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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 = $sha1->transform;
DESCRIPTION
The "Digest::SHA1" module allows you to use the NIST SHA-1 message digest algorithm
from within Perl programs. The algorithm takes as input a message of arbitrary
length and produces as output a 160-bit "fingerprint" or "message digest" of the
input.
The "Digest::SHA1" module provide a procedural interface for simple use, as well as
an object oriented interface that can handle messages of arbitrary length and which
can read files directly.
FUNCTIONS
The following functions can be exported from the "Digest::SHA1" module. No func-
tions are exported by default.
sha1($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 cal-
culating 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 opera-
tion. 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 charac-
ters 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
COPYRIGHT
This library is free software; you can redistribute it and/or modify it under the
same terms as Perl itself.
Copyright 1999-2003 Gisle Aas.
Copyright 1997 Uwe Hollerbach.
AUTHORS
Peter C. Gutmann, Uwe Hollerbach <uh AT alumni.edu>, Gisle Aas <gisle AT aas.no>
perl v5.8.6 2004-04-05 SHA1(3)
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