Merge GH #1180 Refactorings to support Windows Phone

17 files changed, 560 insertions, 480 deletions

diff --git a/src/build-data/buildh.in b/src/build-data/buildh.in
index 6e60718ee..e1337318e 100644
--- a/src/build-data/buildh.in
+++ b/src/build-data/buildh.in
@@ -117,15 +117,14 @@
 
 /*
 * Specifies (in order) the list of entropy sources that will be used
-* to seed an in-memory RNG. The first in the default list: "rdseed" and "rdrand"
-* do not count as contributing any entropy
-* but are included as they are fast and help protect against a
-* seriously broken system RNG.
+* to seed an in-memory RNG. The first in the default list: "rdseed"
+* and "rdrand" do not count as contributing any entropy but are
+* included as they are fast and help protect against a seriously
+* broken system RNG.
 */
 #define BOTAN_ENTROPY_DEFAULT_SOURCES \
-   { "rdseed", "rdrand", "darwin_secrandom", "getentropy", "dev_random", \
-    "win32_cryptoapi", "proc_walk", "system_stats" }
-
+   { "rdseed", "rdrand", "darwin_secrandom", "getentropy", \
+     "dev_random", "system_rng", "proc_walk", "system_stats" }
 
 /* Multiplier on a block cipher's native parallelism */
 #define BOTAN_BLOCK_CIPHER_PAR_MULT 4
diff --git a/src/build-data/os/winphone.txt b/src/build-data/os/winphone.txt
new file mode 100644
index 000000000..ee43ee702
--- /dev/null
+++ b/src/build-data/os/winphone.txt
@@ -0,0 +1,26 @@
+os_type windows
+
+# ?
+program_suffix .exe
+obj_suffix obj
+static_suffix lib
+building_shared_supported no
+
+install_root c:\\Botan
+doc_dir docs
+
+install_cmd_data "copy"
+install_cmd_exec "copy"
+
+<target_features>
+crypto_ng
+gmtime_s
+loadlibrary
+mkgmtime
+query_perf_counter
+rtlsecurezeromemory
+#stl_filesystem_msvc
+threads
+filesystem
+sockets
+</target_features>
diff --git a/src/build-data/policy/bsi.txt b/src/build-data/policy/bsi.txt
index 0f053c337..f66f634ed 100644
--- a/src/build-data/policy/bsi.txt
+++ b/src/build-data/policy/bsi.txt
@@ -57,7 +57,6 @@ aes_ssse3
 clmul
 
 # entropy sources
-cryptoapi_rng
 darwin_secrandom
 dev_random
 proc_walk
diff --git a/src/build-data/policy/modern.txt b/src/build-data/policy/modern.txt
index 588fc7fc8..fb435636c 100644
--- a/src/build-data/policy/modern.txt
+++ b/src/build-data/policy/modern.txt
@@ -76,7 +76,6 @@ rdrand_rng
 system_rng
 
 # entropy sources
-cryptoapi_rng
 darwin_secrandom
 dev_random
 proc_walk
diff --git a/src/build-data/policy/nist.txt b/src/build-data/policy/nist.txt
index 50948d4dc..ad7a552dc 100644
--- a/src/build-data/policy/nist.txt
+++ b/src/build-data/policy/nist.txt
@@ -61,7 +61,6 @@ sha2_32_armv8
 clmul
 
 # entropy sources
-cryptoapi_rng
 darwin_secrandom
 dev_random
 proc_walk
diff --git a/src/lib/entropy/cryptoapi_rng/es_capi.cpp b/src/lib/entropy/cryptoapi_rng/es_capi.cpp
deleted file mode 100644
index 58503c66d..000000000
--- a/src/lib/entropy/cryptoapi_rng/es_capi.cpp
+++ /dev/null
@@ -1,95 +0,0 @@
-/*
-* Win32 CryptoAPI EntropySource
-* (C) 1999-2009,2016 Jack Lloyd
-*
-* Botan is released under the Simplified BSD License (see license.txt)
-*/
-
-#include <botan/internal/es_capi.h>
-#include <botan/parsing.h>
-#define NOMINMAX 1
-#define _WINSOCKAPI_ // stop windows.h including winsock.h
-#include <windows.h>
-#include <wincrypt.h>
-
-namespace Botan {
-
-namespace {
-
-class CSP_Handle_Impl : public Win32_CAPI_EntropySource::CSP_Handle
-   {
-   public:
-      explicit CSP_Handle_Impl(uint64_t capi_provider)
-         {
-         m_valid = ::CryptAcquireContext(&m_handle,
-                                         nullptr,
-                                         nullptr,
-                                         static_cast<DWORD>(capi_provider),
-                                         CRYPT_VERIFYCONTEXT);
-         }
-
-      ~CSP_Handle_Impl()
-         {
-         if(m_valid)
-            ::CryptReleaseContext(m_handle, 0);
-         }
-
-      size_t gen_random(uint8_t out[], size_t n) const
-         {
-         if(m_valid && ::CryptGenRandom(m_handle, static_cast<DWORD>(n), out))
-            return n;
-         return 0;
-         }
-
-   private:
-      bool m_valid;
-      HCRYPTPROV m_handle;
-   };
-
-}
-
-/*
-* Gather Entropy from Win32 CAPI
-*/
-size_t Win32_CAPI_EntropySource::poll(RandomNumberGenerator& rng)
-   {
-   secure_vector<uint8_t> buf(BOTAN_SYSTEM_RNG_POLL_REQUEST);
-   size_t bits = 0;
-
-   for(size_t i = 0; i != m_csp_provs.size(); ++i)
-      {
-      size_t got = m_csp_provs[i]->gen_random(buf.data(), buf.size());
-
-      if(got > 0)
-         {
-         rng.add_entropy(buf.data(), got);
-         bits += got * 8;
-         }
-      }
-
-   return bits;
-   }
-
-/*
-* Win32_Capi_Entropysource Constructor
-*/
-Win32_CAPI_EntropySource::Win32_CAPI_EntropySource(const std::string& provs)
-   {
-   for(std::string prov_name : split_on(provs, ':'))
-      {
-      DWORD prov_type;
-
-      if(prov_name == "RSA_FULL")
-         prov_type = PROV_RSA_FULL;
-      else if(prov_name == "INTEL_SEC")
-         prov_type = PROV_INTEL_SEC;
-      else if(prov_name == "RNG")
-         prov_type = PROV_RNG;
-      else
-         continue;
-
-      m_csp_provs.push_back(std::unique_ptr<CSP_Handle>(new CSP_Handle_Impl(prov_type)));
-      }
-   }
-
-}
diff --git a/src/lib/entropy/cryptoapi_rng/es_capi.h b/src/lib/entropy/cryptoapi_rng/es_capi.h
deleted file mode 100644
index 8439e62fa..000000000
--- a/src/lib/entropy/cryptoapi_rng/es_capi.h
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
-* Win32 CAPI EntropySource
-* (C) 1999-2007 Jack Lloyd
-*
-* Botan is released under the Simplified BSD License (see license.txt)
-*/
-
-#ifndef BOTAN_ENTROPY_SRC_WIN32_CAPI_H__
-#define BOTAN_ENTROPY_SRC_WIN32_CAPI_H__
-
-#include <botan/entropy_src.h>
-#include <vector>
-
-namespace Botan {
-
-/**
-* Win32 CAPI Entropy Source
-*/
-class Win32_CAPI_EntropySource final : public Entropy_Source
-   {
-   public:
-      std::string name() const override { return "win32_cryptoapi"; }
-
-      size_t poll(RandomNumberGenerator& rng) override;
-
-      /**
-      * Win32_Capi_Entropysource Constructor
-      * @param provs list of providers, separated by ':'
-      */
-      explicit Win32_CAPI_EntropySource(const std::string& provs = "");
-
-      class CSP_Handle
-         {
-         public:
-            virtual ~CSP_Handle() {}
-            virtual size_t gen_random(uint8_t out[], size_t n) const = 0;
-         };
-   private:
-      std::vector<std::unique_ptr<CSP_Handle>> m_csp_provs;
-   };
-
-}
-
-#endif
diff --git a/src/lib/entropy/cryptoapi_rng/info.txt b/src/lib/entropy/cryptoapi_rng/info.txt
deleted file mode 100644
index 21b42f2a0..000000000
--- a/src/lib/entropy/cryptoapi_rng/info.txt
+++ /dev/null
@@ -1,20 +0,0 @@
-<defines>
-ENTROPY_SRC_CAPI -> 20131128
-</defines>
-
-<header:internal>
-es_capi.h
-</header:internal>
-
-# We'll just assume CAPI is there; this is OK except for 3.x, early
-# versions of 95, and maybe NT 3.5
-<os>
-windows
-cygwin
-mingw
-</os>
-
-<libs>
-windows -> advapi32.lib
-mingw -> advapi32
-</libs>
diff --git a/src/lib/entropy/entropy_srcs.cpp b/src/lib/entropy/entropy_srcs.cpp
index d9d5cfe4b..76546c5da 100644
--- a/src/lib/entropy/entropy_srcs.cpp
+++ b/src/lib/entropy/entropy_srcs.cpp
@@ -8,6 +8,10 @@
 #include <botan/entropy_src.h>
 #include <botan/rng.h>
 
+#if defined(BOTAN_HAS_SYSTEM_RNG)
+  #include <botan/system_rng.h>
+#endif
+
 #if defined(BOTAN_HAS_ENTROPY_SRC_RDRAND)
   #include <botan/internal/rdrand.h>
 #endif
@@ -20,10 +24,6 @@
   #include <botan/internal/dev_random.h>
 #endif
 
-#if defined(BOTAN_HAS_ENTROPY_SRC_CAPI)
-  #include <botan/internal/es_capi.h>
-#endif
-
 #if defined(BOTAN_HAS_ENTROPY_SRC_WIN32)
   #include <botan/internal/es_win32.h>
 #endif
@@ -42,65 +42,86 @@
 
 namespace Botan {
 
+#if defined(BOTAN_HAS_SYSTEM_RNG)
+
+namespace {
+
+class System_RNG_EntropySource : public Entropy_Source
+   {
+   public:
+      size_t poll(RandomNumberGenerator& rng) override
+         {
+         const size_t poll_bits = BOTAN_RNG_RESEED_POLL_BITS;
+         rng.reseed_from_rng(system_rng(), poll_bits);
+         return poll_bits;
+         }
+
+      std::string name() const override { return system_rng().name(); }
+   };
+
+}
+
+#endif
+
 std::unique_ptr<Entropy_Source> Entropy_Source::create(const std::string& name)
    {
-   if(name == "rdrand")
+#if defined(BOTAN_HAS_SYSTEM_RNG)
+   if(name == "system_rng" || name == "win32_cryptoapi")
       {
+      return std::unique_ptr<Entropy_Source>(new System_RNG_EntropySource);
+      }
+#endif
+
 #if defined(BOTAN_HAS_ENTROPY_SRC_RDRAND)
+   if(name == "rdrand")
+      {
       return std::unique_ptr<Entropy_Source>(new Intel_Rdrand);
-#endif
       }
+#endif
 
+#if defined(BOTAN_HAS_ENTROPY_SRC_RDSEED)
    if(name == "rdseed")
       {
-#if defined(BOTAN_HAS_ENTROPY_SRC_RDSEED)
       return std::unique_ptr<Entropy_Source>(new Intel_Rdseed);
-#endif
       }
+#endif
 
+#if defined(BOTAN_HAS_ENTROPY_SRC_DARWIN_SECRANDOM)
    if(name == "darwin_secrandom")
       {
-#if defined(BOTAN_HAS_ENTROPY_SRC_DARWIN_SECRANDOM)
       return std::unique_ptr<Entropy_Source>(new Darwin_SecRandom);
-#endif
       }
+#endif
 
+#if defined(BOTAN_HAS_ENTROPY_SRC_GETENTROPY)
    if(name == "getentropy")
       {
-#if defined(BOTAN_HAS_ENTROPY_SRC_GETENTROPY)
       return std::unique_ptr<Entropy_Source>(new Getentropy);
-#endif
       }
+#endif
 
+#if defined(BOTAN_HAS_ENTROPY_SRC_DEV_RANDOM)
    if(name == "dev_random")
       {
-#if defined(BOTAN_HAS_ENTROPY_SRC_DEV_RANDOM)
       return std::unique_ptr<Entropy_Source>(new Device_EntropySource(BOTAN_SYSTEM_RNG_POLL_DEVICES));
-#endif
       }
-
-   if(name == "win32_cryptoapi")
-      {
-#if defined(BOTAN_HAS_ENTROPY_SRC_CAPI)
-      return std::unique_ptr<Entropy_Source>(new Win32_CAPI_EntropySource("RSA_FULL"));
 #endif
-      }
 
+#if defined(BOTAN_HAS_ENTROPY_SRC_PROC_WALKER)
    if(name == "proc_walk")
       {
-#if defined(BOTAN_HAS_ENTROPY_SRC_PROC_WALKER)
       const std::string root_dir = BOTAN_ENTROPY_PROC_FS_PATH;
       if(!root_dir.empty())
          return std::unique_ptr<Entropy_Source>(new ProcWalking_EntropySource(root_dir));
-#endif
       }
+#endif
 
+#if defined(BOTAN_HAS_ENTROPY_SRC_WIN32)
    if(name == "system_stats")
       {
-#if defined(BOTAN_HAS_ENTROPY_SRC_WIN32)
       return std::unique_ptr<Entropy_Source>(new Win32_EntropySource);
-#endif
       }
+#endif
 
    return std::unique_ptr<Entropy_Source>();
    }
diff --git a/src/lib/entropy/win32_stats/es_win32.cpp b/src/lib/entropy/win32_stats/es_win32.cpp
index 520848615..0e7056550 100644
--- a/src/lib/entropy/win32_stats/es_win32.cpp
+++ b/src/lib/entropy/win32_stats/es_win32.cpp
@@ -6,7 +6,9 @@
 */
 
 #include <botan/internal/es_win32.h>
+
 #define NOMINMAX 1
+#define _WINSOCKAPI_ // stop windows.h including winsock.h
 #include <windows.h>
 #include <tlhelp32.h>
 
diff --git a/src/lib/rng/system_rng/info.txt b/src/lib/rng/system_rng/info.txt
index 3df7dd387..1ea7eb388 100644
--- a/src/lib/rng/system_rng/info.txt
+++ b/src/lib/rng/system_rng/info.txt
@@ -24,4 +24,12 @@ openbsd
 qnx
 solaris
 windows
+winphone
 </os>
+
+<libs>
+windows -> advapi32.lib
+winphone -> bcrypt.lib
+
+mingw -> advapi32
+</libs>
diff --git a/src/lib/rng/system_rng/system_rng.cpp b/src/lib/rng/system_rng/system_rng.cpp
index 1c3b8e50a..9ee306991 100644
--- a/src/lib/rng/system_rng/system_rng.cpp
+++ b/src/lib/rng/system_rng/system_rng.cpp
@@ -1,6 +1,6 @@
 /*
 * System RNG
-* (C) 2014,2015 Jack Lloyd
+* (C) 2014,2015,2017 Jack Lloyd
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -9,128 +9,188 @@
 #include <botan/build.h>
 
 #if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
+   #define NOMINMAX 1
+   #define _WINSOCKAPI_ // stop windows.h including winsock.h
+   #include <windows.h>
+   #include <wincrypt.h>
 
-#define NOMINMAX 1
-#include <windows.h>
-#include <wincrypt.h>
+#elif defined(BOTAN_TARGET_OS_HAS_CRYPTO_NG)
+   #include <bcrypt.h>
 
 #elif defined(BOTAN_TARGET_OS_HAS_ARC4RANDOM)
-
-#include <stdlib.h>
+   #include <stdlib.h>
 
 #else
-
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <errno.h>
-
+   #include <sys/types.h>
+   #include <sys/stat.h>
+   #include <fcntl.h>
+   #include <unistd.h>
+   #include <errno.h>
 #endif
 
 namespace Botan {
 
 namespace {
 
+#if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
+
 class System_RNG_Impl final : public RandomNumberGenerator
    {
    public:
-      System_RNG_Impl();
-      ~System_RNG_Impl();
+      System_RNG_Impl()
+         {
+         if(!CryptAcquireContext(&m_prov, nullptr, nullptr,
+                                 BOTAN_SYSTEM_RNG_CRYPTOAPI_PROV_TYPE, CRYPT_VERIFYCONTEXT))
+            throw Exception("System_RNG failed to acquire crypto provider");
+         }
 
-      bool is_seeded() const override { return true; }
+      ~System_RNG_Impl()
+         {
+         ::CryptReleaseContext(m_prov, 0);
+         }
+
+      void randomize(uint8_t buf[], size_t len) override
+         {
+         ::CryptGenRandom(m_prov, static_cast<DWORD>(len), buf);
+         }
+
+      void add_entropy(const uint8_t in[], size_t length) override
+         {
+         /*
+         There is no explicit ConsumeRandom, but all values provided in
+         the call are incorporated into the state.
+         */
+         std::vector<uint8_t> buf(in, in + length);
+         ::CryptGenRandom(m_prov, static_cast<DWORD>(buf.size()), buf.data());
+         }
 
+      bool is_seeded() const override { return true; }
       void clear() override {}
+      std::string name() const override { return "cryptoapi"; }
+   private:
+      HCRYPTPROV m_prov;
+   };
 
-      void randomize(uint8_t out[], size_t len) override;
+#elif defined(BOTAN_TARGET_OS_HAS_CRYPTO_NG)
 
-      void add_entropy(const uint8_t in[], size_t length) override;
+class System_RNG_Impl final : public RandomNumberGenerator
+   {
+   public:
+      System_RNG_Impl()
+         {
+         NTSTATUS ret = ::BCryptOpenAlgorithmProvider(&m_prov,
+                                                      BCRYPT_RNG_ALGORITHM,
+                                                      MS_PRIMITIVE_PROVIDER, 0);
+         if(ret != STATUS_SUCCESS)
+            throw Exception("System_RNG failed to acquire crypto provider");
+         }
+
+      ~System_RNG_Impl()
+         {
+         ::BCryptCloseAlgorithmProvider(m_prov, 0);
+         }
 
-      std::string name() const override;
+      void randomize(uint8_t buf[], size_t len) override
+         {
+         ::BCryptGenRandom(m_prov, static_cast<PUCHAR>(buf), static_cast<ULONG>(len), 0);
+         }
 
+      void add_entropy(const uint8_t in[], size_t length) override
+         {
+         /*
+         There is a flag BCRYPT_RNG_USE_ENTROPY_IN_BUFFER to provide
+         entropy inputs, but it is ignored in Windows 8 and later.
+         */
+         }
+
+      bool is_seeded() const override { return true; }
+      void clear() override {}
+      std::string name() const override { return "crypto_ng"; }
    private:
-#if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
-      HCRYPTPROV m_prov;
-#else
-      int m_fd;
-#endif
+      BCRYPT_ALG_HANDLE m_handle;
    };
 
-std::string System_RNG_Impl::name() const
-   {
-#if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
-   return "cryptoapi";
 #elif defined(BOTAN_TARGET_OS_HAS_ARC4RANDOM)
-   return "arc4random";
-#else
-   return BOTAN_SYSTEM_RNG_DEVICE;
-#endif
-   }
 
-System_RNG_Impl::System_RNG_Impl()
+class System_RNG_Impl final : public RandomNumberGenerator
    {
-#if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
+   public:
+      // No constructor or destructor needed as no userland state maintained
 
-   if(!CryptAcquireContext(&m_prov, nullptr, nullptr, BOTAN_SYSTEM_RNG_CRYPTOAPI_PROV_TYPE, CRYPT_VERIFYCONTEXT))
-      throw Exception("System_RNG failed to acquire crypto provider");
+      void randomize(uint8_t buf[], size_t len) override
+         {
+         ::arc4random_buf(buf, len);
+         }
+
+      void add_entropy(const uint8_t[], size_t) override { /* ignored */ }
+      bool is_seeded() const override { return true; }
+      void clear() override {}
+      std::string name() const override { return "arc4random"; }
+   };
 
-#elif defined(BOTAN_TARGET_OS_HAS_ARC4RANDOM)
-   // Nothing to do, arc4random(3) works from the beginning.
 #else
 
-#ifndef O_NOCTTY
-  #define O_NOCTTY 0
-#endif
+// Read a random device
 
-   m_fd = ::open(BOTAN_SYSTEM_RNG_DEVICE, O_RDWR | O_NOCTTY);
-   
-   // Cannot open in read-write mode. Fall back to read-only
-   // Calls to add_entropy will fail, but randomize will work
-   if(m_fd < 0)
-      m_fd = ::open(BOTAN_SYSTEM_RNG_DEVICE, O_RDONLY | O_NOCTTY);
+class System_RNG_Impl final : public RandomNumberGenerator
+   {
+   public:
+      System_RNG_Impl()
+         {
+         #ifndef O_NOCTTY
+            #define O_NOCTTY 0
+         #endif
 
-   if(m_fd < 0)
-      throw Exception("System_RNG failed to open RNG device");
-#endif
-   }
+         m_fd = ::open(BOTAN_SYSTEM_RNG_DEVICE, O_RDWR | O_NOCTTY);
 
-System_RNG_Impl::~System_RNG_Impl()
-   {
-#if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
-   ::CryptReleaseContext(m_prov, 0);
-#elif defined(BOTAN_TARGET_OS_HAS_ARC4RANDOM)
-   // Nothing to do.
-#else
-   ::close(m_fd);
-   m_fd = -1;
-#endif
-   }
+         /*
+         Cannot open in read-write mode. Fall back to read-only,
+         calls to add_entropy will fail, but randomize will work
+         */
+         if(m_fd < 0)
+            m_fd = ::open(BOTAN_SYSTEM_RNG_DEVICE, O_RDONLY | O_NOCTTY);
 
-void System_RNG_Impl::add_entropy(const uint8_t input[], size_t len)
-   {
-#if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
-   /*
-   There is no explicit ConsumeRandom, but all values provided in
-   the call are incorporated into the state.
+         if(m_fd < 0)
+            throw Exception("System_RNG failed to open RNG device");
+         }
 
-   TODO: figure out a way to avoid this copy. Byte at a time updating
-   seems worse than the allocation.
+      ~System_RNG_Impl()
+         {
+         ::close(m_fd);
+         m_fd = -1;
+         }
 
-   for(size_t i = 0; i != len; ++i)
-      {
-      uint8_t b = input[i];
-      ::CryptGenRandom(m_prov, 1, &b);
-      }
-   */
+      void randomize(uint8_t buf[], size_t len) override;
+      void add_entropy(const uint8_t in[], size_t length) override;
+      bool is_seeded() const override { return true; }
+      void clear() override {}
+      std::string name() const override { return BOTAN_SYSTEM_RNG_DEVICE; }
+   private:
+      int m_fd;
+   };
 
-   if(len > 0)
+void System_RNG_Impl::randomize(uint8_t buf[], size_t len)
+   {
+   while(len)
       {
-      secure_vector<uint8_t> buf(input, input + len);
-      ::CryptGenRandom(m_prov, static_cast<DWORD>(buf.size()), buf.data());
+      ssize_t got = ::read(m_fd, buf, len);
+
+      if(got < 0)
+         {
+         if(errno == EINTR)
+            continue;
+         throw Exception("System_RNG read failed error " + std::to_string(errno));
+         }
+      if(got == 0)
+         throw Exception("System_RNG EOF on device"); // ?!?
+
+      buf += got;
+      len -= got;
       }
-#elif defined(BOTAN_TARGET_OS_HAS_ARC4RANDOM)
-   // arc4random(3) reseeds itself from the OpenBSD kernel, not from user land.
-#else
+   }
+
+void System_RNG_Impl::add_entropy(const uint8_t input[], size_t len)
+   {
    while(len)
       {
       ssize_t got = ::write(m_fd, input, len);
@@ -162,34 +222,9 @@ void System_RNG_Impl::add_entropy(const uint8_t input[], size_t len)
       input += got;
       len -= got;
       }
-#endif
    }
 
-void System_RNG_Impl::randomize(uint8_t buf[], size_t len)
-   {
-#if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
-   ::CryptGenRandom(m_prov, static_cast<DWORD>(len), buf);
-#elif defined(BOTAN_TARGET_OS_HAS_ARC4RANDOM)
-   ::arc4random_buf(buf, len);
-#else
-   while(len)
-      {
-      ssize_t got = ::read(m_fd, buf, len);
-
-      if(got < 0)
-         {
-         if(errno == EINTR)
-            continue;
-         throw Exception("System_RNG read failed error " + std::to_string(errno));
-         }
-      if(got == 0)
-         throw Exception("System_RNG EOF on device"); // ?!?
-
-      buf += got;
-      len -= got;
-      }
 #endif
-   }
 
 }
 
diff --git a/src/lib/utils/dyn_load/dyn_load.cpp b/src/lib/utils/dyn_load/dyn_load.cpp
index 1f33dc761..2b24e5f6c 100644
--- a/src/lib/utils/dyn_load/dyn_load.cpp
+++ b/src/lib/utils/dyn_load/dyn_load.cpp
@@ -13,6 +13,7 @@
   #include <dlfcn.h>
 #elif defined(BOTAN_TARGET_OS_HAS_LOADLIBRARY)
   #define NOMINMAX 1
+  #define _WINSOCKAPI_ // stop windows.h including winsock.h
   #include <windows.h>
 #endif
 
diff --git a/src/lib/utils/http_util/http_util.cpp b/src/lib/utils/http_util/http_util.cpp
index 4b0db03a5..73efb7adc 100644
--- a/src/lib/utils/http_util/http_util.cpp
+++ b/src/lib/utils/http_util/http_util.cpp
@@ -9,55 +9,10 @@
 #include <botan/http_util.h>
 #include <botan/parsing.h>
 #include <botan/hex.h>
+#include <botan/internal/os_utils.h>
 #include <botan/internal/stl_util.h>
 #include <sstream>
 
-#if defined(BOTAN_HAS_BOOST_ASIO)
-
-  /*
-  * We don't need serial port support anyway, and asking for it
-  * causes macro conflicts with Darwin's termios.h when this
-  * file is included in the amalgamation. GH #350
-  */
-  #define BOOST_ASIO_DISABLE_SERIAL_PORT
-  #include <boost/asio.hpp>
-
-#elif defined(BOTAN_TARGET_OS_HAS_SOCKETS)
-#if defined(BOTAN_TARGET_OS_IS_WINDOWS)
-  #include <winsock2.h>
-  #include <WS2tcpip.h>
-
-namespace {
-
-int close(int fd)
-   {
-   return ::closesocket(fd);
-   }
-
-int read(int s, void* buf, size_t len)
-   {
-   return ::recv(s, reinterpret_cast<char*>(buf), static_cast<int>(len), 0);
-   }
-
-int write(int s, const char* buf, size_t len)
-   {
-   return ::send(s, reinterpret_cast<const char*>(buf), static_cast<int>(len), 0);
-   }
-
-}
-
-typedef size_t ssize_t;
-#else
-  #include <sys/types.h>
-  #include <sys/socket.h>
-  #include <netdb.h>
-  #include <unistd.h>
-  #include <netinet/in.h>
-#endif
-#else
-  //#warning "No network support enabled in http_util"
-#endif
-
 namespace Botan {
 
 namespace HTTP {
@@ -71,111 +26,36 @@ namespace {
 std::string http_transact(const std::string& hostname,
                           const std::string& message)
    {
-#if defined(BOTAN_HAS_BOOST_ASIO)
-   using namespace boost::asio::ip;
-
-   boost::asio::ip::tcp::iostream tcp;
-
-   tcp.connect(hostname, "http");
-
-   if(!tcp)
-      throw HTTP_Error("HTTP connection to " + hostname + " failed");
-
-   tcp << message;
-   tcp.flush();
-
-   std::ostringstream oss;
-   oss << tcp.rdbuf();
+   std::unique_ptr<OS::Socket> socket;
 
-   return oss.str();
-#elif defined(BOTAN_TARGET_OS_HAS_SOCKETS)
-
-#if defined(BOTAN_TARGET_OS_IS_WINDOWS)
-   WSAData wsa_data;
-   WORD wsa_version = MAKEWORD(2, 2);
-
-   if (::WSAStartup(wsa_version, &wsa_data) != 0)
+   try
       {
-      throw HTTP_Error("WSAStartup() failed: " + std::to_string(WSAGetLastError()));
+      socket = OS::open_socket(hostname, "http");
+      if(!socket)
+         throw Exception("No socket support enabled in build");
       }
-
-   if (LOBYTE(wsa_data.wVersion) != 2 || HIBYTE(wsa_data.wVersion) != 2)
+   catch(std::exception& e)
       {
-      ::WSACleanup();
-      throw HTTP_Error("Could not find a usable version of Winsock.dll");
+      throw HTTP_Error("HTTP connection to " + hostname + " failed: " + e.what());
       }
-#endif
-
-   hostent* host_addr = ::gethostbyname(hostname.c_str());
-   uint16_t port = 80;
-
-   if(!host_addr)
-      throw HTTP_Error("Name resolution failed for " + hostname);
-
-   if(host_addr->h_addrtype != AF_INET) // FIXME
-      throw HTTP_Error("Hostname " + hostname + " resolved to non-IPv4 address");
-
-   struct socket_raii {
-      socket_raii(int fd) : m_fd(fd) {}
-      ~socket_raii()
-         {
-         ::close(m_fd);
-#if defined(BOTAN_TARGET_OS_IS_WINDOWS)
-         ::WSACleanup();
-#endif
-         }
-      int m_fd;
-      };
-
-   int fd = ::socket(PF_INET, SOCK_STREAM, 0);
-   if(fd == -1)
-      throw HTTP_Error("Unable to create TCP socket");
-   socket_raii raii(fd);
 
-   sockaddr_in socket_info;
-   ::memset(&socket_info, 0, sizeof(socket_info));
-   socket_info.sin_family = AF_INET;
-   socket_info.sin_port = htons(port);
-
-   ::memcpy(&socket_info.sin_addr,
-            host_addr->h_addr,
-            host_addr->h_length);
-
-   socket_info.sin_addr = *reinterpret_cast<struct in_addr*>(host_addr->h_addr); // FIXME
-
-   if(::connect(fd, reinterpret_cast<sockaddr*>(&socket_info), sizeof(struct sockaddr)) != 0)
-      throw HTTP_Error("HTTP connection to " + hostname + " failed");
-
-   size_t sent_so_far = 0;
-   while(sent_so_far != message.size())
-      {
-      size_t left = message.size() - sent_so_far;
-      ssize_t sent = ::write(fd, &message[sent_so_far], left);
-
-      if(sent < 0)
-         throw HTTP_Error("write to HTTP server failed, error '" + std::string(::strerror(errno)) + "'");
-      else
-         sent_so_far += static_cast<size_t>(sent);
-      }
+   // Blocks until entire message has been written
+   socket->write(reinterpret_cast<const uint8_t*>(message.data()),
+                 message.size());
 
    std::ostringstream oss;
-   std::vector<char> buf(1024); // arbitrary size
+   std::vector<uint8_t> buf(BOTAN_DEFAULT_BUFFER_SIZE);
    while(true)
       {
-      ssize_t got = ::read(fd, buf.data(), buf.size());
+      const size_t got = socket->read(buf.data(), buf.size());
+      if(got == 0) // EOF
+         break;
 
-      if(got < 0)
-         throw HTTP_Error("read from HTTP server failed, error '" + std::string(::strerror(errno)) + "'");
-      else if(got > 0)
-         oss.write(buf.data(), static_cast<std::streamsize>(got));
-      else
-         break; // EOF
+      oss.write(reinterpret_cast<const char*>(buf.data()),
+                static_cast<std::streamsize>(got));
       }
-   return oss.str();
 
-#else
-   throw HTTP_Error("Cannot connect to " + hostname + ": network code disabled in build");
-#endif
+   return oss.str();
    }
 
 }
diff --git a/src/lib/utils/mem_ops.cpp b/src/lib/utils/mem_ops.cpp
deleted file mode 100644
index c81d4fac2..000000000
--- a/src/lib/utils/mem_ops.cpp
+++ /dev/null
@@ -1,39 +0,0 @@
-/*
-* Memory Scrubbing
-* (C) 2012,2015,2016 Jack Lloyd
-*
-* Botan is released under the Simplified BSD License (see license.txt)
-*/
-
-#include <botan/mem_ops.h>
-
-#if defined(BOTAN_TARGET_OS_HAS_RTLSECUREZEROMEMORY)
-  #define NOMINMAX 1
-  #include <windows.h>
-#endif
-
-namespace Botan {
-
-void secure_scrub_memory(void* ptr, size_t n)
-   {
-#if defined(BOTAN_TARGET_OS_HAS_RTLSECUREZEROMEMORY)
-   ::RtlSecureZeroMemory(ptr, n);
-#elif defined(BOTAN_USE_VOLATILE_MEMSET_FOR_ZERO) && (BOTAN_USE_VOLATILE_MEMSET_FOR_ZERO == 1)
-   /*
-   Call memset through a static volatile pointer, which the compiler
-   should not elide. This construct should be safe in conforming
-   compilers, but who knows. I did confirm that on x86-64 GCC 6.1 and
-   Clang 3.8 both create code that saves the memset address in the
-   data segment and uncondtionally loads and jumps to that address.
-   */
-   static void* (*const volatile memset_ptr)(void*, int, size_t) = std::memset;
-   (memset_ptr)(ptr, 0, n);
-#else
-   volatile uint8_t* p = reinterpret_cast<volatile uint8_t*>(ptr);
-
-   for(size_t i = 0; i != n; ++i)
-      p[i] = 0;
-#endif
-   }
-
-}
diff --git a/src/lib/utils/os_utils.cpp b/src/lib/utils/os_utils.cpp
index d08e7e040..f6ac38c0a 100644
--- a/src/lib/utils/os_utils.cpp
+++ b/src/lib/utils/os_utils.cpp
@@ -12,6 +12,17 @@
 #include <botan/mem_ops.h>
 #include <chrono>
 
+#if defined(BOTAN_HAS_BOOST_ASIO)
+
+  /*
+  * We don't need serial port support anyway, and asking for it
+  * causes macro conflicts with Darwin's termios.h when this
+  * file is included in the amalgamation. GH #350
+  */
+  #define BOOST_ASIO_DISABLE_SERIAL_PORT
+  #include <boost/asio.hpp>
+#endif
+
 #if defined(BOTAN_TARGET_OS_TYPE_IS_UNIX)
   #include <sys/types.h>
   #include <sys/mman.h>
@@ -19,15 +30,280 @@
   #include <unistd.h>
   #include <signal.h>
   #include <setjmp.h>
-#endif
+  #include <sys/socket.h>
+  #include <netinet/in.h>
+  #include <netdb.h>
 
-#if defined(BOTAN_TARGET_OS_IS_WINDOWS) || defined(BOTAN_TARGET_OS_IS_MINGW)
+#elif defined(BOTAN_TARGET_OS_TYPE_IS_WINDOWS)
   #define NOMINMAX 1
+  #include <winsock2.h>
+  #include <WS2tcpip.h>
   #include <windows.h>
 #endif
 
 namespace Botan {
 
+std::unique_ptr<OS::Socket>
+OS::open_socket(const std::string& hostname,
+                const std::string& service)
+   {
+#if defined(BOTAN_HAS_BOOST_ASIO)
+   class Asio_Socket : public OS::Socket
+      {
+      public:
+         Asio_Socket(const std::string& hostname, const std::string& service) :
+            m_tcp(m_io)
+            {
+            boost::asio::ip::tcp::resolver resolver(m_io);
+            boost::asio::ip::tcp::resolver::query query(hostname, service);
+            boost::asio::connect(m_tcp, resolver.resolve(query));
+            }
+
+         void write(const uint8_t buf[], size_t len)
+            {
+            boost::asio::write(m_tcp, boost::asio::buffer(buf, len));
+            }
+
+         size_t read(uint8_t buf[], size_t len)
+            {
+            boost::system::error_code error;
+            size_t got = m_tcp.read_some(boost::asio::buffer(buf, len), error);
+
+            if(error)
+               {
+               if(error == boost::asio::error::eof)
+                  return 0;
+               throw boost::system::system_error(error); // Some other error.
+               }
+
+            return got;
+            }
+
+      private:
+         boost::asio::io_service m_io;
+         boost::asio::ip::tcp::socket m_tcp;
+      };
+
+   return std::unique_ptr<OS::Socket>(new Asio_Socket(hostname, service));
+
+#elif defined(BOTAN_TARGET_OS_IS_WINDOWS)
+
+   class Winsock_Socket : public OS::Socket
+      {
+      public:
+         Winsock_Socket(const std::string& hostname, const std::string& service)
+            {
+            WSAData wsa_data;
+            WORD wsa_version = MAKEWORD(2, 2);
+
+            if (::WSAStartup(wsa_version, &wsa_data) != 0)
+               {
+               throw Exception("WSAStartup() failed: " + std::to_string(WSAGetLastError()));
+               }
+
+            if (LOBYTE(wsa_data.wVersion) != 2 || HIBYTE(wsa_data.wVersion) != 2)
+               {
+               ::WSACleanup();
+               throw Exception("Could not find a usable version of Winsock.dll");
+               }
+
+            addrinfo hints;
+            ::memset(&hints, 0, sizeof(addrinfo));
+            hints.ai_family = AF_UNSPEC;
+            hints.ai_socktype = SOCK_STREAM;
+            addrinfo* res;
+
+            if(::getaddrinfo(hostname.c_str(), service.c_str(), &hints, &res) != 0)
+               {
+               throw Exception("Name resolution failed for " + hostname);
+               }
+
+            for(addrinfo* rp = res; (m_socket < 0) && (rp != nullptr); rp = rp->ai_next)
+               {
+               m_socket = ::socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
+
+               // unsupported socket type?
+               if(m_socket == INVALID_SOCKET)
+                  continue;
+
+               if(::connect(m_socket, rp->ai_addr, rp->ai_addrlen) != 0)
+                  {
+                  ::closesocket(m_socket);
+                  m_socket = INVALID_SOCKET;
+                  continue;
+                  }
+               }
+
+            ::freeaddrinfo(res);
+
+            if(m_socket == INVALID_SOCKET)
+               {
+               throw Exception("Connecting to " + hostname +
+                               " for service " + service + " failed");
+               }
+            }
+
+         ~Winsock_Socket()
+            {
+            ::closesocket(m_socket);
+            m_socket = INVALID_SOCKET;
+            ::WSACleanup();
+            }
+
+         void write(const uint8_t buf[], size_t len)
+            {
+            size_t sent_so_far = 0;
+            while(sent_so_far != len)
+               {
+               const size_t left = len - sent_so_far;
+               int sent = ::send(m_socket,
+                                 reinterpret_cast<const char*>(buf + sent_so_far),
+                                 static_cast<int>(left),
+                                 0);
+
+               if(sent == SOCKET_ERROR)
+                  throw Exception("Socket write failed with error " +
+                                  std::to_string(::WSAGetLastError()));
+               else
+                  sent_so_far += static_cast<size_t>(sent);
+               }
+            }
+
+         size_t read(uint8_t buf[], size_t len)
+            {
+            int got = ::recv(m_socket,
+                             reinterpret_cast<char*>(buf),
+                             static_cast<int>(len), 0);
+
+            if(got == SOCKET_ERROR)
+               throw Exception("Socket read failed with error " +
+                               std::to_string(::WSAGetLastError()));
+            return static_cast<size_t>(got);
+            }
+
+      private:
+         SOCKET m_socket = INVALID_SOCKET;
+      };
+
+   return std::unique_ptr<OS::Socket>(new Winsock_Socket(hostname, service));
+
+#elif defined(BOTAN_TARGET_OS_TYPE_IS_UNIX)
+
+   class BSD_Socket : public OS::Socket
+      {
+      public:
+         BSD_Socket(const std::string& hostname, const std::string& service)
+            {
+            addrinfo hints;
+            ::memset(&hints, 0, sizeof(addrinfo));
+            hints.ai_family = AF_UNSPEC;
+            hints.ai_socktype = SOCK_STREAM;
+            addrinfo* res;
+
+            if(::getaddrinfo(hostname.c_str(), service.c_str(), &hints, &res) != 0)
+               {
+               throw Exception("Name resolution failed for " + hostname);
+               }
+
+            m_fd = -1;
+
+            for(addrinfo* rp = res; (m_fd < 0) && (rp != nullptr); rp = rp->ai_next)
+               {
+               m_fd = ::socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
+
+               if(m_fd < 0)
+                  {
+                  // unsupported socket type?
+                  continue;
+                  }
+
+               if(::connect(m_fd, rp->ai_addr, rp->ai_addrlen) != 0)
+                  {
+                  ::close(m_fd);
+                  m_fd = -1;
+                  continue;
+                  }
+               }
+
+            ::freeaddrinfo(res);
+
+            if(m_fd < 0)
+               {
+               throw Exception("Connecting to " + hostname +
+                               " for service " + service + " failed");
+               }
+            }
+
+         ~BSD_Socket()
+            {
+            ::close(m_fd);
+            m_fd = -1;
+            }
+
+         void write(const uint8_t buf[], size_t len)
+            {
+            size_t sent_so_far = 0;
+            while(sent_so_far != len)
+               {
+               const size_t left = len - sent_so_far;
+               ssize_t sent = ::write(m_fd, &buf[sent_so_far], left);
+               if(sent < 0)
+                  throw Exception("Socket write failed with error '" +
+                                  std::string(::strerror(errno)) + "'");
+               else
+                  sent_so_far += static_cast<size_t>(sent);
+               }
+            }
+
+         size_t read(uint8_t buf[], size_t len)
+            {
+            ssize_t got = ::read(m_fd, buf, len);
+
+            if(got < 0)
+               throw Exception("Socket read failed with error '" +
+                               std::string(::strerror(errno)) + "'");
+            return static_cast<size_t>(got);
+            }
+
+      private:
+         int m_fd;
+      };
+
+   return std::unique_ptr<OS::Socket>(new BSD_Socket(hostname, service));
+
+#else
+   // No sockets for you
+   return std::unique_ptr<Socket>();
+#endif
+   }
+
+// Not defined in OS namespace for historical reasons
+void secure_scrub_memory(void* ptr, size_t n)
+   {
+   // TODO support explicit_bzero
+
+#if defined(BOTAN_TARGET_OS_HAS_RTLSECUREZEROMEMORY)
+   ::RtlSecureZeroMemory(ptr, n);
+
+#elif defined(BOTAN_USE_VOLATILE_MEMSET_FOR_ZERO) && (BOTAN_USE_VOLATILE_MEMSET_FOR_ZERO == 1)
+   /*
+   Call memset through a static volatile pointer, which the compiler
+   should not elide. This construct should be safe in conforming
+   compilers, but who knows. I did confirm that on x86-64 GCC 6.1 and
+   Clang 3.8 both create code that saves the memset address in the
+   data segment and uncondtionally loads and jumps to that address.
+   */
+   static void* (*const volatile memset_ptr)(void*, int, size_t) = std::memset;
+   (memset_ptr)(ptr, 0, n);
+#else
+
+   volatile uint8_t* p = reinterpret_cast<volatile uint8_t*>(ptr);
+
+   for(size_t i = 0; i != n; ++i)
+      p[i] = 0;
+#endif
+   }
+
 uint32_t OS::get_process_id()
    {
 #if defined(BOTAN_TARGET_OS_TYPE_IS_UNIX)
diff --git a/src/lib/utils/os_utils.h b/src/lib/utils/os_utils.h
index cae1192f1..2146e11b3 100644
--- a/src/lib/utils/os_utils.h
+++ b/src/lib/utils/os_utils.h
@@ -23,6 +23,39 @@ namespace OS {
 * this hasn't been tested.
 */
 
+
+/**
+* A wrapper around a simple blocking TCP socket
+*/
+class BOTAN_DLL Socket
+   {
+   public:
+      /**
+      * The socket will be closed upon destruction
+      */
+      virtual ~Socket() {};
+
+      /**
+      * Write to the socket. Blocks until all bytes sent.
+      * Throws on error.
+      */
+      virtual void write(const uint8_t buf[], size_t len) = 0;
+
+      /**
+      * Reads up to len bytes, returns bytes written to buf.
+      * Returns 0 on EOF. Throws on error.
+      */
+      virtual size_t read(uint8_t buf[], size_t len) = 0;
+   };
+
+/**
+* Open up a socket. Will throw on error. Returns null if sockets are
+* not available on this platform.
+*/
+std::unique_ptr<Socket>
+BOTAN_DLL open_socket(const std::string& hostname,
+                      const std::string& service);
+
 /**
 * @return process ID assigned by the operating system.
 * On Unix and Windows systems, this always returns a result