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 argument, 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

SEE ALSO

       perl, bn(3ssl)