SCRYPT(1) BSD General Commands Manual SCRYPT(1)NAMEscrypt — encrypt and decrypt files.
SYNOPSISscrypt {enc | dec} [-M maxmem] [-m maxmemfrac] [-t maxtime] infile
[outfile]
DESCRIPTIONscrypt 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 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.
BSD May 24, 2009 BSD
