Add current version of libSRTP from CVS.

libsrtp/crypto/math/math.c

+/*
+ * math.c
+ *
+ * crypto math operations and data types
+ *
+ * David A. McGrew
+ * Cisco Systems, Inc.
+ */
+/*
+ *      
+ * Copyright (c) 2001-2006 Cisco Systems, Inc.
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ *   Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * 
+ *   Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ * 
+ *   Neither the name of the Cisco Systems, Inc. nor the names of its
+ *   contributors may be used to endorse or promote products derived
+ *   from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "crypto_math.h"
+
+int 
+octet_weight[256] = {
+  0, 1, 1, 2, 1, 2, 2, 3,
+  1, 2, 2, 3, 2, 3, 3, 4,
+  1, 2, 2, 3, 2, 3, 3, 4,
+  2, 3, 3, 4, 3, 4, 4, 5,
+  1, 2, 2, 3, 2, 3, 3, 4,
+  2, 3, 3, 4, 3, 4, 4, 5,
+  2, 3, 3, 4, 3, 4, 4, 5,
+  3, 4, 4, 5, 4, 5, 5, 6,
+  1, 2, 2, 3, 2, 3, 3, 4,
+  2, 3, 3, 4, 3, 4, 4, 5,
+  2, 3, 3, 4, 3, 4, 4, 5,
+  3, 4, 4, 5, 4, 5, 5, 6,
+  2, 3, 3, 4, 3, 4, 4, 5,
+  3, 4, 4, 5, 4, 5, 5, 6,
+  3, 4, 4, 5, 4, 5, 5, 6,
+  4, 5, 5, 6, 5, 6, 6, 7,
+  1, 2, 2, 3, 2, 3, 3, 4,
+  2, 3, 3, 4, 3, 4, 4, 5,
+  2, 3, 3, 4, 3, 4, 4, 5,
+  3, 4, 4, 5, 4, 5, 5, 6,
+  2, 3, 3, 4, 3, 4, 4, 5,
+  3, 4, 4, 5, 4, 5, 5, 6,
+  3, 4, 4, 5, 4, 5, 5, 6,
+  4, 5, 5, 6, 5, 6, 6, 7,
+  2, 3, 3, 4, 3, 4, 4, 5,
+  3, 4, 4, 5, 4, 5, 5, 6,
+  3, 4, 4, 5, 4, 5, 5, 6,
+  4, 5, 5, 6, 5, 6, 6, 7,
+  3, 4, 4, 5, 4, 5, 5, 6,
+  4, 5, 5, 6, 5, 6, 6, 7,
+  4, 5, 5, 6, 5, 6, 6, 7,
+  5, 6, 6, 7, 6, 7, 7, 8
+};
+
+int
+low_bit[256] = {
+  -1, 0, 1, 0, 2, 0, 1, 0,
+  3, 0, 1, 0, 2, 0, 1, 0,
+  4, 0, 1, 0, 2, 0, 1, 0,
+  3, 0, 1, 0, 2, 0, 1, 0,
+  5, 0, 1, 0, 2, 0, 1, 0,
+  3, 0, 1, 0, 2, 0, 1, 0,
+  4, 0, 1, 0, 2, 0, 1, 0,
+  3, 0, 1, 0, 2, 0, 1, 0,
+  6, 0, 1, 0, 2, 0, 1, 0,
+  3, 0, 1, 0, 2, 0, 1, 0,
+  4, 0, 1, 0, 2, 0, 1, 0,
+  3, 0, 1, 0, 2, 0, 1, 0,
+  5, 0, 1, 0, 2, 0, 1, 0,
+  3, 0, 1, 0, 2, 0, 1, 0,
+  4, 0, 1, 0, 2, 0, 1, 0,
+  3, 0, 1, 0, 2, 0, 1, 0,
+  7, 0, 1, 0, 2, 0, 1, 0,
+  3, 0, 1, 0, 2, 0, 1, 0,
+  4, 0, 1, 0, 2, 0, 1, 0,
+  3, 0, 1, 0, 2, 0, 1, 0,
+  5, 0, 1, 0, 2, 0, 1, 0,
+  3, 0, 1, 0, 2, 0, 1, 0,
+  4, 0, 1, 0, 2, 0, 1, 0,
+  3, 0, 1, 0, 2, 0, 1, 0,
+  6, 0, 1, 0, 2, 0, 1, 0,
+  3, 0, 1, 0, 2, 0, 1, 0,
+  4, 0, 1, 0, 2, 0, 1, 0,
+  3, 0, 1, 0, 2, 0, 1, 0,
+  5, 0, 1, 0, 2, 0, 1, 0,
+  3, 0, 1, 0, 2, 0, 1, 0,
+  4, 0, 1, 0, 2, 0, 1, 0,
+  3, 0, 1, 0, 2, 0, 1, 0
+};
+
+
+int
+high_bit[256] = {
+  -1, 0, 1, 1, 2, 2, 2, 2,
+  3, 3, 3, 3, 3, 3, 3, 3,
+  4, 4, 4, 4, 4, 4, 4, 4,
+  4, 4, 4, 4, 4, 4, 4, 4,
+  5, 5, 5, 5, 5, 5, 5, 5,
+  5, 5, 5, 5, 5, 5, 5, 5,
+  5, 5, 5, 5, 5, 5, 5, 5,
+  5, 5, 5, 5, 5, 5, 5, 5,
+  6, 6, 6, 6, 6, 6, 6, 6,
+  6, 6, 6, 6, 6, 6, 6, 6,
+  6, 6, 6, 6, 6, 6, 6, 6,
+  6, 6, 6, 6, 6, 6, 6, 6,
+  6, 6, 6, 6, 6, 6, 6, 6,
+  6, 6, 6, 6, 6, 6, 6, 6,
+  6, 6, 6, 6, 6, 6, 6, 6,
+  6, 6, 6, 6, 6, 6, 6, 6,
+  7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7,
+  7, 7, 7, 7, 7, 7, 7, 7
+};
+
+int
+octet_get_weight(uint8_t octet) {
+  extern int octet_weight[256];
+
+  return octet_weight[octet];
+}  
+
+unsigned char
+v32_weight(v32_t a) {
+  unsigned int wt = 0;
+  
+  wt += octet_weight[a.v8[0]];  /* note: endian-ness makes no difference */
+  wt += octet_weight[a.v8[1]];
+  wt += octet_weight[a.v8[2]];
+  wt += octet_weight[a.v8[3]];
+  
+  return wt;
+}
+
+inline unsigned char
+v32_distance(v32_t x, v32_t y) {
+  x.value ^= y.value;
+  return v32_weight(x);
+}
+
+unsigned int
+v32_dot_product(v32_t a, v32_t b) {
+  a.value &= b.value;
+  return v32_weight(a) & 1;
+}
+
+/*
+ * _bit_string returns a NULL-terminated character string suitable for
+ * printing
+ */
+
+#define MAX_STRING_LENGTH 1024
+
+char bit_string[MAX_STRING_LENGTH];
+
+char *
+octet_bit_string(uint8_t x) {
+  int mask, index;
+
+  for (mask = 1, index = 0; mask < 256; mask <<= 1)
+    if ((x & mask) == 0)
+      bit_string[index++] = '0';
+    else
+      bit_string[index++] = '1';
+
+  bit_string[index++] = 0;  /* NULL terminate string */
+
+  return bit_string;
+}
+
+char *
+v16_bit_string(v16_t x) {
+  int i, mask, index;
+
+  for (i = index = 0; i < 2; i++) {
+    for (mask = 1; mask < 256; mask <<= 1)
+      if ((x.v8[i] & mask) == 0)
+        bit_string[index++] = '0';
+      else
+        bit_string[index++] = '1';
+  }
+  bit_string[index++] = 0;  /* NULL terminate string */
+  return bit_string;
+}
+
+char *
+v32_bit_string(v32_t x) {
+  int i, mask, index;
+
+  for (i = index = 0; i < 4; i++) {
+    for (mask = 128; mask > 0; mask >>= 1)
+      if ((x.v8[i] & mask) == 0)
+        bit_string[index++] = '0';
+      else
+        bit_string[index++] = '1';
+  }
+  bit_string[index++] = 0;  /* NULL terminate string */
+  return bit_string;
+}
+
+char *
+v64_bit_string(const v64_t *x) {
+  int i, mask, index;
+
+  for (i = index = 0; i < 8; i++) {
+    for (mask = 1; mask < 256; mask <<= 1)
+      if ((x->v8[i] & mask) == 0)
+        bit_string[index++] = '0';
+      else
+        bit_string[index++] = '1';
+  }
+  bit_string[index++] = 0;  /* NULL terminate string */
+  return bit_string;
+}
+
+char *
+v128_bit_string(v128_t *x) {
+  int j, index;
+  uint32_t mask;
+  
+  for (j=index=0; j < 4; j++) {
+    for (mask=0x80000000; mask > 0; mask >>= 1) {
+      if (x->v32[j] & mask)
+        bit_string[index] = '1';
+      else
+        bit_string[index] = '0';
+      ++index;
+    }
+  }
+  bit_string[128] = 0; /* null terminate string */
+
+  return bit_string;
+}
+
+uint8_t
+nibble_to_hex_char(uint8_t nibble) {
+  char buf[16] = {'0', '1', '2', '3', '4', '5', '6', '7',
+                  '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
+  return buf[nibble & 0xF];
+}
+
+char *
+octet_hex_string(uint8_t x) {
+
+  bit_string[0]  = nibble_to_hex_char(x >> 4);
+  bit_string[1]  = nibble_to_hex_char(x & 0xF);
+  
+  bit_string[2] = 0; /* null terminate string */
+  return bit_string;
+}
+
+char *
+octet_string_hex_string(const void *str, int length) {
+  const uint8_t *s = str;
+  int i;
+  
+  /* double length, since one octet takes two hex characters */
+  length *= 2;
+
+  /* truncate string if it would be too long */
+  if (length > MAX_STRING_LENGTH)
+    length = MAX_STRING_LENGTH-1;
+  
+  for (i=0; i < length; i+=2) {
+    bit_string[i]   = nibble_to_hex_char(*s >> 4);
+    bit_string[i+1] = nibble_to_hex_char(*s++ & 0xF);
+  }
+  bit_string[i] = 0; /* null terminate string */
+  return bit_string;
+}
+
+char *
+v16_hex_string(v16_t x) {
+  int i, j;
+
+  for (i=j=0; i < 2; i++) {
+    bit_string[j++]  = nibble_to_hex_char(x.v8[i] >> 4);
+    bit_string[j++]  = nibble_to_hex_char(x.v8[i] & 0xF);
+  }
+  
+  bit_string[j] = 0; /* null terminate string */
+  return bit_string;
+}
+
+char *
+v32_hex_string(v32_t x) {
+  int i, j;
+
+  for (i=j=0; i < 4; i++) {
+    bit_string[j++]  = nibble_to_hex_char(x.v8[i] >> 4);
+    bit_string[j++]  = nibble_to_hex_char(x.v8[i] & 0xF);
+  }
+  
+  bit_string[j] = 0; /* null terminate string */
+  return bit_string;
+}
+
+char *
+v64_hex_string(const v64_t *x) {
+  int i, j;
+
+  for (i=j=0; i < 8; i++) {
+    bit_string[j++]  = nibble_to_hex_char(x->v8[i] >> 4);
+    bit_string[j++]  = nibble_to_hex_char(x->v8[i] & 0xF);
+  }
+  
+  bit_string[j] = 0; /* null terminate string */
+  return bit_string;
+}
+
+char *
+v128_hex_string(v128_t *x) {
+  int i, j;
+
+  for (i=j=0; i < 16; i++) {
+    bit_string[j++]  = nibble_to_hex_char(x->v8[i] >> 4);
+    bit_string[j++]  = nibble_to_hex_char(x->v8[i] & 0xF);
+  }
+  
+  bit_string[j] = 0; /* null terminate string */
+  return bit_string;
+}
+
+char *
+char_to_hex_string(char *x, int num_char) {
+  int i, j;
+
+  if (num_char >= 16)
+    num_char = 16;
+  for (i=j=0; i < num_char; i++) {
+    bit_string[j++]  = nibble_to_hex_char(x[i] >> 4);
+    bit_string[j++]  = nibble_to_hex_char(x[i] & 0xF);
+  }
+  
+  bit_string[j] = 0; /* null terminate string */
+  return bit_string;
+}
+
+int
+hex_char_to_nibble(uint8_t c) {
+  switch(c) {
+  case ('0'): return 0x0;
+  case ('1'): return 0x1;
+  case ('2'): return 0x2;
+  case ('3'): return 0x3;
+  case ('4'): return 0x4;
+  case ('5'): return 0x5;
+  case ('6'): return 0x6;
+  case ('7'): return 0x7;
+  case ('8'): return 0x8;
+  case ('9'): return 0x9;
+  case ('a'): return 0xa;
+  case ('A'): return 0xa;
+  case ('b'): return 0xb;
+  case ('B'): return 0xb;
+  case ('c'): return 0xc;
+  case ('C'): return 0xc;
+  case ('d'): return 0xd;
+  case ('D'): return 0xd;
+  case ('e'): return 0xe;
+  case ('E'): return 0xe;
+  case ('f'): return 0xf;
+  case ('F'): return 0xf;
+  default: return -1;   /* this flags an error */
+  }
+  /* NOTREACHED */
+  return -1;  /* this keeps compilers from complaining */
+}
+
+int
+is_hex_string(char *s) {
+  while(*s != 0)
+    if (hex_char_to_nibble(*s++) == -1)
+      return 0;
+  return 1;
+}
+
+uint8_t
+hex_string_to_octet(char *s) {
+  uint8_t x;
+
+  x = (hex_char_to_nibble(s[0]) << 4)
+    | hex_char_to_nibble(s[1] & 0xFF);
+  
+  return x;
+}
+
+/*
+ * hex_string_to_octet_string converts a hexadecimal string
+ * of length 2 * len to a raw octet string of length len
+ */
+
+int
+hex_string_to_octet_string(char *raw, char *hex, int len) {
+  uint8_t x;
+  int tmp;
+  int hex_len;
+
+  hex_len = 0;
+  while (hex_len < len) {
+    tmp = hex_char_to_nibble(hex[0]);
+    if (tmp == -1)
+      return hex_len;
+    x = (tmp << 4);
+    hex_len++;
+    tmp = hex_char_to_nibble(hex[1]);
+    if (tmp == -1)
+      return hex_len;
+    x |= (tmp & 0xff);
+    hex_len++;
+    *raw++ = x;
+    hex += 2;
+  }
+  return hex_len;
+}
+
+v16_t
+hex_string_to_v16(char *s) {
+  v16_t x;
+  int i, j;
+
+  for (i=j=0; i < 4; i += 2, j++) {
+    x.v8[j] = (hex_char_to_nibble(s[i]) << 4)
+      | hex_char_to_nibble(s[i+1] & 0xFF);
+  }
+  return x;
+}
+
+v32_t
+hex_string_to_v32(char *s) {
+  v32_t x;
+  int i, j;
+
+  for (i=j=0; i < 8; i += 2, j++) {
+    x.v8[j] = (hex_char_to_nibble(s[i]) << 4)
+      | hex_char_to_nibble(s[i+1] & 0xFF);
+  }
+  return x;
+}
+
+v64_t
+hex_string_to_v64(char *s) {
+  v64_t x;
+  int i, j;
+
+  for (i=j=0; i < 16; i += 2, j++) {
+    x.v8[j] = (hex_char_to_nibble(s[i]) << 4)
+      | hex_char_to_nibble(s[i+1] & 0xFF);
+  }
+  return x;
+}
+
+v128_t
+hex_string_to_v128(char *s) {
+  v128_t x;
+  int i, j;
+
+  for (i=j=0; i < 32; i += 2, j++) {
+    x.v8[j] = (hex_char_to_nibble(s[i]) << 4)
+      | hex_char_to_nibble(s[i+1] & 0xFF);
+  }
+  return x;
+}
+
+
+
+/* 
+ * the matrix A[] is stored in column format, i.e., A[i] is the ith
+ * column of the matrix 
+ */
+
+uint8_t 
+A_times_x_plus_b(uint8_t A[8], uint8_t x, uint8_t b) {
+  int index = 0;
+  unsigned mask;
+  
+  for (mask=1; mask < 256; mask *= 2) {
+    if (x & mask)
+      b^= A[index];
+    ++index;
+  }
+
+  return b;
+}
+
+inline void
+v16_copy_octet_string(v16_t *x, const uint8_t s[2]) {
+  x->v8[0]  = s[0];
+  x->v8[1]  = s[1];
+}
+
+inline void
+v32_copy_octet_string(v32_t *x, const uint8_t s[4]) {
+  x->v8[0]  = s[0];
+  x->v8[1]  = s[1];
+  x->v8[2]  = s[2];
+  x->v8[3]  = s[3];
+}
+
+inline void
+v64_copy_octet_string(v64_t *x, const uint8_t s[8]) {
+  x->v8[0]  = s[0];
+  x->v8[1]  = s[1];
+  x->v8[2]  = s[2];
+  x->v8[3]  = s[3];
+  x->v8[4]  = s[4];
+  x->v8[5]  = s[5];
+  x->v8[6]  = s[6];
+  x->v8[7]  = s[7];
+}
+
+void
+v128_copy_octet_string(v128_t *x, const uint8_t s[16]) {
+  x->v8[0]  = s[0];
+  x->v8[1]  = s[1];
+  x->v8[2]  = s[2];
+  x->v8[3]  = s[3];
+  x->v8[4]  = s[4];
+  x->v8[5]  = s[5];
+  x->v8[6]  = s[6];
+  x->v8[7]  = s[7];
+  x->v8[8]  = s[8];
+  x->v8[9]  = s[9];
+  x->v8[10] = s[10];
+  x->v8[11] = s[11];
+  x->v8[12] = s[12];
+  x->v8[13] = s[13];
+  x->v8[14] = s[14];
+  x->v8[15] = s[15];
+
+}
+
+#ifndef DATATYPES_USE_MACROS /* little functions are not macros */
+
+void
+v128_set_to_zero(v128_t *x) {
+  _v128_set_to_zero(x);
+}
+
+void
+v128_copy(v128_t *x, const v128_t *y) {
+  _v128_copy(x, y);
+}
+
+void
+v128_xor(v128_t *z, v128_t *x, v128_t *y) {
+  _v128_xor(z, x, y);
+} 
+
+void
+v128_and(v128_t *z, v128_t *x, v128_t *y) {
+  _v128_and(z, x, y);
+}
+
+void
+v128_or(v128_t *z, v128_t *x, v128_t *y) {
+  _v128_or(z, x, y);
+}
+
+void
+v128_complement(v128_t *x) {
+  _v128_complement(x);
+}
+
+int
+v128_is_eq(const v128_t *x, const v128_t *y) {
+  return _v128_is_eq(x, y);
+}
+
+int
+v128_get_bit(const v128_t *x, int i) {
+  return _v128_get_bit(x, i);
+}
+
+void
+v128_set_bit(v128_t *x, int i) {
+  _v128_set_bit(x, i);
+}     
+
+void
+v128_clear_bit(v128_t *x, int i){
+  _v128_clear_bit(x, i);
+}    
+
+void
+v128_set_bit_to(v128_t *x, int i, int y){
+  _v128_set_bit_to(x, i, y);
+}
+
+
+#endif /* DATATYPES_USE_MACROS */
+
+
+inline void
+v128_left_shift2(v128_t *x, int num_bits) {
+  int i;
+  int word_shift = num_bits >> 5;
+  int bit_shift  = num_bits & 31;
+
+  for (i=0; i < (4-word_shift); i++) {
+    x->v32[i] = x->v32[i+word_shift] << bit_shift;
+  }
+  
+  for (   ; i < word_shift; i++) {
+    x->v32[i] = 0;
+  }
+  
+}
+
+void
+v128_right_shift(v128_t *x, int index) {
+  const int base_index = index >> 5;
+  const int bit_index = index & 31;
+  int i, from;
+  uint32_t b;
+    
+  if (index > 127) {
+    v128_set_to_zero(x);
+    return;
+  }
+
+  if (bit_index == 0) {
+
+    /* copy each word from left size to right side */
+    x->v32[4-1] = x->v32[4-1-base_index];
+    for (i=4-1; i > base_index; i--) 
+      x->v32[i-1] = x->v32[i-1-base_index];
+
+  } else {
+    
+    /* set each word to the "or" of the two bit-shifted words */
+    for (i = 4; i > base_index; i--) {
+      from = i-1 - base_index;
+      b = x->v32[from] << bit_index;
+      if (from > 0)
+        b |= x->v32[from-1] >> (32-bit_index);
+      x->v32[i-1] = b;
+    }
+    
+  }
+
+  /* now wrap up the final portion */
+  for (i=0; i < base_index; i++) 
+    x->v32[i] = 0;
+  
+}
+
+void
+v128_left_shift(v128_t *x, int index) {
+  int i;
+  const int base_index = index >> 5;
+  const int bit_index = index & 31;
+
+  if (index > 127) {
+    v128_set_to_zero(x);
+    return;
+  } 
+  
+  if (bit_index == 0) {
+    for (i=0; i < 4 - base_index; i++)
+      x->v32[i] = x->v32[i+base_index];
+  } else {
+    for (i=0; i < 4 - base_index - 1; i++)
+      x->v32[i] = (x->v32[i+base_index] << bit_index) ^
+        (x->v32[i+base_index+1] >> (32 - bit_index));
+    x->v32[4 - base_index-1] = x->v32[4-1] << bit_index;
+  }
+
+  /* now wrap up the final portion */
+  for (i = 4 - base_index; i < 4; i++) 
+    x->v32[i] = 0;
+
+}
+
+
+#if 0
+void
+v128_add(v128_t *z, v128_t *x, v128_t *y) {
+  /* integer addition modulo 2^128    */
+
+#ifdef WORDS_BIGENDIAN
+  uint64_t tmp;
+    
+  tmp = x->v32[3] + y->v32[3];
+  z->v32[3] = (uint32_t) tmp;
+  
+  tmp =  x->v32[2] + y->v32[2] + (tmp >> 32);
+  z->v32[2] = (uint32_t) tmp;
+
+  tmp =  x->v32[1] + y->v32[1] + (tmp >> 32);
+  z->v32[1] = (uint32_t) tmp;
+  
+  tmp =  x->v32[0] + y->v32[0] + (tmp >> 32);
+  z->v32[0] = (uint32_t) tmp;
+
+#else /* assume little endian architecture */
+  uint64_t tmp;
+  
+  tmp = htonl(x->v32[3]) + htonl(y->v32[3]);
+  z->v32[3] = ntohl((uint32_t) tmp);
+  
+  tmp =  htonl(x->v32[2]) + htonl(y->v32[2]) + htonl(tmp >> 32);
+  z->v32[2] = ntohl((uint32_t) tmp);
+
+  tmp =  htonl(x->v32[1]) + htonl(y->v32[1]) + htonl(tmp >> 32);
+  z->v32[1] = ntohl((uint32_t) tmp);
+  
+  tmp =  htonl(x->v32[0]) + htonl(y->v32[0]) + htonl(tmp >> 32);
+  z->v32[0] = ntohl((uint32_t) tmp);
+
+#endif /* WORDS_BIGENDIAN */
+  
+}
+#endif
+
+int
+octet_string_is_eq(uint8_t *a, uint8_t *b, int len) {
+  uint8_t *end = b + len;
+  while (b < end)
+    if (*a++ != *b++)
+      return 1;
+  return 0;
+}
+
+void
+octet_string_set_to_zero(uint8_t *s, int len) {
+  uint8_t *end = s + len;
+
+  do {
+    *s = 0;
+  } while (++s < end);
+  
+}
+
+
+/* functions below not yet tested! */
+
+int
+v32_low_bit(v32_t *w) {
+  int value;
+
+  value = low_bit[w->v8[0]];
+  if (value != -1)
+    return value;
+  value = low_bit[w->v8[1]];
+  if (value != -1)
+    return value + 8;
+  value = low_bit[w->v8[2]];
+  if (value != -1)
+    return value + 16;
+  value = low_bit[w->v8[3]];
+  if (value == -1)
+    return -1;
+  return value + 24;
+}
+
+/* high_bit not done yet */
+
+
+
+
+