DragonFly On-Line Manual Pages

SCRYPT(1)              DragonFly General Commands Manual             SCRYPT(1)

NAME
     scrypt - encrypt and decrypt files.

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

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.

OPTIONS
     -M maxmem      Use at most maxmem bytes of RAM to compute the derived
                    encryption 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
                    derived encryption key.

     In scrypt enc, the memory and CPU time limits are enforced by picking
     appropriate 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
     produce 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 location 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
     demonstration of the scrypt key derivation function.  The scrypt key
     derivation function was invented in March 2009 by Colin Percival in order
     to allow key files from the tarsnap backup system to be passphrase
     protected.

DragonFly 6.5-DEVELOPMENT        May 24, 2009        DragonFly 6.5-DEVELOPMENT