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/*
* SipHash
* (C) 2014,2015 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/internal/mac_utils.h>
#include <botan/siphash.h>
namespace Botan {
BOTAN_REGISTER_NAMED_T_2LEN(MessageAuthenticationCode, SipHash, "SipHash", "base", 2, 4);
namespace {
void SipRounds(u64bit M, secure_vector<u64bit>& V, size_t r)
{
u64bit V0 = V[0], V1 = V[1], V2 = V[2], V3 = V[3];
V3 ^= M;
for(size_t i = 0; i != r; ++i)
{
V0 += V1; V2 += V3;
V1 = rotate_left(V1, 13);
V3 = rotate_left(V3, 16);
V1 ^= V0; V3 ^= V2;
V0 = rotate_left(V0, 32);
V2 += V1; V0 += V3;
V1 = rotate_left(V1, 17);
V3 = rotate_left(V3, 21);
V1 ^= V2; V3 ^= V0;
V2 = rotate_left(V2, 32);
}
V0 ^= M;
V[0] = V0; V[1] = V1; V[2] = V2; V[3] = V3;
}
}
void SipHash::add_data(const byte input[], size_t length)
{
m_words += length;
if(m_mbuf_pos)
{
while(length && m_mbuf_pos != 8)
{
m_mbuf = (m_mbuf >> 8) | (static_cast<u64bit>(input[0]) << 56);
++m_mbuf_pos;
++input;
length--;
}
if(m_mbuf_pos == 8)
{
SipRounds(m_mbuf, m_V, m_C);
m_mbuf_pos = 0;
m_mbuf = 0;
}
}
while(length >= 8)
{
SipRounds(load_le<u64bit>(input, 0), m_V, m_C);
input += 8;
length -= 8;
}
for(size_t i = 0; i != length; ++i)
{
m_mbuf = (m_mbuf >> 8) | (static_cast<u64bit>(input[i]) << 56);
m_mbuf_pos++;
}
}
void SipHash::final_result(byte mac[])
{
m_mbuf = (m_mbuf >> (64-m_mbuf_pos*8)) | (static_cast<u64bit>(m_words) << 56);
SipRounds(m_mbuf, m_V, m_C);
m_V[2] ^= 0xFF;
SipRounds(0, m_V, m_D);
const u64bit X = m_V[0] ^ m_V[1] ^ m_V[2] ^ m_V[3];
store_le(X, mac);
m_mbuf = 0;
m_mbuf_pos = 0;
m_words = 0;
}
void SipHash::key_schedule(const byte key[], size_t)
{
const u64bit K0 = load_le<u64bit>(key, 0);
const u64bit K1 = load_le<u64bit>(key, 1);
m_V.resize(4);
m_V[0] = K0 ^ 0x736F6D6570736575;
m_V[1] = K1 ^ 0x646F72616E646F6D;
m_V[2] = K0 ^ 0x6C7967656E657261;
m_V[3] = K1 ^ 0x7465646279746573;
}
void SipHash::clear()
{
m_V.clear();
}
std::string SipHash::name() const
{
return "SipHash(" + std::to_string(m_C) + "," + std::to_string(m_D) + ")";
}
MessageAuthenticationCode* SipHash::clone() const
{
return new SipHash(m_C, m_D);
}
}
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