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41 lines
1.9 KiB
Plaintext
41 lines
1.9 KiB
Plaintext
The MD5 module allows you to use the RSA Data Security
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Inc. MD5 Message Digest algorithm from within Perl
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programs.
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A new MD5 context object is created with the new
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operation. Multiple simultaneous digest contexts can be
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maintained, if desired. The context is updated with the
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add operation which adds the strings contained in the LIST
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parameter. Note, however, that add('foo', 'bar'),
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add('foo') followed by add('bar') and add('foobar') should
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all give the same result.
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The final message digest value is returned by the digest
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operation as a 16-byte binary string. This operation
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delivers the result of add operations since the last new
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or reset operation. Note that the digest operation is
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effectively a destructive, read-once operation. Once it
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has been performed, the context must be reset before being
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used to calculate another digest value.
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Several convenience functions are also provided. The
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addfile operation takes an open file-handle and reads it
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until end-of file in 1024 byte blocks adding the contents
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to the context. The file-handle can either be specified by
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name or passed as a type-glob reference, as shown in the
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examples below. The hexdigest operation calls digest and
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returns the result as a printable string of hexdecimal
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digits. This is exactly the same operation as performed by
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the unpack operation in the examples below.
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The hash operation can act as either a static member
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function (ie you invoke it on the MD5 class as in the
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synopsis above) or as a normal virtual function. In both
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cases it performs the complete MD5 cycle (reset, add,
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digest) on the supplied scalar value. This is convenient
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for handling small quantities of data. When invoked on the
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class a temporary context is created. When invoked through
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an already created context object, this context is used.
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The latter form is slightly more efficient. The hexhash
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operation is analogous to hexdigest.
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