Provided by: libdigest-sha3-perl_1.04-1build1_amd64 bug

NAME

       Digest::SHA3 - Perl extension for SHA-3

SYNOPSIS

       In programs:

                       # Functional interface

               use Digest::SHA3 qw(sha3_224 sha3_256_hex sha3_512_base64 ...);

               $digest = sha3_224($data);
               $digest = sha3_256_hex($data);
               $digest = sha3_384_base64($data);
               $digest = sha3_512($data);

                       # Object-oriented

               use Digest::SHA3;

               $sha3 = Digest::SHA3->new($alg);

               $sha3->add($data);              # feed data into stream

               $sha3->addfile(*F);
               $sha3->addfile($filename);

               $sha3->add_bits($bits);
               $sha3->add_bits($data, $nbits);

               $digest = $sha3->digest;        # compute digest
               $digest = $sha3->hexdigest;
               $digest = $sha3->b64digest;

                       # Compute extendable-length digest

               $sha3 = Digest::SHA3->new(128000)->add($data);  # SHAKE128
               $digest  = $sha3->squeeze;
               $digest .= $sha3->squeeze;
               ...

               $sha3 = Digest::SHA3->new(256000)->add($data);  # SHAKE256
               $digest  = $sha3->squeeze;
               $digest .= $sha3->squeeze;
               ...

ABSTRACT

       Digest::SHA3 is a complete implementation of the NIST SHA-3 cryptographic hash function,
       as specified in FIPS 202 (SHA-3 Standard: Permutation-Based Hash and Extendable-Output
       Functions).

       The module gives Perl programmers a convenient way to calculate SHA3-224, SHA3-256,
       SHA3-384, and SHA3-512 message digests, as well as variable-length hashes using SHAKE128
       and SHAKE256.  Digest::SHA3 can handle all types of input, including partial-byte data.

DESCRIPTION

       Digest::SHA3 is written in C for speed.  If your platform lacks a C compiler, perhaps you
       can find the module in a binary form compatible with your particular processor and
       operating system.

       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::SHA and you'd prefer the newer flavor of
       the NIST standard, it's a simple 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 SHA3-256 digest of "hello world"
       using each approach:

               use Digest::SHA3 qw(sha3_256_hex);

               $data = "hello world";
               @frags = split(//, $data);

               # all-at-once (Functional style)
               $digest1 = sha3_256_hex($data);

               # in-stages (OOP style)
               $state = Digest::SHA3->new(256);
               for (@frags) { $state->add($_) }
               $digest2 = $state->hexdigest;

               print $digest1 eq $digest2 ?
                       "that's the ticket!\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 SHA3-512 digest:

               use Digest::SHA3;
               $bits = "110" x 148 . "11";
               $sha3 = Digest::SHA3->new(512)->add_bits($bits);
               print $sha3->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 customary packed binary format used for
       Perl strings.

UNICODE AND SIDE EFFECTS

       Perl supports Unicode strings as of version 5.6.  Such strings may contain wide
       characters: namely, characters whose ordinal values are greater than 255.  This can cause
       problems for digest algorithms such as SHA-3 that are specified to operate on sequences of
       bytes.

       The rule by which Digest::SHA3 handles a Unicode string is easy to state, but potentially
       confusing to grasp: the string is interpreted as a sequence of byte values, where each
       byte value is equal to the ordinal value (viz. code point) of its corresponding Unicode
       character.  That way, the Unicode string 'abc' has exactly the same digest value as the
       ordinary string 'abc'.

       Since a wide character does not fit into a byte, the Digest::SHA3 routines croak if they
       encounter one.  Whereas if a Unicode string contains no wide characters, the module
       accepts it quite happily.  The following code illustrates the two cases:

               $str1 = pack('U*', (0..255));
               print sha3_224_hex($str1);              # ok

               $str2 = pack('U*', (0..256));
               print sha3_224_hex($str2);              # croaks

       Be aware that the digest routines silently convert UTF-8 input into its equivalent byte
       sequence in the native encoding (cf. utf8::downgrade).  This side effect influences only
       the way Perl stores the data internally, but otherwise leaves the actual value of the data
       intact.

PADDING OF BASE64 DIGESTS

       By convention, CPAN Digest modules do not pad their Base64 output.  Problems can occur
       when feeding such digests to other software that expects properly padded Base64 encodings.

       For the time being, any necessary padding must be done by the user.  Fortunately, this is
       a simple operation: if the length of a Base64-encoded digest isn't a multiple of 4, simply
       append "=" characters to the end of the digest until it is:

               while (length($b64_digest) % 4) {
                       $b64_digest .= '=';
               }

       To illustrate, sha3_256_base64("abc") is computed to be

               Ophdp0/iJbIEXBcta9OQvYVfCG4+nVJbRr/iRRFDFTI

       which has a length of 43.  So, the properly padded version is

               Ophdp0/iJbIEXBcta9OQvYVfCG4+nVJbRr/iRRFDFTI=

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 any of them.

       In the interest of simplicity, maintainability, and small code size, it's unlikely that
       future versions of this module will support a 32-bit implementation.  Older platforms
       using 32-bit-only compilers should continue to favor 32-bit hash implementations such as
       SHA-1, SHA-224, or SHA-256.  The desire to use the SHA-3 hash standard, dating from 2015,
       should reasonably require that one's compiler adhere to programming language standards
       dating from at least 1999.

       Functional style

       sha3_224($data, ...)
       sha3_256($data, ...)
       sha3_384($data, ...)
       sha3_512($data, ...)
       shake128($data, ...)
       shake256($data, ...)
           Logically joins the arguments into a single string, and returns its
           SHA3-0/224/256/384/512 digest encoded as a binary string.

           The digest size for shake128 is 1344 bits (168 bytes); for shake256, it's 1088 bits
           (136 bytes).  To obtain extendable-output from the SHAKE algorithms, use the object-
           oriented interface with repeated calls to the squeeze method.

       sha3_224_hex($data, ...)
       sha3_256_hex($data, ...)
       sha3_384_hex($data, ...)
       sha3_512_hex($data, ...)
       shake128_hex($data, ...)
       shake256_hex($data, ...)
           Logically joins the arguments into a single string, and returns its
           SHA3-0/224/256/384/512 or SHAKE128/256 digest encoded as a hexadecimal string.

       sha3_224_base64($data, ...)
       sha3_256_base64($data, ...)
       sha3_384_base64($data, ...)
       sha3_512_base64($data, ...)
       shake128_base64($data, ...)
       shake256_base64($data, ...)
           Logically joins the arguments into a single string, and returns its
           SHA3-0/224/256/384/512 or SHAKE128/256 digest encoded as a Base64 string.

           It's important to note that the resulting string does not contain the padding
           characters typical of Base64 encodings.  This omission is deliberate, and is done to
           maintain compatibility with the family of CPAN Digest modules.  See "PADDING OF BASE64
           DIGESTS" for details.

       OOP style

       new($alg)
           Returns a new Digest::SHA3 object.  Allowed values for $alg are 224, 256, 384, and 512
           for the SHA3 algorithms; or 128000 and 256000 for SHAKE128 and SHAKE256, respectively.
           If the argument is missing, SHA3-224 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 associated with $alg.  If the argument is
           missing, the object will continue 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 224, 256, 384, 512,
           1344, and 1088 for SHA3-224, SHA3-256, SHA3-384, SHA3-512, SHAKE128, and SHAKE256,
           respectively.

       algorithm
           Returns the digest algorithm for this object.  The values are 224, 256, 384, 512,
           128000, and 256000 for SHA3-224, SHA3-256, SHA3-384, SHA3-512, SHAKE128, and SHAKE256,
           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:

                   $sha3->add("a"); $sha3->add("b"); $sha3->add("c");
                   $sha3->add("a")->add("b")->add("c");
                   $sha3->add("a", "b", "c");
                   $sha3->add("abc");

           The return value is the updated object itself.

       add_bits($data, $nbits [, $lsb])
       add_bits($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.
           Setting the optional $lsb flag to a true value indicates that the final (partial) byte
           of $data is aligned with the least-significant bit; by default it's aligned with the
           most-significant bit, as required by the parent Digest module.

           The second form takes an ASCII string of "0" and "1" characters as its argument.  It's
           equivalent to

                   $sha3->add_bits(pack("B*", $bits), length($bits));

           So, the following three statements do the same thing:

                   $sha3->add_bits("111100001010");
                   $sha3->add_bits("\xF0\xA0", 12);
                   $sha3->add_bits("\xF0\x0A", 12, 1);

           SHA-3 uses least-significant-bit ordering for its internal operation.  This means that

                   $sha3->add_bits("110");

           is equivalent to

                   $sha3->add_bits("0")->add_bits("1")->add_bits("1");

           Many public test vectors for SHA-3, such as the Keccak known-answer tests, are
           delivered in least-significant-bit format.  Using the optional $lsb flag in these
           cases allows your code to be simpler and more efficient.  See the test directory for
           examples.

           The fact that SHA-2 and SHA-3 employ opposite bit-ordering schemes has caused
           noticeable confusion in the programming community.  Exercise caution if your code
           examines individual bits in data streams.

       addfile(*FILE)
           Reads from FILE until EOF, and appends that data to the current state.  The return
           value is the updated object itself.

       addfile($filename [, $mode])
           Reads the contents of $filename, and appends that data to the current state.  The
           return value is the updated object itself.

           By default, $filename is simply opened and read; no special modes or I/O disciplines
           are used.  To change this, set the optional $mode argument to one of the following
           values:

                   "b"     read file in binary mode

                   "U"     use universal newlines

                   "0"     use BITS mode

           The "U" mode is modeled on Python's "Universal Newlines" concept, whereby DOS and Mac
           OS line terminators are converted internally to UNIX newlines before processing.  This
           ensures consistent digest values when working simultaneously across multiple file
           systems.  The "U" mode influences only text files, namely those passing Perl's -T
           test; binary files are processed with no translation whatsoever.

           The BITS mode ("0") interprets the contents of $filename as a logical stream of bits,
           where each ASCII '0' or '1' character represents a 0 or 1 bit, respectively.  All
           other characters are ignored.  This provides a convenient way to calculate the digest
           values of partial-byte data by using files, rather than having to write programs using
           the add_bits method.

       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::SHA3 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.

       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.

           It's important to note that the resulting string does not contain the padding
           characters typical of Base64 encodings.  This omission is deliberate, and is done to
           maintain compatibility with the family of CPAN Digest modules.  See "PADDING OF BASE64
           DIGESTS" for details.

       squeeze
           Returns the next 168 (136) bytes of the SHAKE128 (SHAKE256) digest encoded as a binary
           string.  The squeeze method may be called repeatedly to construct digests of any
           desired length.

           This method is applicable only to SHAKE128 and SHAKE256 objects.

SEE ALSO

       Digest, Digest::SHA, Digest::Keccak

       The FIPS 202 SHA-3 Standard can be found at:

       <http://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf>

       The Keccak/SHA-3 specifications can be found at:

       <http://keccak.noekeon.org/Keccak-reference-3.0.pdf>
       <http://keccak.noekeon.org/Keccak-submission-3.pdf>

AUTHOR

               Mark Shelor     <mshelor@cpan.org>

ACKNOWLEDGMENTS

       The author is particularly grateful to

               Guido Bertoni
               Joan Daemen
               Michael Peeters
               Chris Skiscim
               Gilles Van Assche

       "Nothing is more fatiguing nor, in the long run, more exasperating than the daily effort
       to believe things which daily become more incredible.  To be done with this effort is an
       indispensible condition of secure and lasting happiness."  - Bertrand Russell

COPYRIGHT AND LICENSE

       Copyright (C) 2012-2018 Mark Shelor

       This library is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.

       perlartistic