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 = $sha1->transform;
DESCRIPTION
The "Digest::SHA1" module allows you to use the NIST SHA-1 message digest algorithm from
within Perl programs. The algorithm takes as input a message of arbitrary length and pro-
duces as output a 160-bit "fingerprint" or "message digest" of the input.
The "Digest::SHA1" module provide a procedural interface for simple use, as well as an
object oriented interface that can handle messages of arbitrary length and which can read
files directly.
FUNCTIONS
The following functions can be exported from the "Digest::SHA1" module. No functions are
exported by default.
sha1($data,...)
This function will concatenate all arguments, calculate the SHA-1 digest of this "mes-
sage", 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 cal-
culate 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 compatibil-
ity 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
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 <>, Gisle Aas <>
perl v5.8.8 2006-01-18 SHA1(3)
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