1 files changed, 90 insertions, 0 deletions
diff --git a/src/lib/pbkdf/pgp_s2k/pgp_s2k.cpp b/src/lib/pbkdf/pgp_s2k/pgp_s2k.cpp
new file mode 100644
index 000000000..d8b5d770e
--- /dev/null
+++ b/src/lib/pbkdf/pgp_s2k/pgp_s2k.cpp
@@ -0,0 +1,90 @@
+/*
+* OpenPGP S2K
+* (C) 1999-2007,2017 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/pgp_s2k.h>
+
+namespace Botan {
+
+//static
+uint8_t OpenPGP_S2K::encode_count(size_t desired_iterations)
+   {
+   /*
+   Only 256 different iterations are actually representable in OpenPGP format ...
+   */
+   for(size_t c = 0; c < 256; ++c)
+      {
+      size_t decoded_iter = OpenPGP_S2K::decode_count(c);
+      if(decoded_iter >= desired_iterations)
+         return c;
+      }
+   }
+
+//static
+size_t OpenPGP_S2K::decode_count(uint8_t iter)
+   {
+   // See RFC 4880 section 3.7.1.3
+   return (16 + (iter & 0x0F)) << ((iter >> 4) + 6);
+   }
+
+size_t OpenPGP_S2K::pbkdf(uint8_t output_buf[], size_t output_len,
+                          const std::string& passphrase,
+                          const uint8_t salt[], size_t salt_len,
+                          size_t iterations,
+                          std::chrono::milliseconds msec) const
+   {
+   if(iterations == 0 && msec.count() > 0) // FIXME
+      throw Not_Implemented("OpenPGP_S2K does not implemented timed KDF");
+
+   secure_vector<uint8_t> input_buf(salt_len + passphrase.size());
+   if(salt_len > 0)
+      {
+      copy_mem(&input_buf[0], salt, salt_len);
+      }
+   if(passphrase.empty() == false)
+      {
+      copy_mem(&input_buf[salt_len],
+               reinterpret_cast<const uint8_t*>(passphrase.data()),
+               passphrase.size());
+      }
+
+   /*
+   The input is always fully processed even if iterations is very small
+   */
+   const size_t to_hash = std::max(iterations, input_buf.size());
+
+   secure_vector<uint8_t> hash_buf(m_hash->output_length());
+
+   size_t pass = 0;
+   size_t generated = 0;
+
+   while(generated != output_len)
+      {
+      const size_t output_this_pass =
+         std::min(hash_buf.size(), output_len - generated);
+
+      // Preload some number of zero bytes (empty first iteration)
+      std::vector<uint8_t> zero_padding(pass);
+      m_hash->update(zero_padding);
+
+      size_t left = to_hash;
+      while(left > 0)
+         {
+         const size_t input_to_take = std::min(left, input_buf.size());
+         m_hash->update(input_buf.data(), input_to_take);
+         left -= input_to_take;
+         }
+
+      m_hash->final(hash_buf.data());
+      copy_mem(output_buf + generated, hash_buf.data(), output_this_pass);
+      generated += output_this_pass;
+      ++pass;
+      }
+
+   return iterations;
+   }
+
+}