Explain how a digital signature is employed for providing a proof of authenticity (not integrity!) of a file.

  • For clarification This is not a homework but to increase personal knowledge – aziz alhaj Oct 23 '18 at 10:54
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    It is still too broad and shows not even an attempt of your own research, similar to your previous question. And given the tags you've set (i.e. malware and security-theater) it looks like that you not even understand the basics of what you are asking about, i.e. what a digital signature is, what authenticity and what integrity mean. – Steffen Ullrich Oct 23 '18 at 12:03
  • Can you prove authenticity if you can't prove integrity? – vidarlo Oct 23 '18 at 13:01
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    We expect that you have done at least a little research before asking here. When I google "digital signature authenticity" I get a large number of hits explaining these concepts. Please make sure that you have taken some steps of your own to answer these questions. – schroeder Oct 23 '18 at 13:39
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    @azizalhaj I do not understand your question about "fruit" – schroeder Oct 23 '18 at 14:34

A digital signature is generated with a private key and can be validated by anybody who has the public key. So, the digital signature of an object (e.g. a file) ensures that the one who generated the signature (the signer) is the one having the private key. This is called "signer authenticity". As the signature is tied to the content (i.e. a different object would have a different signature), it also verifies that the object (e.g. the file) has not been modified in its way to the receiver.

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