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luther7hrol

Member

Registered: 2013-12-09

Posts: 33

Can't PGP decrypt message

Hello,

I'm having problems with decrypting messages from a friend. I have his public key imported and signed as trustworthy, but I could't decrypt messages he encrypts with my key.
Enigmail says: "Error: signature verification failed", and by trying manually through gpg i get the following:

You need a passphrase to unlock the secret key for
user: "Luther Throl <luther7hrol@riseup.net>"
4096-bit RSA key, ID 4EDC5AAA, created 2014-01-23 (main key ID C874D86F)

gpg: problem with the agent: Line passed to IPC too long
gpg: encrypted with 4096-bit RSA key, ID 4EDC5AAA, created 2014-01-23
      "Luther Throl <luther7hrol@riseup.net>"
gpg: public key decryption failed: Operation cancelled
gpg: decryption failed: No secret key

Last edited by luther7hrol (2014-01-26 22:48:00)

/dev/zero

Member

From: Melbourne, Australia

Registered: 2011-10-20

Posts: 1,247

Re: Can't PGP decrypt message

Hello,

I'm having problems with decrypting messages from a friend. I have his public key imported and signed as trustworthy, but I could't decrypt messages he encrypts with my key.

The way you've worded this suggests you're not clear on how public/private keypair systems work. Having your friend's public key is irrelevant to whether or not your friend can send you encrypted messages. To send you encrypted messages, there is only one requirement: that you have your private key kept secret on your destination machine, and your friend has access to your public key from their machine.

Enigmail says: "Error: signature verification failed", and by trying manually through gpg i get the following:

You need a passphrase to unlock the secret key for
user: "Luther Throl <luther7hrol@riseup.net>"
4096-bit RSA key, ID 4EDC5AAA, created 2014-01-23 (main key ID C874D86F)

gpg: problem with the agent: Line passed to IPC too long
gpg: encrypted with 4096-bit RSA key, ID 4EDC5AAA, created 2014-01-23
      "Luther Throl <luther7hrol@riseup.net>"
gpg: public key decryption failed: Operation cancelled
gpg: decryption failed: No secret key

This doesn't say a lot without knowledge of what commands you used to generate the key and decrypt the message.

When I was learning to use GPG/PGP, I set up some dummy accounts on my machine for fake users called Alice, Bob and Eve. Then I did exercises like setting up key pairs for Alice and Bob, and have Bob create a signed message encrypted for Alice, and then see what information Eve can discover when "she" intercepts the message. You might wish to consider doing similar exercises.

luther7hrol

Member

Registered: 2013-12-09

Posts: 33

Re: Can't PGP decrypt message

I am sort of new in PGP. But I am reading and eager to learn. The command I used to decrypt the message was simply "gpg" without arguments, and then pasted the encrypted text.
I created and uploaded my keys with seahorse, and then started reading about gpg in command line. My assumption was if I create my own key, sign it and upload publicly, that it will have the other, secret key, created and stored somewhere in disk, without me having to manually cope with it. I was obviously, wrong.

EDIT: I did it, using pure gpg command line, and using this way I managed to understand how key really function. I generated a new key pair and was able to decrypt the message I encrypted, the problem was in using seahorse and enigmail which do not cover the all needed steps within.

Thank you.

Last edited by luther7hrol (2014-01-27 15:57:47)