package Math::Prime::Util::RandomPrimes; use strict; use warnings; use Carp qw/carp croak confess/; use Math::Prime::Util qw/ prime_get_config verify_prime is_provable_prime_with_cert primorial prime_count nth_prime is_prob_prime is_strong_pseudoprime next_prime prev_prime urandomb urandomm random_bytes /; BEGIN { $Math::Prime::Util::RandomPrimes::AUTHORITY = 'cpan:DANAJ'; $Math::Prime::Util::RandomPrimes::VERSION = '0.73'; } BEGIN { do { require Math::BigInt; Math::BigInt->import(try=>"GMP,Pari"); } unless defined $Math::BigInt::VERSION; use constant OLD_PERL_VERSION=> $] < 5.008; use constant MPU_MAXBITS => (~0 == 4294967295) ? 32 : 64; use constant MPU_64BIT => MPU_MAXBITS == 64; use constant MPU_32BIT => MPU_MAXBITS == 32; use constant MPU_MAXPARAM => MPU_32BIT ? 4294967295 : 18446744073709551615; use constant MPU_MAXDIGITS => MPU_32BIT ? 10 : 20; use constant MPU_USE_XS => prime_get_config->{'xs'}; use constant MPU_USE_GMP => prime_get_config->{'gmp'}; *_bigint_to_int = \&Math::Prime::Util::_bigint_to_int; } ################################################################################ # These are much faster than straightforward trial division when n is big. # You'll want to first do a test up to and including 23. my @_big_gcd; my $_big_gcd_top = 20046; my $_big_gcd_use = -1; sub _make_big_gcds { return if $_big_gcd_use >= 0; if (prime_get_config->{'gmp'}) { $_big_gcd_use = 0; return; } if (Math::BigInt->config()->{lib} !~ /^Math::BigInt::(GMP|Pari)/) { $_big_gcd_use = 0; return; } $_big_gcd_use = 1; my $p0 = primorial(Math::BigInt->new( 520)); my $p1 = primorial(Math::BigInt->new(2052)); my $p2 = primorial(Math::BigInt->new(6028)); my $p3 = primorial(Math::BigInt->new($_big_gcd_top)); $_big_gcd[0] = $p0->bdiv(223092870)->bfloor->as_int; $_big_gcd[1] = $p1->bdiv($p0)->bfloor->as_int; $_big_gcd[2] = $p2->bdiv($p1)->bfloor->as_int; $_big_gcd[3] = $p3->bdiv($p2)->bfloor->as_int; } ################################################################################ ################################################################################ # For random primes, there are two good papers that should be examined: # # "Fast Generation of Prime Numbers and Secure Public-Key # Cryptographic Parameters" by Ueli M. Maurer, 1995 # http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.26.2151 # related discussions: # http://www.daimi.au.dk/~ivan/provableprimesproject.pdf # Handbook of Applied Cryptography by Menezes, et al. # # "Close to Uniform Prime Number Generation With Fewer Random Bits" # by Pierre-Alain Fouque and Mehdi Tibouchi, 2011 # http://eprint.iacr.org/2011/481 # # Some things to note: # # 1) Joye and Paillier have patents on their methods. Never use them. # # 2) The easy method of next_prime(random number), known as PRIMEINC, is # fast but gives a terrible distribution. It has a positive bias and # most importantly the probability for a prime is proportional to its # gap, meaning some numbers in the range will be thousands of times # more likely than others). On the contrary however, nobody has a way # to exploit this, and it's not-uncommon to see used. # # We use: # TRIVIAL range within native integer size (2^32 or 2^64) # FTA1 random_nbit_prime with 65+ bits # INVA1 other ranges with 65+ bit range # where # TRIVIAL = monte-carlo method or equivalent, perfect uniformity. # FTA1 = Fouque/Tibouchi A1, very close to uniform # INVA1 = inverted FTA1, less uniform but works with arbitrary ranges # # The random_maurer_prime function uses Maurer's FastPrime algorithm. # # If Math::Prime::Util::GMP is installed, these functions will be many times # faster than other methods (e.g. Math::Pari monte-carlo or Crypt::Primes). # # Timings on Macbook. # The "with GMP" numbers use Math::Prime::Util::GMP 0.44. # The "no GMP" numbers are with no Math::BigInt backend, so very slow in comparison. # If another backend was used (GMP, Pari, LTM) it would be more comparable. # # random_nbit_prime random_maurer_prime # n-bits no GMP w/ MPU::GMP no GMP w/ MPU::GMP # ---------- -------- ----------- -------- ----------- # 24-bit 1uS same same same # 64-bit 5uS same same same # 128-bit 0.12s 70uS 0.29s 166uS # 256-bit 0.66s 379uS 1.82s 800uS # 512-bit 7.8s 0.0022s 16.2s 0.0044s # 1024-bit ---- 0.019s ---- 0.037s # 2048-bit ---- 0.23s ---- 0.35s # 4096-bit ---- 2.4s ---- 5.2s # # Random timings for 10M calls on i4770K: # 0.39 Math::Random::MTwist 0.13 # 0.41 ntheory <==== us # 0.89 system rand # 1.76 Math::Random::MT::Auto # 5.35 Bytes::Random::Secure OO w/ISAAC::XS # 7.43 Math::Random::Secure w/ISAAC::XS # 12.40 Math::Random::Secure # 12.78 Bytes::Random::Secure OO # 13.86 Bytes::Random::Secure function w/ISAAC::XS # 21.95 Bytes::Random::Secure function # 822.1 Crypt::Random # # time perl -E 'use Math::Random::MTwist "irand32"; irand32() for 1..10000000;' # time perl -E 'sub irand {int(rand(4294967296));} irand() for 1..10000000;' # time perl -E 'use Math::Random::MT::Auto; sub irand { Math::Random::MT::Auto::irand() & 0xFFFFFFFF } irand() for 1..10000000;' # time perl -E 'use Math::Random::Secure qw/irand/; irand() for 1..10000000;' # time perl -E 'use Bytes::Random::Secure qw/random_bytes/; sub irand {return unpack("L",random_bytes(4));} irand() for 1..10000000;' # time perl -E 'use Bytes::Random::Secure; my $rng = Bytes::Random::Secure->new(); sub irand {return $rng->irand;} irand() for 1..10000000;' # time perl -E 'use Crypt::Random qw/makerandom/; sub irand {makerandom(Size=>32, Uniform=>1, Strength=>0)} irand() for 1..100_000;' # > haveged daemon running to stop /dev/random blocking # > Both BRS and CR have more features that this isn't measuring. # # To verify distribution: # perl -Iblib/lib -Iblib/arch -MMath::Prime::Util=:all -E 'my %freq; $n=1000000; $freq{random_nbit_prime(6)}++ for (1..$n); printf("%4d %6.3f%%\n", $_, 100.0*$freq{$_}/$n) for sort {$a<=>$b} keys %freq;' # perl -Iblib/lib -Iblib/arch -MMath::Prime::Util=:all -E 'my %freq; $n=1000000; $freq{random_prime(1260437,1260733)}++ for (1..$n); printf("%4d %6.3f%%\n", $_, 100.0*$freq{$_}/$n) for sort {$a<=>$b} keys %freq;' # Sub to call with low and high already primes and verified range. my $_random_prime = sub { my($low,$high) = @_; my $prime; #{ my $bsize = 100; my @bins; my $counts = 10000000; # for my $c (1..$counts) { $bins[ $_IRANDF->($bsize-1) ]++; } # for my $b (0..$bsize) {printf("%4d %8.5f%%\n", $b, $bins[$b]/$counts);} } # low and high are both odds, and low < high. # This is fast for small values, low memory, perfectly uniform, and # consumes the minimum amount of randomness needed. But it isn't feasible # with large values. Also note that low must be a prime. if ($high <= 262144 && MPU_USE_XS) { my $li = prime_count(2, $low); my $irange = prime_count($low, $high); my $rand = urandomm($irange); return nth_prime($li + $rand); } $low-- if $low == 2; # Low of 2 becomes 1 for our program. # Math::BigInt::GMP's RT 71548 will wreak havoc if we don't do this. $low = Math::BigInt->new("$low") if ref($high) eq 'Math::BigInt'; confess "Invalid _random_prime parameters: $low, $high" if ($low % 2) == 0 || ($high % 2) == 0; # We're going to look at the odd numbers only. my $oddrange = (($high - $low) >> 1) + 1; croak "Large random primes not supported on old Perl" if OLD_PERL_VERSION && MPU_64BIT && $oddrange > 4294967295; # If $low is large (e.g. >10 digits) and $range is small (say ~10k), it # would be fastest to call primes in the range and randomly pick one. I'm # not implementing it now because it seems like a rare case. # If the range is reasonably small, generate using simple Monte Carlo # method (aka the 'trivial' method). Completely uniform. if ($oddrange < MPU_MAXPARAM) { my $loop_limit = 2000 * 1000; # To protect against broken rand if ($low > 11) { while ($loop_limit-- > 0) { $prime = $low + 2 * urandomm($oddrange); next if !($prime % 3) || !($prime % 5) || !($prime % 7) || !($prime % 11); return $prime if is_prob_prime($prime); } } else { while ($loop_limit-- > 0) { $prime = $low + 2 * urandomm($oddrange); next if $prime > 11 && (!($prime % 3) || !($prime % 5) || !($prime % 7) || !($prime % 11)); return 2 if $prime == 1; # Remember the special case for 2. return $prime if is_prob_prime($prime); } } croak "Random function broken?"; } # We have an ocean of range, and a teaspoon to hold randomness. # Since we have an arbitrary range and not a power of two, I don't see how # Fouque's algorithm A1 could be used (where we generate lower bits and # generate random sets of upper). Similarly trying to simply generate # upper bits is full of ways to trip up and get non-uniform results. # # What I'm doing here is: # # 1) divide the range into semi-evenly sized partitions, where each part # is as close to $rand_max_val as we can. # 2) randomly select one of the partitions. # 3) iterate choosing random values within the partition. # # The downside is that we're skewing a _lot_ farther from uniformity than # we'd like. Imagine we started at 0 with 1e18 partitions of size 100k # each. # Probability of '5' being returned = # 1.04e-22 = 1e-18 (chose first partition) * 1/9592 (chose '5') # Probability of '100003' being returned = # 1.19e-22 = 1e-18 (chose second partition) * 1/8392 (chose '100003') # Probability of '99999999999999999999977' being returned = # 5.20e-22 = 1e-18 (chose last partition) * 1/1922 (chose '99...77') # So the primes in the last partition will show up 5x more often. # The partitions are selected uniformly, and the primes within are selected # uniformly, but the number of primes in each bucket is _not_ uniform. # Their individual probability of being selected is the probability of the # partition (uniform) times the probability of being selected inside the # partition (uniform with respect to all other primes in the same # partition, but each partition is different and skewed). # # Partitions are typically much larger than 100k, but with a huge range # we still see this (e.g. ~3x from 0-10^30, ~10x from 0-10^100). # # When selecting n-bit or n-digit primes, this effect is MUCH smaller, as # the skew becomes approx lg(2^n) / lg(2^(n-1)) which is pretty close to 1. # # # Another idea I'd like to try sometime is: # pclo = prime_count_lower(low); # pchi = prime_count_upper(high); # do { # $nth = random selection between pclo and pchi # $prguess = nth_prime_approx($nth); # } while ($prguess >= low) && ($prguess <= high); # monte carlo select a prime in $prguess-2**24 to $prguess+2**24 # which accounts for the prime distribution. my($binsize, $nparts); my $rand_part_size = 1 << (MPU_64BIT ? 32 : 31); if (ref($oddrange) eq 'Math::BigInt') { # Go to some trouble here because some systems are wonky, such as # giving us +a/+b = -r. Also note the quotes for the bigint argument. # Without that, Math::BigInt::GMP can return garbage. my($nbins, $rem); ($nbins, $rem) = $oddrange->copy->bdiv( "$rand_part_size" ); $nbins++ if $rem > 0; $nbins = $nbins->as_int(); ($binsize,$rem) = $oddrange->copy->bdiv($nbins); $binsize++ if $rem > 0; $binsize = $binsize->as_int(); $nparts = $oddrange->copy->bdiv($binsize)->as_int(); $low = $high->copy->bzero->badd($low) if ref($low) ne 'Math::BigInt'; } else { my $nbins = int($oddrange / $rand_part_size); $nbins++ if $nbins * $rand_part_size != $oddrange; $binsize = int($oddrange / $nbins); $binsize++ if $binsize * $nbins != $oddrange; $nparts = int($oddrange/$binsize); } $nparts-- if ($nparts * $binsize) == $oddrange; my $rpart = urandomm($nparts+1); my $primelow = $low + 2 * $binsize * $rpart; my $partsize = ($rpart < $nparts) ? $binsize : $oddrange - ($nparts * $binsize); $partsize = _bigint_to_int($partsize) if ref($partsize) eq 'Math::BigInt'; #warn "range $oddrange = $nparts * $binsize + ", $oddrange - ($nparts * $binsize), "\n"; #warn " chose part $rpart size $partsize\n"; #warn " primelow is $low + 2 * $binsize * $rpart = $primelow\n"; #die "Result could be too large" if ($primelow + 2*($partsize-1)) > $high; # Generate random numbers in the interval until one is prime. my $loop_limit = 2000 * 1000; # To protect against broken rand # Simply things for non-bigints. if (ref($low) ne 'Math::BigInt') { while ($loop_limit-- > 0) { my $rand = urandomm($partsize); $prime = $primelow + $rand + $rand; croak "random prime failure, $prime > $high" if $prime > $high; if ($prime <= 23) { $prime = 2 if $prime == 1; # special case for low = 2 next unless (0,0,1,1,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,1,0,0,0,1)[$prime]; return $prime; } next if !($prime % 3) || !($prime % 5) || !($prime % 7) || !($prime % 11); # It looks promising. Check it. next unless is_prob_prime($prime); return $prime; } croak "Random function broken?"; } # By checking a wheel 30 mod, we can skip anything that would be a multiple # of 2, 3, or 5, without even having to create the bigint prime. my @w30 = (1,0,5,4,3,2,1,0,3,2,1,0,1,0,3,2,1,0,1,0,3,2,1,0,5,4,3,2,1,0); my $primelow30 = $primelow % 30; $primelow30 = _bigint_to_int($primelow30) if ref($primelow30) eq 'Math::BigInt'; # Big GCD's are hugely fast with GMP or Pari, but super slow with Calc. _make_big_gcds() if $_big_gcd_use < 0; while ($loop_limit-- > 0) { my $rand = urandomm($partsize); # Check wheel-30 mod my $rand30 = $rand % 30; next if $w30[($primelow30 + 2*$rand30) % 30] && ($rand > 3 || $primelow > 5); # Construct prime $prime = $primelow + $rand + $rand; croak "random prime failure, $prime > $high" if $prime > $high; if ($prime <= 23) { $prime = 2 if $prime == 1; # special case for low = 2 next unless (0,0,1,1,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,1,0,0,0,1)[$prime]; return $prime; } # With GMP, the fastest thing to do is check primality. if (MPU_USE_GMP) { next unless Math::Prime::Util::GMP::is_prime($prime); return $prime; } # No MPU:GMP, so primality checking is slow. Skip some composites here. next unless Math::BigInt::bgcd($prime, 7436429) == 1; if ($_big_gcd_use && $prime > $_big_gcd_top) { next unless Math::BigInt::bgcd($prime, $_big_gcd[0]) == 1; next unless Math::BigInt::bgcd($prime, $_big_gcd[1]) == 1; next unless Math::BigInt::bgcd($prime, $_big_gcd[2]) == 1; next unless Math::BigInt::bgcd($prime, $_big_gcd[3]) == 1; } # It looks promising. Check it. next unless is_prob_prime($prime); return $prime; } croak "Random function broken?"; }; # Cache of tight bounds for each digit. Helps performance a lot. my @_random_ndigit_ranges = (undef, [2,7], [11,97] ); my @_random_nbit_ranges = (undef, undef, [2,3],[5,7] ); my %_random_cache_small; # For fixed small ranges with XS, e.g. 6-digit, 18-bit sub _random_xscount_prime { my($low,$high) = @_; my($istart, $irange); my $cachearef = $_random_cache_small{$low,$high}; if (defined $cachearef) { ($istart, $irange) = @$cachearef; } else { my $beg = ($low <= 2) ? 2 : next_prime($low-1); my $end = ($high < ~0) ? prev_prime($high + 1) : prev_prime($high); ($istart, $irange) = ( prime_count(2, $beg), prime_count($beg, $end) ); $_random_cache_small{$low,$high} = [$istart, $irange]; } my $rand = urandomm($irange); return nth_prime($istart + $rand); } sub random_prime { my($low,$high) = @_; return if $high < 2 || $low > $high; if ($high-$low > 1000000000) { # Range is large, just make them odd if needed. $low = 2 if $low < 2; $low++ if $low > 2 && ($low % 2) == 0; $high-- if ($high % 2) == 0; } else { # Tighten the range to the nearest prime. $low = ($low <= 2) ? 2 : next_prime($low-1); $high = ($high == ~0) ? prev_prime($high) : prev_prime($high + 1); return $low if ($low == $high) && is_prob_prime($low); return if $low >= $high; # At this point low and high are both primes, and low < high. } # At this point low and high are both primes, and low < high. return $_random_prime->($low, $high); } sub random_ndigit_prime { my($digits) = @_; croak "random_ndigit_prime, digits must be >= 1" unless $digits >= 1; return _random_xscount_prime( int(10 ** ($digits-1)), int(10 ** $digits) ) if $digits <= 6 && MPU_USE_XS; my $bigdigits = $digits >= MPU_MAXDIGITS; if ($bigdigits && prime_get_config->{'nobigint'}) { croak "random_ndigit_prime with -nobigint, digits out of range" if $digits > MPU_MAXDIGITS; # Special case for nobigint and threshold digits if (!defined $_random_ndigit_ranges[$digits]) { my $low = int(10 ** ($digits-1)); my $high = ~0; $_random_ndigit_ranges[$digits] = [next_prime($low),prev_prime($high)]; } } if (!defined $_random_ndigit_ranges[$digits]) { if ($bigdigits) { my $low = Math::BigInt->new('10')->bpow($digits-1); my $high = Math::BigInt->new('10')->bpow($digits); # Just pull the range in to the nearest odd. $_random_ndigit_ranges[$digits] = [$low+1, $high-1]; } else { my $low = int(10 ** ($digits-1)); my $high = int(10 ** $digits); # Note: Perl 5.6.2 cannot represent 10**15 as an integer, so things # will crash all over the place if you try. We can stringify it, but # will just fail tests later. $_random_ndigit_ranges[$digits] = [next_prime($low),prev_prime($high)]; } } my ($low, $high) = @{$_random_ndigit_ranges[$digits]}; return $_random_prime->($low, $high); } my @_random_nbit_m; my @_random_nbit_lambda; my @_random_nbit_arange; sub random_nbit_prime { my($bits) = @_; croak "random_nbit_prime, bits must be >= 2" unless $bits >= 2; $bits = int("$bits"); # Very small size, use the nth-prime method if ($bits <= 20 && MPU_USE_XS) { if ($bits <= 4) { return (2,3)[urandomb(1)] if $bits == 2; return (5,7)[urandomb(1)] if $bits == 3; return (11,13)[urandomb(1)] if $bits == 4; } return _random_xscount_prime( 1 << ($bits-1), 1 << $bits ); } croak "Mid-size random primes not supported on broken old Perl" if OLD_PERL_VERSION && MPU_64BIT && $bits > 49 && $bits <= 64; # Fouque and Tibouchi (2011) Algorithm 1 (basic) # Modified to make sure the nth bit is always set. # # Example for random_nbit_prime(512) on 64-bit Perl: # p: 1aaaaaaaabbbbbbbbbbbbbbbbbbbb1 # ^^ ^ ^--- Trailing 1 so p is odd # || +--- 512-63-2 = 447 lower bits selected before loop # |+--- 63 upper bits selected in loop, repeated until p is prime # +--- upper bit is 1 so we generate an n-bit prime # total: 1 + 63 + 447 + 1 = 512 bits # # Algorithm 2 is implemented in a previous commit on github. The problem # is that it doesn't set the nth bit, and making that change requires a # modification of the algorithm. It was not a lot faster than this A1 # with the native int trial division. If the irandf function was very # slow, then A2 would look more promising. # if (1 && $bits > 64) { my $l = (MPU_64BIT && $bits > 79) ? 63 : 31; $l = 49 if $l == 63 && OLD_PERL_VERSION; # Fix for broken Perl 5.6 $l = $bits-2 if $bits-2 < $l; my $brand = urandomb($bits-$l-2); $brand = Math::BigInt->new("$brand") unless ref($brand) eq 'Math::BigInt'; my $b = $brand->blsft(1)->binc(); # Precalculate some modulii so we can do trial division on native int # 9699690 = 2*3*5*7*11*13*17*19, so later operations can be native ints my @premod; my $bpremod = _bigint_to_int($b->copy->bmod(9699690)); my $twopremod = _bigint_to_int(Math::BigInt->new(2)->bmodpow($bits-$l-1, 9699690)); foreach my $zi (0 .. 19-1) { foreach my $pm (3, 5, 7, 11, 13, 17, 19) { next if $zi >= $pm || defined $premod[$pm]; $premod[$pm] = $zi if ( ($twopremod*$zi+$bpremod) % $pm) == 0; } } _make_big_gcds() if $_big_gcd_use < 0; if (!MPU_USE_GMP) { require Math::Prime::Util::PP; } my $loop_limit = 1_000_000; while ($loop_limit-- > 0) { my $a = (1 << $l) + urandomb($l); # $a % s == $premod[s] => $p % s == 0 => p will be composite next if $a % 3 == $premod[ 3] || $a % 5 == $premod[ 5] || $a % 7 == $premod[ 7] || $a % 11 == $premod[11] || $a % 13 == $premod[13] || $a % 17 == $premod[17] || $a % 19 == $premod[19]; my $p = Math::BigInt->new("$a")->blsft($bits-$l-1)->badd($b); #die " $a $b $p" if $a % 11 == $premod[11] && $p % 11 != 0; #die "!$a $b $p" if $a % 11 != $premod[11] && $p % 11 == 0; if (MPU_USE_GMP) { next unless Math::Prime::Util::GMP::is_prime($p); } else { next unless Math::BigInt::bgcd($p, 1348781387) == 1; # 23-43 if ($_big_gcd_use && $p > $_big_gcd_top) { next unless Math::BigInt::bgcd($p, $_big_gcd[0]) == 1; next unless Math::BigInt::bgcd($p, $_big_gcd[1]) == 1; next unless Math::BigInt::bgcd($p, $_big_gcd[2]) == 1; next unless Math::BigInt::bgcd($p, $_big_gcd[3]) == 1; } # We know we don't have GMP and are > 2^64, so go directly to this. next unless Math::Prime::Util::PP::is_bpsw_prime($p); } return $p; } croak "Random function broken?"; } # The Trivial method. Great uniformity, and fine for small sizes. It # gets very slow as the bit size increases, but that is why we have the # method above for bigints. if (1) { my $loop_limit = 2_000_000; if ($bits > MPU_MAXBITS) { my $p = Math::BigInt->bone->blsft($bits-1)->binc(); while ($loop_limit-- > 0) { my $n = Math::BigInt->new(''.urandomb($bits-2))->blsft(1)->badd($p); return $n if is_prob_prime($n); } } else { my $p = (1 << ($bits-1)) + 1; while ($loop_limit-- > 0) { my $n = $p + (urandomb($bits-2) << 1); return $n if is_prob_prime($n); } } croak "Random function broken?"; } else { # Send through the generic random_prime function. Decently fast, but # quite a bit slower than the F&T A1 method above. if (!defined $_random_nbit_ranges[$bits]) { if ($bits > MPU_MAXBITS) { my $low = Math::BigInt->new('2')->bpow($bits-1); my $high = Math::BigInt->new('2')->bpow($bits); # Don't pull the range in to primes, just odds $_random_nbit_ranges[$bits] = [$low+1, $high-1]; } else { my $low = 1 << ($bits-1); my $high = ($bits == MPU_MAXBITS) ? ~0-1 : ~0 >> (MPU_MAXBITS - $bits); $_random_nbit_ranges[$bits] = [next_prime($low-1),prev_prime($high+1)]; # Example: bits = 7. # low = 1<<6 = 64. next_prime(64-1) = 67 # high = ~0 >> (64-7) = 127. prev_prime(127+1) = 127 } } my ($low, $high) = @{$_random_nbit_ranges[$bits]}; return $_random_prime->($low, $high); } } # For stripping off the header on certificates so they can be combined. sub _strip_proof_header { my $proof = shift; $proof =~ s/^\[MPU - Primality Certificate\]\nVersion \S+\n+Proof for:\nN (\d+)\n+//ms; return $proof; } sub random_maurer_prime { my $k = shift; croak "random_maurer_prime, bits must be >= 2" unless $k >= 2; $k = int("$k"); return random_nbit_prime($k) if $k <= MPU_MAXBITS && !OLD_PERL_VERSION; my ($n, $cert) = random_maurer_prime_with_cert($k); croak "maurer prime $n failed certificate verification!" unless verify_prime($cert); return $n; } sub random_maurer_prime_with_cert { my $k = shift; croak "random_maurer_prime, bits must be >= 2" unless $k >= 2; $k = int("$k"); # This should never happen. Trap now to prevent infinite loop. croak "number of bits must not be a bigint" if ref($k) eq 'Math::BigInt'; # Results for random_nbit_prime are proven for all native bit sizes. my $p0 = MPU_MAXBITS; $p0 = 49 if OLD_PERL_VERSION && MPU_MAXBITS > 49; if ($k <= $p0) { my $n = random_nbit_prime($k); my ($isp, $cert) = is_provable_prime_with_cert($n); croak "small nbit prime could not be proven" if $isp != 2; return ($n, $cert); } # Set verbose to 3 to get pretty output like Crypt::Primes my $verbose = prime_get_config->{'verbose'}; local $| = 1 if $verbose > 2; do { require Math::BigFloat; Math::BigFloat->import(); } if !defined $Math::BigFloat::VERSION; # Ignore Maurer's g and c that controls how much trial division is done. my $r = Math::BigFloat->new("0.5"); # relative size of the prime q my $m = 20; # makes sure R is big enough # Generate a random prime q of size $r*$k, where $r >= 0.5. Try to # cleverly select r to match the size of a typical random factor. if ($k > 2*$m) { do { my $s = Math::Prime::Util::drand(); $r = Math::BigFloat->new(2)->bpow($s-1); } while ($k*$r >= $k-$m); } # I've seen +0, +1, and +2 here. Maurer uses +0. Menezes uses +1. # We can use +1 because we're using BLS75 theorem 3 later. my $smallk = int(($r * $k)->bfloor->bstr) + 1; my ($q, $qcert) = random_maurer_prime_with_cert($smallk); $q = Math::BigInt->new("$q") unless ref($q) eq 'Math::BigInt'; my $I = Math::BigInt->new(2)->bpow($k-2)->bdiv($q)->bfloor->as_int(); print "r = $r k = $k q = $q I = $I\n" if $verbose && $verbose != 3; $qcert = ($q < Math::BigInt->new("18446744073709551615")) ? "" : _strip_proof_header($qcert); # Big GCD's are hugely fast with GMP or Pari, but super slow with Calc. _make_big_gcds() if $_big_gcd_use < 0; my $ONE = Math::BigInt->bone; my $TWO = $ONE->copy->binc; my $loop_limit = 1_000_000 + $k * 1_000; while ($loop_limit-- > 0) { # R is a random number between $I+1 and 2*$I #my $R = $I + 1 + urandomm( $I ); my $R = $I->copy->binc->badd( urandomm($I) ); #my $n = 2 * $R * $q + 1; my $nm1 = $TWO->copy->bmul($R)->bmul($q); my $n = $nm1->copy->binc; # We constructed a promising looking $n. Now test it. print "." if $verbose > 2; if (MPU_USE_GMP) { # MPU::GMP::is_prob_prime has fast tests built in. next unless Math::Prime::Util::GMP::is_prob_prime($n); } else { # No GMP, so first do trial divisions, then a SPSP test. next unless Math::BigInt::bgcd($n, 111546435)->is_one; if ($_big_gcd_use && $n > $_big_gcd_top) { next unless Math::BigInt::bgcd($n, $_big_gcd[0])->is_one; next unless Math::BigInt::bgcd($n, $_big_gcd[1])->is_one; next unless Math::BigInt::bgcd($n, $_big_gcd[2])->is_one; next unless Math::BigInt::bgcd($n, $_big_gcd[3])->is_one; } print "+" if $verbose > 2; next unless is_strong_pseudoprime($n, 3); } print "*" if $verbose > 2; # We could pick a random generator by doing: # Step 1: pick a random r # Step 2: compute g = r^((n-1)/q) mod p # Step 3: if g == 1, goto Step 1. # Note that n = 2*R*q+1, hence the exponent is 2*R. # We could set r = 0.3333 earlier, then use BLS75 theorem 5 here. # The chain would be shorter, requiring less overall work for # large inputs. Maurer's paper discusses the idea. # Use BLS75 theorem 3. This is easier and possibly faster than # BLS75 theorem 4 (Pocklington) used by Maurer's paper. # Check conditions -- these should be redundant. my $m = $TWO * $R; if (! ($q->is_odd && $q > 2 && $m > 0 && $m * $q + $ONE == $n && $TWO*$q+$ONE > $n->copy->bsqrt()) ) { carp "Maurer prime failed BLS75 theorem 3 conditions. Retry."; next; } # Find a suitable a. Move on if one isn't found quickly. foreach my $trya (2, 3, 5, 7, 11, 13) { my $a = Math::BigInt->new($trya); # m/2 = R (n-1)/2 = (2*R*q)/2 = R*q next unless $a->copy->bmodpow($R, $n) != $nm1; next unless $a->copy->bmodpow($R*$q, $n) == $nm1; print "($k)" if $verbose > 2; croak "Maurer prime $n=2*$R*$q+1 failed BPSW" unless is_prob_prime($n); my $cert = "[MPU - Primality Certificate]\nVersion 1.0\n\n" . "Proof for:\nN $n\n\n" . "Type BLS3\nN $n\nQ $q\nA $a\n" . $qcert; return ($n, $cert); } # Didn't pass the selected a values. Try another R. } croak "Failure in random_maurer_prime, could not find a prime\n"; } # End of random_maurer_prime sub random_shawe_taylor_prime_with_cert { my $k = shift; my $seed = random_bytes(512/8); my($status,$prime,$prime_seed,$prime_gen_counter,$cert) = _ST_Random_prime($k, $seed); croak "Shawe-Taylor random prime failure" unless $status; croak "Shawe-Taylor random prime failure: prime $prime failed certificate verification!" unless verify_prime($cert); return ($prime,$cert); } sub _seed_plus_one { my($s) = @_; for (my $i = length($s)-1; $i >= 0; $i--) { vec($s, $i, 8)++; last unless vec($s, $i, 8) == 0; } return $s; } sub _ST_Random_prime { # From FIPS 186-4 my($k, $input_seed) = @_; croak "Shawe-Taylor random prime must have length >= 2" if $k < 2; $k = int("$k"); croak "Shawe-Taylor random prime, invalid input seed" unless defined $input_seed && length($input_seed) >= 32; if (!defined $Digest::SHA::VERSION) { eval { require Digest::SHA; my $version = $Digest::SHA::VERSION; $version =~ s/[^\d.]//g; $version >= 4.00; } or do { croak "Must have Digest::SHA 4.00 or later"; }; } my $k2 = Math::BigInt->new(2)->bpow($k-1); if ($k < 33) { my $seed = $input_seed; my $prime_gen_counter = 0; my $kmask = 0xFFFFFFFF >> (32-$k); # Does the mod operation my $kstencil = (1 << ($k-1)) | 1; # Sets high and low bits while (1) { my $seedp1 = _seed_plus_one($seed); my $cvec = Digest::SHA::sha256($seed) ^ Digest::SHA::sha256($seedp1); # my $c = Math::BigInt->from_hex('0x' . unpack("H*", $cvec)); # $c = $k2 + ($c % $k2); # $c = (2 * ($c >> 1)) + 1; my($c) = unpack("N*", substr($cvec,-4,4)); $c = ($c & $kmask) | $kstencil; $prime_gen_counter++; $seed = _seed_plus_one($seedp1); my ($isp, $cert) = is_provable_prime_with_cert($c); return (1,$c,$seed,$prime_gen_counter,$cert) if $isp; return (0,0,0,0) if $prime_gen_counter > 10000 + 16*$k; } } my($status,$c0,$seed,$prime_gen_counter,$cert) = _ST_Random_prime( (($k+1)>>1)+1, $input_seed); return (0,0,0,0) unless $status; $cert = ($c0 < Math::BigInt->new("18446744073709551615")) ? "" : _strip_proof_header($cert); my $iterations = int(($k + 255) / 256) - 1; # SHA256 generates 256 bits my $old_counter = $prime_gen_counter; my $xstr = ''; for my $i (0 .. $iterations) { $xstr = Digest::SHA::sha256_hex($seed) . $xstr; $seed = _seed_plus_one($seed); } my $x = Math::BigInt->from_hex('0x'.$xstr); $x = $k2 + ($x % $k2); my $t = ($x + 2*$c0 - 1) / (2*$c0); _make_big_gcds() if $_big_gcd_use < 0; while (1) { if (2*$t*$c0 + 1 > 2*$k2) { $t = ($k2 + 2*$c0 - 1) / (2*$c0); } my $c = 2*$t*$c0 + 1; $prime_gen_counter++; # Don't do the Pocklington check unless the candidate looks prime my $looks_prime = 0; if (MPU_USE_GMP) { # MPU::GMP::is_prob_prime has fast tests built in. $looks_prime = Math::Prime::Util::GMP::is_prob_prime($c); } else { # No GMP, so first do trial divisions, then a SPSP test. $looks_prime = Math::BigInt::bgcd($c, 111546435)->is_one; if ($looks_prime && $_big_gcd_use && $c > $_big_gcd_top) { $looks_prime = Math::BigInt::bgcd($c, $_big_gcd[0])->is_one && Math::BigInt::bgcd($c, $_big_gcd[1])->is_one && Math::BigInt::bgcd($c, $_big_gcd[2])->is_one && Math::BigInt::bgcd($c, $_big_gcd[3])->is_one; } $looks_prime = 0 if $looks_prime && !is_strong_pseudoprime($c, 3); } if ($looks_prime) { # We could use a in (2,3,5,7,11,13), but pedantically use FIPS 186-4. my $astr = ''; for my $i (0 .. $iterations) { $astr = Digest::SHA::sha256_hex($seed) . $astr; $seed = _seed_plus_one($seed); } my $a = Math::BigInt->from_hex('0x'.$astr); $a = ($a % ($c-3)) + 2; my $z = $a->copy->bmodpow(2*$t,$c); if (Math::BigInt::bgcd($z-1,$c)->is_one && $z->copy->bmodpow($c0,$c)->is_one) { croak "Shawe-Taylor random prime failure at ($k): $c not prime" unless is_prob_prime($c); $cert = "[MPU - Primality Certificate]\nVersion 1.0\n\n" . "Proof for:\nN $c\n\n" . "Type Pocklington\nN $c\nQ $c0\nA $a\n" . $cert; return (1, $c, $seed, $prime_gen_counter, $cert); } } else { # Update seed "as if" we performed the Pocklington check from FIPS 186-4 for my $i (0 .. $iterations) { $seed = _seed_plus_one($seed); } } return (0,0,0,0) if $prime_gen_counter > 10000 + 16*$k + $old_counter; $t++; } } # Gordon's algorithm for generating a strong prime. sub random_strong_prime { my $t = shift; croak "random_strong_prime, bits must be >= 128" unless $t >= 128; $t = int("$t"); croak "Random strong primes must be >= 173 bits on old Perl" if OLD_PERL_VERSION && MPU_64BIT && $t < 173; my $l = (($t+1) >> 1) - 2; my $lp = int($t/2) - 20; my $lpp = $l - 20; while (1) { my $qp = random_nbit_prime($lp); my $qpp = random_nbit_prime($lpp); $qp = Math::BigInt->new("$qp") unless ref($qp) eq 'Math::BigInt'; $qpp = Math::BigInt->new("$qpp") unless ref($qpp) eq 'Math::BigInt'; my ($il, $rem) = Math::BigInt->new(2)->bpow($l-1)->bdec()->bdiv(2*$qpp); $il++ if $rem > 0; $il = $il->as_int(); my $iu = Math::BigInt->new(2)->bpow($l)->bsub(2)->bdiv(2*$qpp)->as_int(); my $istart = $il + urandomm($iu - $il + 1); for (my $i = $istart; $i <= $iu; $i++) { # Search for q my $q = 2 * $i * $qpp + 1; next unless is_prob_prime($q); my $pp = $qp->copy->bmodpow($q-2, $q)->bmul(2)->bmul($qp)->bdec(); my ($jl, $rem) = Math::BigInt->new(2)->bpow($t-1)->bsub($pp)->bdiv(2*$q*$qp); $jl++ if $rem > 0; $jl = $jl->as_int(); my $ju = Math::BigInt->new(2)->bpow($t)->bdec()->bsub($pp)->bdiv(2*$q*$qp)->as_int(); my $jstart = $jl + urandomm($ju - $jl + 1); for (my $j = $jstart; $j <= $ju; $j++) { # Search for p my $p = $pp + 2 * $j * $q * $qp; return $p if is_prob_prime($p); } } } } sub random_proven_prime { my $k = shift; my ($n, $cert) = random_proven_prime_with_cert($k); croak "random_proven_prime $n failed certificate verification!" unless verify_prime($cert); return $n; } sub random_proven_prime_with_cert { my $k = shift; if (prime_get_config->{'gmp'} && $k <= 450) { my $n = random_nbit_prime($k); my ($isp, $cert) = is_provable_prime_with_cert($n); croak "small nbit prime could not be proven" if $isp != 2; return ($n, $cert); } return random_maurer_prime_with_cert($k); } 1; __END__ # ABSTRACT: Generate random primes =pod =encoding utf8 =head1 NAME Math::Prime::Util::RandomPrimes - Generate random primes =head1 VERSION Version 0.73 =head1 SYNOPSIS =head1 DESCRIPTION Routines to generate random primes, including constructing proven primes. =head1 RANDOM PRIME FUNCTIONS =head2 random_prime Generate a random prime between C and C. If given one argument, C will be 2. =head2 random_ndigit_prime Generate a random prime with C digits. C must be at least 1. =head2 random_nbit_prime Generate a random prime with C bits. C must be at least 2. =head2 random_maurer_prime Construct a random provable prime of C bits using Maurer's FastPrime algorithm. C must be at least 2. =head2 random_maurer_prime_with_cert Construct a random provable prime of C bits using Maurer's FastPrime algorithm. C must be at least 2. Returns a list of two items: the prime and the certificate. =head2 random_shawe_taylor_prime Construct a random provable prime of C bits using Shawe-Taylor's algorithm. C must be at least 2. The implementation is from FIPS 186-4 and uses SHA-256 with 512 bits of randomness. =head2 random_shawe_taylor_prime_with_cert Construct a random provable prime of C bits using Shawe-Taylor's algorithm. C must be at least 2. Returns a list of two items: the prime and the certificate. =head2 random_strong_prime Construct a random strong prime of C bits. C must be at least 128. =head2 random_proven_prime Generate or construct a random provable prime of C bits. C must be at least 2. =head2 random_proven_prime_with_cert Generate or construct a random provable prime of C bits. C must be at least 2. Returns a list of two items: the prime and the certificate. =head1 SEE ALSO L =head1 AUTHORS Dana Jacobsen Edana@acm.orgE =head1 COPYRIGHT Copyright 2012-2013 by Dana Jacobsen Edana@acm.orgE This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. =cut