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SCRYPT(1)		FreeBSD	General	Commands Manual		     SCRYPT(1)

NAME
     scrypt -- encrypt and decrypt files.

SYNOPSIS
     scrypt {enc | dec | info} [-f] [-M	maxmem]	[-m maxmemfrac]	[-t maxtime]
	    [-P] infile	[outfile]
     scrypt --version

DESCRIPTION
     scrypt enc	encrypts infile	and writes the result to outfile if specified,
     or	the standard output otherwise.	The user will be prompted to enter a
     passphrase	(twice)	to be used to generate a derived encryption key.

     scrypt dec	decrypts infile	and writes the result to outfile if specified,
     or	the standard output otherwise.	The user will be prompted to enter the
     passphrase	used at	encryption time	to generate the	derived	encryption
     key.

     scrypt info provides information about the	encryption parameters used for
     infile.

     If	-P is not given, scrypt	reads passphrases from its controlling termi-
     nal, or failing that, from	stdin.	Prompts	are only printed when scrypt
     is	reading	passphrases from some terminal.	 If -P is given, then scrypt
     does not print any	prompts, and reads a passphrase	from stdin.

OPTIONS
     -f		    Force the decryption to proceed even if it is anticipated
		    to require an excessive amount of memory or	CPU time.

     -M	maxmem	    Use	at most	maxmem bytes of	RAM to compute the derived en-
		    cryption key.

     -m	maxmemfrac  Use	at most	the fraction maxmemfrac	of the available RAM
		    to compute the derived encryption key.

     -t	maxtime	    Use	at most	maxtime	seconds	of CPU time to compute the de-
		    rived encryption key.

     -P		    Always read	passphrase from	stdin, and do so only once
		    even when encrypting.  This	cannot be used if infile is
		    also stdin (aka '-').

     --version	    Print version of scrypt, and exit.

     In	scrypt enc, the	memory and CPU time limits are enforced	by picking ap-
     propriate parameters to the scrypt	key derivation function.  In scrypt
     dec, the memory and CPU time limits are enforced by exiting with an error
     if	decrypting the file would require too much memory or CPU time.

EXIT STATUS
     The scrypt	utility	exits 0	on success, and	>0 if an error occurs.

     Note that if the input encrypted file is corrupted, scrypt	dec may	pro-
     duce output prior to determining that the input was corrupt and exiting
     with a non-zero status; so	users should direct the	output to a safe loca-
     tion and check the	exit status of scrypt before using the decrypted data.

SEE ALSO
     Colin Percival, Stronger Key Derivation via Sequential Memory-Hard
     Functions,	May 2009, Presented at BSDCan'09.

HISTORY
     The scrypt	utility	was written in May 2009	by Colin Percival as a demon-
     stration of the scrypt key	derivation function.  The scrypt key deriva-
     tion function was invented	in March 2009 by Colin Percival	in order to
     allow key files from the tarsnap backup system to be passphrase pro-
     tected.

FreeBSD	13.0		      September	11, 2019		  FreeBSD 13.0

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXIT STATUS | SEE ALSO | HISTORY

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