For passhash9, add another interface that allows the caller to specify

which PRF they want to use. The old interface just calls this new
version with alg_id set to 0 which is HMAC(SHA-1), which was
previously the only supported PRF.

Assign new codepoints for HMAC(SHA-256) and CMAC(Blowfish) to allow
their use with passhash9.

Have the generate+check tests run a test for each supported PRF.

2 files changed, 35 insertions, 14 deletions

diff --git a/src/constructs/passhash/passhash9.cpp b/src/constructs/passhash/passhash9.cpp
index 920aafc4c..6618f36fa 100644
--- a/src/constructs/passhash/passhash9.cpp
+++ b/src/constructs/passhash/passhash9.cpp
@@ -23,6 +23,8 @@ const u32bit ALGID_BYTES = 1;
 const u32bit SALT_BYTES = 12; // 96 bits of salt
 const u32bit PASSHASH9_PBKDF_OUTPUT_LEN = 24; // 192 bits output
 
+const byte PASSHASH9_DEFAULT_ALGO = 0; // HMAC(SHA-1)
+
 const u32bit WORK_FACTOR_SCALE = 10000;
 
 MessageAuthenticationCode* get_pbkdf_prf(byte alg_id)
@@ -33,34 +35,37 @@ MessageAuthenticationCode* get_pbkdf_prf(byte alg_id)
       {
       if(alg_id == 0)
          return af.make_mac("HMAC(SHA-1)");
+      else if(alg_id == 1)
+         return af.make_mac("HMAC(SHA-256)");
+      else if(alg_id == 2)
+         return af.make_mac("CMAC(Blowfish)");
       }
    catch(Algorithm_Not_Found) {}
 
    return 0;
    }
 
-std::pair<byte, MessageAuthenticationCode*> choose_pbkdf_prf()
-   {
-   for(byte alg_id = 0; alg_id != 255; ++alg_id)
-      {
-      MessageAuthenticationCode* prf = get_pbkdf_prf(alg_id);
-      if(prf)
-         return std::make_pair(alg_id, prf);
-      }
+}
 
-   throw Internal_Error("Passhash9: No PRF available");
+std::string generate_passhash9(const std::string& pass,
+                               RandomNumberGenerator& rng,
+                               u16bit work_factor)
+   {
+   return generate_passhash9(pass, PASSHASH9_DEFAULT_ALGO, rng, work_factor);
    }
 
-}
-
 std::string generate_passhash9(const std::string& pass,
+                               byte alg_id,
                                RandomNumberGenerator& rng,
                                u16bit work_factor)
    {
-   std::pair<byte, MessageAuthenticationCode*> prf = choose_pbkdf_prf();
-   byte alg_id = prf.first;
+   MessageAuthenticationCode* prf = get_pbkdf_prf(alg_id);
+
+   if(!prf)
+      throw Invalid_Argument("Passhash9: Algorithm id " + to_string(alg_id) +
+                             " is not defined");
 
-   PKCS5_PBKDF2 kdf(prf.second); // takes ownership of pointer
+   PKCS5_PBKDF2 kdf(prf); // takes ownership of pointer
 
    SecureVector<byte> salt(SALT_BYTES);
    rng.randomize(&salt[0], salt.size());
diff --git a/src/constructs/passhash/passhash9.h b/src/constructs/passhash/passhash9.h
index 8900d55d3..92cc391dc 100644
--- a/src/constructs/passhash/passhash9.h
+++ b/src/constructs/passhash/passhash9.h
@@ -23,6 +23,22 @@ std::string BOTAN_DLL generate_passhash9(const std::string& password,
                                          u16bit work_factor = 10);
 
 /**
+* Create a password hash using PBKDF2
+* @param password the password
+* @param alg_id specifies which PRF to use with PBKDF2
+*        0 is HMAC(SHA-1)
+*        1 is HMAC(SHA-256)
+*        2 is CMAC(Blowfish)
+*        all other values are currently undefined
+* @param rng a random number generator
+* @param work_factor how much work to do to slow down guessing attacks
+*/
+std::string BOTAN_DLL generate_passhash9(const std::string& password,
+                                         byte alg_id,
+                                         RandomNumberGenerator& rng,
+                                         u16bit work_factor = 10);
+
+/**
 * Check a previously created password hash
 * @param password the password to check against
 * @param hash the stored hash to check against