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.\" ========================================================================
.\"
.IX Title "Rhash 3pm"
.TH Rhash 3pm "2012-01-09" "perl v5.14.2" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
Rhash \- Perl extension for LibRHash Hash library
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&  use Rhash;
\&  
\&  my $msg = "a message text";
\&  print "MD5 = " . Rhash\->new(Rhash::MD5)\->update($msg)\->hash() . "\en";
\&  
\&  # more complex example \- calculate two hash functions simultaniously
\&  my $r = Rhash\->new(Rhash::MD5 | Rhash::SHA1);
\&  $r\->update("a message text")\->update(" another message");
\&  print  "MD5  = ". $r\->hash(Rhash::MD5) . "\en";
\&  print  "SHA1 = ". $r\->hash(Rhash::SHA1) . "\en";
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Rhash module is an object-oriented interface to the LibRHash library,
which allows one to simultaniously calculate several hash functions for a file or a text message.
.SH "SUPPORTED ALGORITHMS"
.IX Header "SUPPORTED ALGORITHMS"
The module supports the following hashing algorithms:
\&\s-1CRC32\s0,  \s-1MD4\s0, \s-1MD5\s0,  \s-1SHA1\s0, \s-1SHA256\s0, \s-1SHA512\s0,
\&\s-1AICH\s0, \s-1ED2K\s0, Tiger,  \s-1DC++\s0 \s-1TTH\s0,  BitTorrent \s-1BTIH\s0, \s-1GOST\s0 R 34.11\-94, \s-1RIPEMD\-160\s0,
\&\s-1HAS\-160\s0, EDON-R 256/512, Whirlpool and Snefru\-128/256.
.SH "CONSTRUCTOR"
.IX Header "CONSTRUCTOR"
Creates and returns new Rhash object.
.PP
.Vb 2
\&  my $r = Rhash\->new($hash_id);
\&  my $p = new Rhash($hash_id); # alternative way to call the constructor
.Ve
.PP
The \f(CW$hash_id\fR parameter can be union (via bitwise \s-1OR\s0) of any of the following bit-flags:
.PP
.Vb 10
\&  Rhash::CRC32,
\&  Rhash::MD4,
\&  Rhash::MD5,
\&  Rhash::SHA1,
\&  Rhash::TIGER,
\&  Rhash::TTH,
\&  Rhash::BTIH,
\&  Rhash::ED2K,
\&  Rhash::AICH,
\&  Rhash::WHIRLPOOL,
\&  Rhash::RIPEMD160,
\&  Rhash::GOST,
\&  Rhash::GOST_CRYPTOPRO,
\&  Rhash::HAS160,
\&  Rhash::SNEFRU128,
\&  Rhash::SNEFRU256,
\&  Rhash::SHA224,
\&  Rhash::SHA256,
\&  Rhash::SHA384,
\&  Rhash::SHA512,
\&  Rhash::EDONR256,
\&  Rhash::EDONR512
.Ve
.PP
Also the Rhash::ALL bit mask is the union of all listed bit-flags.
So the object created via Rhash\->new(Rhash::ALL) calculates all
supported hash functions for the same data.
.SH "COMPUTING HASHES"
.IX Header "COMPUTING HASHES"
.ie n .IP "$rhash\->update( $msg )" 4
.el .IP "\f(CW$rhash\fR\->update( \f(CW$msg\fR )" 4
.IX Item "$rhash->update( $msg )"
Calculates hashes of the \f(CW$msg\fR string.
The method can be called repeatedly with chunks of the message to be hashed.
It returns the \f(CW$rhash\fR object itself allowing the following construct:
.Sp
.Vb 1
\&  $rhash = Rhash\->new(Rhash::MD5)\->update( $chunk1 )\->update( $chunk2 );
.Ve
.ie n .IP "$rhash\->update_file( $file_path, $start, $size )" 4
.el .IP "\f(CW$rhash\fR\->update_file( \f(CW$file_path\fR, \f(CW$start\fR, \f(CW$size\fR )" 4
.IX Item "$rhash->update_file( $file_path, $start, $size )"
.PD 0
.ie n .IP "$rhash\->update_fd( $fd, $start, $size )" 4
.el .IP "\f(CW$rhash\fR\->update_fd( \f(CW$fd\fR, \f(CW$start\fR, \f(CW$size\fR )" 4
.IX Item "$rhash->update_fd( $fd, $start, $size )"
.PD
Calculate a hash of the file (or its part) specified by \f(CW$file_path\fR or a file descriptor \f(CW$fd\fR.
The update_fd method doesn't close the \f(CW$fd\fR, leaving the file position after the hashed block.
The optional \f(CW$start\fR and \f(CW$size\fR specify the block of the file to hash.
No error is reported if the \f(CW$size\fR is grater than the number of the unread bytes left in the file.
.Sp
Returns the number of characters actually read, 0 at end of file, 
or undef if there was an error (in the latter case $! is also set).
.Sp
.Vb 9
\&  use Rhash;
\&  my $r = new Rhash(Rhash::SHA1);
\&  open(my $fd, "<", "input.txt") or die "cannot open < input.txt: $!";
\&  while ((my $n = $r\->update_fd($fd, undef, 1024) != 0) {
\&      print "$n bytes hashed. The SHA1 hash is " . $r\->final()\->hash() . "\en";
\&      $r\->reset();
\&  }
\&  defined($n) or die "read error for input.txt: $!";
\&  close($fd);
.Ve
.ie n .IP "$rhash\->\fIfinal()\fR" 4
.el .IP "\f(CW$rhash\fR\->\fIfinal()\fR" 4
.IX Item "$rhash->final()"
Finishes calculation for all data buffered by updating methods and stops hash
calculation. The function is called automatically by any of the 
\&\f(CW$rhash\fR\->hash*() methods if the \fIfinal()\fR call was skipped.
.ie n .IP "$rhash\->\fIreset()\fR" 4
.el .IP "\f(CW$rhash\fR\->\fIreset()\fR" 4
.IX Item "$rhash->reset()"
Resets the \f(CW$rhash\fR object to the initial state.
.ie n .IP "$rhash\->\fIhashed_length()\fR" 4
.el .IP "\f(CW$rhash\fR\->\fIhashed_length()\fR" 4
.IX Item "$rhash->hashed_length()"
Returns the total length of the hashed message.
.ie n .IP "$rhash\->\fIhash_id()\fR" 4
.el .IP "\f(CW$rhash\fR\->\fIhash_id()\fR" 4
.IX Item "$rhash->hash_id()"
Returns the hash mask, the \f(CW$rhash\fR object was constructed with.
.SH "FORMATING HASH VALUE"
.IX Header "FORMATING HASH VALUE"
Computed hash can be formated as a hexadecimal string (in the forward or
reverse byte order), a base32/base64\-encoded string or as raw binary data.
.ie n .IP "$rhash\->hash( $hash_id )" 4
.el .IP "\f(CW$rhash\fR\->hash( \f(CW$hash_id\fR )" 4
.IX Item "$rhash->hash( $hash_id )"
Returns the hash string in the default format,
which can be hexadecimal or base32. Actually the method is equvalent of
.Sp
.Vb 2
\&  (Rhash::is_base32($hash_id) ? $rhash\->hash_base32($hash_id) :
\&    $rhash\->hash_hex($hash_id))
.Ve
.Sp
If the optional \f(CW$hash_id\fR parameter is omited or zero, then the method returns the hash
for the algorithm contained in \f(CW$rhash\fR with the lowest identifier.
.ie n .IP "$rhash\->hash_hex( $hash_id )" 4
.el .IP "\f(CW$rhash\fR\->hash_hex( \f(CW$hash_id\fR )" 4
.IX Item "$rhash->hash_hex( $hash_id )"
Returns a specified hash in the hexadecimal format.
.ie n .IP "$rhash\->hash_rhex( $hash_id )" 4
.el .IP "\f(CW$rhash\fR\->hash_rhex( \f(CW$hash_id\fR )" 4
.IX Item "$rhash->hash_rhex( $hash_id )"
Returns a hexadecimal string of the hash in reversed bytes order.
Some programs prefer to output \s-1GOST\s0 hash in this format.
.ie n .IP "$rhash\->hash_base32( $hash_id )" 4
.el .IP "\f(CW$rhash\fR\->hash_base32( \f(CW$hash_id\fR )" 4
.IX Item "$rhash->hash_base32( $hash_id )"
Returns a specified hash in the base32 format.
.ie n .IP "$rhash\->hash_base64( $hash_id )" 4
.el .IP "\f(CW$rhash\fR\->hash_base64( \f(CW$hash_id\fR )" 4
.IX Item "$rhash->hash_base64( $hash_id )"
Returns a specified hash in the base64 format.
.ie n .IP "$rhash\->magnet_link( $filename, $hash_mask )" 4
.el .IP "\f(CW$rhash\fR\->magnet_link( \f(CW$filename\fR, \f(CW$hash_mask\fR )" 4
.IX Item "$rhash->magnet_link( $filename, $hash_mask )"
Returns the magnet link containing the computed hashes, filesize, and,
optionaly, \f(CW$filename\fR. The \f(CW$filename\fR (if specified) is URL-encoded,
by converting special characters into the %<hexadecimal\-code> form.
The optional parameter \f(CW$hash_mask\fR can limit which hash values to put
into the link.
.SH "STATIC INFORMATION METHODS"
.IX Header "STATIC INFORMATION METHODS"
.IP "\fIRhash::count()\fR" 4
.IX Item "Rhash::count()"
Returns the number of supported hash algorithms
.IP "Rhash::is_base32($hash_id)" 4
.IX Item "Rhash::is_base32($hash_id)"
Returns nonzero if default output format is Base32 for the hash function specified by \f(CW$hash_id\fR.
Retruns zero if default format is hexadecimal.
.IP "Rhash::get_digest_size($hash_id)" 4
.IX Item "Rhash::get_digest_size($hash_id)"
Returns the size in bytes of raw binary hash of the specified hash algorithm.
.IP "Rhash::get_hash_length($hash_id)" 4
.IX Item "Rhash::get_hash_length($hash_id)"
Returns the length of a hash string in default output format for the specified hash algorithm.
.IP "Rhash::get_name($hash_id)" 4
.IX Item "Rhash::get_name($hash_id)"
Returns the name of the specified hash algorithm.
.SH "ALTERNATIVE WAY TO COMPUTE HASH"
.IX Header "ALTERNATIVE WAY TO COMPUTE HASH"
.ie n .IP "Rhash::msg($hash_id, $message)" 4
.el .IP "Rhash::msg($hash_id, \f(CW$message\fR)" 4
.IX Item "Rhash::msg($hash_id, $message)"
Computes and returns a single hash (in its default format) of the \f(CW$message\fR by the selected hash algorithm.
.Sp
.Vb 2
\&  use Rhash;
\&  print "SHA1( \*(Aqabc\*(Aq ) = " . Rhash::msg(Rhash::SHA1, "abc");
.Ve
.SH "LICENSE"
.IX Header "LICENSE"
.Vb 6
\& Permission is hereby granted, free of charge,  to any person obtaining a copy
\& of this software and associated documentation files (the "Software"), to deal
\& in the Software without restriction,  including without limitation the rights
\& to  use,  copy,  modify,  merge, publish, distribute, sublicense, and/or sell
\& copies  of  the Software,  and  to permit  persons  to whom  the Software  is
\& furnished to do so.
\&
\& The Software  is distributed in the hope that it will be useful,  but WITHOUT
\& ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
\& FOR A PARTICULAR PURPOSE.  Use  this  program  at  your  own  risk!
.Ve