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Bignum(3)		       User Contributed Perl Documentation			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 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)

perl v5.16.3				    2007-05-20					Bignum(3)
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