huschi.net

SHA1(3)               User Contributed Perl Documentation              SHA1(3)

NAME
       Digest::SHA1 - Perl interface to the SHA-1 algorithm
SYNOPSIS
        # Functional style
        use Digest::SHA1  qw(sha1 sha1_hex sha1_base64);
        $digest = sha1($data);
        $digest = sha1_hex($data);
        $digest = sha1_base64($data);
        $digest = sha1_transform($data);

        # OO style
        use Digest::SHA1;
        $sha1 = Digest::SHA1->new;
        $sha1->add($data);
        $sha1->addfile(*FILE);
        $sha1_copy = $sha1->clone;
        $digest = $sha1->digest;
        $digest = $sha1->hexdigest;
        $digest = $sha1->b64digest;
        $digest = $sha1->transform;
DESCRIPTION
       The "Digest::SHA1" module allows you to use the NIST SHA-1 message
       digest algorithm from within Perl programs.  The algorithm takes as
       input a message of arbitrary length and produces as output a 160-bit
       "fingerprint" or "message digest" of the input.
       In 2005, security flaws were identified in SHA-1, namely that a
       possible mathematical weakness might exist, indicating that a stronger
       hash function would be desirable.  The Digest::SHA module implements
       the stronger algorithms in the SHA family.
       The "Digest::SHA1" module provide a procedural interface for simple
       use, as well as an object oriented interface that can handle messages
       of arbitrary length and which can read files directly.
FUNCTIONS
       The following functions can be exported from the "Digest::SHA1" module.
       No functions are exported by default.
       sha1($data,...)
           This function will concatenate all arguments, calculate the SHA-1
           digest of this "message", and return it in binary form.  The
           returned string will be 20 bytes long.
           The result of sha1("a", "b", "c") will be exactly the same as the
           result of sha1("abc").
       sha1_hex($data,...)
           Same as sha1(), but will return the digest in hexadecimal form.
           The length of the returned string will be 40 and it will only
           contain characters from this set: '0'..'9' and 'a'..'f'.
       sha1_base64($data,...)
           Same as sha1(), but will return the digest as a base64 encoded
           string.  The length of the returned string will be 27 and it will
           only contain characters from this set: 'A'..'Z', 'a'..'z',
           '0'..'9', '+' and '/'.
           Note that the base64 encoded string returned is not padded to be a
           multiple of 4 bytes long.  If you want interoperability with other
           base64 encoded sha1 digests you might want to append the redundant
           string "=" to the result.
       sha1_transform($data)
           Implements the basic SHA1 transform on a 64 byte block. The $data
           argument and the returned $digest are in binary form. This
           algorithm is used in NIST FIPS 186-2
METHODS
       The object oriented interface to "Digest::SHA1" is described in this
       section.  After a "Digest::SHA1" object has been created, you will add
       data to it and finally ask for the digest in a suitable format.  A
       single object can be used to calculate multiple digests.
       The following methods are provided:
       $sha1 = Digest::SHA1->new
           The constructor returns a new "Digest::SHA1" object which
           encapsulate the state of the SHA-1 message-digest algorithm.
           If called as an instance method (i.e. $sha1->new) it will just
           reset the state the object to the state of a newly created object.
           No new object is created in this case.
       $sha1->reset
           This is just an alias for $sha1->new.
       $sha1->clone
           This a copy of the $sha1 object. It is useful when you do not want
           to destroy the digests state, but need an intermediate value of the
           digest, e.g. when calculating digests iteratively on a continuous
           data stream.  Example:
               my $sha1 = Digest::SHA1->new;
               while (<>) {
                   $sha1->add($_);
                   print "Line $.: ", $sha1->clone->hexdigest, "\n";
               }
       $sha1->add($data,...)
           The $data provided as argument are appended to the message we
           calculate the digest for.  The return value is the $sha1 object
           itself.
           All these lines will have the same effect on the state of the $sha1
           object:
               $sha1->add("a"); $sha1->add("b"); $sha1->add("c");
               $sha1->add("a")->add("b")->add("c");
               $sha1->add("a", "b", "c");
               $sha1->add("abc");
       $sha1->addfile($io_handle)
           The $io_handle will be read until EOF and its content appended to
           the message we calculate the digest for.  The return value is the
           $sha1 object itself.
           The addfile() method will croak() if it fails reading data for some
           reason.  If it croaks it is unpredictable what the state of the
           $sha1 object will be in. The addfile() method might have been able
           to read the file partially before it failed.  It is probably wise
           to discard or reset the $sha1 object if this occurs.
           In most cases you want to make sure that the $io_handle is in
           "binmode" before you pass it as argument to the addfile() method.
       $sha1->add_bits($data, $nbits)
       $sha1->add_bits($bitstring)
           This implementation of SHA-1 only supports byte oriented input so
           you might only add bits as multiples of 8.  If you need bit level
           support please consider using the "Digest::SHA" module instead.
           The add_bits() method is provided here for compatibility with other
           digest implementations.  See Digest for description of the
           arguments that add_bits() take.
       $sha1->digest
           Return the binary digest for the message.  The returned string will
           be 20 bytes long.
           Note that the "digest" operation is effectively a destructive,
           read-once operation. Once it has been performed, the "Digest::SHA1"
           object is automatically "reset" and can be used to calculate
           another digest value.  Call $sha1->clone->digest if you want to
           calculate the digest without reseting the digest state.
       $sha1->hexdigest
           Same as $sha1->digest, but will return the digest in hexadecimal
           form. The length of the returned string will be 40 and it will only
           contain characters from this set: '0'..'9' and 'a'..'f'.
       $sha1->b64digest
           Same as $sha1->digest, but will return the digest as a base64
           encoded string.  The length of the returned string will be 27 and
           it will only contain characters from this set: 'A'..'Z', 'a'..'z',
           '0'..'9', '+' and '/'.
           The base64 encoded string returned is not padded to be a multiple
           of 4 bytes long.  If you want interoperability with other base64
           encoded SHA-1 digests you might want to append the string "=" to
           the result.
SEE ALSO
       Digest, Digest::HMAC_SHA1, Digest::SHA, Digest::MD5
       http://www.itl.nist.gov/fipspubs/fip180-1.htm
       http://en.wikipedia.org/wiki/SHA_hash_functions
COPYRIGHT
       This library is free software; you can redistribute it and/or modify it
       under the same terms as Perl itself.
        Copyright 1999-2004 Gisle Aas.
        Copyright 1997 Uwe Hollerbach.
AUTHORS
       Peter C. Gutmann, Uwe Hollerbach <uh AT alumni.edu>, Gisle Aas
       <gisle AT aas.no>

perl v5.16.3                      2010-07-03                           SHA1(3)