SHA(3)
NAME
Digest::SHA - Perl extension for SHA-1/224/256/384/512
SYNOPSIS (SHA)
In programs:
# Functional interface
use Digest::SHA qw(sha1 sha1_hex sha1_base64 ...);
$digest = sha1($data);
$digest = sha1_hex($data);
$digest = sha1_base64($data);
$digest = sha256($data);
$digest = sha384_hex($data);
$digest = sha512_base64($data);
# Object-oriented
use Digest::SHA;
$sha = Digest::SHA->new($alg);
$sha->add($data); # feed data into stream
$sha->addfile(*F);
$sha->add_bits($bits);
$sha->add_bits($data, $nbits);
$sha_copy = $sha->clone; # if needed, make copy of
$sha->dump($file); # current digest state,
$sha->load($file); # or save it on disk
$digest = $sha->digest; # compute digest
$digest = $sha->hexdigest;
$digest = $sha->b64digest;
From the command line:
$ shasum files
$ shasum --help
SYNOPSIS (HMAC-SHA)
# Functional interface only
use Digest::SHA qw(hmac_sha1 hmac_sha1_hex ...);
$digest = hmac_sha1($data, $key);
$digest = hmac_sha224_hex($data, $key);
$digest = hmac_sha256_base64($data, $key);
ABSTRACT
Digest::SHA is a complete implementation of the NIST Secure Hash Stan-
dard. It gives Perl programmers a convenient way to calculate SHA-1,
SHA-224, SHA-256, SHA-384, and SHA-512 message digests. The module can
handle all types of input, including partial-byte data.
DESCRIPTION
Digest::SHA is written in C for speed. If your platform lacks a C com-
piler, you can install the functionally equivalent (but much slower)
Digest::SHA::PurePerl module.
The programming interface is easy to use: it's the same one found in
CPAN's Digest module. So, if your applications currently use
Digest::MD5 and you'd prefer the stronger security of SHA, it's a sim-
ple matter to convert them.
The interface provides two ways to calculate digests: all-at-once, or
in stages. To illustrate, the following short program computes the
SHA-256 digest of "hello world" using each approach:
use Digest::SHA qw(sha256_hex);
$data = "hello world";
@frags = split(//, $data);
# all-at-once (Functional style)
$digest1 = sha256_hex($data);
# in-stages (OOP style)
$state = Digest::SHA->new(256);
for (@frags) { $state->add($_) }
$digest2 = $state->hexdigest;
print $digest1 eq $digest2 ?
"whew!\n" : "oops!\n";
To calculate the digest of an n-bit message where n is not a multiple
of 8, use the add_bits() method. For example, consider the 446-bit
message consisting of the bit-string "110" repeated 148 times, followed
by "11". Here's how to display its SHA-1 digest:
use Digest::SHA;
$bits = "110" x 148 . "11";
$sha = Digest::SHA->new(1)->add_bits($bits);
print $sha->hexdigest, "\n";
Note that for larger bit-strings, it's more efficient to use the two-
argument version add_bits($data, $nbits), where $data is in the custom-
ary packed binary format used for Perl strings.
The module also lets you save intermediate SHA states to disk, or dis-
play them on standard output. The dump() method generates portable,
human-readable text describing the current state of computation. You
can subsequently retrieve the file with load() to resume where the cal-
culation left off.
To see what a state description looks like, just run the following:
use Digest::SHA;
Digest::SHA->new->add("Shaw" x 1962)->dump;
As an added convenience, the Digest::SHA module offers routines to cal-
culate keyed hashes using the HMAC-SHA-1/224/256/384/512 algorithms.
These services exist in functional form only, and mimic the style and
behavior of the sha(), sha_hex(), and sha_base64() functions.
# Test vector from draft-ietf-ipsec-ciph-sha-256-01.txt
use Digest::SHA qw(hmac_sha256_hex);
print hmac_sha256_hex("Hi There", chr(0x0b) x 32), "\n";
EXPORT
None by default.
EXPORTABLE FUNCTIONS
Provided your C compiler supports a 64-bit type (e.g. the long long of
C99, or __int64 used by Microsoft C/C++), all of these functions will
be available for use. Otherwise, you won't be able to perform the
SHA-384 and SHA-512 transforms, both of which require 64-bit opera-
tions.
Functional style
sha1($data, ...)
sha224($data, ...)
sha256($data, ...)
sha384($data, ...)
sha512($data, ...)
Logically joins the arguments into a single string, and returns its
SHA-1/224/256/384/512 digest encoded as a binary string.
sha1_hex($data, ...)
sha224_hex($data, ...)
sha256_hex($data, ...)
sha384_hex($data, ...)
sha512_hex($data, ...)
Logically joins the arguments into a single string, and returns its
SHA-1/224/256/384/512 digest encoded as a hexadecimal string.
sha1_base64($data, ...)
sha224_base64($data, ...)
sha256_base64($data, ...)
sha384_base64($data, ...)
sha512_base64($data, ...)
Logically joins the arguments into a single string, and returns its
SHA-1/224/256/384/512 digest encoded as a Base64 string.
OOP style
new($alg)
Returns a new Digest::SHA object. Allowed values for $alg are 1,
224, 256, 384, or 512. It's also possible to use common string
representations of the algorithm (e.g. "sha256", "SHA-384"). If
the argument is missing, SHA-1 will be used by default.
Invoking new as an instance method will not create a new object;
instead, it will simply reset the object to the initial state asso-
ciated with $alg. If the argument is missing, the object will con-
tinue using the same algorithm that was selected at creation.
reset($alg)
This method has exactly the same effect as new($alg). In fact,
reset is just an alias for new.
hashsize
Returns the number of digest bits for this object. The values are
160, 224, 256, 384, and 512 for SHA-1, SHA-224, SHA-256, SHA-384,
and SHA-512, respectively.
algorithm
Returns the digest algorithm for this object. The values are 1,
224, 256, 384, and 512 for SHA-1, SHA-224, SHA-256, SHA-384, and
SHA-512, respectively.
clone
Returns a duplicate copy of the object.
add($data, ...)
Logically joins the arguments into a single string, and uses it to
update the current digest state. In other words, the following
statements have the same effect:
$sha->add("a"); $sha->add("b"); $sha->add("c");
$sha->add("a")->add("b")->add("c");
$sha->add("a", "b", "c");
$sha->add("abc");
The return value is the updated object itself.
add_bits($data, $nbits)
add_bits($bits)
Updates the current digest state by appending bits to it. The
return value is the updated object itself.
The first form causes the most-significant $nbits of $data to be
appended to the stream. The $data argument is in the customary
binary format used for Perl strings.
The second form takes an ASCII string of "0" and "1" characters as
its argument. It's equivalent to
$sha->add_bits(pack("B*", $bits), length($bits));
So, the following two statements do the same thing:
$sha->add_bits("111100001010");
$sha->add_bits("\xF0\xA0", 12);
addfile(*FILE)
Reads from FILE until EOF, and appends that data to the current
state. The return value is the updated object itself.
This method is inherited if Digest::base is installed on your sys-
tem. Otherwise, a functionally equivalent substitute is used.
dump($filename)
Provides persistent storage of intermediate SHA states by writing a
portable, human-readable representation of the current state to
$filename. If the argument is missing, or equal to the empty
string, the state information will be written to STDOUT.
load($filename)
Returns a Digest::SHA object representing the intermediate SHA
state that was previously dumped to $filename. If called as a
class method, a new object is created; if called as an instance
method, the object is reset to the state contained in $filename.
If the argument is missing, or equal to the empty string, the state
information will be read from STDIN.
digest
Returns the digest encoded as a binary string.
Note that the digest method is a read-once operation. Once it has
been performed, the Digest::SHA object is automatically reset in
preparation for calculating another digest value. Call
$sha->clone->digest if it's necessary to preserve the original
digest state.
hexdigest
Returns the digest encoded as a hexadecimal string.
Like digest, this method is a read-once operation. Call
$sha->clone->hexdigest if it's necessary to preserve the original
digest state.
This method is inherited if Digest::base is installed on your sys-
tem. Otherwise, a functionally equivalent substitute is used.
b64digest
Returns the digest encoded as a Base64 string.
Like digest, this method is a read-once operation. Call
$sha->clone->b64digest if it's necessary to preserve the original
digest state.
This method is inherited if Digest::base is installed on your sys-
tem. Otherwise, a functionally equivalent substitute is used.
HMAC-SHA-1/224/256/384/512
hmac_sha1($data, $key)
hmac_sha224($data, $key)
hmac_sha256($data, $key)
hmac_sha384($data, $key)
hmac_sha512($data, $key)
Returns the HMAC-SHA-1/224/256/384/512 digest of $data/$key, with
the result encoded as a binary string. Multiple $data arguments
are allowed, provided that $key is the last argument in the list.
hmac_sha1_hex($data, $key)
hmac_sha224_hex($data, $key)
hmac_sha256_hex($data, $key)
hmac_sha384_hex($data, $key)
hmac_sha512_hex($data, $key)
Returns the HMAC-SHA-1/224/256/384/512 digest of $data/$key, with
the result encoded as a hexadecimal string. Multiple $data argu-
ments are allowed, provided that $key is the last argument in the
list.
hmac_sha1_base64($data, $key)
hmac_sha224_base64($data, $key)
hmac_sha256_base64($data, $key)
hmac_sha384_base64($data, $key)
hmac_sha512_base64($data, $key)
Returns the HMAC-SHA-1/224/256/384/512 digest of $data/$key, with
the result encoded as a Base64 string. Multiple $data arguments
are allowed, provided that $key is the last argument in the list.
SEE ALSO
Digest, Digest::SHA::PurePerl
The Secure Hash Standard (FIPS PUB 180-2) can be found at:
<http://csrc.nist.gov/publications/fips/fips180-2/fips180-2with-
changenotice.pdf>
The Keyed-Hash Message Authentication Code (HMAC):
<http://csrc.nist.gov/publications/fips/fips198/fips-198a.pdf>
AUTHOR
Mark Shelor <mshelor@cpan.org>
ACKNOWLEDGMENTS
The author is particularly grateful to
Gisle Aas
Chris Carey
Julius Duque
Jeffrey Friedl
Robert Gilmour
Brian Gladman
Andy Lester
Alex Muntada
Chris Skiscim
Martin Thurn
Adam Woodbury
for offering their valuable comments, suggestions, and technical exper-
tise.
COPYRIGHT AND LICENSE
Copyright (C) 2003-2004 Mark Shelor
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
perlartistic
perl v5.8.6 2004-11-10 SHA(3)
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