16 files changed, 277 insertions, 213 deletions

diff --git a/checks/check.cpp b/checks/check.cpp
index 93d7e9b94..5cf5c1c31 100644
--- a/checks/check.cpp
+++ b/checks/check.cpp
@@ -102,6 +102,8 @@ int main(int argc, char* argv[])
 
       Botan::LibraryInitializer init("thread_safe=no");
 
+      //Botan::global_state().algorithm_factory().set_preferred_provider("SHA-160", "core");
+
       Botan::AutoSeeded_RNG rng;
 
       if(opts.is_set("help") || argc <= 1)
diff --git a/configure.pl b/configure.pl
index 8fa976fff..737800665 100755
--- a/configure.pl
+++ b/configure.pl
@@ -13,7 +13,7 @@ use Sys::Hostname;
 
 my $MAJOR_VERSION = 1;
 my $MINOR_VERSION = 7;
-my $PATCH_VERSION = 21;
+my $PATCH_VERSION = 22;
 
 my $VERSION_STRING = "$MAJOR_VERSION.$MINOR_VERSION.$PATCH_VERSION";
 
diff --git a/doc/log.txt b/doc/log.txt
index 923279e34..02c5609f9 100644
--- a/doc/log.txt
+++ b/doc/log.txt
@@ -1,4 +1,7 @@
 
+* 1.7.22, ????-??-??
+ - Add provider preferences to Algorithm_Factory
+
 * 1.7.21, 2008-11-11
  - Make algorithm lookup much more configuable
  - Add facilities for runtime performance testing of algorithms
diff --git a/readme.txt b/readme.txt
index 505f59a63..c11a1ea27 100644
--- a/readme.txt
+++ b/readme.txt
@@ -1,4 +1,4 @@
-Botan 1.7.21 2008-11-11
+Botan 1.7.22 ????-??-??
 http://botan.randombit.net/
 
 Please note that this is an experimental / development version of
diff --git a/src/algo_factory/algo_cache.h b/src/algo_factory/algo_cache.h
index 699078b03..17ea9964a 100644
--- a/src/algo_factory/algo_cache.h
+++ b/src/algo_factory/algo_cache.h
@@ -5,25 +5,46 @@
 #ifndef BOTAN_ALGORITHM_CACHE_TEMPLATE_H__
 #define BOTAN_ALGORITHM_CACHE_TEMPLATE_H__
 
-#include <botan/scan_name.h>
 #include <botan/mutex.h>
+#include <botan/stl_util.h>
 #include <string>
+#include <vector>
 #include <map>
 
 namespace Botan {
 
 /**
+* @param prov_name a provider name
+* @return weight for this provider
+*/
+u32bit static_provider_weight(const std::string& prov_name);
+
+/**
 * Algorithm_Cache (used by Algorithm_Factory)
 */
 template<typename T>
 class Algorithm_Cache
    {
    public:
-      const T* get(const SCAN_Name& request);
+      const T* get(const std::string& algo_spec,
+                   const std::string& pref_provider);
+
+      /**
+      * Add a new algorithm implementation to the cache
+      */
       void add(T* algo,
                const std::string& requested_name,
-               const std::string& provider);
+               const std::string& provider_name);
+
+      /**
+      * Set the preferred provider
+      */
+      void set_preferred_provider(const std::string& algo_spec,
+                                  const std::string& provider);
 
+      /**
+      * Return the list of providers of this algorithm
+      */
       std::vector<std::string> providers_of(const std::string& algo_name);
 
       Algorithm_Cache(Mutex* m) : mutex(m) {}
@@ -38,17 +59,18 @@ class Algorithm_Cache
 
       Mutex* mutex;
       std::map<std::string, std::string> aliases;
+      std::map<std::string, std::string> pref_providers;
       std::map<std::string, std::map<std::string, T*> > algorithms;
    };
 
 /**
 * Look for an algorithm implementation in the cache, also checking aliases
+* Assumes object lock is held
 */
 template<typename T>
 typename Algorithm_Cache<T>::algorithms_iterator
 Algorithm_Cache<T>::find_algorithm(const std::string& algo_spec)
    {
-   // Assumes mutex is held
    algorithms_iterator algo = algorithms.find(algo_spec);
 
    // Not found? Check if a known alias
@@ -65,40 +87,51 @@ Algorithm_Cache<T>::find_algorithm(const std::string& algo_spec)
    }
 
 /**
-* Look for an algorithm implementation in the cache
+* Look for an algorithm implementation by a particular provider
 */
 template<typename T>
-const T* Algorithm_Cache<T>::get(const SCAN_Name& request)
+const T* Algorithm_Cache<T>::get(const std::string& algo_spec,
+                                 const std::string& requested_provider)
    {
    Mutex_Holder lock(mutex);
 
-   algorithms_iterator algo = find_algorithm(request.as_string());
-   if(algo == algorithms.end()) // not found at all
+   algorithms_iterator algo = find_algorithm(algo_spec);
+   if(algo == algorithms.end()) // algo not found at all (no providers)
       return 0;
 
-   const std::string requested_provider = request.provider();
-
+   // If a provider is requested specifically, return it or fail entirely
    if(requested_provider != "")
       {
-      provider_iterator provider = algo->second.find(requested_provider);
-
-      if(provider != algo->second.end())
-         return provider->second;
+      provider_iterator prov = algo->second.find(requested_provider);
+      if(prov != algo->second.end())
+         return prov->second;
+      return 0;
       }
-   else // no specific provider requested: pick one
+
+   const T* prototype = 0;
+   std::string prototype_provider;
+   u32bit prototype_prov_weight = 0;
+
+   const std::string pref_provider = search_map(pref_providers, algo_spec);
+
+   for(provider_iterator i = algo->second.begin(); i != algo->second.end(); ++i)
       {
-      provider_iterator provider = algo->second.begin();
+      const std::string prov_name = i->first;
+      const u32bit prov_weight = static_provider_weight(prov_name);
 
-      while(provider != algo->second.end())
-         ++provider;
+      // preferred prov exists, return immediately
+      if(prov_name == pref_provider)
+         return i->second;
 
-      provider = algo->second.begin();
-      // @fixme: Just picks the lexicographically first one
-      if(provider != algo->second.end())
-         return provider->second;
+      if(prototype == 0 || prov_weight > prototype_prov_weight)
+         {
+         prototype = i->second;
+         prototype_provider = i->first;
+         prototype_prov_weight = prov_weight;
+         }
       }
 
-   return 0; // cache miss
+   return prototype;
    }
 
 /**
@@ -151,6 +184,18 @@ Algorithm_Cache<T>::providers_of(const std::string& algo_name)
    }
 
 /**
+* Set the preferred provider for an algorithm
+*/
+template<typename T>
+void Algorithm_Cache<T>::set_preferred_provider(const std::string& algo_spec,
+                                                const std::string& provider)
+   {
+   Mutex_Holder lock(mutex);
+
+   pref_providers[algo_spec] = provider;
+   }
+
+/**
 * Algorithm_Cache<T> Destructor
 */
 template<typename T>
diff --git a/src/algo_factory/algo_factory.cpp b/src/algo_factory/algo_factory.cpp
index 0756d02d8..5b300b7c6 100644
--- a/src/algo_factory/algo_factory.cpp
+++ b/src/algo_factory/algo_factory.cpp
@@ -45,9 +45,25 @@ void Algorithm_Factory::add_engine(Engine* engine)
    engines.push_back(engine);
    }
 
-/*************************************************
-* Get an engine out of the list                  *
-*************************************************/
+/**
+* Set the preferred provider for an algorithm
+*/
+void Algorithm_Factory::set_preferred_provider(const std::string& algo_spec,
+                                               const std::string& provider)
+   {
+   if(prototype_block_cipher(algo_spec))
+      block_cipher_cache.set_preferred_provider(algo_spec, provider);
+   else if(prototype_stream_cipher(algo_spec))
+      stream_cipher_cache.set_preferred_provider(algo_spec, provider);
+   else if(prototype_hash_function(algo_spec))
+      hash_cache.set_preferred_provider(algo_spec, provider);
+   else if(prototype_mac(algo_spec))
+      mac_cache.set_preferred_provider(algo_spec, provider);
+   }
+
+/**
+* Get an engine out of the list
+*/
 Engine* Algorithm_Factory::get_engine_n(u32bit n) const
    {
    if(n >= engines.size())
@@ -57,180 +73,173 @@ Engine* Algorithm_Factory::get_engine_n(u32bit n) const
 
 /**
 * Return the possible providers of a request
+* Note: assumes you don't have different types by the same name
 */
 std::vector<std::string>
-Algorithm_Factory::providers_of(const std::string& algo_name)
+Algorithm_Factory::providers_of(const std::string& algo_spec)
    {
-   if(prototype_block_cipher(algo_name))
-      return block_cipher_cache.providers_of(algo_name);
-
-   if(prototype_stream_cipher(algo_name))
-      return stream_cipher_cache.providers_of(algo_name);
-
-   if(prototype_hash_function(algo_name))
-      return hash_cache.providers_of(algo_name);
-
-   if(prototype_mac(algo_name))
-      return mac_cache.providers_of(algo_name);
-
-   return std::vector<std::string>();
+   if(prototype_block_cipher(algo_spec))
+      return block_cipher_cache.providers_of(algo_spec);
+   else if(prototype_stream_cipher(algo_spec))
+      return stream_cipher_cache.providers_of(algo_spec);
+   else if(prototype_hash_function(algo_spec))
+      return hash_cache.providers_of(algo_spec);
+   else if(prototype_mac(algo_spec))
+      return mac_cache.providers_of(algo_spec);
+   else
+      return std::vector<std::string>();
    }
 
 /**
 * Return the prototypical block cipher cooresponding to this request
 */
 const BlockCipher*
-Algorithm_Factory::prototype_block_cipher(const SCAN_Name& request)
+Algorithm_Factory::prototype_block_cipher(const std::string& algo_spec,
+                                          const std::string& provider)
    {
-   if(const BlockCipher* cache_hit = block_cipher_cache.get(request))
-      return cache_hit;
+   if(const BlockCipher* hit = block_cipher_cache.get(algo_spec, provider))
+      return hit;
 
+   SCAN_Name scan_name(algo_spec);
    for(u32bit i = 0; i != engines.size(); ++i)
       {
-      const std::string provider = engines[i]->provider_name();
-
-      SCAN_Name request_i(request.as_string(), provider);
-
-      if(BlockCipher* impl = engines[i]->find_block_cipher(request_i, *this))
-         block_cipher_cache.add(impl, request.as_string(), provider);
+      if(BlockCipher* impl = engines[i]->find_block_cipher(scan_name, *this))
+         block_cipher_cache.add(impl, algo_spec, engines[i]->provider_name());
       }
 
-   return block_cipher_cache.get(request);
+   return block_cipher_cache.get(algo_spec, provider);
    }
 
 /**
-* Return a new block cipher cooresponding to this request
+* Return the prototypical stream cipher cooresponding to this request
 */
-BlockCipher* Algorithm_Factory::make_block_cipher(const SCAN_Name& request)
+const StreamCipher*
+Algorithm_Factory::prototype_stream_cipher(const std::string& algo_spec,
+                                           const std::string& provider)
    {
-   if(const BlockCipher* prototype = prototype_block_cipher(request))
-      return prototype->clone();
-   throw Algorithm_Not_Found(request.as_string());
+   if(const StreamCipher* hit = stream_cipher_cache.get(algo_spec, provider))
+      return hit;
+
+   SCAN_Name scan_name(algo_spec);
+   for(u32bit i = 0; i != engines.size(); ++i)
+      {
+      if(StreamCipher* impl = engines[i]->find_stream_cipher(scan_name, *this))
+         stream_cipher_cache.add(impl, algo_spec, engines[i]->provider_name());
+      }
+
+   return stream_cipher_cache.get(algo_spec, provider);
    }
 
 /**
-* Add a new block cipher
+* Return the prototypical object cooresponding to this request (if found)
 */
-void Algorithm_Factory::add_block_cipher(BlockCipher* block_cipher,
-                                         const std::string& provider)
+const HashFunction*
+Algorithm_Factory::prototype_hash_function(const std::string& algo_spec,
+                                           const std::string& provider)
    {
-   block_cipher_cache.add(block_cipher, block_cipher->name(), provider);
+   if(const HashFunction* hit = hash_cache.get(algo_spec, provider))
+      return hit;
+
+   SCAN_Name scan_name(algo_spec);
+   for(u32bit i = 0; i != engines.size(); ++i)
+      {
+      if(HashFunction* impl = engines[i]->find_hash(scan_name, *this))
+         hash_cache.add(impl, algo_spec, engines[i]->provider_name());
+      }
+
+   return hash_cache.get(algo_spec, provider);
    }
 
 /**
-* Return the prototypical stream cipher cooresponding to this request
+* Return the prototypical object cooresponding to this request
 */
-const StreamCipher*
-Algorithm_Factory::prototype_stream_cipher(const SCAN_Name& request)
+const MessageAuthenticationCode*
+Algorithm_Factory::prototype_mac(const std::string& algo_spec,
+                                 const std::string& provider)
    {
-   if(const StreamCipher* cache_hit = stream_cipher_cache.get(request))
-      return cache_hit;
+   if(const MessageAuthenticationCode* hit = mac_cache.get(algo_spec, provider))
+      return hit;
 
+   SCAN_Name scan_name(algo_spec);
    for(u32bit i = 0; i != engines.size(); ++i)
       {
-      const std::string provider = engines[i]->provider_name();
-
-      SCAN_Name request_i(request.as_string(), provider);
-
-      if(StreamCipher* impl = engines[i]->find_stream_cipher(request_i, *this))
-         stream_cipher_cache.add(impl, request.as_string(), provider);
+      if(MessageAuthenticationCode* impl = engines[i]->find_mac(scan_name, *this))
+         mac_cache.add(impl, algo_spec, engines[i]->provider_name());
       }
 
-   return stream_cipher_cache.get(request);
+   return mac_cache.get(algo_spec, provider);
    }
 
 /**
-* Return a new stream cipher cooresponding to this request
+* Return a new block cipher cooresponding to this request
 */
-StreamCipher* Algorithm_Factory::make_stream_cipher(const SCAN_Name& request)
+BlockCipher* Algorithm_Factory::make_block_cipher(const std::string& algo_spec,
+                                                  const std::string& provider)
    {
-   if(const StreamCipher* prototype = prototype_stream_cipher(request))
-      return prototype->clone();
-   throw Algorithm_Not_Found(request.as_string());
+   if(const BlockCipher* proto = prototype_block_cipher(algo_spec, provider))
+      return proto->clone();
+   throw Algorithm_Not_Found(algo_spec);
    }
 
 /**
-* Add a new stream cipher
+* Return a new stream cipher cooresponding to this request
 */
-void Algorithm_Factory::add_stream_cipher(StreamCipher* stream_cipher,
-                                         const std::string& provider)
+StreamCipher* Algorithm_Factory::make_stream_cipher(const std::string& algo_spec,
+                                                    const std::string& provider)
    {
-   stream_cipher_cache.add(stream_cipher, stream_cipher->name(), provider);
+   if(const StreamCipher* prototype = prototype_stream_cipher(algo_spec, provider))
+      return prototype->clone();
+   throw Algorithm_Not_Found(algo_spec);
    }
 
 /**
-* Return the prototypical object cooresponding to this request (if found)
+* Return a new object cooresponding to this request
 */
-const HashFunction*
-Algorithm_Factory::prototype_hash_function(const SCAN_Name& request)
+HashFunction* Algorithm_Factory::make_hash_function(const std::string& algo_spec,
+                                                    const std::string& provider)
    {
-   if(const HashFunction* cache_hit = hash_cache.get(request))
-      return cache_hit;
-
-   for(u32bit i = 0; i != engines.size(); ++i)
-      {
-      const std::string provider = engines[i]->provider_name();
-
-      SCAN_Name request_i(request.as_string(), provider);
-
-      if(HashFunction* impl = engines[i]->find_hash(request_i, *this))
-         hash_cache.add(impl, request.as_string(), provider);
-      }
-
-   return hash_cache.get(request);
+   if(const HashFunction* prototype = prototype_hash_function(algo_spec, provider))
+      return prototype->clone();
+   throw Algorithm_Not_Found(algo_spec);
    }
 
 /**
 * Return a new object cooresponding to this request
 */
-HashFunction* Algorithm_Factory::make_hash_function(const SCAN_Name& request)
+MessageAuthenticationCode*
+Algorithm_Factory::make_mac(const std::string& algo_spec,
+                            const std::string& provider)
    {
-   if(const HashFunction* prototype = prototype_hash_function(request))
+   if(const MessageAuthenticationCode* prototype = prototype_mac(algo_spec, provider))
       return prototype->clone();
-   throw Algorithm_Not_Found(request.as_string());
+   throw Algorithm_Not_Found(algo_spec);
    }
 
 /**
-* Add a new hash
+* Add a new block cipher
 */
-void Algorithm_Factory::add_hash_function(HashFunction* hash,
-                                          const std::string& provider)
+void Algorithm_Factory::add_block_cipher(BlockCipher* block_cipher,
+                                         const std::string& provider)
    {
-   hash_cache.add(hash, hash->name(), provider);
+   block_cipher_cache.add(block_cipher, block_cipher->name(), provider);
    }
 
 /**
-* Return the prototypical object cooresponding to this request
+* Add a new stream cipher
 */
-const MessageAuthenticationCode*
-Algorithm_Factory::prototype_mac(const SCAN_Name& request)
+void Algorithm_Factory::add_stream_cipher(StreamCipher* stream_cipher,
+                                         const std::string& provider)
    {
-   if(const MessageAuthenticationCode* cache_hit = mac_cache.get(request))
-      return cache_hit;
-
-   for(u32bit i = 0; i != engines.size(); ++i)
-      {
-      const std::string provider = engines[i]->provider_name();
-
-      SCAN_Name request_i(request.as_string(), provider);
-
-      if(MessageAuthenticationCode* impl =
-            engines[i]->find_mac(request_i, *this))
-         mac_cache.add(impl, request.as_string(), provider);
-      }
-
-   return mac_cache.get(request);
+   stream_cipher_cache.add(stream_cipher, stream_cipher->name(), provider);
    }
 
 /**
-* Return a new object cooresponding to this request
+* Add a new hash
 */
-MessageAuthenticationCode*
-Algorithm_Factory::make_mac(const SCAN_Name& request)
+void Algorithm_Factory::add_hash_function(HashFunction* hash,
+                                          const std::string& provider)
    {
-   if(const MessageAuthenticationCode* prototype = prototype_mac(request))
-      return prototype->clone();
-   throw Algorithm_Not_Found(request.as_string());
+   hash_cache.add(hash, hash->name(), provider);
    }
 
 /**
diff --git a/src/algo_factory/algo_factory.h b/src/algo_factory/algo_factory.h
index 07a8c93f1..fbaf26ebf 100644
--- a/src/algo_factory/algo_factory.h
+++ b/src/algo_factory/algo_factory.h
@@ -7,11 +7,9 @@
 #define BOTAN_ALGORITHM_FACTORY_H__
 
 #include <botan/algo_cache.h>
-#include <botan/scan_name.h>
 #include <botan/mutex.h>
 #include <string>
 #include <vector>
-#include <map>
 
 namespace Botan {
 
@@ -29,11 +27,70 @@ class MessageAuthenticationCode;
 class BOTAN_DLL Algorithm_Factory
    {
    public:
+      /**
+      * Contructor
+      * @param mf a mutex factory
+      */
       Algorithm_Factory(Mutex_Factory& mf);
+
+      /**
+      * Destructor
+      */
       ~Algorithm_Factory();
 
+      /**
+      * Add an engine implementation to this factory (how steampunk)
+      */
       void add_engine(class Engine*);
 
+      /*
+      * Provider management
+      */
+      std::vector<std::string> providers_of(const std::string& algo_spec);
+
+      void set_preferred_provider(const std::string& algo_spec,
+                                  const std::string& provider);
+
+      /*
+      * Block cipher operations
+      */
+      const BlockCipher* prototype_block_cipher(const std::string& algo_spec,
+                                                const std::string& provider = "");
+      BlockCipher* make_block_cipher(const std::string& algo_spec,
+                                     const std::string& provider = "");
+      void add_block_cipher(BlockCipher* hash, const std::string& provider);
+
+      /*
+      * Stream cipher operations
+      */
+      const StreamCipher* prototype_stream_cipher(const std::string& algo_spec,
+                                                  const std::string& provider = "");
+      StreamCipher* make_stream_cipher(const std::string& algo_spec,
+                                       const std::string& provider = "");
+      void add_stream_cipher(StreamCipher* hash, const std::string& provider);
+
+      /*
+      * Hash function operations
+      */
+      const HashFunction* prototype_hash_function(const std::string& algo_spec,
+                                                  const std::string& provider = "");
+      HashFunction* make_hash_function(const std::string& algo_spec,
+                                       const std::string& provider = "");
+      void add_hash_function(HashFunction* hash, const std::string& provider);
+
+      /*
+      * MAC operations
+      */
+      const MessageAuthenticationCode* prototype_mac(const std::string& algo_spec,
+                                                     const std::string& provider = "");
+      MessageAuthenticationCode* make_mac(const std::string& algo_spec,
+                                          const std::string& provider = "");
+      void add_mac(MessageAuthenticationCode* mac,
+                   const std::string& provider);
+
+      /*
+      * Deprecated
+      */
       class BOTAN_DLL Engine_Iterator
          {
          public:
@@ -45,28 +102,6 @@ class BOTAN_DLL Algorithm_Factory
          };
       friend class Engine_Iterator;
 
-      std::vector<std::string> providers_of(const std::string& algo_spec);
-
-      // Block cipher operations
-      const BlockCipher* prototype_block_cipher(const SCAN_Name& request);
-      BlockCipher* make_block_cipher(const SCAN_Name& request);
-      void add_block_cipher(BlockCipher* hash, const std::string& provider);
-
-      // Stream cipher operations
-      const StreamCipher* prototype_stream_cipher(const SCAN_Name& request);
-      StreamCipher* make_stream_cipher(const SCAN_Name& request);
-      void add_stream_cipher(StreamCipher* hash, const std::string& provider);
-
-      // Hash function operations
-      const HashFunction* prototype_hash_function(const SCAN_Name& request);
-      HashFunction* make_hash_function(const SCAN_Name& request);
-      void add_hash_function(HashFunction* hash, const std::string& provider);
-
-      // MAC operations
-      const MessageAuthenticationCode* prototype_mac(const SCAN_Name& request);
-      MessageAuthenticationCode* make_mac(const SCAN_Name& request);
-      void add_mac(MessageAuthenticationCode* mac,
-                   const std::string& provider);
    private:
       class Engine* get_engine_n(u32bit) const;
 
diff --git a/src/algo_factory/info.txt b/src/algo_factory/info.txt
index 34f2a94cc..937b91353 100644
--- a/src/algo_factory/info.txt
+++ b/src/algo_factory/info.txt
@@ -12,4 +12,5 @@ utils
 algo_factory.cpp
 algo_factory.h
 algo_cache.h
+prov_weight.cpp
 </add>
diff --git a/src/benchmark/benchmark.cpp b/src/benchmark/benchmark.cpp
index 41e41bfcc..fe6cf0a41 100644
--- a/src/benchmark/benchmark.cpp
+++ b/src/benchmark/benchmark.cpp
@@ -137,32 +137,33 @@ algorithm_benchmark(const std::string& name,
       {
       const std::string provider = providers[i];
 
-      SCAN_Name request(name, provider);
-
       std::pair<u32bit, u64bit> results = std::make_pair(0, 0);
 
-      if(const BlockCipher* proto = af.prototype_block_cipher(request))
+      if(const BlockCipher* proto =
+            af.prototype_block_cipher(name, provider))
          {
          std::auto_ptr<BlockCipher> block_cipher(proto->clone());
          results = bench_block_cipher(block_cipher.get(), timer,
                                       ns_per_provider,
                                       &buf[0], buf.size());
          }
-      else if(const StreamCipher* proto = af.prototype_stream_cipher(request))
+      else if(const StreamCipher* proto =
+                 af.prototype_stream_cipher(name, provider))
          {
          std::auto_ptr<StreamCipher> stream_cipher(proto->clone());
          results = bench_stream_cipher(stream_cipher.get(), timer,
                                        ns_per_provider,
                                        &buf[0], buf.size());
          }
-      else if(const HashFunction* proto = af.prototype_hash_function(request))
+      else if(const HashFunction* proto =
+                 af.prototype_hash_function(name, provider))
          {
          std::auto_ptr<HashFunction> hash(proto->clone());
          results = bench_hash(hash.get(), timer, ns_per_provider,
                               &buf[0], buf.size());
          }
       else if(const MessageAuthenticationCode* proto =
-                af.prototype_mac(request))
+                 af.prototype_mac(name, provider))
          {
          std::auto_ptr<MessageAuthenticationCode> mac(proto->clone());
          results = bench_mac(mac.get(), timer, ns_per_provider,
diff --git a/src/engine/def_engine/lookup_mac.cpp b/src/engine/def_engine/lookup_mac.cpp
index ae44bbe3d..35f17e134 100644
--- a/src/engine/def_engine/lookup_mac.cpp
+++ b/src/engine/def_engine/lookup_mac.cpp
@@ -59,7 +59,7 @@ Default_Engine::find_mac(const SCAN_Name& request,
 
 #if defined(BOTAN_HAS_ANSI_X919_MAC)
    if(request.algo_name() == "X9.19-MAC" && request.arg_count() == 0)
-      return new ANSI_X919_MAC(af.make_block_cipher(SCAN_Name("DES")));
+      return new ANSI_X919_MAC(af.make_block_cipher("DES"));
 #endif
 
    return 0;
diff --git a/src/libstate/get_enc.cpp b/src/libstate/get_enc.cpp
index a5231db91..60a92d53e 100644
--- a/src/libstate/get_enc.cpp
+++ b/src/libstate/get_enc.cpp
@@ -146,7 +146,7 @@ EMSA* get_emsa(const std::string& algo_spec)
       if(request.arg_count() == 1)
          return new EMSA4(af.make_hash_function(request.arg(0)));
 
-      if(request.arg_count() == 2 && request.arg_as_string(1) != "MGF1")
+      if(request.arg_count() == 2 && request.arg(1) != "MGF1")
          return new EMSA4(af.make_hash_function(request.arg(0)));
 
       if(request.arg_count() == 3)
@@ -179,7 +179,7 @@ EME* get_eme(const std::string& algo_spec)
    if(request.algo_name() == "EME1" && request.arg_count_between(1, 2))
       {
       if(request.arg_count() == 1 ||
-         (request.arg_count() == 2 && request.arg_as_string(1) == "MGF1"))
+         (request.arg_count() == 2 && request.arg(1) == "MGF1"))
          {
          return new EME1(af.make_hash_function(request.arg(0)));
          }
@@ -213,7 +213,7 @@ KDF* get_kdf(const std::string& algo_spec)
 
 #if defined(BOTAN_HAS_X942_PRF)
    if(request.algo_name() == "X9.42-PRF" && request.arg_count() == 1)
-      return new X942_PRF(request.arg_as_string(0)); // OID
+      return new X942_PRF(request.arg(0)); // OID
 #endif
 
 #if defined(BOTAN_HAS_TLS_V10_PRF)
diff --git a/src/pbe/get_pbe.cpp b/src/pbe/get_pbe.cpp
index 985f61cf8..5fa0291c8 100644
--- a/src/pbe/get_pbe.cpp
+++ b/src/pbe/get_pbe.cpp
@@ -27,8 +27,8 @@ PBE* get_pbe(const std::string& algo_spec)
    SCAN_Name request(algo_spec);
 
    const std::string pbe = request.algo_name();
-   SCAN_Name digest_name = request.arg(0);
-   const std::string cipher = request.arg_as_string(1);
+   std::string digest_name = request.arg(0);
+   const std::string cipher = request.arg(1);
 
    std::vector<std::string> cipher_spec = split_on(cipher, '/');
    if(cipher_spec.size() != 2)
@@ -48,7 +48,7 @@ PBE* get_pbe(const std::string& algo_spec)
 
    const HashFunction* hash_function = af.make_hash_function(digest_name);
    if(!hash_function)
-      throw Algorithm_Not_Found(digest_name.as_string());
+      throw Algorithm_Not_Found(digest_name);
 
    if(request.arg_count() != 2)
       throw Invalid_Algorithm_Name(algo_spec);
@@ -84,8 +84,8 @@ PBE* get_pbe(const OID& pbe_oid, DataSource& params)
       if(request.arg_count() != 2)
          throw Invalid_Algorithm_Name(request.as_string());
 
-      SCAN_Name digest_name = request.arg(0);
-      const std::string cipher = request.arg_as_string(1);
+      std::string digest_name = request.arg(0);
+      const std::string cipher = request.arg(1);
 
       std::vector<std::string> cipher_spec = split_on(cipher, '/');
       if(cipher_spec.size() != 2)
@@ -105,7 +105,7 @@ PBE* get_pbe(const OID& pbe_oid, DataSource& params)
 
       const HashFunction* hash_function = af.make_hash_function(digest_name);
       if(!hash_function)
-         throw Algorithm_Not_Found(digest_name.as_string());
+         throw Algorithm_Not_Found(digest_name);
 
       PBE* pbe = new PBE_PKCS5v15(block_cipher->clone(),
                                   hash_function->clone(),
diff --git a/src/pbe/pbes2/pbes2.cpp b/src/pbe/pbes2/pbes2.cpp
index 25be6f98a..3935bd702 100644
--- a/src/pbe/pbes2/pbes2.cpp
+++ b/src/pbe/pbes2/pbes2.cpp
@@ -176,7 +176,7 @@ void PBE_PKCS5v20::decode_params(DataSource& source)
    BER_Decoder(enc_algo.parameters).decode(iv, OCTET_STRING).verify_end();
 
    block_cipher = af.make_block_cipher(cipher_spec[0]);
-   hash_function = af.make_hash_function(SCAN_Name("SHA-160"));
+   hash_function = af.make_hash_function("SHA-160");
 
    if(key_length == 0)
       key_length = block_cipher->MAXIMUM_KEYLENGTH;
diff --git a/src/selftest/selftest.cpp b/src/selftest/selftest.cpp
index f18ab5f7e..4222dc3c9 100644
--- a/src/selftest/selftest.cpp
+++ b/src/selftest/selftest.cpp
@@ -80,7 +80,7 @@ bool passes_self_tests(Algorithm_Factory& af)
   {
   try
      {
-     if(const BlockCipher* proto = af.prototype_block_cipher(SCAN_Name("DES")))
+     if(const BlockCipher* proto = af.prototype_block_cipher("DES"))
         {
         cipher_kat(proto,
                 "0123456789ABCDEF", "1234567890ABCDEF",
@@ -92,7 +92,7 @@ bool passes_self_tests(Algorithm_Factory& af)
                 "F3096249C7F46E51163A8CA0FFC94C27FA2F80F480B86F75");
         }
 
-     if(const BlockCipher* proto = af.prototype_block_cipher(SCAN_Name("TripleDES")))
+     if(const BlockCipher* proto = af.prototype_block_cipher("TripleDES"))
         {
         cipher_kat(proto,
                 "385D7189A5C3D485E1370AA5D408082B5CCCCB5E19F2D90E",
@@ -105,7 +105,7 @@ bool passes_self_tests(Algorithm_Factory& af)
                 "E26BA806A59B03303C62C2EFF32D3ACDD5D5F35EBCC53371");
         }
 
-     if(const BlockCipher* proto = af.prototype_block_cipher(SCAN_Name("AES")))
+     if(const BlockCipher* proto = af.prototype_block_cipher("AES"))
         {
         cipher_kat(proto,
                    "2B7E151628AED2A6ABF7158809CF4F3C",
@@ -124,7 +124,7 @@ bool passes_self_tests(Algorithm_Factory& af)
                    "010C041999E03F36448624483E582D0E");
         }
 
-     if(const HashFunction* proto = af.prototype_hash_function(SCAN_Name("SHA-1")))
+     if(const HashFunction* proto = af.prototype_hash_function("SHA-1"))
         {
         do_kat("", "DA39A3EE5E6B4B0D3255BFEF95601890AFD80709",
                proto->name(), new Hash_Filter(proto->clone()));
@@ -144,7 +144,7 @@ bool passes_self_tests(Algorithm_Factory& af)
                               SymmetricKey("0B0B0B0B0B0B0B0B0B0B0B0B0B0B0B0B0B0B0B0B")));
         }
 
-     if(const HashFunction* proto = af.prototype_hash_function(SCAN_Name("SHA-256")))
+     if(const HashFunction* proto = af.prototype_hash_function("SHA-256"))
         {
         do_kat("",
                  "E3B0C44298FC1C149AFBF4C8996FB924"
diff --git a/src/utils/scan_name.cpp b/src/utils/scan_name.cpp
index f5a1a9245..c0e931e14 100644
--- a/src/utils/scan_name.cpp
+++ b/src/utils/scan_name.cpp
@@ -40,11 +40,9 @@ parse_and_deref_aliases(const std::string& algo_spec)
 
 }
 
-SCAN_Name::SCAN_Name(const std::string& algo_spec,
-                     const std::string& provider)
+SCAN_Name::SCAN_Name(const std::string& algo_spec)
    {
    orig_algo_spec = algo_spec;
-   m_provider = provider;
 
    name = parse_and_deref_aliases(algo_spec);
 
@@ -52,15 +50,7 @@ SCAN_Name::SCAN_Name(const std::string& algo_spec,
       throw Decoding_Error("Bad SCAN name " + algo_spec);
    }
 
-SCAN_Name SCAN_Name::arg(u32bit i) const
-   {
-   if(i > arg_count())
-      throw std::range_error("SCAN_Name::argument");
-
-   return SCAN_Name(name[i+1], m_provider);
-   }
-
-std::string SCAN_Name::arg_as_string(u32bit i) const
+std::string SCAN_Name::arg(u32bit i) const
    {
    if(i > arg_count())
       throw std::range_error("SCAN_Name::argument");
diff --git a/src/utils/scan_name.h b/src/utils/scan_name.h
index b01411c94..4e391c37d 100644
--- a/src/utils/scan_name.h
+++ b/src/utils/scan_name.h
@@ -22,10 +22,8 @@ class SCAN_Name
    public:
       /**
       @param algo_spec A SCAN name
-      @param providers An optional provider name
       */
-      SCAN_Name(const std::string& algo_spec,
-                const std::string& providers = "");
+      SCAN_Name(const std::string& algo_spec);
 
       /**
       @return the original input string
@@ -33,11 +31,6 @@ class SCAN_Name
       std::string as_string() const { return orig_algo_spec; }
 
       /**
-      @return the provider name (or empty)
-      */
-      std::string provider() const { return m_provider; }
-
-      /**
       @return the algorithm name
       */
       std::string algo_name() const { return name[0]; }
@@ -48,15 +41,6 @@ class SCAN_Name
       u32bit arg_count() const { return name.size() - 1; }
 
       /**
-      @param provider a provider name
-      @returns if this provider was allowed by the request
-      */
-      bool provider_allowed(const std::string& provider) const
-         {
-         return (m_provider == "" || m_provider == provider);
-         }
-
-      /**
       @return if the number of arguments is between lower and upper
       */
       bool arg_count_between(u32bit lower, u32bit upper) const
@@ -66,13 +50,7 @@ class SCAN_Name
       @param i which argument
       @return the ith argument
       */
-      std::string arg_as_string(u32bit i) const;
-
-      /**
-      @param i which argument
-      @return the ith argument
-      */
-      SCAN_Name arg(u32bit i) const;
+      std::string arg(u32bit i) const;
 
       /**
       @param i which argument
@@ -80,7 +58,7 @@ class SCAN_Name
       */
       u32bit arg_as_u32bit(u32bit i, u32bit def_value) const;
    private:
-      std::string orig_algo_spec, m_provider;
+      std::string orig_algo_spec;
       std::vector<std::string> name;
    };