Add XTEA decryption

1 files changed, 47 insertions, 11 deletions

diff --git a/src/block/xtea_sse2/xtea_sse2.cpp b/src/block/xtea_sse2/xtea_sse2.cpp
index db7775103..5d9c7dd05 100644
--- a/src/block/xtea_sse2/xtea_sse2.cpp
+++ b/src/block/xtea_sse2/xtea_sse2.cpp
@@ -1,5 +1,5 @@
 /*
-* XTEA SSE2
+* XTEA in SIMD
 * (C) 2009 Jack Lloyd
 *
 * Distributed under the terms of the Botan license
@@ -24,7 +24,10 @@ void xtea_encrypt_8(const byte in[64], byte out[64], const u32bit EK[64])
 
    for(u32bit i = 0; i != 32; i += 2)
       {
-      SIMD_32 K0(EK[2*i]), K1(EK[2*i+1]), K2(EK[2*i+2]), K3(EK[2*i+3]);
+      SIMD_32 K0(EK[2*i  ]);
+      SIMD_32 K1(EK[2*i+1]);
+      SIMD_32 K2(EK[2*i+2]);
+      SIMD_32 K3(EK[2*i+3]);
 
       L0 += (((R0 << 4) ^ (R0 >> 5)) + R0) ^ K0;
       L1 += (((R1 << 4) ^ (R1 >> 5)) + R1) ^ K0;
@@ -47,6 +50,43 @@ void xtea_encrypt_8(const byte in[64], byte out[64], const u32bit EK[64])
    R1.store_be(out + 48);
    }
 
+void xtea_decrypt_8(const byte in[64], byte out[64], const u32bit EK[64])
+   {
+   SIMD_32 L0 = SIMD_32::load_be(in     );
+   SIMD_32 R0 = SIMD_32::load_be(in + 16);
+   SIMD_32 L1 = SIMD_32::load_be(in + 32);
+   SIMD_32 R1 = SIMD_32::load_be(in + 48);
+
+   SIMD_32::transpose(L0, R0, L1, R1);
+
+   for(u32bit i = 0; i != 32; i += 2)
+      {
+      SIMD_32 K0(EK[63 - 2*i]);
+      SIMD_32 K1(EK[62 - 2*i]);
+      SIMD_32 K2(EK[61 - 2*i]);
+      SIMD_32 K3(EK[60 - 2*i]);
+
+      R0 -= (((L0 << 4) ^ (L0 >> 5)) + L0) ^ K0;
+      R1 -= (((L1 << 4) ^ (L1 >> 5)) + L1) ^ K0;
+
+      L0 -= (((R0 << 4) ^ (R0 >> 5)) + R0) ^ K1;
+      L1 -= (((R1 << 4) ^ (R1 >> 5)) + R1) ^ K1;
+
+      R0 -= (((L0 << 4) ^ (L0 >> 5)) + L0) ^ K2;
+      R1 -= (((L1 << 4) ^ (L1 >> 5)) + L1) ^ K2;
+
+      L0 -= (((R0 << 4) ^ (R0 >> 5)) + R0) ^ K3;
+      L1 -= (((R1 << 4) ^ (R1 >> 5)) + R1) ^ K3;
+      }
+
+   SIMD_32::transpose(L0, R0, L1, R1);
+
+   L0.store_be(out);
+   R0.store_be(out + 16);
+   L1.store_be(out + 32);
+   R1.store_be(out + 48);
+   }
+
 }
 
 /*
@@ -54,8 +94,6 @@ void xtea_encrypt_8(const byte in[64], byte out[64], const u32bit EK[64])
 */
 void XTEA_SSE2::encrypt_n(const byte in[], byte out[], u32bit blocks) const
    {
-   memset(out, 0, blocks * BLOCK_SIZE);
-
    while(blocks >= 8)
       {
       xtea_encrypt_8(in, out, this->EK);
@@ -72,15 +110,13 @@ void XTEA_SSE2::encrypt_n(const byte in[], byte out[], u32bit blocks) const
 */
 void XTEA_SSE2::decrypt_n(const byte in[], byte out[], u32bit blocks) const
    {
-#if 0
-   while(blocks >= 4)
+   while(blocks >= 8)
       {
-      xtea_decrypt_4(in, out, this->EK);
-      in += 4 * BLOCK_SIZE;
-      out += 4 * BLOCK_SIZE;
-      blocks -= 4;
+      xtea_decrypt_8(in, out, this->EK);
+      in += 8 * BLOCK_SIZE;
+      out += 8 * BLOCK_SIZE;
+      blocks -= 8;
       }
-#endif
 
    XTEA::decrypt_n(in, out, blocks);
    }