idea_sse2.cpp

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/*
* IDEA in SSE2
* (C) 2009 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
 
#include <botan/idea_sse2.h>
#include <emmintrin.h>
 
namespace Botan {
 
namespace {
 
inline __m128i mul(__m128i X, u16bit K_16)
   {
   const __m128i zeros = _mm_set1_epi16(0);
   const __m128i ones = _mm_set1_epi16(1);
 
   const __m128i K = _mm_set1_epi16(K_16);
 
   const __m128i X_is_zero = _mm_cmpeq_epi16(X, zeros);
   const __m128i K_is_zero = _mm_cmpeq_epi16(K, zeros);
 
   const __m128i mul_lo = _mm_mullo_epi16(X, K);
   const __m128i mul_hi = _mm_mulhi_epu16(X, K);
 
   __m128i T = _mm_sub_epi16(mul_lo, mul_hi);
 
   // Unsigned compare; cmp = 1 if mul_lo < mul_hi else 0
   const __m128i subs = _mm_subs_epu16(mul_hi, mul_lo);
   const __m128i cmp = _mm_min_epu8(
     _mm_or_si128(subs, _mm_srli_epi16(subs, 8)), ones);
 
   T = _mm_add_epi16(T, cmp);
 
   /* Selection: if X[i] is zero then assign 1-K
                 if K is zero then assign 1-X[i]
 
      Could if() off value of K_16 for the second, but this gives a
      constant time implementation which is a nice bonus.
   */
 
   T = _mm_or_si128(
      _mm_andnot_si128(X_is_zero, T),
      _mm_and_si128(_mm_sub_epi16(ones, K), X_is_zero));
 
   T = _mm_or_si128(
      _mm_andnot_si128(K_is_zero, T),
      _mm_and_si128(_mm_sub_epi16(ones, X), K_is_zero));
 
   return T;
   }
 
/*
* 4x8 matrix transpose
*
* FIXME: why do I need the extra set of unpack_epi32 here? Inverse in
* transpose_out doesn't need it. Something with the shuffle? Removing
* that extra unpack could easily save 3-4 cycles per block, and would
* also help a lot with register pressure on 32-bit x86
*/
void transpose_in(__m128i& B0, __m128i& B1, __m128i& B2, __m128i& B3)
   {
   __m128i T0 = _mm_unpackhi_epi32(B0, B1);
   __m128i T1 = _mm_unpacklo_epi32(B0, B1);
   __m128i T2 = _mm_unpackhi_epi32(B2, B3);
   __m128i T3 = _mm_unpacklo_epi32(B2, B3);
 
   __m128i T4 = _mm_unpacklo_epi32(T0, T1);
   __m128i T5 = _mm_unpackhi_epi32(T0, T1);
   __m128i T6 = _mm_unpacklo_epi32(T2, T3);
   __m128i T7 = _mm_unpackhi_epi32(T2, T3);
 
   T0 = _mm_shufflehi_epi16(T4, _MM_SHUFFLE(1, 3, 0, 2));
   T1 = _mm_shufflehi_epi16(T5, _MM_SHUFFLE(1, 3, 0, 2));
   T2 = _mm_shufflehi_epi16(T6, _MM_SHUFFLE(1, 3, 0, 2));
   T3 = _mm_shufflehi_epi16(T7, _MM_SHUFFLE(1, 3, 0, 2));
 
   T0 = _mm_shufflelo_epi16(T0, _MM_SHUFFLE(1, 3, 0, 2));
   T1 = _mm_shufflelo_epi16(T1, _MM_SHUFFLE(1, 3, 0, 2));
   T2 = _mm_shufflelo_epi16(T2, _MM_SHUFFLE(1, 3, 0, 2));
   T3 = _mm_shufflelo_epi16(T3, _MM_SHUFFLE(1, 3, 0, 2));
 
   T0 = _mm_shuffle_epi32(T0, _MM_SHUFFLE(3, 1, 2, 0));
   T1 = _mm_shuffle_epi32(T1, _MM_SHUFFLE(3, 1, 2, 0));
   T2 = _mm_shuffle_epi32(T2, _MM_SHUFFLE(3, 1, 2, 0));
   T3 = _mm_shuffle_epi32(T3, _MM_SHUFFLE(3, 1, 2, 0));
 
   B0 = _mm_unpacklo_epi64(T0, T2);
   B1 = _mm_unpackhi_epi64(T0, T2);
   B2 = _mm_unpacklo_epi64(T1, T3);
   B3 = _mm_unpackhi_epi64(T1, T3);
   }
 
/*
* 4x8 matrix transpose (reverse)
*/
void transpose_out(__m128i& B0, __m128i& B1, __m128i& B2, __m128i& B3)
   {
   __m128i T0 = _mm_unpacklo_epi64(B0, B1);
   __m128i T1 = _mm_unpacklo_epi64(B2, B3);
   __m128i T2 = _mm_unpackhi_epi64(B0, B1);
   __m128i T3 = _mm_unpackhi_epi64(B2, B3);
 
   T0 = _mm_shuffle_epi32(T0, _MM_SHUFFLE(3, 1, 2, 0));
   T1 = _mm_shuffle_epi32(T1, _MM_SHUFFLE(3, 1, 2, 0));
   T2 = _mm_shuffle_epi32(T2, _MM_SHUFFLE(3, 1, 2, 0));
   T3 = _mm_shuffle_epi32(T3, _MM_SHUFFLE(3, 1, 2, 0));
 
   T0 = _mm_shufflehi_epi16(T0, _MM_SHUFFLE(3, 1, 2, 0));
   T1 = _mm_shufflehi_epi16(T1, _MM_SHUFFLE(3, 1, 2, 0));
   T2 = _mm_shufflehi_epi16(T2, _MM_SHUFFLE(3, 1, 2, 0));
   T3 = _mm_shufflehi_epi16(T3, _MM_SHUFFLE(3, 1, 2, 0));
 
   T0 = _mm_shufflelo_epi16(T0, _MM_SHUFFLE(3, 1, 2, 0));
   T1 = _mm_shufflelo_epi16(T1, _MM_SHUFFLE(3, 1, 2, 0));
   T2 = _mm_shufflelo_epi16(T2, _MM_SHUFFLE(3, 1, 2, 0));
   T3 = _mm_shufflelo_epi16(T3, _MM_SHUFFLE(3, 1, 2, 0));
 
   B0 = _mm_unpacklo_epi32(T0, T1);
   B1 = _mm_unpackhi_epi32(T0, T1);
   B2 = _mm_unpacklo_epi32(T2, T3);
   B3 = _mm_unpackhi_epi32(T2, T3);
   }
 
/*
* IDEA encryption/decryption in SSE2
*/
void idea_op_8(const byte in[64], byte out[64], const u16bit EK[52])
   {
   const __m128i* in_mm = reinterpret_cast<const __m128i*>(in);
 
   __m128i B0 = _mm_loadu_si128(in_mm + 0);
   __m128i B1 = _mm_loadu_si128(in_mm + 1);
   __m128i B2 = _mm_loadu_si128(in_mm + 2);
   __m128i B3 = _mm_loadu_si128(in_mm + 3);
 
   transpose_in(B0, B1, B2, B3);
 
   // byte swap
   B0 = _mm_or_si128(_mm_slli_epi16(B0, 8), _mm_srli_epi16(B0, 8));
   B1 = _mm_or_si128(_mm_slli_epi16(B1, 8), _mm_srli_epi16(B1, 8));
   B2 = _mm_or_si128(_mm_slli_epi16(B2, 8), _mm_srli_epi16(B2, 8));
   B3 = _mm_or_si128(_mm_slli_epi16(B3, 8), _mm_srli_epi16(B3, 8));
 
   for(size_t i = 0; i != 8; ++i)
      {
      B0 = mul(B0, EK[6*i+0]);
      B1 = _mm_add_epi16(B1, _mm_set1_epi16(EK[6*i+1]));
      B2 = _mm_add_epi16(B2, _mm_set1_epi16(EK[6*i+2]));
      B3 = mul(B3, EK[6*i+3]);
 
      __m128i T0 = B2;
 
      B2 = _mm_xor_si128(B2, B0);
      B2 = mul(B2, EK[6*i+4]);
 
      __m128i T1 = B1;
 
      B1 = _mm_xor_si128(B1, B3);
      B1 = _mm_add_epi16(B1, B2);
      B1 = mul(B1, EK[6*i+5]);
 
      B2 = _mm_add_epi16(B2, B1);
 
      B0 = _mm_xor_si128(B0, B1);
      B1 = _mm_xor_si128(B1, T0);
      B3 = _mm_xor_si128(B3, B2);
      B2 = _mm_xor_si128(B2, T1);
      }
 
   B0 = mul(B0, EK[48]);
   B1 = _mm_add_epi16(B1, _mm_set1_epi16(EK[50]));
   B2 = _mm_add_epi16(B2, _mm_set1_epi16(EK[49]));
   B3 = mul(B3, EK[51]);
 
   // byte swap
   B0 = _mm_or_si128(_mm_slli_epi16(B0, 8), _mm_srli_epi16(B0, 8));
   B1 = _mm_or_si128(_mm_slli_epi16(B1, 8), _mm_srli_epi16(B1, 8));
   B2 = _mm_or_si128(_mm_slli_epi16(B2, 8), _mm_srli_epi16(B2, 8));
   B3 = _mm_or_si128(_mm_slli_epi16(B3, 8), _mm_srli_epi16(B3, 8));
 
   transpose_out(B0, B2, B1, B3);
 
   __m128i* out_mm = reinterpret_cast<__m128i*>(out);
 
   _mm_storeu_si128(out_mm + 0, B0);
   _mm_storeu_si128(out_mm + 1, B2);
   _mm_storeu_si128(out_mm + 2, B1);
   _mm_storeu_si128(out_mm + 3, B3);
   }
 
}
 
/*
* IDEA Encryption
*/
void IDEA_SSE2::encrypt_n(const byte in[], byte out[], size_t blocks) const
   {
   const u16bit* KS = &this->get_EK()[0];
 
   while(blocks >= 8)
      {
      idea_op_8(in, out, KS);
      in += 8 * BLOCK_SIZE;
      out += 8 * BLOCK_SIZE;
      blocks -= 8;
      }
 
   if(blocks)
     IDEA::encrypt_n(in, out, blocks);
   }
 
/*
* IDEA Decryption
*/
void IDEA_SSE2::decrypt_n(const byte in[], byte out[], size_t blocks) const
   {
   const u16bit* KS = &this->get_DK()[0];
 
   while(blocks >= 8)
      {
      idea_op_8(in, out, KS);
      in += 8 * BLOCK_SIZE;
      out += 8 * BLOCK_SIZE;
      blocks -= 8;
      }
 
   if(blocks)
     IDEA::decrypt_n(in, out, blocks);
   }
 
}