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BigInteger: put guardrails on isPrime() and randomPrime()

This commit is contained in:
terrafrost 2024-02-23 08:57:22 -06:00
parent d430fb9d8d
commit ad5dbdf212
1 changed files with 40 additions and 1 deletions
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41
phpseclib/Math/BigInteger.php
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@ -749,6 +749,33 @@ class Math_BigInteger
return $result;
}
/**
* Return the size of a BigInteger in bits
*
* @return int
*/
function getLength()
{
if (MATH_BIGINTEGER_MODE != MATH_BIGINTEGER_MODE_INTERNAL) {
return strlen($this->toBits());
}
$max = count($this->value) - 1;
return $max != -1 ?
$max * MATH_BIGINTEGER_BASE + ceil(log($a->value[$max] + 1, 2)) :
0;
}
/**
* Return the size of a BigInteger in bytes
*
* @return int
*/
function getLengthInBytes()
{
return ceil($this->getLength() / 8);
}
/**
* Copy an object
*
@ -3286,6 +3313,11 @@ class Math_BigInteger
$min = $temp;
}
$length = $max->getLength();
if ($length > 8196) {
user_error('Generation of random prime numbers larger than 8196 has been disabled');
}
static $one, $two;
if (!isset($one)) {
$one = new Math_BigInteger(1);
@ -3393,7 +3425,14 @@ class Math_BigInteger
*/
function isPrime($t = false)
{
$length = strlen($this->toBytes());
$length = $this->getLength();
// OpenSSL limits RSA keys to 16384 bits. The length of an RSA key is equal to the length of the modulo, which is
// produced by multiplying the primes p and q by one another. The largest number two 8196 bit primes can produce is
// a 16384 bit number so, basically, 8196 bit primes are the largest OpenSSL will generate and if that's the largest
// that it'll generate it also stands to reason that that's the largest you'll be able to test primality on
if ($length > 8196) {
user_error('Primality testing is not supported for numbers larger than 8196 bits');
}
if (!$t) {
// see HAC 4.49 "Note (controlling the error probability)"