1 files changed, 122 insertions, 0 deletions
diff --git a/comm/third_party/botan/src/lib/kdf/hkdf/hkdf.cpp b/comm/third_party/botan/src/lib/kdf/hkdf/hkdf.cpp
new file mode 100644
index 0000000000..0a62648fcd
--- /dev/null
+++ b/comm/third_party/botan/src/lib/kdf/hkdf/hkdf.cpp
@@ -0,0 +1,122 @@
+/*
+* HKDF
+* (C) 2013,2015,2017 Jack Lloyd
+* (C) 2016 René Korthaus, Rohde & Schwarz Cybersecurity
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include <botan/hkdf.h>
+#include <botan/loadstor.h>
+
+namespace Botan {
+
+size_t HKDF::kdf(uint8_t key[], size_t key_len,
+                 const uint8_t secret[], size_t secret_len,
+                 const uint8_t salt[], size_t salt_len,
+                 const uint8_t label[], size_t label_len) const
+   {
+   HKDF_Extract extract(m_prf->clone());
+   HKDF_Expand expand(m_prf->clone());
+   secure_vector<uint8_t> prk(m_prf->output_length());
+
+   extract.kdf(prk.data(), prk.size(), secret, secret_len, salt, salt_len, nullptr, 0);
+   return expand.kdf(key, key_len, prk.data(), prk.size(), nullptr, 0, label, label_len);
+   }
+
+size_t HKDF_Extract::kdf(uint8_t key[], size_t key_len,
+                         const uint8_t secret[], size_t secret_len,
+                         const uint8_t salt[], size_t salt_len,
+                         const uint8_t[], size_t) const
+   {
+   secure_vector<uint8_t> prk;
+   if(salt_len == 0)
+      {
+      m_prf->set_key(std::vector<uint8_t>(m_prf->output_length()));
+      }
+   else
+      {
+      m_prf->set_key(salt, salt_len);
+      }
+
+   m_prf->update(secret, secret_len);
+   m_prf->final(prk);
+
+   const size_t written = std::min(prk.size(), key_len);
+   copy_mem(&key[0], prk.data(), written);
+   // FIXME: returns truncated output
+   return written;
+   }
+
+size_t HKDF_Expand::kdf(uint8_t key[], size_t key_len,
+                        const uint8_t secret[], size_t secret_len,
+                        const uint8_t salt[], size_t salt_len,
+                        const uint8_t label[], size_t label_len) const
+   {
+   m_prf->set_key(secret, secret_len);
+
+   uint8_t counter = 1;
+   secure_vector<uint8_t> h;
+   size_t offset = 0;
+
+   while(offset != key_len && counter != 0)
+      {
+      m_prf->update(h);
+      m_prf->update(label, label_len);
+      m_prf->update(salt, salt_len);
+      m_prf->update(counter++);
+      m_prf->final(h);
+
+      const size_t written = std::min(h.size(), key_len - offset);
+      copy_mem(&key[offset], h.data(), written);
+      offset += written;
+      }
+
+   // FIXME: returns truncated output
+   return offset;
+   }
+
+secure_vector<uint8_t>
+hkdf_expand_label(const std::string& hash_fn,
+                  const uint8_t secret[], size_t secret_len,
+                  const std::string& label,
+                  const uint8_t hash_val[], size_t hash_val_len,
+                  size_t length)
+   {
+   BOTAN_ARG_CHECK(length <= 0xFFFF, "HKDF-Expand-Label requested output too large");
+   BOTAN_ARG_CHECK(label.size() <= 0xFF, "HKDF-Expand-Label label too long");
+   BOTAN_ARG_CHECK(hash_val_len <= 0xFF, "HKDF-Expand-Label hash too long");
+
+   const uint16_t length16 = static_cast<uint16_t>(length);
+
+   auto mac = MessageAuthenticationCode::create_or_throw("HMAC(" + hash_fn + ")");
+
+   HKDF_Expand hkdf(mac.release());
+
+   secure_vector<uint8_t> output(length16);
+   std::vector<uint8_t> prefix(3 + label.size() + 1);
+
+   prefix[0] = get_byte(0, length16);
+   prefix[1] = get_byte(1, length16);
+   prefix[2] = static_cast<uint8_t>(label.size());
+
+   copy_mem(prefix.data() + 3,
+            cast_char_ptr_to_uint8(label.data()),
+            label.size());
+
+   prefix[3 + label.size()] = static_cast<uint8_t>(hash_val_len);
+
+   /*
+   * We do something a little dirty here to avoid copying the hash_val,
+   * making use of the fact that Botan's KDF interface supports label+salt,
+   * and knowing that our HKDF hashes first param label then param salt.
+   */
+   hkdf.kdf(output.data(), output.size(),
+            secret, secret_len,
+            hash_val, hash_val_len,
+            prefix.data(), prefix.size());
+
+   return output;
+   }
+
+}