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