Add an implementation of Skein-512

3 files changed, 309 insertions, 0 deletions

diff --git a/src/hash/skein/info.txt b/src/hash/skein/info.txt
new file mode 100644
index 000000000..d2d482d81
--- /dev/null
+++ b/src/hash/skein/info.txt
@@ -0,0 +1,10 @@
+realname "Skein"
+
+define SKEIN_512
+
+load_on auto
+
+<add>
+skein_512.cpp
+skein_512.h
+</add>
diff --git a/src/hash/skein/skein_512.cpp b/src/hash/skein/skein_512.cpp
new file mode 100644
index 000000000..266465b98
--- /dev/null
+++ b/src/hash/skein/skein_512.cpp
@@ -0,0 +1,258 @@
+/**
+* The Skein-512 hash function
+* (C) 2009 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/skein_512.h>
+#include <botan/loadstor.h>
+#include <botan/parsing.h>
+#include <algorithm>
+#include <stdexcept>
+
+namespace Botan {
+
+namespace {
+
+enum type_code {
+   SKEIN_KEY = 0,
+   SKEIN_CONFIG = 4,
+   SKEIN_PERSONALIZATION = 8,
+   SKEIN_PUBLIC_KEY = 12,
+   SKEIN_KEY_IDENTIFIER = 16,
+   SKEIN_NONCE = 20,
+   SKEIN_MSG = 48,
+   SKEIN_OUTPUT = 63
+};
+
+void ubi_512(u64bit H[9], u64bit T[], const byte msg[], u64bit msg_len)
+   {
+   bool first = true;
+
+   while(msg_len || first)
+      {
+      first = false;
+      const u64bit to_proc = std::min<u64bit>(msg_len, 64);
+      T[0] += to_proc;
+
+      u64bit M[8] = { 0 };
+      for(u32bit j = 0; j != to_proc / 8; ++j)
+         M[j] = load_le<u64bit>(msg, j);
+
+      if(to_proc % 8)
+         {
+         for(u32bit j = 0; j != to_proc % 8; ++j)
+            M[to_proc/8] |= ((u64bit)msg[8*(to_proc/8)+j] << (8*j));
+         }
+
+      H[8] = H[0] ^ H[1] ^ H[2] ^ H[3] ^
+             H[4] ^ H[5] ^ H[6] ^ H[7] ^ 0x5555555555555555;
+
+      T[2] = T[0] ^ T[1];
+
+      const u64bit K0 = H[0];
+      const u64bit K1 = H[1];
+      const u64bit K2 = H[2];
+      const u64bit K3 = H[3];
+      const u64bit K4 = H[4];
+      const u64bit K5 = H[5];
+      const u64bit K6 = H[6];
+      const u64bit K7 = H[7];
+
+      u64bit X0 = M[0] + K0;
+      u64bit X1 = M[1] + K1;
+      u64bit X2 = M[2] + K2;
+      u64bit X3 = M[3] + K3;
+      u64bit X4 = M[4] + K4;
+      u64bit X5 = M[5] + K5 + T[0];
+      u64bit X6 = M[6] + K6 + T[1];
+      u64bit X7 = M[7] + K7;
+
+#define SKEIN_ROUND(I1,I2,I3,I4,I5,I6,I7,I8,ROT1,ROT2,ROT3,ROT4)   \
+      do {                                                         \
+         X##I1 += X##I2; X##I2 = rotate_left(X##I2, ROT1) ^ X##I1; \
+         X##I3 += X##I4; X##I4 = rotate_left(X##I4, ROT2) ^ X##I3; \
+         X##I5 += X##I6; X##I6 = rotate_left(X##I6, ROT3) ^ X##I5; \
+         X##I7 += X##I8; X##I8 = rotate_left(X##I8, ROT4) ^ X##I7; \
+      } while(0);
+
+#define SKEIN_INJECT_KEY(r)                     \
+      do {                                      \
+         X0 += H[(r  ) % 9];                    \
+         X1 += H[(r+1) % 9];                    \
+         X2 += H[(r+2) % 9];                    \
+         X3 += H[(r+3) % 9];                    \
+         X4 += H[(r+4) % 9];                    \
+         X5 += H[(r+5) % 9] + T[(r  ) % 3];     \
+         X6 += H[(r+6) % 9] + T[(r+1) % 3];     \
+         X7 += H[(r+7) % 9] + (r);              \
+      } while(0);
+
+#define SKEIN_8_ROUNDS(R1,R2)                      \
+      do {                                         \
+         SKEIN_ROUND(0,1,2,3,4,5,6,7,38,30,50,53); \
+         SKEIN_ROUND(2,1,4,7,6,5,0,3,48,20,43,31); \
+         SKEIN_ROUND(4,1,6,3,0,5,2,7,34,14,15,27); \
+         SKEIN_ROUND(6,1,0,7,2,5,4,3,26,12,58, 7); \
+                                                   \
+         SKEIN_INJECT_KEY(R1);                     \
+                                                   \
+         SKEIN_ROUND(0,1,2,3,4,5,6,7,33,49, 8,42); \
+         SKEIN_ROUND(2,1,4,7,6,5,0,3,39,27,41,14); \
+         SKEIN_ROUND(4,1,6,3,0,5,2,7,29,26,11, 9); \
+         SKEIN_ROUND(6,1,0,7,2,5,4,3,33,51,39,35); \
+                                                   \
+         SKEIN_INJECT_KEY(R2);                     \
+      } while(0);
+
+      SKEIN_8_ROUNDS(1,2);
+      SKEIN_8_ROUNDS(3,4);
+      SKEIN_8_ROUNDS(5,6);
+      SKEIN_8_ROUNDS(7,8);
+      SKEIN_8_ROUNDS(9,10);
+      SKEIN_8_ROUNDS(11,12);
+      SKEIN_8_ROUNDS(13,14);
+      SKEIN_8_ROUNDS(15,16);
+      SKEIN_8_ROUNDS(17,18);
+
+      // message feed forward
+      H[0] = X0 ^ M[0];
+      H[1] = X1 ^ M[1];
+      H[2] = X2 ^ M[2];
+      H[3] = X3 ^ M[3];
+      H[4] = X4 ^ M[4];
+      H[5] = X5 ^ M[5];
+      H[6] = X6 ^ M[6];
+      H[7] = X7 ^ M[7];
+
+      T[1] &= ~((u64bit)1 << 62); // clear first flag if set
+
+      msg_len -= to_proc;
+      msg += to_proc;
+      }
+   }
+
+void reset_tweak(u64bit T[3], type_code type, bool final)
+   {
+   T[0] = 0;
+   T[1] = ((u64bit)type << 56) | ((u64bit)1 << 62) | ((u64bit)final << 63);
+   }
+
+void initial_block(u64bit H[9], u64bit T[3], u32bit output_bits)
+   {
+   clear_mem(H, 9);
+
+   byte config_str[32] = { 0x53, 0x48, 0x41, 0x33, 0x01, 0x00, 0 };
+   store_le(output_bits, config_str + 8);
+
+   reset_tweak(T, SKEIN_CONFIG, true);
+   ubi_512(H, T, config_str, sizeof(config_str));
+
+#if 0
+   if(personalization != "")
+      {
+      const byte* bits = reinterpret_cast<const byte*>(personalization.data());
+
+      // FIXME: will be wrong if personalization > 64 bytes b/c final
+      // bit is set for all blocks
+
+      reset_tweak(T, SKEIN_PERSONALIZATION, true);
+      ubi_512(H, T, bits, personalization.length());
+      }
+#endif
+
+   reset_tweak(T, SKEIN_MSG, false);
+   }
+
+}
+
+Skein_512::Skein_512(u32bit arg_output_bits) :
+   HashFunction(arg_output_bits / 8, 64),
+   output_bits(arg_output_bits), buf_pos(0)
+   {
+   if(output_bits == 0 || output_bits % 8 != 0)
+      throw std::invalid_argument("Bad output bits size for Skein-512");
+
+   initial_block(H, T, output_bits);
+   }
+
+std::string Skein_512::name() const
+   {
+   return "Skein-512(" + to_string(output_bits) + ")";
+   }
+
+void Skein_512::clear() throw()
+   {
+   H.clear();
+   T.clear();
+   buffer.clear();
+   buf_pos = 0;
+   }
+
+void Skein_512::add_data(const byte input[], u32bit length)
+   {
+   if(buf_pos)
+      {
+      buffer.copy(buf_pos, input, length);
+      if(buf_pos + length > 64)
+         {
+         ubi_512(H, T, &buffer[0], buffer.size());
+
+         input += (64 - buf_pos);
+         length -= (64 - buf_pos);
+         buf_pos = 0;
+         }
+      }
+
+   const u32bit full_blocks = (length - 1) / 64;
+
+   if(full_blocks)
+      ubi_512(H, T, input, 64*full_blocks);
+
+   length -= full_blocks * 64;
+
+   buffer.copy(buf_pos, input + full_blocks * 64, length);
+   buf_pos += length;
+   }
+
+void Skein_512::final_result(byte out[])
+   {
+   T[1] |= ((u64bit)1 << 63); // final block flag
+
+   for(u32bit i = buf_pos; i != buffer.size(); ++i)
+      buffer[i] = 0;
+
+   ubi_512(H, T, &buffer[0], buf_pos);
+
+   byte counter[8] = { 0 };
+
+   u32bit out_bytes = output_bits / 8;
+
+   SecureBuffer<u64bit, 9> H_out;
+
+   while(out_bytes)
+      {
+      const u32bit to_proc = std::min<u32bit>(out_bytes, 64);
+
+      H_out.copy(H.begin(), 8);
+
+      reset_tweak(T, SKEIN_OUTPUT, true);
+      ubi_512(H_out, T, counter, sizeof(counter));
+
+      for(u32bit i = 0; i != to_proc; ++i)
+         out[i] = get_byte(7-i%8, H_out[i/8]);
+
+      out_bytes -= to_proc;
+      out += to_proc;
+
+      for(u32bit i = 0; i != sizeof(counter); ++i)
+         if(++counter[i])
+            break;
+      }
+
+   buf_pos = 0;
+   initial_block(H, T, output_bits);
+   }
+
+}
diff --git a/src/hash/skein/skein_512.h b/src/hash/skein/skein_512.h
new file mode 100644
index 000000000..a585ff47f
--- /dev/null
+++ b/src/hash/skein/skein_512.h
@@ -0,0 +1,41 @@
+/**
+* The Skein-512 hash function
+* (C) 2009 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_SKEIN_H__
+#define BOTAN_SKEIN_H__
+
+#include <botan/secmem.h>
+#include <botan/hash.h>
+#include <string>
+
+namespace Botan {
+
+class Skein_512 : public HashFunction
+   {
+   public:
+      Skein_512(u32bit output_bits = 512);
+
+      HashFunction* clone() const { return new Skein_512(output_bits); }
+
+      std::string name() const;
+
+      void clear() throw();
+   private:
+      void add_data(const byte input[], u32bit length);
+      void final_result(byte out[]);
+
+      u32bit output_bits;
+      SecureBuffer<u64bit, 9> H;
+      SecureBuffer<u64bit, 3> T;
+
+      SecureBuffer<byte, 64> buffer;
+      u32bit buf_pos;
+   };
+
+}
+
+#endif