1 files changed, 169 insertions, 0 deletions
diff --git a/src/lib/block/idea/idea.cpp b/src/lib/block/idea/idea.cpp
new file mode 100644
index 000000000..61a938c57
--- /dev/null
+++ b/src/lib/block/idea/idea.cpp
@@ -0,0 +1,169 @@
+/*
+* IDEA
+* (C) 1999-2010 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/idea.h>
+#include <botan/loadstor.h>
+
+namespace Botan {
+
+namespace {
+
+/*
+* Multiplication modulo 65537
+*/
+inline u16bit mul(u16bit x, u16bit y)
+   {
+   const u32bit P = static_cast<u32bit>(x) * y;
+
+   // P ? 0xFFFF : 0
+   const u16bit P_mask = !P - 1;
+
+   const u32bit P_hi = P >> 16;
+   const u32bit P_lo = P & 0xFFFF;
+
+   const u16bit r_1 = (P_lo - P_hi) + (P_lo < P_hi);
+   const u16bit r_2 = 1 - x - y;
+
+   return (r_1 & P_mask) | (r_2 & ~P_mask);
+   }
+
+/*
+* Find multiplicative inverses modulo 65537
+*
+* 65537 is prime; thus Fermat's little theorem tells us that
+* x^65537 == x modulo 65537, which means
+* x^(65537-2) == x^-1 modulo 65537 since
+* x^(65537-2) * x == 1 mod 65537
+*
+* Do the exponentiation with a basic square and multiply: all bits are
+* of exponent are 1 so we always multiply
+*/
+u16bit mul_inv(u16bit x)
+   {
+   u16bit y = x;
+
+   for(size_t i = 0; i != 15; ++i)
+      {
+      y = mul(y, y); // square
+      y = mul(y, x);
+      }
+
+   return y;
+   }
+
+/**
+* IDEA is involutional, depending only on the key schedule
+*/
+void idea_op(const byte in[], byte out[], size_t blocks, const u16bit K[52])
+   {
+   const size_t BLOCK_SIZE = 8;
+
+   for(size_t i = 0; i != blocks; ++i)
+      {
+      u16bit X1 = load_be<u16bit>(in, 0);
+      u16bit X2 = load_be<u16bit>(in, 1);
+      u16bit X3 = load_be<u16bit>(in, 2);
+      u16bit X4 = load_be<u16bit>(in, 3);
+
+      for(size_t j = 0; j != 8; ++j)
+         {
+         X1 = mul(X1, K[6*j+0]);
+         X2 += K[6*j+1];
+         X3 += K[6*j+2];
+         X4 = mul(X4, K[6*j+3]);
+
+         u16bit T0 = X3;
+         X3 = mul(X3 ^ X1, K[6*j+4]);
+
+         u16bit T1 = X2;
+         X2 = mul((X2 ^ X4) + X3, K[6*j+5]);
+         X3 += X2;
+
+         X1 ^= X2;
+         X4 ^= X3;
+         X2 ^= T0;
+         X3 ^= T1;
+         }
+
+      X1  = mul(X1, K[48]);
+      X2 += K[50];
+      X3 += K[49];
+      X4  = mul(X4, K[51]);
+
+      store_be(out, X1, X3, X2, X4);
+
+      in += BLOCK_SIZE;
+      out += BLOCK_SIZE;
+      }
+   }
+
+}
+
+/*
+* IDEA Encryption
+*/
+void IDEA::encrypt_n(const byte in[], byte out[], size_t blocks) const
+   {
+   idea_op(in, out, blocks, &EK[0]);
+   }
+
+/*
+* IDEA Decryption
+*/
+void IDEA::decrypt_n(const byte in[], byte out[], size_t blocks) const
+   {
+   idea_op(in, out, blocks, &DK[0]);
+   }
+
+/*
+* IDEA Key Schedule
+*/
+void IDEA::key_schedule(const byte key[], size_t)
+   {
+   EK.resize(52);
+   DK.resize(52);
+
+   for(size_t i = 0; i != 8; ++i)
+      EK[i] = load_be<u16bit>(key, i);
+
+   for(size_t i = 1, j = 8, offset = 0; j != 52; i %= 8, ++i, ++j)
+      {
+      EK[i+7+offset] = static_cast<u16bit>((EK[(i     % 8) + offset] << 9) |
+                                           (EK[((i+1) % 8) + offset] >> 7));
+      offset += (i == 8) ? 8 : 0;
+      }
+
+   DK[51] = mul_inv(EK[3]);
+   DK[50] = -EK[2];
+   DK[49] = -EK[1];
+   DK[48] = mul_inv(EK[0]);
+
+   for(size_t i = 1, j = 4, counter = 47; i != 8; ++i, j += 6)
+      {
+      DK[counter--] = EK[j+1];
+      DK[counter--] = EK[j];
+      DK[counter--] = mul_inv(EK[j+5]);
+      DK[counter--] = -EK[j+3];
+      DK[counter--] = -EK[j+4];
+      DK[counter--] = mul_inv(EK[j+2]);
+      }
+
+   DK[5] = EK[47];
+   DK[4] = EK[46];
+   DK[3] = mul_inv(EK[51]);
+   DK[2] = -EK[50];
+   DK[1] = -EK[49];
+   DK[0] = mul_inv(EK[48]);
+   }
+
+void IDEA::clear()
+   {
+   zap(EK);
+   zap(DK);
+   }
+
+}