add kdf1 implementation according to iso-18033 (preparation for ecies)

1 files changed, 35 insertions, 0 deletions

diff --git a/src/lib/kdf/kdf1_iso18033/kdf1_iso18033.cpp b/src/lib/kdf/kdf1_iso18033/kdf1_iso18033.cpp
new file mode 100644
index 000000000..3ff717993
--- /dev/null
+++ b/src/lib/kdf/kdf1_iso18033/kdf1_iso18033.cpp
@@ -0,0 +1,35 @@
+/*
+* KDF1 from ISO 18033
+* (C) 2016 Philipp Weber
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include <botan/kdf1_iso18033.h>
+
+namespace Botan {
+
+size_t KDF1_18033::kdf(byte key[], size_t key_len,
+                       const byte secret[], size_t secret_len,
+                       const byte salt[], size_t salt_len) const
+   {
+   u32bit counter = 0;
+   secure_vector<byte> h;
+
+   size_t offset = 0;
+   while(offset != key_len && counter != 0xFFFFFFFF)
+      {
+      m_hash->update(secret, secret_len);
+      m_hash->update_be(counter++);
+      m_hash->update(salt, salt_len);
+      m_hash->final(h);
+
+      const size_t added = std::min(h.size(), key_len - offset);
+      copy_mem(&key[offset], h.data(), added);
+      offset += added;
+      }
+
+   return offset;
+   }
+
+}