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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 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

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 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

http://www.itl.nist.gov/fipspubs/fip180-1.htm  

COPYRIGHT

 Copyright 1999-2004 Gisle Aas.
 Copyright 1997 Uwe Hollerbach.

AUTHORS

Index

NAME

SYNOPSIS

DESCRIPTION

FUNCTIONS

METHODS

SEE ALSO

COPYRIGHT

AUTHORS

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