misc/srp6/srp6_files.h
@@ -0,0 +1,53 @@
+/*
+* SRP-6a File Handling
+* (C) 2011 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#ifndef BOTAN_SRP6A_FILES_H__
+#define BOTAN_SRP6A_FILES_H__
+
+#include <botan/bigint.h>
+#include <string>
+#include <map>
+
+namespace Botan {
+
+/**
+* A GnuTLS compatible SRP6 authenticator file
+*/
+class BOTAN_DLL SRP6_Authenticator_File
+   {
+   public:
+      /**
+      * @param filename will be opened and processed as a SRP
+      * authenticator file
+      */
+      SRP6_Authenticator_File(const std::string& filename);
+
+      bool lookup_user(const std::string& username,
+                       BigInt& v,
+                       std::vector<byte>& salt,
+                       std::string& group_id) const;
+   private:
+      struct SRP6_Data
+         {
+         SRP6_Data() {}
+
+         SRP6_Data(const BigInt& v,
+                   const std::vector<byte>& salt,
+                   const std::string& group_id) :
+            v(v), salt(salt), group_id(group_id) {}
+
+         BigInt v;
+         std::vector<byte> salt;
+         std::string group_id;
+         };
+
+      std::map<std::string, SRP6_Data> entries;
+   };
+
+}
+
+#endif