1 files changed, 111 insertions, 0 deletions
diff --git a/lib/pbkdf/pbkdf2/pbkdf2.cpp b/lib/pbkdf/pbkdf2/pbkdf2.cpp
new file mode 100644
index 000000000..c24bcaff8
--- /dev/null
+++ b/lib/pbkdf/pbkdf2/pbkdf2.cpp
@@ -0,0 +1,111 @@
+/*
+* PBKDF2
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/pbkdf2.h>
+#include <botan/get_byte.h>
+#include <botan/internal/xor_buf.h>
+#include <botan/internal/rounding.h>
+
+namespace Botan {
+
+/*
+* Return a PKCS #5 PBKDF2 derived key
+*/
+std::pair<size_t, OctetString>
+PKCS5_PBKDF2::key_derivation(size_t key_len,
+                             const std::string& passphrase,
+                             const byte salt[], size_t salt_len,
+                             size_t iterations,
+                             std::chrono::milliseconds msec) const
+   {
+   if(key_len == 0)
+      return std::make_pair(iterations, OctetString());
+
+   try
+      {
+      mac->set_key(reinterpret_cast<const byte*>(passphrase.data()),
+                   passphrase.length());
+      }
+   catch(Invalid_Key_Length)
+      {
+      throw Exception(name() + " cannot accept passphrases of length " +
+                      std::to_string(passphrase.length()));
+      }
+
+   secure_vector<byte> key(key_len);
+
+   byte* T = &key[0];
+
+   secure_vector<byte> U(mac->output_length());
+
+   const size_t blocks_needed = round_up(key_len, mac->output_length()) / mac->output_length();
+
+   std::chrono::microseconds usec_per_block =
+      std::chrono::duration_cast<std::chrono::microseconds>(msec) / blocks_needed;
+
+   u32bit counter = 1;
+   while(key_len)
+      {
+      size_t T_size = std::min<size_t>(mac->output_length(), key_len);
+
+      mac->update(salt, salt_len);
+      mac->update_be(counter);
+      mac->final(&U[0]);
+
+      xor_buf(T, &U[0], T_size);
+
+      if(iterations == 0)
+         {
+         /*
+         If no iterations set, run the first block to calibrate based
+         on how long hashing takes on whatever machine we're running on.
+         */
+
+         const auto start = std::chrono::high_resolution_clock::now();
+
+         iterations = 1; // the first iteration we did above
+
+         while(true)
+            {
+            mac->update(U);
+            mac->final(&U[0]);
+            xor_buf(T, &U[0], T_size);
+            iterations++;
+
+            /*
+            Only break on relatively 'even' iterations. For one it
+            avoids confusion, and likely some broken implementations
+            break on getting completely randomly distributed values
+            */
+            if(iterations % 10000 == 0)
+               {
+               auto time_taken = std::chrono::high_resolution_clock::now() - start;
+               auto usec_taken = std::chrono::duration_cast<std::chrono::microseconds>(time_taken);
+               if(usec_taken > usec_per_block)
+                  break;
+               }
+            }
+         }
+      else
+         {
+         for(size_t i = 1; i != iterations; ++i)
+            {
+            mac->update(U);
+            mac->final(&U[0]);
+            xor_buf(T, &U[0], T_size);
+            }
+         }
+
+      key_len -= T_size;
+      T += T_size;
+      ++counter;
+      }
+
+   return std::make_pair(iterations, key);
+   }
+
+}