Complex classes like Curve often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use Curve, and based on these observations, apply Extract Interface, too.
1 | <?php |
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22 | class Curve |
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23 | { |
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24 | /** |
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25 | * Elliptic curve over the field of integers modulo a prime. |
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26 | * |
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27 | * @var GMP |
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28 | */ |
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29 | private $a; |
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30 | |||
31 | /** |
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32 | * @var GMP |
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33 | */ |
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34 | private $b; |
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35 | |||
36 | /** |
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37 | * @var GMP |
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38 | */ |
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39 | private $prime; |
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40 | |||
41 | /** |
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42 | * Binary length of keys associated with these curve parameters. |
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43 | * |
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44 | * @var int |
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45 | */ |
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46 | private $size; |
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47 | |||
48 | /** |
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49 | * @var Point |
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50 | */ |
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51 | private $generator; |
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52 | |||
53 | public function __construct(int $size, GMP $prime, GMP $a, GMP $b, Point $generator) |
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54 | { |
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55 | $this->size = $size; |
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56 | $this->prime = $prime; |
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57 | $this->a = $a; |
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58 | $this->b = $b; |
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59 | $this->generator = $generator; |
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60 | } |
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61 | |||
62 | public function __toString(): string |
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63 | { |
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64 | return 'curve('.Math::toString($this->getA()).', '.Math::toString($this->getB()).', '.Math::toString($this->getPrime()).')'; |
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65 | } |
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66 | |||
67 | public function getA(): GMP |
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68 | { |
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69 | return $this->a; |
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70 | } |
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71 | |||
72 | public function getB(): GMP |
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73 | { |
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74 | return $this->b; |
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75 | } |
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76 | |||
77 | public function getPrime(): GMP |
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78 | { |
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79 | return $this->prime; |
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80 | } |
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81 | |||
82 | public function getSize(): int |
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83 | { |
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84 | return $this->size; |
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85 | } |
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86 | |||
87 | /** |
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88 | * @throws RuntimeException if the curve does not contain the point |
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89 | */ |
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90 | public function getPoint(GMP $x, GMP $y, ?GMP $order = null): Point |
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91 | { |
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92 | if (!$this->contains($x, $y)) { |
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93 | throw new RuntimeException('Curve '.$this->__toString().' does not contain point ('.Math::toString($x).', '.Math::toString($y).')'); |
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94 | } |
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95 | $point = Point::create($x, $y, $order); |
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96 | if (!\is_null($order)) { |
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97 | $mul = $this->mul($point, $order); |
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98 | if (!$mul->isInfinity()) { |
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99 | throw new RuntimeException('SELF * ORDER MUST EQUAL INFINITY.'); |
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100 | } |
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101 | } |
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102 | |||
103 | return $point; |
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104 | } |
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105 | |||
106 | /** |
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107 | * @throws RuntimeException if the coordinates are out of range |
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108 | */ |
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109 | public function getPublicKeyFrom(GMP $x, GMP $y): PublicKey |
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110 | { |
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111 | $zero = gmp_init(0, 10); |
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112 | if (Math::cmp($x, $zero) < 0 || Math::cmp($this->generator->getOrder(), $x) <= 0 || Math::cmp($y, $zero) < 0 || Math::cmp($this->generator->getOrder(), $y) <= 0) { |
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113 | throw new RuntimeException('Generator point has x and y out of range.'); |
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114 | } |
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115 | $point = $this->getPoint($x, $y); |
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116 | |||
117 | return new PublicKey($point); |
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118 | } |
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119 | |||
120 | public function contains(GMP $x, GMP $y): bool |
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121 | { |
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122 | return Math::equals( |
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123 | ModularArithmetic::sub( |
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124 | Math::pow($y, 2), |
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125 | Math::add( |
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126 | Math::add( |
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127 | Math::pow($x, 3), |
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128 | Math::mul($this->getA(), $x) |
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129 | ), |
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130 | $this->getB() |
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131 | ), |
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132 | $this->getPrime() |
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133 | ), |
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134 | gmp_init(0, 10) |
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135 | ); |
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136 | } |
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137 | |||
138 | public function add(Point $one, Point $two): Point |
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139 | { |
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140 | if ($two->isInfinity()) { |
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141 | return clone $one; |
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142 | } |
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143 | |||
144 | if ($one->isInfinity()) { |
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145 | return clone $two; |
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146 | } |
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147 | |||
148 | if (Math::equals($two->getX(), $one->getX())) { |
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149 | if (Math::equals($two->getY(), $one->getY())) { |
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150 | return $this->getDouble($one); |
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151 | } |
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152 | |||
153 | return Point::infinity(); |
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154 | } |
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155 | |||
156 | $slope = ModularArithmetic::div( |
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157 | Math::sub($two->getY(), $one->getY()), |
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158 | Math::sub($two->getX(), $one->getX()), |
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159 | $this->getPrime() |
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160 | ); |
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161 | |||
162 | $xR = ModularArithmetic::sub( |
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163 | Math::sub(Math::pow($slope, 2), $one->getX()), |
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164 | $two->getX(), |
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165 | $this->getPrime() |
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166 | ); |
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167 | |||
168 | $yR = ModularArithmetic::sub( |
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169 | Math::mul($slope, Math::sub($one->getX(), $xR)), |
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170 | $one->getY(), |
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171 | $this->getPrime() |
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172 | ); |
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173 | |||
174 | return $this->getPoint($xR, $yR, $one->getOrder()); |
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175 | } |
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176 | |||
177 | public function mul(Point $one, GMP $n): Point |
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178 | { |
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179 | if ($one->isInfinity()) { |
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180 | return Point::infinity(); |
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181 | } |
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182 | |||
183 | /** @var GMP $zero */ |
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184 | $zero = gmp_init(0, 10); |
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185 | if (Math::cmp($one->getOrder(), $zero) > 0) { |
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186 | $n = Math::mod($n, $one->getOrder()); |
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187 | } |
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188 | |||
189 | if (Math::equals($n, $zero)) { |
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190 | return Point::infinity(); |
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191 | } |
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192 | |||
193 | /** @var Point[] $r */ |
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194 | $r = [ |
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195 | Point::infinity(), |
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196 | clone $one, |
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197 | ]; |
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198 | |||
199 | $k = $this->getSize(); |
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200 | $n = str_pad(Math::baseConvert(Math::toString($n), 10, 2), $k, '0', STR_PAD_LEFT); |
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201 | |||
202 | for ($i = 0; $i < $k; ++$i) { |
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203 | $j = $n[$i]; |
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204 | Point::cswap($r[0], $r[1], $j ^ 1); |
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205 | $r[0] = $this->add($r[0], $r[1]); |
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206 | $r[1] = $this->getDouble($r[1]); |
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207 | Point::cswap($r[0], $r[1], $j ^ 1); |
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208 | } |
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209 | |||
210 | $this->validate($r[0]); |
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211 | |||
212 | return $r[0]; |
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213 | } |
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214 | |||
215 | /** |
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216 | * @param Curve $other |
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217 | */ |
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218 | public function cmp(self $other): int |
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219 | { |
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220 | $equal = Math::equals($this->getA(), $other->getA()) && |
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221 | Math::equals($this->getB(), $other->getB()) && |
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222 | Math::equals($this->getPrime(), $other->getPrime()); |
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223 | |||
224 | return $equal ? 0 : 1; |
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225 | } |
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226 | |||
227 | /** |
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228 | * @param Curve $other |
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229 | */ |
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230 | public function equals(self $other): bool |
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231 | { |
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232 | return 0 === $this->cmp($other); |
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233 | } |
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234 | |||
235 | public function getDouble(Point $point): Point |
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264 | |||
265 | public function createPrivateKey(): PrivateKey |
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269 | |||
270 | public function createPublicKey(PrivateKey $privateKey): PublicKey |
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276 | |||
277 | public function getGenerator(): Point |
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278 | { |
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279 | return $this->generator; |
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280 | } |
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281 | |||
282 | /** |
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283 | * @throws RuntimeException if the point is invalid |
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284 | */ |
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285 | private function validate(Point $point): void |
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286 | { |
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287 | if (!$point->isInfinity() && !$this->contains($point->getX(), $point->getY())) { |
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288 | throw new RuntimeException('Invalid point'); |
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289 | } |
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290 | } |
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291 | |||
292 | private function generate(): GMP |
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304 | |||
305 | /** |
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306 | * Returns the number of bits used to store this number. Non-significant upper bits are not counted. |
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307 | * |
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308 | * @see https://www.openssl.org/docs/crypto/BN_num_bytes.html |
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309 | */ |
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310 | private function bnNumBits(GMP $x): int |
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324 | } |
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325 |
It seems like the type of the argument is not accepted by the function/method which you are calling.
In some cases, in particular if PHP’s automatic type-juggling kicks in this might be fine. In other cases, however this might be a bug.
We suggest to add an explicit type cast like in the following example: