bignum(3)

NAME

Crypt::OpenSSL::Bignum - OpenSSL's multiprecision integer arithmetic

SYNOPSIS

use Crypt::OpenSSL::Bignum;
my $bn = Crypt::OpenSSL::Bignum->new_from_decimal( "1000" );
# or
my $bn = Crypt::OpenSSL::Bignum->new_from_word( 1000 );
# or
my $bn = Crypt::OpenSSL::Bignum->new_from_hex("0x3e8");
# or
my $bn = Crypt::OpenSSL::Bignum->new_from_bin(pack( "C*", 3, 232 ))
use Crypt::OpenSSL::Bignum::CTX;
sub print_factorial
{
  my( $n ) = @_;
  my $fac = Crypt::OpenSSL::Bignum->one();
  my $ctx = Crypt::OpenSSL::Bignum::CTX->new();
  foreach my $i (1 .. $n)
  {
    $fac->mul( Crypt::OpenSSL::Bignum->new_from_word( $i ), $ctx, $fac );
  }
  print "$n factorial is ", $fac->to_decimal(), "\n";
}

DESCRIPTION

Crypt::OpenSSL::Bignum provides access to OpenSSL multiprecision integer arithmetic libraries. Presently, many though not all of the arithmetic operations that OpenSSL provides are exposed to perl. In addition, this module can be used to provide access to bignum values produced by other OpenSSL modules, such as key parameters from
Crypt::OpenSSL::RSA.

NOTE: Many of the methods in this package can croak, so use eval, or Error.pm's try/catch mechanism to capture errors.

Class Methods

new_from_word: Create a new Crypt::OpenSSL::Bignum object whose value will be the word given. Note that numbers represneted by objects created using this method are necessarily between 0 and 2^32 - 1.
new_from_decimal: Create a new Crypt::OpenSSL::Bignum object whose value is specified by the given decimal representation.
new_from_hex: Create a new Crypt::OpenSSL::Bignum object whose value is specified by the given hexidecimal representation.
new_from_bin: Create a new Crypt::OpenSSL::Bignum object whose value is specified by the given packed binary string. Note that objects created using this method are necessarily nonnegative.
zero: Returns a new Crypt::OpenSSL::Bignum object representing 0
one Returns a new Crypt::OpenSSL::Bignum object representing 1
bless_pointer: Given a pointer to a OpenSSL BIGNUM object in memory, construct and return Crypt::OpenSSL::Bignum object around this. Note that the
underlying BIGNUM object will be destroyed (via
BN_clear_free(3ssl)) when the returned Crypt::OpenSSL::Bignum object is no longer referenced, so the pointer passed to this
method should only be referenced via the returned perl object after calling bless_pointer.; This method is intended only for use by XSUB writers writing code
that interfaces with OpenSSL library methods, and who wish to be
able to return a BIGNUM structure to perl as a
Crypt::OpenSSL::Bignum object.

Instance Methods

to_decimal: Return a decimal string representation of this object.
to_hex: Return a hexidecimal string representation of this object.
to_bin: Return a packed binary string representation of this object. Note that sign is ignored, so that to bin called on a
Crypt::OpenSSL::Bignum object representing a negative number
returns the same value as it would called on an object representing that number's absolute value.
get_word: Return a scalar integer representation of this object, if it can be represented as an unsigned long.
is_zero: Returns true of this object represents 0.
is_one: Returns true of this object represents 1.
is_odd: Returns true of this object represents an odd number.
copy: Returns a copy of this object.
add This method returns the sum of this object and the first argument.: If only one argument is passed, a new Crypt::OpenSSL::Bignum object is created for the return value; otherwise, the value of second
argument is set to the result and returned.
sub This method returns the difference of this object and the first: argument. If only one argument is passed, a new
Crypt::OpenSSL::Bignum object is created for the return value; otherwise, the value of second argument is set to the result and
returned.
mul This method returns the product of this object and the first argu: ment, using the second argument, a Crypt::OpenSSL::Bignum::CTX
object, as a scratchpad. If only two arguments are passed, a new
Crypt::OpenSSL::Bignum object is created for the return value; otherwise, the value of third argument is set to the result and
returned.
div This method returns a list consisting of quotient and the remainder: obtained by dividing this object by the first argument, using the
second argument, a Crypt::OpenSSL::Bignum::CTX object, as a
scratchpad. If only two arguments are passed, new
Crypt::OpenSSL::Bignum objects is created for both return values.
If a third argument is passed, otherwise, the value of third argument is set to the quotient. If a fourth argument is passed, the
value of the fourth argument is set to the remainder.
exp This method returns the product of this object exponeniated by the: first argument, using the second argument, a
Crypt::OpenSSL::Bignum::CTX object, as a scratchpad.
mod_exp: This method returns the product of this object exponeniated by the first argument, modulo the second argument, using the third argument, a Crypt::OpenSSL::Bignum::CTX object, as a scratchpad.
pointer_copy: This method is intended only for use by XSUB writers wanting to
have access to the underlying BIGNUM structure referenced by a
Crypt::OpenSSL::Bignum perl object so that they can pass them to
other routines in the OpenSSL library. It returns a perl scalar
whose IV can be cast to a BIGNUM* value. This can then be passed
to an XSUB which can work with the BIGNUM directly. Note that the BIGNUM object pointed to will be a copy of the BIGNUM object
wrapped by the instance; it is thus the responsiblity of the client to free space allocated by this BIGNUM object if and when it is
done with it. See also bless_pointer.

AUTHOR

Ian Robertson, iroberts@cpan.org

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In section

See also