NAME

SHA - Perl interface to the NIST Secure Hash Algorithm

SYNOPSIS

use SHA;

$context = new SHA;
$context->reset();

$context->add(LIST);
$context->addfile(HANDLE);

$digest = $context->digest();
$string = $context->hexdigest();

DESCRIPTION

The SHA module allows you to use the NIST SHA message digest algorithm from within Perl programs.

A new SHA context object is created with the new operation. Multiple simultaneous digest contexts can be maintained, if desired. The context is updated with the add operation which adds the strings contained in the LIST parameter. Adding two strings separately is equivalent to adding their concatenation: add('foo', 'bar') produces the same effect as add('foo'), add('bar'), which in turn produces the same effect as add('foobar').

The final message digest value is returned by the digest operation as a 16-byte binary string. This operation delivers the result of operations since the last new or reset operation. Once the operation has been performed, the context must be reset before being used to calculate another digest value.

Two convenience functions are also provided. The addfile operation takes an open file-handle and reads it until end-of file in 8192-byte blocks adding the contents to the context. The hexdigest operation calls digest and returns the result as a printable string of hexdecimal digits in eight-digit groups.

EXAMPLE AND VALIDATION

$sha = new SHA;

print "EXPECT:   0164b8a9 14cd2a5e 74c4f7ff 082c4d97 f1edf880\n";

$sha->reset();
$sha->add("abc");
print "RESULT 1: " . $sha->hexdigest() . "\n";

$sha->reset();
$sha->add("a", "bc");
print "RESULT 2: " . $sha->hexdigest() . "\n";

$sha->reset();
$sha->add("ab", "c");
print "RESULT 3: " . $sha->hexdigest() . "\n";

$sha->reset();
$sha->add("a", "b", "c");
print "RESULT 4: " . $sha->hexdigest() . "\n";

$sha->reset();
$sha->add("ab");
$sha->add("c");
print "RESULT 5: " . $sha->hexdigest() . "\n";

$sha->reset();
$sha->add("a");
$sha->add("bc");
print "RESULT 6: " . $sha->hexdigest() . "\n";

$sha->reset();
$sha->add("a");
$sha->add("b");
$sha->add("c");
print "RESULT 7: " . $sha->hexdigest() . "\n";

The above example will produce the output

EXPECT:   0164b8a9 14cd2a5e 74c4f7ff 082c4d97 f1edf880
RESULT 1: 0164b8a9 14cd2a5e 74c4f7ff 082c4d97 f1edf880
RESULT 2: 0164b8a9 14cd2a5e 74c4f7ff 082c4d97 f1edf880
RESULT 3: 0164b8a9 14cd2a5e 74c4f7ff 082c4d97 f1edf880
RESULT 4: 0164b8a9 14cd2a5e 74c4f7ff 082c4d97 f1edf880
RESULT 5: 0164b8a9 14cd2a5e 74c4f7ff 082c4d97 f1edf880
RESULT 6: 0164b8a9 14cd2a5e 74c4f7ff 082c4d97 f1edf880
RESULT 7: 0164b8a9 14cd2a5e 74c4f7ff 082c4d97 f1edf880

provided that the implementation is working correctly.

NOTE

The SHA extension may be redistributed under the same terms as Perl. The SHA code is in the public domain. It was heavily modified by Uwe Hollerbach following the implementation by Peter Gutmann.

AUTHOR

The SHA interface was written by Uwe Hollerbach uh@alumni.caltech.edu following the MD5 interface written by Neil Winton (N.Winton@axion.bt.co.uk).