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)