1 files changed, 98 insertions, 0 deletions
diff --git a/comm/third_party/botan/src/lib/kdf/sp800_56a/sp800_56a.cpp b/comm/third_party/botan/src/lib/kdf/sp800_56a/sp800_56a.cpp
new file mode 100644
index 0000000000..8e9bcf8560
--- /dev/null
+++ b/comm/third_party/botan/src/lib/kdf/sp800_56a/sp800_56a.cpp
@@ -0,0 +1,98 @@
+/*
+* KDF defined in NIST SP 800-56a (Approved Alternative 1)
+*
+* (C) 2017 Ribose Inc. Written by Krzysztof Kwiatkowski.
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include <botan/sp800_56a.h>
+#include <botan/scan_name.h>
+#include <botan/exceptn.h>
+
+namespace Botan {
+
+namespace {
+
+template<class AuxiliaryFunction_t>
+size_t SP800_56A_kdf(
+   AuxiliaryFunction_t& auxfunc,
+   uint8_t key[], size_t key_len,
+   const uint8_t secret[], size_t secret_len,
+   const uint8_t label[], size_t label_len)
+   {
+   const uint64_t kRepsUpperBound = (1ULL << 32);
+
+   const size_t digest_len = auxfunc.output_length();
+
+   const size_t reps = key_len / digest_len + ((key_len % digest_len) ? 1 : 0);
+
+   if (reps >= kRepsUpperBound)
+      {
+      // See SP-800-56A, point 5.8.1
+      throw Invalid_Argument("SP800-56A KDF requested output too large");
+      }
+
+   uint32_t counter = 1;
+   secure_vector<uint8_t> result;
+   for(size_t i = 0; i < reps; i++)
+      {
+      auxfunc.update_be(counter++);
+      auxfunc.update(secret, secret_len);
+      auxfunc.update(label, label_len);
+      auxfunc.final(result);
+
+      const size_t offset = digest_len * i;
+      const size_t len = std::min(result.size(), key_len - offset);
+      copy_mem(&key[offset], result.data(), len);
+      }
+
+   return key_len;
+   }
+
+}
+
+size_t SP800_56A_Hash::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
+   {
+   /*
+   * TODO: should we reject a non-empty salt with an exception?
+   * Ignoring the salt seems quite dangerous to applications which
+   * don't expect it.
+   */
+   BOTAN_UNUSED(salt, salt_len);
+
+   return SP800_56A_kdf(*m_hash, key, key_len, secret, secret_len, label, label_len);
+   }
+
+SP800_56A_HMAC::SP800_56A_HMAC(MessageAuthenticationCode* mac) : m_mac(mac)
+   {
+   // TODO: we need a MessageAuthenticationCode::is_hmac
+   const SCAN_Name req(m_mac->name());
+   if(req.algo_name() != "HMAC")
+      {
+      throw Algorithm_Not_Found("Only HMAC can be used with KDF SP800-56A");
+      }
+   }
+
+size_t SP800_56A_HMAC::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
+   {
+   /*
+   * SP 800-56A specifies if the salt is empty then a block of zeros
+   * equal to the hash's underlying block size are used. However this
+   * is equivalent to setting a zero-length key, so the same call
+   * works for either case.
+   */
+   m_mac->set_key(salt, salt_len);
+
+   return SP800_56A_kdf(*m_mac, key, key_len, secret, secret_len, label, label_len);
+   }
+
+
+
+}