1 files changed, 15 insertions, 20 deletions
diff --git a/src/lib/kdf/kdf2/kdf2.cpp b/src/lib/kdf/kdf2/kdf2.cpp
index c7b355580..f1a702887 100644
--- a/src/lib/kdf/kdf2/kdf2.cpp
+++ b/src/lib/kdf/kdf2/kdf2.cpp
@@ -12,32 +12,27 @@ namespace Botan {
 
 BOTAN_REGISTER_KDF_1HASH(KDF2, "KDF2");
 
-/*
-* KDF2 Key Derivation Mechanism
-*/
-secure_vector<byte> KDF2::derive(size_t out_len,
-                                const byte secret[], size_t secret_len,
-                                const byte P[], size_t P_len) const
+size_t KDF2::kdf(byte key[], size_t key_len,
+                 const byte secret[], size_t secret_len,
+                 const byte salt[], size_t salt_len) const
    {
-   secure_vector<byte> output;
    u32bit counter = 1;
+   secure_vector<byte> h;
 
-   while(out_len && counter)
+   size_t offset = 0;
+   while(offset != key_len && counter != 0)
       {
-      hash->update(secret, secret_len);
-      hash->update_be(counter);
-      hash->update(P, P_len);
-
-      secure_vector<byte> hash_result = hash->final();
-
-      size_t added = std::min(hash_result.size(), out_len);
-      output += std::make_pair(&hash_result[0], added);
-      out_len -= added;
-
-      ++counter;
+      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[0], added);
+      offset += added;
       }
 
-   return output;
+   return offset;
    }
 
 }