Add proper SRP6 tests

Fixes GH #1917

2 files changed, 102 insertions, 14 deletions

diff --git a/src/lib/misc/srp6/srp6.cpp b/src/lib/misc/srp6/srp6.cpp
index 825c38589..0bd9b192a 100644
--- a/src/lib/misc/srp6/srp6.cpp
+++ b/src/lib/misc/srp6/srp6.cpp
@@ -1,6 +1,6 @@
 /*
 * SRP-6a (RFC 5054 compatatible)
-* (C) 2011,2012 Jack Lloyd
+* (C) 2011,2012,2019 Jack Lloyd
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -82,9 +82,22 @@ srp6_client_agree(const std::string& identifier,
                   const BigInt& B,
                   RandomNumberGenerator& rng)
    {
-   const size_t a_bits = 256;
-
    DL_Group group(group_id);
+   const size_t a_bits = group.exponent_bits();
+
+   return srp6_client_agree(identifier, password, group, hash_id, salt, B, a_bits, rng);
+   }
+
+std::pair<BigInt, SymmetricKey>
+srp6_client_agree(const std::string& identifier,
+                  const std::string& password,
+                  const DL_Group& group,
+                  const std::string& hash_id,
+                  const std::vector<uint8_t>& salt,
+                  const BigInt& B,
+                  const size_t a_bits,
+                  RandomNumberGenerator& rng)
+   {
    const BigInt& g = group.get_g();
    const BigInt& p = group.get_p();
 
@@ -117,10 +130,18 @@ BigInt generate_srp6_verifier(const std::string& identifier,
                               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);
-   // FIXME: x should be size of hash fn
+   return generate_srp6_verifier(identifier, password, salt, group, hash_id);
+   }
+
+BigInt generate_srp6_verifier(const std::string& identifier,
+                              const std::string& password,
+                              const std::vector<uint8_t>& salt,
+                              const DL_Group& group,
+                              const std::string& hash_id)
+   {
+   const BigInt x = compute_x(hash_id, identifier, password, salt);
+   // FIXME: x should be size of hash fn so avoid computing x.bits() here
    return group.power_g_p(x, x.bits());
    }
 
@@ -129,9 +150,18 @@ BigInt SRP6_Server_Session::step1(const BigInt& v,
                                   const std::string& hash_id,
                                   RandomNumberGenerator& rng)
    {
-   const size_t b_bits = 256;
-
    DL_Group group(group_id);
+   const size_t b_bits = group.exponent_bits();
+
+   return this->step1(v, group, hash_id, b_bits, rng);
+   }
+
+BigInt SRP6_Server_Session::step1(const BigInt& v,
+                                  const DL_Group& group,
+                                  const std::string& hash_id,
+                                  size_t b_bits,
+                                  RandomNumberGenerator& rng)
+   {
    const BigInt& g = group.get_g();
    const BigInt& p = group.get_p();
 
diff --git a/src/lib/misc/srp6/srp6.h b/src/lib/misc/srp6/srp6.h
index ad880946a..cf41b1ef2 100644
--- a/src/lib/misc/srp6/srp6.h
+++ b/src/lib/misc/srp6/srp6.h
@@ -1,6 +1,6 @@
 /*
 * SRP-6a (RFC 5054 compatatible)
-* (C) 2011,2012 Jack Lloyd
+* (C) 2011,2012,2019 Jack Lloyd
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -14,6 +14,7 @@
 
 namespace Botan {
 
+class DL_Group;
 class RandomNumberGenerator;
 
 /**
@@ -37,6 +38,30 @@ BOTAN_PUBLIC_API(2,0) srp6_client_agree(const std::string& username,
                             const BigInt& B,
                             RandomNumberGenerator& rng);
 
+
+/**
+* SRP6a Client side
+* @param username the username we are attempting login for
+* @param password the password we are attempting to use
+* @param group 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 a_bits size of secret exponent in bits
+* @param rng is a random number generator
+*
+* @return (A,K) the client public key and the shared secret key
+*/
+std::pair<BigInt,SymmetricKey> BOTAN_PUBLIC_API(2,11)
+   srp6_client_agree(const std::string& username,
+                     const std::string& password,
+                     const DL_Group& group,
+                     const std::string& hash_id,
+                     const std::vector<uint8_t>& salt,
+                     const BigInt& B,
+                     size_t a_bits,
+                     RandomNumberGenerator& rng);
+
 /**
 * Generate a new SRP-6 verifier
 * @param identifier a username or other client identifier
@@ -45,11 +70,27 @@ BOTAN_PUBLIC_API(2,0) srp6_client_agree(const std::string& username,
 * @param group_id specifies the shared SRP group
 * @param hash_id specifies a secure hash function
 */
-BigInt BOTAN_PUBLIC_API(2,0) generate_srp6_verifier(const std::string& identifier,
-                                        const std::string& password,
-                                        const std::vector<uint8_t>& salt,
-                                        const std::string& group_id,
-                                        const std::string& hash_id);
+BigInt BOTAN_PUBLIC_API(2,0)
+   generate_srp6_verifier(const std::string& identifier,
+                          const std::string& password,
+                          const std::vector<uint8_t>& salt,
+                          const std::string& group_id,
+                          const std::string& hash_id);
+
+/**
+* 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_PUBLIC_API(2,11)
+   generate_srp6_verifier(const std::string& identifier,
+                          const std::string& password,
+                          const std::vector<uint8_t>& salt,
+                          const DL_Group& group,
+                          const std::string& hash_id);
 
 /**
 * Return the group id for this SRP param set, or else thrown an
@@ -80,6 +121,23 @@ class BOTAN_PUBLIC_API(2,0) SRP6_Server_Session final
                    RandomNumberGenerator& rng);
 
       /**
+      * Server side step 1
+      * This version of step1 added in 2.11
+      *
+      * @param v the verification value saved from client registration
+      * @param group the SRP group
+      * @param hash_id the SRP hash in use
+      * @param rng a random number generator
+      * @param b_bits size of secret exponent in bits
+      * @return SRP-6 B value
+      */
+      BigInt step1(const BigInt& v,
+                   const DL_Group& group,
+                   const std::string& hash_id,
+                   const size_t b_bits,
+                   RandomNumberGenerator& rng);
+
+      /**
       * Server side step 2
       * @param A the client's value
       * @return shared symmetric key