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/*
* (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 Invalid_Authentication_Tag("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 Invalid_Authentication_Tag("NIST key unwrap failed");
const size_t len = (ICV_out & 0xFFFFFFFF);
if(R.size() < 8 || len > R.size() || len < R.size() - 8)
throw Invalid_Authentication_Tag("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 Invalid_Authentication_Tag("NIST key unwrap failed");
}
R.resize(R.size() - padding);
return R;
}
}
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