1 files changed, 172 insertions, 0 deletions
diff --git a/src/cipher/idea/idea.cpp b/src/cipher/idea/idea.cpp
new file mode 100644
index 000000000..a2b076015
--- /dev/null
+++ b/src/cipher/idea/idea.cpp
@@ -0,0 +1,172 @@
+/*************************************************
+* IDEA Source File                               *
+* (C) 1999-2007 Jack Lloyd                       *
+*************************************************/
+
+#include <botan/idea.h>
+#include <botan/loadstor.h>
+
+namespace Botan {
+
+namespace {
+
+/*************************************************
+* Multiplication modulo 65537                    *
+*************************************************/
+inline u16bit mul(u16bit x, u16bit y)
+   {
+   if(x && y)
+      {
+      u32bit T = static_cast<u32bit>(x) * y;
+      x = static_cast<u16bit>(T >> 16);
+      y = static_cast<u16bit>(T & 0xFFFF);
+      return static_cast<u16bit>(y - x + ((y < x) ? 1 : 0));
+      }
+   else
+      return static_cast<u16bit>(1 - x - y);
+   }
+
+/*************************************************
+* Find multiplicative inverses modulo 65537      *
+*************************************************/
+u16bit mul_inv(u16bit x)
+   {
+   if(x <= 1)
+      return x;
+
+   u16bit t0 = static_cast<u16bit>(65537 / x), t1 = 1;
+   u16bit y = static_cast<u16bit>(65537 % x);
+
+   while(y != 1)
+      {
+      u16bit q = x / y;
+      x %= y;
+      t1 += q * t0;
+
+      if(x == 1)
+         return t1;
+
+      q = y / x;
+      y %= x;
+      t0 += q * t1;
+      }
+   return (1 - t0);
+   }
+
+}
+
+/*************************************************
+* IDEA Encryption                                *
+*************************************************/
+void IDEA::enc(const byte in[], byte out[]) const
+   {
+   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(u32bit j = 0; j != 8; ++j)
+      {
+      X1 = mul(X1, EK[6*j+0]);
+      X2 += EK[6*j+1];
+      X3 += EK[6*j+2];
+      X4 = mul(X4, EK[6*j+3]);
+
+      u16bit T0 = X3;
+      X3 = mul(X3 ^ X1, EK[6*j+4]);
+
+      u16bit T1 = X2;
+      X2 = mul((X2 ^ X4) + X3, EK[6*j+5]);
+      X3 += X2;
+
+      X1 ^= X2;
+      X4 ^= X3;
+      X2 ^= T0;
+      X3 ^= T1;
+      }
+
+   X1  = mul(X1, EK[48]);
+   X2 += EK[50];
+   X3 += EK[49];
+   X4  = mul(X4, EK[51]);
+
+   store_be(out, X1, X3, X2, X4);
+   }
+
+/*************************************************
+* IDEA Decryption                                *
+*************************************************/
+void IDEA::dec(const byte in[], byte out[]) const
+   {
+   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(u32bit j = 0; j != 8; ++j)
+      {
+      X1 = mul(X1, DK[6*j+0]);
+      X2 += DK[6*j+1];
+      X3 += DK[6*j+2];
+      X4 = mul(X4, DK[6*j+3]);
+
+      u16bit T0 = X3;
+      X3 = mul(X3 ^ X1, DK[6*j+4]);
+
+      u16bit T1 = X2;
+      X2 = mul((X2 ^ X4) + X3, DK[6*j+5]);
+      X3 += X2;
+
+      X1 ^= X2;
+      X4 ^= X3;
+      X2 ^= T0;
+      X3 ^= T1;
+      }
+
+   X1  = mul(X1, DK[48]);
+   X2 += DK[50];
+   X3 += DK[49];
+   X4  = mul(X4, DK[51]);
+
+   store_be(out, X1, X3, X2, X4);
+   }
+
+/*************************************************
+* IDEA Key Schedule                              *
+*************************************************/
+void IDEA::key(const byte key[], u32bit)
+   {
+   for(u32bit j = 0; j != 8; ++j)
+      EK[j] = load_be<u16bit>(key, j);
+
+   for(u32bit j = 1, k = 8, offset = 0; k != 52; j %= 8, ++j, ++k)
+      {
+      EK[j+7+offset] = static_cast<u16bit>((EK[(j     % 8) + offset] << 9) |
+                                           (EK[((j+1) % 8) + offset] >> 7));
+      offset += (j == 8) ? 8 : 0;
+      }
+
+   DK[51] = mul_inv(EK[3]);
+   DK[50] = -EK[2];
+   DK[49] = -EK[1];
+   DK[48] = mul_inv(EK[0]);
+
+   for(u32bit j = 1, k = 4, counter = 47; j != 8; ++j, k += 6)
+      {
+      DK[counter--] = EK[k+1];
+      DK[counter--] = EK[k];
+      DK[counter--] = mul_inv(EK[k+5]);
+      DK[counter--] = -EK[k+3];
+      DK[counter--] = -EK[k+4];
+      DK[counter--] = mul_inv(EK[k+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]);
+   }
+
+}