Digest::SHA1(3pm)

1SHA1(3)               User Contributed Perl Documentation              SHA1(3)
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NAME

6       Digest::SHA1 - Perl interface to the SHA-1 algorithm
7

SYNOPSIS

9        # Functional style
10        use Digest::SHA1  qw(sha1 sha1_hex sha1_base64);
11
12        $digest = sha1($data);
13        $digest = sha1_hex($data);
14        $digest = sha1_base64($data);
15        $digest = sha1_transform($data);
16
17
18        # OO style
19        use Digest::SHA1;
20
21        $sha1 = Digest::SHA1->new;
22
23        $sha1->add($data);
24        $sha1->addfile(*FILE);
25
26        $sha1_copy = $sha1->clone;
27
28        $digest = $sha1->digest;
29        $digest = $sha1->hexdigest;
30        $digest = $sha1->b64digest;
31        $digest = $sha1->transform;
32

DESCRIPTION

34       The "Digest::SHA1" module allows you to use the NIST SHA-1 message
35       digest algorithm from within Perl programs.  The algorithm takes as
36       input a message of arbitrary length and produces as output a 160-bit
37       "fingerprint" or "message digest" of the input.
38
39       In 2005, security flaws were identified in SHA-1, namely that a
40       possible mathematical weakness might exist, indicating that a stronger
41       hash function would be desirable.  The Digest::SHA module implements
42       the stronger algorithms in the SHA family.
43
44       The "Digest::SHA1" module provide a procedural interface for simple
45       use, as well as an object oriented interface that can handle messages
46       of arbitrary length and which can read files directly.
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FUNCTIONS

49       The following functions can be exported from the "Digest::SHA1" module.
50       No functions are exported by default.
51
52       sha1($data,...)
53           This function will concatenate all arguments, calculate the SHA-1
54           digest of this "message", and return it in binary form.  The
55           returned string will be 20 bytes long.
56
57           The result of sha1("a", "b", "c") will be exactly the same as the
58           result of sha1("abc").
59
60       sha1_hex($data,...)
61           Same as sha1(), but will return the digest in hexadecimal form.
62           The length of the returned string will be 40 and it will only
63           contain characters from this set: '0'..'9' and 'a'..'f'.
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65       sha1_base64($data,...)
66           Same as sha1(), but will return the digest as a base64 encoded
67           string.  The length of the returned string will be 27 and it will
68           only contain characters from this set: 'A'..'Z', 'a'..'z',
69           '0'..'9', '+' and '/'.
70
71           Note that the base64 encoded string returned is not padded to be a
72           multiple of 4 bytes long.  If you want interoperability with other
73           base64 encoded sha1 digests you might want to append the redundant
74           string "=" to the result.
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76       sha1_transform($data)
77           Implements the basic SHA1 transform on a 64 byte block. The $data
78           argument and the returned $digest are in binary form. This
79           algorithm is used in NIST FIPS 186-2
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METHODS

82       The object oriented interface to "Digest::SHA1" is described in this
83       section.  After a "Digest::SHA1" object has been created, you will add
84       data to it and finally ask for the digest in a suitable format.  A
85       single object can be used to calculate multiple digests.
86
87       The following methods are provided:
88
89       $sha1 = Digest::SHA1->new
90           The constructor returns a new "Digest::SHA1" object which
91           encapsulate the state of the SHA-1 message-digest algorithm.
92
93           If called as an instance method (i.e. $sha1->new) it will just
94           reset the state the object to the state of a newly created object.
95           No new object is created in this case.
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97       $sha1->reset
98           This is just an alias for $sha1->new.
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100       $sha1->clone
101           This a copy of the $sha1 object. It is useful when you do not want
102           to destroy the digests state, but need an intermediate value of the
103           digest, e.g. when calculating digests iteratively on a continuous
104           data stream.  Example:
105
106               my $sha1 = Digest::SHA1->new;
107               while (<>) {
108                   $sha1->add($_);
109                   print "Line $.: ", $sha1->clone->hexdigest, "\n";
110               }
111
112       $sha1->add($data,...)
113           The $data provided as argument are appended to the message we
114           calculate the digest for.  The return value is the $sha1 object
115           itself.
116
117           All these lines will have the same effect on the state of the $sha1
118           object:
119
120               $sha1->add("a"); $sha1->add("b"); $sha1->add("c");
121               $sha1->add("a")->add("b")->add("c");
122               $sha1->add("a", "b", "c");
123               $sha1->add("abc");
124
125       $sha1->addfile($io_handle)
126           The $io_handle will be read until EOF and its content appended to
127           the message we calculate the digest for.  The return value is the
128           $sha1 object itself.
129
130           The addfile() method will croak() if it fails reading data for some
131           reason.  If it croaks it is unpredictable what the state of the
132           $sha1 object will be in. The addfile() method might have been able
133           to read the file partially before it failed.  It is probably wise
134           to discard or reset the $sha1 object if this occurs.
135
136           In most cases you want to make sure that the $io_handle is in
137           "binmode" before you pass it as argument to the addfile() method.
138
139       $sha1->add_bits($data, $nbits)
140       $sha1->add_bits($bitstring)
141           This implementation of SHA-1 only supports byte oriented input so
142           you might only add bits as multiples of 8.  If you need bit level
143           support please consider using the "Digest::SHA" module instead.
144           The add_bits() method is provided here for compatibility with other
145           digest implementations.  See Digest for description of the
146           arguments that add_bits() take.
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148       $sha1->digest
149           Return the binary digest for the message.  The returned string will
150           be 20 bytes long.
151
152           Note that the "digest" operation is effectively a destructive,
153           read-once operation. Once it has been performed, the "Digest::SHA1"
154           object is automatically "reset" and can be used to calculate
155           another digest value.  Call $sha1->clone->digest if you want to
156           calculate the digest without reseting the digest state.
157
158       $sha1->hexdigest
159           Same as $sha1->digest, but will return the digest in hexadecimal
160           form. The length of the returned string will be 40 and it will only
161           contain characters from this set: '0'..'9' and 'a'..'f'.
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163       $sha1->b64digest
164           Same as $sha1->digest, but will return the digest as a base64
165           encoded string.  The length of the returned string will be 27 and
166           it will only contain characters from this set: 'A'..'Z', 'a'..'z',
167           '0'..'9', '+' and '/'.
168
169           The base64 encoded string returned is not padded to be a multiple
170           of 4 bytes long.  If you want interoperability with other base64
171           encoded SHA-1 digests you might want to append the string "=" to
172           the result.
173

COPYRIGHT

182       This library is free software; you can redistribute it and/or modify it
183       under the same terms as Perl itself.
184
185        Copyright 1999-2004 Gisle Aas.
186        Copyright 1997 Uwe Hollerbach.
187

AUTHORS

189       Peter C. Gutmann, Uwe Hollerbach <uh@alumni.caltech.edu>, Gisle Aas
190       <gisle@aas.no>
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194perl v5.16.3                      2010-07-03                           SHA1(3)