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How to pass the passphrase into GPG for decryption

Kristopher Birdyshaw

February 07, 2012 18:05

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Hi Guys!

I have a good one for you....I have a file that is encrypted that I am decrypting. I have the newest version of GPG for windows installed on the machine. I also have the private key used for decryption in the key ring. I am able to run the command line and get the passphrase prompt. Once I input the passphrase all works well...so I know the command is just fine. However, since we want this automated, I want to be able to pass in the passphrase so no one has to manually enter it each time the process is run.

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14 comments

• 0
  
  Mike O'Quinn February 07, 2012 18:05

  I don't see you using the RunExe workflow task here. How are you calling your GPG (is this the same as PGP?) from Centerprise?

• 0
  
  Mike O'Quinn February 07, 2012 18:06

  Hi Mike,
  
  I have just now figured out the issue. I appear to have not saved the workflow before all of the gpg modifications. I have done so now. Just to give you guys some insight if the question comes up again, the command should read...
  
  --batch --yes --passphrase <passphrase> -o <output file location/name or parameter> -d <decrypt file location/name or parameter>
  
  For my instance, I have used parameters to feed in to the command line.
  
  Also, yes, GPG is like PGP....only that GPG is freeware and is more flexible.

• 0
  
  Laurence Duggan March 26, 2012 14:41

  in case you were still have problems with this, i figured this out about 2 weeks ago...

  the best way to do this is to write a Batch file.  it doesn't matter whether you're using gpg4win or gnupg in order to execute the decryption.  PGP and GPG are both handled by these programs.

  There a few important things to know when decrypting through command-line or in a .BAT file.

  First - you need to pipe the passphrase using ECHO

  Second - you MUST point to your private and public key rings.  When you use the command-line, this isn't necessary because the command line auto-detects your default keyrings.  But when using a 3rd party application like Centerprise, or a .bat file, you have to point to you public AND private key-rings to make it work.

  Third - when using centerprise, simply point to the .bat file, run IN the location where the files are, and simply leave the arguments in the "run program" task blank.

  Here's my command-line using a .bat in the "run program" task with Centerprise:

   

  BEGIN COMMANDS:

  echo YOURpassPHRASE|gpg --keyring "C:\directory\filepath" --secret-keyring "C:\directory\filepath" --batch --yes --passphrase-fd 0 -o DesiredOutputFileName.extension -d TargetEncrypted File

  END COMMANDS:

  a few notes:

  -The only place you type your passphrase is after echo.  the --passphrase is an option.

  -key ring directory/filenames must be wrapped in quotes

  - the "--passphrase-fd 0" is a must

  - the "decryption" or "-d" is the only command in this entire command line.  everything else is a switch or option.

  - after typing "-d" you do not need to wrap the filepath in quotes, because you've already targetted the "RUN-IN" within the centerprise run program task

   

  Hope this helps.

  -Laurence

   

   

• 0
  
  Kristopher Birdyshaw March 26, 2012 15:37

  Hi Laurence,

  Thanks for the comment. This should also be very helpful. The comment right before yours shows what I did to make it work. Since I am using GPG, I did not require the use of a .bat file, due to centerprise being able to call the program natively. The other biggest difference in both of our commands was the use of the echo command. Fortunately, I didn't require the use of that (again, because I didn't use the .bat file).

  One thing I did have to change, however, was for centerprise to expect a different success number. I think it defaults to 0 or 1, and it should have been 2 or 3...I forget.

   

  Thanks again. It's nice to see that people are looking at these!

   

  Kris.

• 0
  
  翊超 张 October 23, 2013 05:36

  Mike Oquinn.you solve my problem,thank you very much

• 0
  
  Rodney James Sturtz Jr October 25, 2013 22:50

  i was looking for help w/ this issue.  altho the answer was found here it wasnt as clear as i would've liked, so...

   

  gpg --passphrase THISISTHEPASSPHRASE -o C:\OUTPUTFILENAME -d C:\FILETODECRYPT.GPG

   

  hope this helps

   

  jim

• 0
  
  Virendrasingh Thakur October 31, 2013 14:39

  hi Mike,

  I get and error that batch is not recognized as internal or external command when I run the below. Can you please help?

  --batch --yes --passphrase <passphrase> -o <output file location/name or parameter> -d <decrypt file location/name or parameter>

• 0
  
  Virendrasingh Thakur October 31, 2013 14:47

  hi Jim,

  when I run the below command it shows the message 'Reading passphrase from file descriptor 0 ...' and then if i press enter it throws error as bad passphrase even though it works when I manual pass the passphrase with basic commands

• 0
  
  Virendrasingh Thakur October 31, 2013 14:48

  gpg --passphrase THISISTHEPASSPHRASE -o C:\OUTPUTFILENAME -d C:\FILETODECRYPT

• 0
  
  Jim Sturtz October 31, 2013 15:09

  Hi Viren,

  I'm using XP, so am not sure the following commands will work for you.

  drop to dos and do it manually.

  right click over the black command window, then pick select all

  move cursor up to the title bar of the command window, right click, select edit, then copy.

  having done that, if you open an editor and 'paste' you should have the exact command (along with other stuff) in the editor that worked.

  delete out everything except the command line for the gpg.  save the file to your testing folder as a .bat or .cmd file.

  try running that file.  that should work exactly like what you typed in.  

  think that will get you going.

  hgh.

  jim

   

   

   

   

   

• 0
  
  Virendrasingh Thakur November 01, 2013 05:40

  that didn't work. 

• 0
  
  Jim Sturtz November 01, 2013 06:20

  hmm.  could you post the exact .bat/.cmd file except disguise the passphrase, make it be xxxx or somesuch, but show the rest?

  jim

• 0
  
  Virendrasingh Thakur November 05, 2013 06:21

  the below command given by Laurence worked. Thanks you Laurence for that. Also, I need to call it from Third party application lets see how it works. Thanks Jim for the help offered, I appreciate it.

  echo YOURpassPHRASE|gpg --keyring "C:\directory\filepath" --secret-keyring "C:\directory\filepath" --batch --yes --passphrase-fd 0 -o DesiredOutputFileName.extension -d TargetEncrypted File

  Thanks,

  Viren

• 0
  
  Shreyas Kulkarni October 22, 2019 13:54

  Hi All,

  I am trying to automate a decryption process. And I am totally new to Powershell. I have installed GPG4win in my system and will be using Public/Private key for encryption.

  Could someone please help to share the sample script created for the same.

  Thanks,

  Shreyas