Expose HOTP to FFI

5 files changed, 174 insertions, 5 deletions

diff --git a/doc/todo.rst b/doc/todo.rst
index 08beda1e9..25561c6ab 100644
--- a/doc/todo.rst
+++ b/doc/todo.rst
@@ -137,7 +137,7 @@ FFI and Bindings
 * Expose compression
 * Expose more of X.509 (CRLs, PKCS10, OCSP, cert signing, etc)
 * Expose TLS
-* Expose TOTP/HOTP
+* Expose TOTP
 * Expose NIST key wrap with padding
 * Expose secret sharing
 * Expose deterministic PRNG
diff --git a/src/lib/ffi/ffi.h b/src/lib/ffi/ffi.h
index 54c01174c..8a4570c52 100644
--- a/src/lib/ffi/ffi.h
+++ b/src/lib/ffi/ffi.h
@@ -1440,6 +1440,42 @@ int botan_key_unwrap3394(const uint8_t wrapped_key[], size_t wrapped_key_len,
                          uint8_t key[], size_t *key_len);
 
 /**
+* HOTP
+*/
+
+typedef struct botan_hotp_struct* botan_hotp_t;
+
+/**
+* Initialize an HOTP instance
+*/
+int botan_hotp_init(botan_hotp_t* hotp,
+                    const uint8_t key[], size_t key_len,
+                    const char* hash_algo,
+                    size_t digits);
+
+/**
+* Destroy a HOTP instance
+*/
+int botan_hotp_destroy(botan_hotp_t hotp);
+
+/**
+* Generate an HOTP code for the provided counter
+*/
+int botan_hotp_generate(botan_hotp_t hotp,
+                        uint32_t* hotp_code,
+                        uint64_t hotp_counter);
+
+/**
+* Verify an HOTP code
+*/
+int botan_hotp_check(botan_hotp_t hotp,
+                     uint64_t* next_hotp_counter,
+                     uint32_t hotp_code,
+                     uint64_t hotp_counter,
+                     size_t resync_range);
+
+
+/**
 * Format Preserving Encryption
 */
 
diff --git a/src/lib/ffi/ffi_hotp.cpp b/src/lib/ffi/ffi_hotp.cpp
new file mode 100644
index 000000000..ae761450f
--- /dev/null
+++ b/src/lib/ffi/ffi_hotp.cpp
@@ -0,0 +1,100 @@
+/*
+* (C) 2018 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include <botan/ffi.h>
+#include <botan/internal/ffi_util.h>
+
+#if defined(BOTAN_HAS_HOTP)
+   #include <botan/hotp.h>
+#endif
+
+extern "C" {
+
+using namespace Botan_FFI;
+
+#if defined(BOTAN_HAS_HOTP)
+
+BOTAN_FFI_DECLARE_STRUCT(botan_hotp_struct, Botan::HOTP, 0x89CBF191);
+
+#endif
+
+int botan_hotp_init(botan_hotp_t* hotp,
+                    const uint8_t key[], size_t key_len,
+                    const char* hash_algo,
+                    size_t digits)
+   {
+   if(hotp == nullptr || key == nullptr || hash_algo == nullptr)
+      return BOTAN_FFI_ERROR_NULL_POINTER;
+
+   *hotp = nullptr;
+
+#if defined(BOTAN_HAS_HOTP)
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
+
+      *hotp = new botan_hotp_struct(new Botan::HOTP(
+                Botan::SymmetricKey(key, key_len),
+                hash_algo,
+                digits));
+      return BOTAN_FFI_SUCCESS;
+      });
+#else
+   BOTAN_UNUSED(hotp, key, key_len, hash_algo, digits);
+   return BOTAN_FFI_ERROR_NOT_IMPLEMENTED;
+#endif
+   }
+
+int botan_hotp_destroy(botan_hotp_t hotp)
+   {
+#if defined(BOTAN_HAS_HOTP)
+   return BOTAN_FFI_CHECKED_DELETE(hotp);
+#else
+   BOTAN_UNUSED(hotp);
+   return BOTAN_FFI_ERROR_NOT_IMPLEMENTED;
+#endif
+   }
+
+int botan_hotp_generate(botan_hotp_t hotp,
+                        uint32_t* hotp_code,
+                        uint64_t hotp_counter)
+   {
+#if defined(BOTAN_HAS_HOTP)
+   if(hotp == nullptr || hotp_code == nullptr)
+      return BOTAN_FFI_ERROR_NULL_POINTER;
+
+   return BOTAN_FFI_DO(Botan::HOTP, hotp, h, {
+      *hotp_code = h.generate_hotp(hotp_counter);
+      });
+
+#else
+   BOTAN_UNUSED(hotp, hotp_code, hotp_counter);
+   return BOTAN_FFI_ERROR_NOT_IMPLEMENTED;
+#endif
+   }
+
+int botan_hotp_check(botan_hotp_t hotp,
+                     uint64_t* next_hotp_counter,
+                     uint32_t hotp_code,
+                     uint64_t hotp_counter,
+                     size_t resync_range)
+   {
+#if defined(BOTAN_HAS_HOTP)
+   return BOTAN_FFI_DO(Botan::HOTP, hotp, h, {
+
+      auto resp = h.verify_hotp(hotp_code, hotp_counter, resync_range);
+
+      if(next_hotp_counter)
+         *next_hotp_counter = resp.second;
+
+      return (resp.first == true) ? BOTAN_FFI_SUCCESS : BOTAN_FFI_INVALID_VERIFIER;
+      });
+
+#else
+   BOTAN_UNUSED(hotp, next_hotp_counter, hotp_code, hotp_counter, resync_range);
+   return BOTAN_FFI_ERROR_NOT_IMPLEMENTED;
+#endif
+   }
+
+}
diff --git a/src/lib/misc/hotp/hotp.cpp b/src/lib/misc/hotp/hotp.cpp
index e4dc6e5e3..c4c0c7770 100644
--- a/src/lib/misc/hotp/hotp.cpp
+++ b/src/lib/misc/hotp/hotp.cpp
@@ -39,9 +39,7 @@ HOTP::HOTP(const SymmetricKey& key, const std::string& hash_algo, size_t digits)
 
 uint32_t HOTP::generate_hotp(uint64_t counter)
    {
-   uint8_t counter8[8] = { 0 };
-   store_be(counter, counter8);
-   m_mac->update(counter8, sizeof(counter8));
+   m_mac->update_be(counter);
    const secure_vector<uint8_t> mac = m_mac->final();
 
    const size_t offset = mac[mac.size()-1] & 0x0F;
diff --git a/src/tests/test_ffi.cpp b/src/tests/test_ffi.cpp
index 14eb28875..52dbe7348 100644
--- a/src/tests/test_ffi.cpp
+++ b/src/tests/test_ffi.cpp
@@ -1520,6 +1520,41 @@ class FFI_Unit_Tests final : public Test
          return result;
          }
 
+      Test::Result ffi_test_hotp()
+         {
+         Test::Result result("FFI HOTP");
+
+         const std::vector<uint8_t> key = Botan::hex_decode("3132333435363738393031323334353637383930");
+         const size_t digits = 6;
+
+         botan_hotp_t hotp;
+         uint32_t hotp_val;
+
+         TEST_FFI_OK(botan_hotp_init, (&hotp, key.data(), key.size(), "SHA-1", digits));
+
+         TEST_FFI_OK(botan_hotp_generate, (hotp, &hotp_val, 0));
+         result.confirm("Valid value for counter 0", hotp_val == 755224);
+         TEST_FFI_OK(botan_hotp_generate, (hotp, &hotp_val, 1));
+         result.confirm("Valid value for counter 0", hotp_val == 287082);
+         TEST_FFI_OK(botan_hotp_generate, (hotp, &hotp_val, 2));
+         result.confirm("Valid value for counter 0", hotp_val == 359152);
+         TEST_FFI_OK(botan_hotp_generate, (hotp, &hotp_val, 0));
+         result.confirm("Valid value for counter 0", hotp_val == 755224);
+
+         uint64_t next_ctr = 0;
+
+         TEST_FFI_OK(botan_hotp_check, (hotp, &next_ctr, 755224, 0, 0));
+         result.confirm("HOTP resync", next_ctr == 1);
+         TEST_FFI_OK(botan_hotp_check, (hotp, nullptr, 359152, 2, 0));
+         TEST_FFI_RC(1, botan_hotp_check, (hotp, nullptr, 359152, 1, 0));
+         TEST_FFI_RC(1, botan_hotp_check, (hotp, &next_ctr, 359152, 0, 2));
+         result.confirm("HOTP resync", next_ctr == 3);
+
+         TEST_FFI_OK(botan_hotp_destroy, (hotp));
+
+         return result;
+         }
+
       Test::Result ffi_test_keywrap()
          {
          Test::Result result("FFI keywrap");
@@ -2377,7 +2412,7 @@ class FFI_Unit_Tests final : public Test
 
       Test::Result ffi_test_elgamal(botan_rng_t rng)
          {
-         Test::Result result("FFI ELGAMAL");
+         Test::Result result("FFI ElGamal");
 
          botan_privkey_t priv;