man.postnix Miscellaneous man pages of Plan 9 related material

     IDEA(1)                                                   IDEA(1)

     NAME
          idea - encrypt/decrypt a file with the IDEA cipher

     SYNOPSIS
          idea [ -e ] [ -d ] key [ datafile ]

     DESCRIPTION
          Idea encrypts or decrypts data using the IDEA (International
          Data Encryption Algorithm) cipher first proposed by Xuejia
          Lai and James Massey in 1990.

          The -e option encrypts the data and the -d option decrypts
          the data. Exactly one of these must be specified on the com-
          mand line.

          The key is any 16 character string which is used as the key
          for both encryption and decryption.

          The data to be encrypted/decrypted is either in datafile or
          is read from standard input. If no input file is given, the
          output from idea is always sent to standard output. For
          encryption, if an input file is specified the output is sent
          to a file with the name datafile.id. For decryption, if an
          input file is specified it should have a .id extension and
          the output is sent to a file whose name is that of datafile
          without the .id extension.

     EXAMPLES
          Encrypt the data in the file A10076795.gz:

               idea -e 'abcd2345 $+*LMNO' A10076795.gz

          The encrypted data is put in the file A10076795.gz.id. Once
          this file is transmitted, the receiver can then decrypt it,
          as long as he has the key, with:

               idea -d 'abcd2345 $+*LMNO' A10076795.gz.id

          The decryped data is put in the file A10076795.gz.

          Note that the quotes around the key are interpreted by the
          shell and simply delimit the key string.

     SOURCE
          /appl/cmd/idea.b
          /utils/idea/idea.c

     Page 1                       Plan 9            (printed 12/20/25)