[CentOS] gpg can't decrypt message

Wed Oct 1 16:07:04 UTC 2014
Valeri Galtsev <galtsev at kicp.uchicago.edu>

On Wed, October 1, 2014 10:19 am, Nicolas Thierry-Mieg wrote:
>
>
> On 10/01/2014 05:16 PM, Nicolas Thierry-Mieg wrote:
>> On 10/01/2014 04:58 PM, Tim Dunphy wrote:
>>> Hey guys,
>>>
>>>
>>>   Having a little gpg issue I was wondering if someone could help me
>>> with.
>>>
>>>   A friend of mine sent me an encrypted message. So I searched online
>>> and
>>> found a a set of keys that correspond with his email address. And
>>> imported
>>> them. But when I go to decrypt the message, this is what I get:
>>>
>>> [root at ops:~] #gpg --decrypt roger-message
>>> gpg: encrypted with 2048-bit RSA key, ID 9617EA5C, created 2014-10-01
>>>        "Roger Sherman <rsherman at viddler.com>"
>>> *gpg: encrypted with RSA key, ID 9A41C766*
>>> *gpg: decryption failed: secret key not available*
>>>
>> <snip>
>>> So maybe I just didn't import the right key? Or do you think the
>>> message
>>> wasn't sent correctly? Who's the dummy here? Me or him? :)
>>
>> looks like he encrypted with HIS public key. So you need his private key
>> to decrypt, obviously you don't have that.
>> I believe it's the other way around: he should encrpyt with your public
>> key, then you are the only person capable of decrypting (with your
>> private key).
>
> BTW what would be the point of encrypting, if anyone can just grab a key
> online and decrypt? :-)
>

If you can decrypt his message with his public key, this tells you that
the person who has access to secret key of the pair was the one who
encrypted the message. This ensures that you know that he is the one who
indeed sent this message.

Somebody, correct me...

Valeri

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Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247
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