1 | |
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2 | /**************************************************************************\ |
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3 | |
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4 | MODULE: ZZ |
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5 | |
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6 | SUMMARY: |
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7 | |
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8 | The class ZZ is used to represent signed, arbitrary length integers. |
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9 | |
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10 | Routines are provided for all of the basic arithmetic operations, as |
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11 | well as for some more advanced operations such as primality testing. |
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12 | Space is automatically managed by the constructors and destructors. |
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13 | |
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14 | This module also provides routines for generating small primes, and |
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15 | fast routines for performing modular arithmetic on single-precision |
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16 | numbers. |
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17 | |
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18 | |
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19 | \**************************************************************************/ |
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20 | |
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21 | #include <NTL/tools.h> |
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22 | |
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23 | |
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24 | class ZZ { |
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25 | public: |
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26 | |
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27 | ZZ(); // initial value is 0 |
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28 | |
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29 | ZZ& operator=(const ZZ& a); // assignment operator |
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30 | ZZ& operator=(long a); |
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31 | |
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32 | ZZ(const ZZ& a); // copy constructor |
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33 | ~ZZ(); // destructor |
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34 | |
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35 | |
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36 | // ... |
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37 | |
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38 | }; |
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39 | |
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40 | |
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41 | // NOTE: A ZZ is represented as a sequence of "zzigits", |
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42 | // where each zzigit is between 0 and 2^{NTL_ZZ_NBITS-1}. |
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43 | |
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44 | // NTL_ZZ_NBITS is macros defined in <NTL/ZZ.h>. |
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45 | |
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46 | // SIZE INVARIANT: the number of bits in a ZZ is always less than |
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47 | // 2^(NTL_BITS_PER_LONG-4). |
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48 | |
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49 | |
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50 | |
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51 | /**************************************************************************\ |
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52 | |
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53 | Comparison |
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54 | |
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55 | \**************************************************************************/ |
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56 | |
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57 | |
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58 | |
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59 | // The usual comparison operators: |
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60 | |
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61 | long operator==(const ZZ& a, const ZZ& b); |
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62 | long operator!=(const ZZ& a, const ZZ& b); |
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63 | long operator<(const ZZ& a, const ZZ& b); |
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64 | long operator>(const ZZ& a, const ZZ& b); |
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65 | long operator<=(const ZZ& a, const ZZ& b); |
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66 | long operator>=(const ZZ& a, const ZZ& b); |
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67 | |
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68 | // other stuff: |
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69 | |
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70 | long sign(const ZZ& a); // returns sign of a (-1, 0, +1) |
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71 | long IsZero(const ZZ& a); // test for 0 |
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72 | long IsOne(const ZZ& a); // test for 1 |
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73 | |
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74 | long compare(const ZZ& a, const ZZ& b); // returns sign of a-b (-1, 0, or 1). |
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75 | |
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76 | // PROMOTIONS: the comparison operators and the function compare |
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77 | // support promotion from long to ZZ on (a, b). |
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78 | |
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79 | |
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80 | /**************************************************************************\ |
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81 | |
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82 | Addition |
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83 | |
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84 | \**************************************************************************/ |
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85 | |
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86 | |
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87 | // operator notation: |
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88 | |
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89 | ZZ operator+(const ZZ& a, const ZZ& b); |
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90 | ZZ operator-(const ZZ& a, const ZZ& b); |
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91 | ZZ operator-(const ZZ& a); // unary - |
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92 | |
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93 | ZZ& operator+=(ZZ& x, const ZZ& a); |
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94 | ZZ& operator+=(ZZ& x, long a); |
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95 | |
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96 | ZZ& operator-=(ZZ& x, const ZZ& a); |
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97 | ZZ& operator-=(ZZ& x, long a); |
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98 | |
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99 | ZZ& operator++(ZZ& x); // prefix |
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100 | void operator++(ZZ& x, int); // postfix |
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101 | |
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102 | ZZ& operator--(ZZ& x); // prefix |
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103 | void operator--(ZZ& x, int); // postfix |
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104 | |
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105 | |
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106 | |
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107 | // procedural versions: |
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108 | |
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109 | void add(ZZ& x, const ZZ& a, const ZZ& b); // x = a + b |
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110 | void sub(ZZ& x, const ZZ& a, const ZZ& b); // x = a - b |
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111 | void SubPos(ZZ& x, const ZZ& a, const ZZ& b); // x = a-b; assumes a >= b >= 0. |
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112 | void negate(ZZ& x, const ZZ& a); // x = -a |
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113 | |
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114 | void abs(ZZ& x, const ZZ& a); // x = |a| |
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115 | ZZ abs(const ZZ& a); |
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116 | |
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117 | // PROMOTIONS: binary +, -, as well as the procedural versions add, sub |
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118 | // support promotions from long to ZZ on (a, b). |
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119 | |
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120 | |
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121 | /**************************************************************************\ |
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122 | |
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123 | Multiplication |
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124 | |
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125 | \**************************************************************************/ |
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126 | |
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127 | // operator notation: |
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128 | |
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129 | ZZ operator*(const ZZ& a, const ZZ& b); |
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130 | |
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131 | ZZ& operator*=(ZZ& x, const ZZ& a); |
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132 | ZZ& operator*=(ZZ& x, long a); |
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133 | |
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134 | // procedural versions: |
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135 | |
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136 | void mul(ZZ& x, const ZZ& a, const ZZ& b); // x = a * b |
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137 | |
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138 | void sqr(ZZ& x, const ZZ& a); // x = a*a |
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139 | ZZ sqr(const ZZ& a); |
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140 | |
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141 | // PROMOTIONS: operator * and procedure mul support promotion |
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142 | // from long to ZZ on (a, b). |
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143 | |
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144 | |
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145 | /**************************************************************************\ |
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146 | |
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147 | Division |
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148 | |
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149 | \**************************************************************************/ |
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150 | |
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151 | |
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152 | // operator notation: |
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153 | |
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154 | ZZ operator/(const ZZ& a, const ZZ& b); |
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155 | ZZ operator/(const ZZ& a, long b); |
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156 | |
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157 | ZZ operator%(const ZZ& a, const ZZ& b); |
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158 | long operator%(const ZZ& a, long b); |
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159 | |
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160 | ZZ& operator/=(ZZ& x, const ZZ& b); |
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161 | ZZ& operator/=(ZZ& x, long b); |
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162 | |
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163 | ZZ& operator%=(ZZ& x, const ZZ& b); |
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164 | |
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165 | |
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166 | // procedural versions: |
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167 | |
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168 | void DivRem(ZZ& q, ZZ& r, const ZZ& a, const ZZ& b); |
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169 | // q = floor(a/b), r = a - b*q. |
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170 | // This implies that: |
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171 | // |r| < |b|, and if r != 0, sign(r) = sign(b) |
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172 | |
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173 | void div(ZZ& q, const ZZ& a, const ZZ& b); |
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174 | // q = floor(a/b) |
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175 | |
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176 | void rem(ZZ& r, const ZZ& a, const ZZ& b); |
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177 | // q = floor(a/b), r = a - b*q |
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178 | |
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179 | |
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180 | // single-precision variants: |
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181 | |
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182 | long DivRem(ZZ& q, const ZZ& a, long b); |
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183 | // q = floor(a/b), r = a - b*q, return value is r. |
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184 | |
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185 | long rem(const ZZ& a, long b); |
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186 | // q = floor(a/b), r = a - b*q, return value is r. |
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187 | |
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188 | |
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189 | // divisibility testing: |
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190 | |
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191 | long divide(ZZ& q, const ZZ& a, const ZZ& b); |
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192 | long divide(ZZ& q, const ZZ& a, long b); |
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193 | // if b | a, sets q = a/b and returns 1; otherwise returns 0. |
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194 | |
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195 | long divide(const ZZ& a, const ZZ& b); |
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196 | long divide(const ZZ& a, long b); |
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197 | // if b | a, returns 1; otherwise returns 0. |
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198 | |
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199 | |
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200 | /**************************************************************************\ |
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201 | |
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202 | GCD's |
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203 | |
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204 | \**************************************************************************/ |
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205 | |
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206 | |
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207 | void GCD(ZZ& d, const ZZ& a, const ZZ& b); |
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208 | ZZ GCD(const ZZ& a, const ZZ& b); |
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209 | |
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210 | // d = gcd(a, b) (which is always non-negative). Uses a binary GCD |
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211 | // algorithm. |
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212 | |
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213 | |
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214 | |
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215 | void XGCD(ZZ& d, ZZ& s, ZZ& t, const ZZ& a, const ZZ& b); |
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216 | |
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217 | // d = gcd(a, b) = a*s + b*t. |
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218 | |
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219 | // The coefficients s and t are defined according to the standard |
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220 | // Euclidean algorithm applied to |a| and |b|, with the signs then |
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221 | // adjusted according to the signs of a and b. |
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222 | |
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223 | // The implementation may or may not Euclid's algorithm, |
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224 | // but the coefficients a and t are always computed as if |
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225 | // it did. |
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226 | |
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227 | |
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228 | // special-purpose single-precision variants: |
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229 | |
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230 | long GCD(long a, long b); |
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231 | // return value is gcd(a, b) (which is always non-negative) |
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232 | |
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233 | void XGCD(long& d, long& s, long& t, long a, long b); |
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234 | // d = gcd(a, b) = a*s + b*t. |
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235 | |
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236 | // The coefficients s and t are defined according to the standard |
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237 | // Euclidean algorithm applied to |a| and |b|, with the signs then |
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238 | // adjusted according to the signs of a and b. |
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239 | |
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240 | |
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241 | |
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242 | /**************************************************************************\ |
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243 | |
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244 | Modular Arithmetic |
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245 | |
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246 | The following routines perform arithmetic mod n, where n > 1. |
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247 | |
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248 | All arguments (other than exponents) are assumed to be in the range |
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249 | 0..n-1. Some routines may check this and raise an error if this |
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250 | does not hold. Others may not, and the behaviour is unpredictable |
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251 | in this case. |
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252 | |
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253 | \**************************************************************************/ |
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254 | |
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255 | |
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256 | |
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257 | void AddMod(ZZ& x, const ZZ& a, const ZZ& b, const ZZ& n); // x = (a+b)%n |
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258 | ZZ AddMod(const ZZ& a, const ZZ& b, const ZZ& n); |
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259 | |
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260 | void SubMod(ZZ& x, const ZZ& a, const ZZ& b, const ZZ& n); // x = (a-b)%n |
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261 | ZZ SubMod(const ZZ& a, const ZZ& b, const ZZ& n); |
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262 | |
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263 | void NegateMod(ZZ& x, const ZZ& a, const ZZ& n); // x = -a % n |
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264 | ZZ NegateMod(const ZZ& a, const ZZ& n); |
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265 | |
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266 | void MulMod(ZZ& x, const ZZ& a, const ZZ& b, const ZZ& n); // x = (a*b)%n |
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267 | ZZ MulMod(const ZZ& a, const ZZ& b, const ZZ& n); |
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268 | |
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269 | void SqrMod(ZZ& x, const ZZ& a, const ZZ& n); // x = a^2 % n |
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270 | ZZ SqrMod(const ZZ& a, const ZZ& n); |
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271 | |
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272 | void InvMod(ZZ& x, const ZZ& a, const ZZ& n); |
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273 | ZZ InvMod(const ZZ& a, const ZZ& n); |
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274 | // x = a^{-1} mod n (0 <= x < n); error is raised occurs if inverse |
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275 | // not defined |
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276 | |
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277 | long InvModStatus(ZZ& x, const ZZ& a, const ZZ& n); |
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278 | // if gcd(a,b) = 1, then return-value = 0, x = a^{-1} mod n; |
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279 | // otherwise, return-value = 1, x = gcd(a, n) |
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280 | |
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281 | void PowerMod(ZZ& x, const ZZ& a, const ZZ& e, const ZZ& n); |
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282 | ZZ PowerMod(const ZZ& a, const ZZ& e, const ZZ& n); |
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283 | |
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284 | void PowerMod(ZZ& x, const ZZ& a, long e, const ZZ& n); |
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285 | ZZ PowerMod(const ZZ& a, long e, const ZZ& n); |
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286 | |
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287 | // x = a^e % n (e may be negative) |
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288 | |
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289 | |
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290 | // PROMOTIONS: AddMod, SubMod, and MulMod (both procedural and functional |
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291 | // forms) support promotions from long to ZZ on (a, b). |
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292 | |
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293 | |
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294 | /**************************************************************************\ |
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295 | |
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296 | Single-precision modular arithmetic |
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297 | |
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298 | These routines implement single-precision modular arithmetic. If n is |
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299 | the modulus, all inputs should be in the range 0..n-1. The number n |
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300 | itself should be in the range 2..NTL_SP_BOUND-1. |
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301 | |
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302 | Most of these routines are, of course, implemented as fast inline |
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303 | functions. No checking is done that inputs are in range. |
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304 | |
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305 | \**************************************************************************/ |
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306 | |
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307 | |
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308 | |
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309 | |
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310 | long AddMod(long a, long b, long n); // return (a+b)%n |
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311 | |
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312 | long SubMod(long a, long b, long n); // return (a-b)%n |
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313 | |
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314 | long NegateMod(long a, long n); // return (-a)%n |
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315 | |
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316 | long MulMod(long a, long b, long n); // return (a*b)%n |
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317 | |
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318 | long MulMod(long a, long b, long n, double ninv); |
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319 | // return (a*b)%n. ninv = 1/((double) n). This is faster if n is |
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320 | // fixed for many multiplications. |
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321 | |
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322 | |
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323 | long MulMod2(long a, long b, long n, double bninv); |
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324 | // return (a*b)%n. bninv = ((double) b)/((double) n). This is faster |
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325 | // if both n and b are fixed for many multiplications. |
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326 | // Note: This is OBSOLETE -- use MulModPrecon (see below) for |
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327 | // better performance. |
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328 | |
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329 | |
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330 | long MulDivRem(long& q, long a, long b, long n, double bninv); |
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331 | // return (a*b)%n, set q = (a*b)/n. bninv = ((double) b)/((double) n) |
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332 | |
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333 | long InvMod(long a, long n); |
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334 | // computes a^{-1} mod n. Error is raised if undefined. |
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335 | |
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336 | long PowerMod(long a, long e, long n); |
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337 | // computes a^e mod n (e may be negative) |
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338 | |
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339 | |
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340 | |
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341 | // The following are variants of MulMod2 above that may be significantly |
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342 | // faster on certain machines. The implmentation varies depending |
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343 | // on the settings of the flags NTL_SPMM_ULL and NTL_SPMM_UL. |
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344 | // By default (no flags), the implementation is the same as MulMod2 above. |
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345 | // It is best to let the Wizard script select the optimal flag. |
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346 | |
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347 | typedef mulmod_precon_t /* depends on implementation */ ; |
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348 | |
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349 | mulmod_precon_t PrepMulModPrecon(long b, long n, double ninv); |
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350 | // Prepares preconditioning. ninv = 1/((double) n) |
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351 | |
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352 | long MulModPrecon(long a, long b, long n, mulmod_precon_t bninv); |
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353 | // return (a*b)%n. bninv = MulModPrecon(b, n, ninv). |
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354 | |
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355 | // Example of use: |
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356 | // long a, b, n, c; |
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357 | // ... |
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358 | // double ninv = 1/((double) n); |
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359 | // mulmod_precon_t bninv = PrepMulModPrecon(b, n, ninv); |
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360 | // ... |
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361 | // c = MulModPrecon(a, b, n, bninv); // c = (a*b) % n |
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362 | |
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363 | |
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364 | |
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365 | |
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366 | |
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367 | |
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368 | /**************************************************************************\ |
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369 | |
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370 | Shift Operations |
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371 | |
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372 | LeftShift by n means multiplication by 2^n |
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373 | RightShift by n means division by 2^n, with truncation toward zero |
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374 | (so the sign is preserved). |
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375 | |
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376 | A negative shift amount reverses the direction of the shift. |
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377 | |
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378 | \**************************************************************************/ |
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379 | |
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380 | // operator notation: |
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381 | |
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382 | ZZ operator<<(const ZZ& a, long n); |
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383 | ZZ operator>>(const ZZ& a, long n); |
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384 | |
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385 | ZZ& operator<<=(ZZ& x, long n); |
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386 | ZZ& operator>>=(ZZ& x, long n); |
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387 | |
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388 | // procedural versions: |
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389 | |
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390 | void LeftShift(ZZ& x, const ZZ& a, long n); |
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391 | ZZ LeftShift(const ZZ& a, long n); |
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392 | |
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393 | void RightShift(ZZ& x, const ZZ& a, long n); |
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394 | ZZ RightShift(const ZZ& a, long n); |
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395 | |
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396 | |
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397 | |
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398 | /**************************************************************************\ |
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399 | |
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400 | Bits and Bytes |
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401 | |
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402 | \**************************************************************************/ |
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403 | |
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404 | |
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405 | |
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406 | long MakeOdd(ZZ& x); |
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407 | // removes factors of 2 from x, returns the number of 2's removed |
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408 | // returns 0 if x == 0 |
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409 | |
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410 | long NumTwos(const ZZ& x); |
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411 | // returns max e such that 2^e divides x if x != 0, and returns 0 if x == 0. |
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412 | |
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413 | long IsOdd(const ZZ& a); // test if a is odd |
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414 | |
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415 | long NumBits(const ZZ& a); |
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416 | long NumBits(long a); |
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417 | // returns the number of bits in binary represenation of |a|; |
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418 | // NumBits(0) = 0 |
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419 | |
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420 | |
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421 | long bit(const ZZ& a, long k); |
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422 | long bit(long a, long k); |
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423 | // returns bit k of |a|, position 0 being the low-order bit. |
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424 | // If k < 0 or k >= NumBits(a), returns 0. |
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425 | |
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426 | |
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427 | void trunc(ZZ& x, const ZZ& a, long k); |
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428 | // x = low order k bits of |a|. |
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429 | // If k <= 0, x = 0. |
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430 | |
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431 | // two functional variants: |
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432 | ZZ trunc_ZZ(const ZZ& a, long k); |
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433 | long trunc_long(const ZZ& a, long k); |
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434 | |
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435 | long SetBit(ZZ& x, long p); |
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436 | // returns original value of p-th bit of |a|, and replaces p-th bit of |
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437 | // a by 1 if it was zero; low order bit is bit 0; error if p < 0; |
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438 | // the sign of x is maintained |
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439 | |
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440 | long SwitchBit(ZZ& x, long p); |
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441 | // returns original value of p-th bit of |a|, and switches the value |
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442 | // of p-th bit of a; low order bit is bit 0; error if p < 0 |
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443 | // the sign of x is maintained |
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444 | |
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445 | long weight(const ZZ& a); // returns Hamming weight of |a| |
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446 | long weight(long a); |
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447 | |
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448 | // bit-wise Boolean operations, procedural form: |
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449 | |
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450 | void bit_and(ZZ& x, const ZZ& a, const ZZ& b); // x = |a| AND |b| |
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451 | void bit_or(ZZ& x, const ZZ& a, const ZZ& b); // x = |a| OR |b| |
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452 | void bit_xor(ZZ& x, const ZZ& a, const ZZ& b); // x = |a| XOR |b| |
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453 | |
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454 | // bit-wise Boolean operations, operator notation: |
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455 | |
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456 | ZZ operator&(const ZZ& a, const ZZ& b); |
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457 | ZZ operator|(const ZZ& a, const ZZ& b); |
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458 | ZZ operator^(const ZZ& a, const ZZ& b); |
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459 | |
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460 | // PROMOTIONS: the above bit-wise operations (both procedural |
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461 | // and operator forms) provide promotions from long to ZZ on (a, b). |
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462 | |
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463 | ZZ& operator&=(ZZ& x, const ZZ& b); |
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464 | ZZ& operator&=(ZZ& x, long b); |
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465 | |
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466 | ZZ& operator|=(ZZ& x, const ZZ& b); |
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467 | ZZ& operator|=(ZZ& x, long b); |
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468 | |
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469 | ZZ& operator^=(ZZ& x, const ZZ& b); |
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470 | ZZ& operator^=(ZZ& x, long b); |
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471 | |
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472 | |
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473 | |
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474 | // conversions between byte sequences and ZZ's |
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475 | |
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476 | void ZZFromBytes(ZZ& x, const unsigned char *p, long n); |
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477 | ZZ ZZFromBytes(const unsigned char *p, long n); |
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478 | // x = sum(p[i]*256^i, i=0..n-1). |
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479 | // NOTE: in the unusual event that a char is more than 8 bits, |
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480 | // only the low order 8 bits of p[i] are used |
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481 | |
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482 | void BytesFromZZ(unsigned char *p, const ZZ& a, long n); |
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483 | // Computes p[0..n-1] such that abs(a) == sum(p[i]*256^i, i=0..n-1) mod 256^n. |
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484 | |
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485 | long NumBytes(const ZZ& a); |
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486 | long NumBytes(long a); |
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487 | // returns # of base 256 digits needed to represent abs(a). |
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488 | // NumBytes(0) == 0. |
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489 | |
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490 | |
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491 | |
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492 | /**************************************************************************\ |
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493 | |
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494 | Pseudo-Random Numbers |
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495 | |
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496 | \**************************************************************************/ |
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497 | |
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498 | |
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499 | // Routines for generating pseudo-random numbers. |
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500 | |
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501 | // These routines generate high qualtity, cryptographically strong |
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502 | // pseudo-random numbers. They are implemented so that their behaviour |
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503 | // is completely independent of the underlying hardware and long |
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504 | // integer implementation. Note, however, that other routines |
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505 | // throughout NTL use pseudo-random numbers, and because of this, |
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506 | // the word size of the machine can impact the sequence of numbers |
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507 | // seen by a client program. |
---|
508 | |
---|
509 | |
---|
510 | void SetSeed(const ZZ& s); |
---|
511 | // Initializes generator with a "seed" s. |
---|
512 | // s is first hashed to generate the initial state, so it is |
---|
513 | // not necessary that s itself looks random, just that |
---|
514 | // it has a lot of "entropy". |
---|
515 | // If SetSeed is not called before using the routines below, |
---|
516 | // a default initial state is used. |
---|
517 | // Calling SetSeed with s == 0, e.g. SetSeed(ZZ::zero()), |
---|
518 | // has the effect of re-setting the state to the default initial state. |
---|
519 | // Routine ZZFromBytes (above) may be useful. |
---|
520 | |
---|
521 | |
---|
522 | void RandomBnd(ZZ& x, const ZZ& n); |
---|
523 | ZZ RandomBnd(const ZZ& n); |
---|
524 | long RandomBnd(long n); |
---|
525 | // x = pseudo-random number in the range 0..n-1, or 0 if n <= 0 |
---|
526 | |
---|
527 | void RandomBits(ZZ& x, long l); |
---|
528 | ZZ RandomBits_ZZ(long l); |
---|
529 | long RandomBits_long(long l); |
---|
530 | // x = pseudo-random number in the range 0..2^l-1. |
---|
531 | |
---|
532 | void RandomLen(ZZ& x, long l); |
---|
533 | ZZ RandomLen_ZZ(long l); |
---|
534 | long RandomLen_long(long l); |
---|
535 | // x = psuedo-random number with precisely l bits, |
---|
536 | // or 0 of l <= 0. |
---|
537 | |
---|
538 | unsigned long RandomBits_ulong(long l); |
---|
539 | // returns a pseudo-random number in the range 0..2^l-1 |
---|
540 | |
---|
541 | unsigned long RandomWord(); |
---|
542 | // returns a word filled with pseudo-random bits. |
---|
543 | // Equivalent to RandomBits_ulong(NTL_BITS_PER_LONG). |
---|
544 | |
---|
545 | |
---|
546 | /**************************************************************************\ |
---|
547 | |
---|
548 | Incremental Chinese Remaindering |
---|
549 | |
---|
550 | \**************************************************************************/ |
---|
551 | |
---|
552 | long CRT(ZZ& a, ZZ& p, const ZZ& A, const ZZ& P); |
---|
553 | long CRT(ZZ& a, ZZ& p, long A, long P); |
---|
554 | |
---|
555 | // 0 <= A < P, (p, P) = 1; computes a' such that a' = a mod p, |
---|
556 | // a' = A mod P, and -p*P/2 < a' <= p*P/2; sets a := a', p := p*P, and |
---|
557 | // returns 1 if a's value has changed, otherwise 0 |
---|
558 | |
---|
559 | |
---|
560 | /**************************************************************************\ |
---|
561 | |
---|
562 | Rational Reconstruction |
---|
563 | |
---|
564 | \**************************************************************************/ |
---|
565 | |
---|
566 | long ReconstructRational(ZZ& a, ZZ& b, const ZZ& x, const ZZ& m, |
---|
567 | const ZZ& a_bound, const ZZ& b_bound); |
---|
568 | |
---|
569 | // 0 <= x < m, m > 2 * a_bound * b_bound, |
---|
570 | // a_bound >= 0, b_bound > 0 |
---|
571 | |
---|
572 | // This routine either returns 0, leaving a and b unchanged, |
---|
573 | // or returns 1 and sets a and b so that |
---|
574 | // (1) a = b x (mod m), |
---|
575 | // (2) |a| <= a_bound, 0 < b <= b_bound, and |
---|
576 | // (3) gcd(m, b) = gcd(a, b). |
---|
577 | |
---|
578 | // If there exist a, b satisfying (1), (2), and |
---|
579 | // (3') gcd(m, b) = 1, |
---|
580 | // then a, b are uniquely determined if we impose the additional |
---|
581 | // condition that gcd(a, b) = 1; moreover, if such a, b exist, |
---|
582 | // then these values are returned by the routine. |
---|
583 | |
---|
584 | // Unless the calling routine can *a priori* guarantee the existence |
---|
585 | // of a, b satisfying (1), (2), and (3'), |
---|
586 | // then to ensure correctness, the calling routine should check |
---|
587 | // that gcd(m, b) = 1, or equivalently, gcd(a, b) = 1. |
---|
588 | |
---|
589 | // This is implemented using a variant of Lehmer's extended |
---|
590 | // Euclidean algorithm. |
---|
591 | |
---|
592 | // Literature: see G. Collins and M. Encarnacion, J. Symb. Comp. 20:287-297, |
---|
593 | // 1995; P. Wang, M. Guy, and J. Davenport, SIGSAM Bulletin 16:2-3, 1982. |
---|
594 | |
---|
595 | |
---|
596 | /**************************************************************************\ |
---|
597 | |
---|
598 | Primality Testing |
---|
599 | and Prime Number Generation |
---|
600 | |
---|
601 | \**************************************************************************/ |
---|
602 | |
---|
603 | void GenPrime(ZZ& n, long l, long err = 80); |
---|
604 | ZZ GenPrime_ZZ(long l, long err = 80); |
---|
605 | long GenPrime_long(long l, long err = 80); |
---|
606 | |
---|
607 | // GenPrime generates a random prime n of length l so that the |
---|
608 | // probability that the resulting n is composite is bounded by 2^(-err). |
---|
609 | // This calls the routine RandomPrime below, and uses results of |
---|
610 | // Damgard, Landrock, Pomerance to "optimize" |
---|
611 | // the number of Miller-Rabin trials at the end. |
---|
612 | |
---|
613 | void GenGermainPrime(ZZ& n, long l, long err = 80); |
---|
614 | ZZ GenGermainPrime_ZZ(long l, long err = 80); |
---|
615 | long GenGermainPrime_long(long l, long err = 80); |
---|
616 | |
---|
617 | // A (Sophie) Germain prime is a prime p such that p' = 2*p+1 is also a prime. |
---|
618 | // Such primes are useful for cryptographic applications...cryptographers |
---|
619 | // sometimes call p' a "strong" or "safe" prime. |
---|
620 | // GenGermainPrime generates a random Germain prime n of length l |
---|
621 | // so that the probability that either n or 2*n+1 is not a prime |
---|
622 | // is bounded by 2^(-err). |
---|
623 | |
---|
624 | |
---|
625 | long ProbPrime(const ZZ& n, long NumTrials = 10); |
---|
626 | long ProbPrime(long n, long NumTrials = 10); |
---|
627 | // performs up to NumTrials Miller-witness tests (after some trial division). |
---|
628 | |
---|
629 | void RandomPrime(ZZ& n, long l, long NumTrials=10); |
---|
630 | ZZ RandomPrime_ZZ(long l, long NumTrials=10); |
---|
631 | long RandomPrime_long(long l, long NumTrials=10); |
---|
632 | // n = random l-bit prime. Uses ProbPrime with NumTrials. |
---|
633 | |
---|
634 | void NextPrime(ZZ& n, const ZZ& m, long NumTrials=10); |
---|
635 | ZZ NextPrime(const ZZ& m, long NumTrials=10); |
---|
636 | // n = smallest prime >= m. Uses ProbPrime with NumTrials. |
---|
637 | |
---|
638 | long NextPrime(long m, long NumTrials=10); |
---|
639 | // Single precision version of the above. |
---|
640 | // Result will always be bounded by NTL_ZZ_SP_BOUND, and an |
---|
641 | // error is raised if this cannot be satisfied. |
---|
642 | |
---|
643 | long MillerWitness(const ZZ& n, const ZZ& w); |
---|
644 | // Tests if w is a witness to compositeness a la Miller. Assumption: n is |
---|
645 | // odd and positive, 0 <= w < n. |
---|
646 | // Return value of 1 implies n is composite. |
---|
647 | // Return value of 0 indicates n might be prime. |
---|
648 | |
---|
649 | |
---|
650 | /**************************************************************************\ |
---|
651 | |
---|
652 | Exponentiation |
---|
653 | |
---|
654 | \**************************************************************************/ |
---|
655 | |
---|
656 | |
---|
657 | void power(ZZ& x, const ZZ& a, long e); // x = a^e (e >= 0) |
---|
658 | ZZ power(const ZZ& a, long e); |
---|
659 | |
---|
660 | void power(ZZ& x, long a, long e); |
---|
661 | |
---|
662 | // two functional variants: |
---|
663 | ZZ power_ZZ(long a, long e); |
---|
664 | long power_long(long a, long e); |
---|
665 | |
---|
666 | void power2(ZZ& x, long e); // x = 2^e (e >= 0) |
---|
667 | ZZ power2_ZZ(long e); |
---|
668 | |
---|
669 | |
---|
670 | /**************************************************************************\ |
---|
671 | |
---|
672 | Square Roots |
---|
673 | |
---|
674 | \**************************************************************************/ |
---|
675 | |
---|
676 | |
---|
677 | void SqrRoot(ZZ& x, const ZZ& a); // x = floor(a^{1/2}) (a >= 0) |
---|
678 | ZZ SqrRoot(const ZZ& a); |
---|
679 | |
---|
680 | long SqrRoot(long a); |
---|
681 | |
---|
682 | |
---|
683 | |
---|
684 | |
---|
685 | /**************************************************************************\ |
---|
686 | |
---|
687 | Jacobi symbol and modular square roots |
---|
688 | |
---|
689 | \**************************************************************************/ |
---|
690 | |
---|
691 | |
---|
692 | long Jacobi(const ZZ& a, const ZZ& n); |
---|
693 | // compute Jacobi symbol of a and n; assumes 0 <= a < n, n odd |
---|
694 | |
---|
695 | void SqrRootMod(ZZ& x, const ZZ& a, const ZZ& n); |
---|
696 | ZZ SqrRootMod(const ZZ& a, const ZZ& n); |
---|
697 | // computes square root of a mod n; assumes n is an odd prime, and |
---|
698 | // that a is a square mod n, with 0 <= a < n. |
---|
699 | |
---|
700 | |
---|
701 | |
---|
702 | |
---|
703 | /**************************************************************************\ |
---|
704 | |
---|
705 | Input/Output |
---|
706 | |
---|
707 | I/O Format: |
---|
708 | |
---|
709 | Numbers are written in base 10, with an optional minus sign. |
---|
710 | |
---|
711 | \**************************************************************************/ |
---|
712 | |
---|
713 | istream& operator>>(istream& s, ZZ& x); |
---|
714 | ostream& operator<<(ostream& s, const ZZ& a); |
---|
715 | |
---|
716 | |
---|
717 | |
---|
718 | /**************************************************************************\ |
---|
719 | |
---|
720 | Miscellany |
---|
721 | |
---|
722 | \**************************************************************************/ |
---|
723 | |
---|
724 | |
---|
725 | // The following macros are defined: |
---|
726 | |
---|
727 | #define NTL_ZZ_NBITS (...) // number of bits in a zzigit; |
---|
728 | // a ZZ is represented as a sequence of zzigits. |
---|
729 | |
---|
730 | #define NTL_SP_NBITS (...) // max number of bits in a "single-precision" number |
---|
731 | |
---|
732 | #define NTL_WSP_NBITS (...) // max number of bits in a "wide single-precision" |
---|
733 | // number |
---|
734 | |
---|
735 | // The following relations hold: |
---|
736 | // NTL_SP_NBITS <= NTL_WSP_NBITS <= NTL_ZZ_NBITS |
---|
737 | // 26 <= NTL_SP_NBITS <= min(NTL_BITS_PER_LONG-2, NTL_DOUBLE_PRECISION-3) |
---|
738 | // NTL_WSP_NBITS <= NTL_BITS_PER_LONG-2 |
---|
739 | // |
---|
740 | // Note that NTL_ZZ_NBITS may be less than, equal to, or greater than |
---|
741 | // NTL_BITS_PER_LONG -- no particular relationship should be assumed to hold. |
---|
742 | // In particular, expressions like (1L << NTL_ZZ_BITS) might overflow. |
---|
743 | // |
---|
744 | // "single-precision" numbers are meant to be used in conjunction with the |
---|
745 | // single-precision modular arithmetic routines. |
---|
746 | // |
---|
747 | // "wide single-precision" numbers are meant to be used in conjunction |
---|
748 | // with the ZZ arithmetic routines for optimal efficiency. |
---|
749 | |
---|
750 | // The following auxilliary macros are also defined |
---|
751 | |
---|
752 | #define NTL_FRADIX (...) // double-precision value of 2^NTL_ZZ_NBITS |
---|
753 | |
---|
754 | #define NTL_SP_BOUND (1L << NTL_SP_NBITS) |
---|
755 | #define NTL_WSP_BOUND (1L << NTL_WSP_NBITS) |
---|
756 | |
---|
757 | |
---|
758 | // Backward compatability note: |
---|
759 | // Prior to version 5.0, the macro NTL_NBITS was defined, |
---|
760 | // along with the macro NTL_RADIX defined to be (1L << NTL_NBITS). |
---|
761 | // While these macros are still available when using NTL's traditional |
---|
762 | // long integer package (i.e., when NTL_GMP_LIP is not set), |
---|
763 | // they are not available when using the GMP as the primary long integer |
---|
764 | // package (i.e., when NTL_GMP_LIP is set). |
---|
765 | // Furthermore, when writing portable programs, one should avoid these macros. |
---|
766 | // Note that when using traditional long integer arithmetic, we have |
---|
767 | // NTL_ZZ_NBITS = NTL_SP_NBITS = NTL_WSP_NBITS = NTL_NBITS. |
---|
768 | |
---|
769 | |
---|
770 | // Here are some additional functions. |
---|
771 | |
---|
772 | void clear(ZZ& x); // x = 0 |
---|
773 | void set(ZZ& x); // x = 1 |
---|
774 | |
---|
775 | void swap(ZZ& x, ZZ& y); |
---|
776 | // swap x and y (done by "pointer swapping", if possible). |
---|
777 | |
---|
778 | double log(const ZZ& a); |
---|
779 | // returns double precision approximation to log(a) |
---|
780 | |
---|
781 | long NextPowerOfTwo(long m); |
---|
782 | // returns least nonnegative k such that 2^k >= m |
---|
783 | |
---|
784 | long ZZ::size() const; |
---|
785 | // a.size() returns the number of zzigits of |a|; the |
---|
786 | // size of 0 is 0. |
---|
787 | |
---|
788 | void ZZ::SetSize(long k) |
---|
789 | // a.SetSize(k) does not change the value of a, but simply pre-allocates |
---|
790 | // space for k zzigits. |
---|
791 | |
---|
792 | long ZZ::SinglePrecision() const; |
---|
793 | // a.SinglePrecision() is a predicate that tests if abs(a) < NTL_SP_BOUND |
---|
794 | |
---|
795 | long ZZ::WideSinglePrecision() const; |
---|
796 | // a.WideSinglePrecision() is a predicate that tests if abs(a) < NTL_WSP_BOUND |
---|
797 | |
---|
798 | long digit(const ZZ& a, long k); |
---|
799 | // returns k-th zzigit of |a|, position 0 being the low-order |
---|
800 | // zzigit. |
---|
801 | // NOTE: this routine is only available when using NTL's traditional |
---|
802 | // long integer arithmetic, and should not be used in programs |
---|
803 | // that are meant to be portable. |
---|
804 | |
---|
805 | void ZZ::kill(); |
---|
806 | // a.kill() sets a to zero and frees the space held by a. |
---|
807 | |
---|
808 | ZZ::ZZ(INIT_SIZE_TYPE, long k); |
---|
809 | // ZZ(INIT_SIZE, k) initializes to 0, but space is pre-allocated so |
---|
810 | // that numbers x with x.size() <= k can be stored without |
---|
811 | // re-allocation. |
---|
812 | |
---|
813 | static const ZZ& ZZ::zero(); |
---|
814 | // ZZ::zero() yields a read-only reference to zero, if you need it. |
---|
815 | |
---|
816 | |
---|
817 | |
---|
818 | |
---|
819 | /**************************************************************************\ |
---|
820 | |
---|
821 | Small Prime Generation |
---|
822 | |
---|
823 | primes are generated in sequence, starting at 2, and up to a maximum |
---|
824 | that is no more than min(NTL_SP_BOUND, 2^30). |
---|
825 | |
---|
826 | Example: print the primes up to 1000 |
---|
827 | |
---|
828 | #include <NTL/ZZ.h> |
---|
829 | |
---|
830 | main() |
---|
831 | { |
---|
832 | PrimeSeq s; |
---|
833 | long p; |
---|
834 | |
---|
835 | p = s.next(); |
---|
836 | while (p <= 1000) { |
---|
837 | cout << p << "\n"; |
---|
838 | p = s.next(); |
---|
839 | } |
---|
840 | } |
---|
841 | |
---|
842 | \**************************************************************************/ |
---|
843 | |
---|
844 | |
---|
845 | |
---|
846 | class PrimeSeq { |
---|
847 | public: |
---|
848 | PrimeSeq(); |
---|
849 | ~PrimeSeq(); |
---|
850 | |
---|
851 | long next(); |
---|
852 | // returns next prime in the sequence. returns 0 if list of small |
---|
853 | // primes is exhausted. |
---|
854 | |
---|
855 | void reset(long b); |
---|
856 | // resets generator so that the next prime in the sequence is the |
---|
857 | // smallest prime >= b. |
---|
858 | |
---|
859 | private: |
---|
860 | PrimeSeq(const PrimeSeq&); // disabled |
---|
861 | void operator=(const PrimeSeq&); // disabled |
---|
862 | |
---|
863 | }; |
---|
864 | |
---|
865 | |
---|