I am looking for help to figure out how to tie a secret key with a passphrase to encrypt a file using GPG.
I had tested many option (--encrypt, --sign, --recipient, --symmetric, etc), but in all of them, I was able to decrypt the file typing only the passphrase, even in a machine where I don't have the public nor the private/secret keys.
Is there a way to force the user to have the secret key and to be asked to type the passphrase?
I am open to any other idea that force a double security check to decrypt the protected file.
Thanks,
during decryption process type
gpg --allow-secret-key-import --import PrivateKey.gpg
after that prompt will appear for passphrase, enter the passphrase and after that decrypt file using
gpg filename.gpg
Related
I am attempting to create a GCP Signed URL using instructions here. When I run the gsutil command to create my signed-url I am immediately prompted to enter my "Keystore password". So this:
gsutil signurl -d 10m my-private-key.json gs://my-storage-bucket/index.html
results in this:
Keystore password: [I enter a wrong password]
Encountered an error while refreshing access token. If you are using a service account,
please verify that the gs_service_key_file field in your config file(s), /Users/my-user/.boto, /Users/my-user/.config/gcloud/legacy_credentials/my-gcp-user-email/.boto, is correct.
To be frank I haven't the slightest what my keystore password is or even what keystore it is talking about. Is it a local Mac keystore? Is it a GCP keystore? Something else?
Any clues as to what keystore is being referenced or even how I might go about changing the password to something else are appreciated.
Here's what the signurl documentation says:
gsutil signurl [-c <content_type>] [-d <duration>] [-m <http_method>] \
[-p <password>] [-r <region>] keystore-file url...
[...]
gsutil signurl <private-key-file> gs://some-bucket/some-object/
The signurl command uses the private key for a service account (the
'' argument) to generate the cryptographic signature
for the generated URL. The private key file must be in PKCS12 or JSON
format. If the private key is encrypted the signed url command will
prompt for the passphrase used to protect the private key file
(default 'notasecret'). For more information regarding generating a
private key for use with the signurl command please see the
Authentication documentation.
So, the first argument after signurl, which in your question is my-private-key.json, is the keystore. It contains a private key.
Usually we encrypt private keys so that they are harder to steal. So when you created my-private-key.json, you were probably asked for a passphrase, and the passphrase was used to encrypt the private key.
But gsutil needs to decrypt the private key before it can use it to sign your URL. So gsutil needs the passphrase that was used to encrypt the private key. You need to enter that passphrase at the Keystore password: prompt. If you don't remember the passphrase you used to create the private key, then you will need to create a new private key.
(Perhaps the passphrase is in fact “notasecret”?)
I am trying to get a better understanding of what is going on with gpg.
If you have a file and sign it: gpg --sign file.txt
you can verify it with: gpg --verify file.txt.gpg
when you get a successful output: gpg: Signature made...
But when you sign AND encrypt a file: gpg --encrypt --sign -r test#email.com file.txt
and then run --verify on the encrypted file I get: gpg: verify signatures failed: Unexpected error
I know that I can just call --decrypt on the file and it will verify and decrypt it, but what if I want to verify only?
I figured out the answer to this and then some. So I am going to add some additional information for clarity.
First of all, I realize based on the last line to this answer that gpg uses SIGN THEN ENCRYPT. Which means calling --verify or any variation to verify on an encrypted file will just output gpg: verify signatures failed: Unexpected error. This happens because the signature is "hidden" in encryption, so when you try to call --verify on the file, it will not see a signature.
Secondly, the --decrypt flag will both decrypt the file AND if the file is signed, verify it too.
Here is what --decrypt is doing. It looks at your default secret keyring secring.kbx in ~/.gnupg to use a secret key for decrypting the file. Then after it is decrypted, it looks at your default public keyring pubring.kbx in the folder ~/.gnupg and tries to verify the signature on the file, if it has one.
If it has no signature, it will just decrypt the file.
If it has a signature, but you don't have the public key, it will decrypt the file but it will fail to verify the signature.
If it has a signature and you have the public key, it will decrypt and verify.
With that said, there is no reason to verify a signed file BEFORE decrypting it.
Thirdly, as an added bonus, you can also specify a keyring you want to use for decrypting and verification. Say you want to use a temporary keyring to verify signatures or for what ever reason you want a temporary keyring to decrypt the message too.
You can specify the keyrings for --decrypt to use with the following command:
gpg --secret-keyring path/to/temp/secring.kbx --keyring path/to/temp/pubring.kbx --decrypt file.txt.gpg
This command will look for the secret ring and public ring at the specified paths in order to use those rings for decryption and verification instead of the default rings found in ~/.gnupg. Want to use a default ring with a temp ring? Just omit the flag and path to the ring you want defaulted.
All in all, for encrypted and signed files, if you want to decrypt and verify that file, you need to make sure that the private key for decryption is in your secret keyring and the public key for verification is in your public keyring.
One thing to understand about GPG encrypt & sign, which isn't very well explained, is that the signature can only be verified by the recipient.
Suppose Alice encrypts a file to send to Bob. She will encrypt with Bob's public key, and sign with her private key.
gpg --output encrypted.gpg --recipient B0B0000000000000000000000000000000000000 --armor --sign --default-key A11CE00000000000000000000000000000000000 --encrypt file-to-encrypt.txt
There's no way now for Alice, or anyone who does not have Bob's private key, to verify the signature.
Now Bob will decrypt the file. If it is signed, he'll see information about the signature in the output:
$ gpg --decrypt encrypted.gpg > decrypted.txt
gpg: encrypted with 2048-bit RSA key, ID D83A4C12B3840EBA, created 2020-09-24
"Alice <alice#example.com>"
gpg: Signature made 09/28/20 13:16:47 Eastern Daylight Time
gpg: using RSA key A11CE00000000000000000000000000000000000
gpg: Good signature from "Alice <alice#example.com>" [ultimate]
Note the Signature made and Good signature lines in the output.
$ gpg --encrypt --sign -r test#email.com file.txt
After file.txt.gpg generated, try the command below:
$ gpg -d file.txt.gpg
or just execute:
$ gpg file.txt.gpg
I want to encrypt a file using a passphrase, which I did using gpg --gen-key to create a key (I used the default options) in the command line, and I also go this to work in an "automated" way without user interaction.
But, I'd like to specify the passphrase stored in a separate file. This is what I'm running now:
gpg --batch --gen-key "D:\Staging\FileContainingKeySettings.txt"
And what's in the file called "FileContainingKeySettings.txt" is this:
%echo Generating a default key
Key-Type: default
Subkey-Type: default
Name-Real: PBJ
Name-Comment: test
Name-Email: PBJ#pbj.com
Expire-Date: 0
Passphrase:blah
%commit
%echo done
So that works and generates the key.
Then I call this:
gpg --batch --yes -r PBJ --output D:\Staging\newEncryptedFile.txt --encrypt
D:\Staging\textfiletobeencrypted.csv
And this works too.
So now I have 1 problem and 1 question. The problem is that I need to specify the passphrase to reference a file that looks like this (but much longer):
-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: BCPG v1.47
[encoding]
-----END PGP PUBLIC KEY BLOCK-----
instead of using the password where I wrote "blah"^, and I haven't found a way to do this online or from any other team members around me. How can I do that?
Question: I also notice now that the file I was sent containing the encryption key reads at the top
" -----BEGIN PGP PUBLIC KEY BLOCK-----"
...which says it uses PGP (but I am using gpg). I know that gpg and pgp are different and read about them, but can I even do what I'm trying to do using gpg to encrypt a file with a key that was apparently generated with pgp?
(in Windows)
UPDATE: Now I may have gotten this working, although I still have to validate by having the other person decrypt the message (it works fine when I decrypt it). Silly I didn't think of this code change earlier when I've actually tried this before...I simply changed my cmd call from this part:
gpg --batch --gen-key "D:\Staging\FileContainingKeySettings.txt"
to this instead, specifying the passphrase file location here instead:
gpg --batch --passphrase "D:\Staging\FileWithActualKey.txt --gen-key
"D:\Staging\FileContainingKeySettings.txt"
and I took the password line out of the file "FileContainingKeySettings" altogether. I haven't tested this by having the other person decrypt it yet on their end...I hope it worked. At least I didn't get error. But now when I run this line again to actually do encryption, it works:
gpg --batch --yes -r PBJ --output D:\Staging\newEncryptedFile.txt --encrypt
D:\Staging\textfiletobeencrypted.csv
I'm trying to decrypt a file using gpg and getting this error:
$ gpg --no-tty --batch --verbose --decrypt --passphrase foo file.enc
Version: GnuPG v1.4.11 (GNU/Linux)
gpg: armor header:
gpg: CAST5 encrypted data
gpg: encrypted with 1 passphrase
gpg: decryption failed: Bad session key
I tried to reload the gpg agent, no luck:
$ gpgconf --reload gpg-agent
How to solve that?
For the record, if somebody will encounter this problem, too:
The problem was, that the encryption was done using gpg version 1.4.11 and the decryption was using gpg version 2.0.22.
After upgrading the encryption to gpg2 (2.0.17), everything worked fine.
I found this, which seems to be the magic that I could not find anywhere else:
Try adding --pinentry-mode loopback to your command. Maybe there is a
problem with your installation / pinentry program so that it does not start or
you are accidentally using a dummy / test pinentry which provides the wrong
passphrase.
I encrypted my file with a passphrase file in batch mode. When I tried to decrypt my file I got the dreaded "bad session key" message.
I created a passphrase file with Vim for Windows, and Vim left \r\n at the end of the text line even though I did not hit carriage return. gpg ignored the \n but retained the \r as part of the passphrase!
Vim for Windows can be induced to not leave \r\n, but it is easier to just use Notepad without a carriage return at the end of line. Best to check your passphrase file with a hexdump to be sure. There are other ways to get hurt by \r\n issues when supplying the passphrase using the command line, so be alert to it.
My collegue has sent me by email his gpg private key generated by:
gpg --export-secret-keys --armor <id> > private_key.asc
instead of his gpg public key as (I supposed) recoverable by:
gpg --armor --output public_key.gpg --export
Is now his gpg key "corrupted", in the sense that having sent it by email its integrity is no more trusted?
Should he revoke that key?
The worst case assumption is that someone listened to the mail and is right now trying to guess the passphrase chosen by your colleague. The safest (and imho correct) thing to do is to revoke the key and generate a new one.