6 files changed, 33 insertions, 2 deletions
diff --git a/src/lib/pubkey/dsa/dsa.cpp b/src/lib/pubkey/dsa/dsa.cpp
index 15dc45373..9c8ae0821 100644
--- a/src/lib/pubkey/dsa/dsa.cpp
+++ b/src/lib/pubkey/dsa/dsa.cpp
@@ -17,7 +17,9 @@
   #include <botan/rfc6979.h>
 #endif
 
-#include <future>
+#if defined(BOTAN_TARGET_OS_HAS_THREADS)
+  #include <future>
+#endif
 
 namespace Botan {
 
@@ -124,11 +126,17 @@ DSA_Signature_Operation::raw_sign(const byte msg[], size_t msg_len,
    const BigInt k = BigInt::random_integer(rng, 1, m_q);
 #endif
 
+#if defined(BOTAN_TARGET_OS_HAS_THREADS)
    auto future_r = std::async(std::launch::async,
                               [&]() { return m_mod_q.reduce(m_powermod_g_p(k)); });
 
    BigInt s = inverse_mod(k, m_q);
    const BigInt r = future_r.get();
+#else
+   BigInt s = inverse_mod(k, m_q);
+   const BigInt r = m_mod_q.reduce(m_powermod_g_p(k));
+#endif
+
    s = m_mod_q.multiply(s, mul_add(m_x, r, i));
 
    // With overwhelming probability, a bug rather than actual zero r/s
@@ -184,11 +192,16 @@ bool DSA_Verification_Operation::verify(const byte msg[], size_t msg_len,
 
    s = inverse_mod(s, m_q);
 
+#if defined(BOTAN_TARGET_OS_HAS_THREADS)
    auto future_s_i = std::async(std::launch::async,
       [&]() { return m_powermod_g_p(m_mod_q.multiply(s, i)); });
 
    BigInt s_r = m_powermod_y_p(m_mod_q.multiply(s, r));
    BigInt s_i = future_s_i.get();
+#else
+   BigInt s_r = m_powermod_y_p(m_mod_q.multiply(s, r));
+   BigInt s_i = m_powermod_g_p(m_mod_q.multiply(s, i));
+#endif
 
    s = m_mod_p.multiply(s_i, s_r);
 
diff --git a/src/lib/pubkey/pkcs8.cpp b/src/lib/pubkey/pkcs8.cpp
index ddf9be2f0..96dfd5e44 100644
--- a/src/lib/pubkey/pkcs8.cpp
+++ b/src/lib/pubkey/pkcs8.cpp
@@ -262,6 +262,8 @@ Private_Key* load_key(DataSource& source,
       throw PKCS8_Exception( "Internal error: Attempt to read password for unencrypted key" );}, false);
    }
 
+#if defined(BOTAN_TARGET_OS_HAS_FILESYSTEM)
+
 /*
 * Extract an encrypted private key and return it
 */
@@ -293,6 +295,7 @@ Private_Key* load_key(const std::string& fsname,
    return load_key(source, rng, []() -> std::string {
       throw PKCS8_Exception( "Internal error: Attempt to read password for unencrypted key" );}, false);
    }
+#endif
 
 /*
 * Make a copy of this private key
diff --git a/src/lib/pubkey/pkcs8.h b/src/lib/pubkey/pkcs8.h
index 791a612df..9cc350285 100644
--- a/src/lib/pubkey/pkcs8.h
+++ b/src/lib/pubkey/pkcs8.h
@@ -108,6 +108,7 @@ BOTAN_DLL Private_Key* load_key(DataSource& source,
 BOTAN_DLL Private_Key* load_key(DataSource& source,
                                 RandomNumberGenerator& rng);
 
+#if defined(BOTAN_TARGET_OS_HAS_FILESYSTEM)
 /**
 * Load an encrypted key from a file.
 * @param filename the path to the file containing the encoded key
@@ -136,6 +137,7 @@ BOTAN_DLL Private_Key* load_key(const std::string& filename,
 */
 BOTAN_DLL Private_Key* load_key(const std::string& filename,
                                 RandomNumberGenerator& rng);
+#endif
 
 /**
 * Copy an existing encoded key object.
diff --git a/src/lib/pubkey/rsa/rsa.cpp b/src/lib/pubkey/rsa/rsa.cpp
index b40f485e3..d201ca277 100644
--- a/src/lib/pubkey/rsa/rsa.cpp
+++ b/src/lib/pubkey/rsa/rsa.cpp
@@ -14,12 +14,16 @@
 #include <botan/workfactor.h>
 #include <botan/der_enc.h>
 #include <botan/ber_dec.h>
-#include <future>
 
 #if defined(BOTAN_HAS_OPENSSL)
   #include <botan/internal/openssl.h>
 #endif
 
+#if defined(BOTAN_TARGET_OS_HAS_THREADS)
+#include <future>
+#endif
+
+
 namespace Botan {
 
 size_t RSA_PublicKey::estimated_strength() const
@@ -218,9 +222,14 @@ class RSA_Private_Operation
 
       BigInt private_op(const BigInt& m) const
          {
+#if defined(BOTAN_TARGET_OS_HAS_THREADS)
          auto future_j1 = std::async(std::launch::async, m_powermod_d1_p, m);
          BigInt j2 = m_powermod_d2_q(m);
          BigInt j1 = future_j1.get();
+#else
+         BigInt j1 = m_powermod_d1_p(m);
+         BigInt j2 = m_powermod_d2_q(m);
+#endif
 
          j1 = m_mod_p.reduce(sub_mul(j1, j2, m_c));
 
diff --git a/src/lib/pubkey/x509_key.cpp b/src/lib/pubkey/x509_key.cpp
index ccb94cea7..08e17bfed 100644
--- a/src/lib/pubkey/x509_key.cpp
+++ b/src/lib/pubkey/x509_key.cpp
@@ -78,6 +78,7 @@ Public_Key* load_key(DataSource& source)
       }
    }
 
+#if defined(BOTAN_TARGET_OS_HAS_FILESYSTEM)
 /*
 * Extract a public key and return it
 */
@@ -86,6 +87,7 @@ Public_Key* load_key(const std::string& fsname)
    DataSource_Stream source(fsname, true);
    return X509::load_key(source);
    }
+#endif
 
 /*
 * Extract a public key and return it
diff --git a/src/lib/pubkey/x509_key.h b/src/lib/pubkey/x509_key.h
index cbb0412d2..7162b338e 100644
--- a/src/lib/pubkey/x509_key.h
+++ b/src/lib/pubkey/x509_key.h
@@ -46,12 +46,14 @@ BOTAN_DLL std::string PEM_encode(const Public_Key& key);
 */
 BOTAN_DLL Public_Key* load_key(DataSource& source);
 
+#if defined(BOTAN_TARGET_OS_HAS_FILESYSTEM)
 /**
 * Create a public key from a file
 * @param filename pathname to the file to load
 * @return new public key object
 */
 BOTAN_DLL Public_Key* load_key(const std::string& filename);
+#endif
 
 /**
 * Create a public key from a memory region.