From fea9c14d9696615f9d1cf52e0bb578c8a54c2c6a Mon Sep 17 00:00:00 2001
From: Jack Lloyd <jack@randombit.net>
Date: Sun, 19 Nov 2017 13:11:17 -0500
Subject: Add AES key wrap with padding

---
 src/lib/misc/nist_keywrap/nist_keywrap.cpp | 209 +++++++++++++++++++++++++++++
 1 file changed, 209 insertions(+)
 create mode 100644 src/lib/misc/nist_keywrap/nist_keywrap.cpp

(limited to 'src/lib/misc/nist_keywrap/nist_keywrap.cpp')

diff --git a/src/lib/misc/nist_keywrap/nist_keywrap.cpp b/src/lib/misc/nist_keywrap/nist_keywrap.cpp
new file mode 100644
index 000000000..c349f97aa
--- /dev/null
+++ b/src/lib/misc/nist_keywrap/nist_keywrap.cpp
@@ -0,0 +1,209 @@
+/*
+* (C) 2011,2017 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include <botan/nist_keywrap.h>
+#include <botan/block_cipher.h>
+#include <botan/loadstor.h>
+#include <botan/exceptn.h>
+
+namespace Botan {
+
+namespace {
+
+std::vector<uint8_t>
+raw_nist_key_wrap(const uint8_t input[],
+                  size_t input_len,
+                  const BlockCipher& bc,
+                  uint64_t ICV)
+   {
+   const size_t n = (input_len + 7) / 8;
+
+   secure_vector<uint8_t> R((n + 1) * 8);
+   secure_vector<uint8_t> A(16);
+
+   store_be(ICV, A.data());
+
+   copy_mem(&R[8], input, input_len);
+
+   for(size_t j = 0; j <= 5; ++j)
+      {
+      for(size_t i = 1; i <= n; ++i)
+         {
+         const uint32_t t = static_cast<uint32_t>((n * j) + i);
+
+         copy_mem(&A[8], &R[8*i], 8);
+
+         bc.encrypt(A.data());
+         copy_mem(&R[8*i], &A[8], 8);
+
+         uint8_t t_buf[4] = { 0 };
+         store_be(t, t_buf);
+         xor_buf(&A[4], t_buf, 4);
+         }
+      }
+
+   copy_mem(R.data(), A.data(), 8);
+
+   return std::vector<uint8_t>(R.begin(), R.end());
+   }
+
+secure_vector<uint8_t>
+raw_nist_key_unwrap(const uint8_t input[],
+                    size_t input_len,
+                    const BlockCipher& bc,
+                    uint64_t& ICV_out)
+   {
+   if(input_len < 16 || input_len % 8 != 0)
+      throw Invalid_Argument("Bad input size for NIST key unwrap");
+
+   const size_t n = (input_len - 8) / 8;
+
+   secure_vector<uint8_t> R(n * 8);
+   secure_vector<uint8_t> A(16);
+
+   for(size_t i = 0; i != 8; ++i)
+      A[i] = input[i];
+
+   copy_mem(R.data(), input + 8, input_len - 8);
+
+   for(size_t j = 0; j <= 5; ++j)
+      {
+      for(size_t i = n; i != 0; --i)
+         {
+         const uint32_t t = static_cast<uint32_t>((5 - j) * n + i);
+
+         uint8_t t_buf[4] = { 0 };
+         store_be(t, t_buf);
+
+         xor_buf(&A[4], t_buf, 4);
+
+         copy_mem(&A[8], &R[8*(i-1)], 8);
+
+         bc.decrypt(A.data());
+
+         copy_mem(&R[8*(i-1)], &A[8], 8);
+         }
+      }
+
+   ICV_out = load_be<uint64_t>(A.data(), 0);
+
+   return R;
+   }
+
+}
+
+std::vector<uint8_t>
+nist_key_wrap(const uint8_t input[],
+              size_t input_len,
+              const BlockCipher& bc)
+   {
+   if(bc.block_size() != 16)
+      throw Invalid_Argument("NIST key wrap algorithm requires a 128-bit cipher");
+
+   if(input_len % 8 != 0)
+      throw Invalid_Argument("Bad input size for NIST key wrap");
+
+   return raw_nist_key_wrap(input, input_len, bc, 0xA6A6A6A6A6A6A6A6);
+   }
+
+secure_vector<uint8_t>
+nist_key_unwrap(const uint8_t input[],
+                size_t input_len,
+                const BlockCipher& bc)
+   {
+   if(bc.block_size() != 16)
+      throw Invalid_Argument("NIST key wrap algorithm requires a 128-bit cipher");
+
+   if(input_len < 16 || input_len % 8 != 0)
+      throw Invalid_Argument("Bad input size for NIST key unwrap");
+
+   uint64_t ICV_out = 0;
+
+   secure_vector<uint8_t> R = raw_nist_key_unwrap(input, input_len, bc, ICV_out);
+
+   if(ICV_out != 0xA6A6A6A6A6A6A6A6)
+      throw Integrity_Failure("NIST key unwrap failed");
+
+   return R;
+   }
+
+std::vector<uint8_t>
+nist_key_wrap_padded(const uint8_t input[],
+                     size_t input_len,
+                     const BlockCipher& bc)
+   {
+   if(bc.block_size() != 16)
+      throw Invalid_Argument("NIST key wrap algorithm requires a 128-bit cipher");
+
+   const uint64_t ICV = 0xA65959A600000000 | static_cast<uint32_t>(input_len);
+
+   if(input_len <= 8)
+      {
+      /*
+      * Special case for small inputs: if input <= 8 bytes just use ECB
+      */
+      std::vector<uint8_t> block(16);
+      store_be(ICV, block.data());
+      copy_mem(block.data() + 8, input, input_len);
+      bc.encrypt(block);
+      return block;
+      }
+   else
+      {
+      return raw_nist_key_wrap(input, input_len, bc, ICV);
+      }
+   }
+
+secure_vector<uint8_t>
+nist_key_unwrap_padded(const uint8_t input[],
+                       size_t input_len,
+                       const BlockCipher& bc)
+   {
+   if(bc.block_size() != 16)
+      throw Invalid_Argument("NIST key wrap algorithm requires a 128-bit cipher");
+
+   if(input_len < 16 || input_len % 8 != 0)
+      throw Invalid_Argument("Bad input size for NIST key unwrap");
+
+   uint64_t ICV_out = 0;
+   secure_vector<uint8_t> R;
+
+   if(input_len == 16)
+      {
+      secure_vector<uint8_t> block(input, input + input_len);
+      bc.decrypt(block);
+
+      ICV_out = load_be<uint64_t>(block.data(), 0);
+      R.resize(8);
+      copy_mem(R.data(), block.data() + 8, 8);
+      }
+   else
+      {
+      R = raw_nist_key_unwrap(input, input_len, bc, ICV_out);
+      }
+
+   if((ICV_out >> 32) != 0xA65959A6)
+      throw Integrity_Failure("NIST key unwrap failed");
+
+   const size_t len = (ICV_out & 0xFFFFFFFF);
+
+   if(len > R.size() || len < R.size() - 8)
+      throw Integrity_Failure("NIST key unwrap failed");
+
+   const size_t padding = R.size() - len;
+
+   for(size_t i = 0; i != padding; ++i)
+      {
+      if(R[R.size() - i - 1] != 0)
+         throw Integrity_Failure("NIST key unwrap failed");
+      }
+
+   R.resize(R.size() - padding);
+
+   return R;
+   }
+
+}
-- 
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