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Re^2: using a pipe

by drock (Beadle)
on Dec 30, 2005 at 03:16 UTC ( #519936=note: print w/replies, xml ) Need Help??


in reply to Re: using a pipe
in thread using a pipe

the passphrase is coming from a file on my unix box. gpg needs it as stdin like so: cat file |gpg. the password is in the file being opened or cat'ed. the stdout goes as stdin to the gpg decryption process. I am using the --passphrase-fd 0 option, but you still need to cat the file first.

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Re^3: using a pipe
by Celada (Monk) on Dec 30, 2005 at 06:00 UTC

    OK, so if I understand correctly,

    • The passphrase comes from file
    • The input (ciphertext) is in a file and gpg is given this file on its command line, and
    • The output goes into another file, again directed by a command line option.

    The first thing to notice is that the cat might be unnecesary. In other words,

    cat file | gpg
    should have the same effect as
    gpg <file

    but the second is simpler and eliminates an unnecesary pipeline stage. In either case the contents of file becomes the standard input for gpg. The only reason it would matter is if for some reason gpg really insisted that the passphrase-fd be a pipe.

    If that will do, then you may be able to reduce the whole thing down to something as simple as this:

    # Open the file open(FILE, "<file") || die; # Run gpg # Notice that we are not going to bother to try to # make the file become stdin to gpg. We're just going # to tell gpg which file descriptor it's already # accessible as. system("gpg", "--passphrase-fd=" . fileno(FILE), "--decrypt", "--output", "cleartext-filename", "ciphertext-filename"); close FILE;

    That's the true intent of gpg's passphrase-fd option: to give it a file descriptor for some other file besides the three stdio ones.

      ok thank you soo much, but I am getting this error upon a manual decryption it tell me this:
      C:\Program Files\GNU\GnuPG>gpg --passphrase-fd=ohiohea1th_is --decrypt + --output decrypted.txt tstfil e.asc Reading passphrase from file descriptor 0 ... You need a passphrase to unlock the secret key for user: "derek smith" 2048-bit ELG-E key, ID 985DB557, created 2005-12-30 (main key ID 4A673 +EF3) gpg: encrypted with 2048-bit ELG-E key, ID 985DB557, created 2005-12-3 +0 "derek smith" gpg: public key decryption failed: bad passphrase gpg: decryption failed: secret key not available
      ####### and with
      --passphrase-fd= open (PASS, "+<$pass") using . fileno(PASS) I get this error: Reading passphrase from file descriptor 3 ... You need a passphrase to unlock the secret key for user: "derek smith" 2048-bit ELG-E key, ID 985DB557, created 2005-12-30 (main key ID 4A673 +EF3) gpg: encrypted with 2048-bit ELG-E key, ID 985DB557, created 2005-12-3 +0 "derek smith" gpg: public key decryption failed: bad passphrase gpg: decryption failed: secret key not available Press any key to continue . . .
      ####### I know my passphrase is right b/c I executed:
      C:\Program Files\GNU\GnuPG>echo ohiohea1th_is|gpg --passphrase-fd=0 -- +decrypt --output decrypted.txt tstfile.asc Reading passphrase from file descriptor 0 You need a passphrase to unlock the secret key for user: "derek smith" 2048-bit ELG-E key, ID 985DB557, created 2005-12-30 (main key ID 4A673 +EF3) gpg: encrypted with 2048-bit ELG-E key, ID 985DB557, created 2005-12-3 +0 "derek smith" C:\Program Files\GNU\GnuPG>dir Volume in drive C is IBM_PRELOAD Volume Serial Number is 2863-8FD9 Directory of C:\Program Files\GNU\GnuPG 12/30/2005 02:49 PM <DIR> . 12/30/2005 02:49 PM <DIR> .. 12/30/2005 02:49 PM 15 decrypted.txt
      and it worked!

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