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idea - encrypt/decrypt a file with the IDEA cipher


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


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 command 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.


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.



IDEA(1) Rev:  Thu Feb 15 14:42:47 GMT 2007