pegh

pegh is a file encryption tool using passwords and authenticated encryption. It is simple, secure, and returns proper exit codes so you can tell whether encryption or decryption failed or not.

pegh is Klingon for secret

Usage

# encrypt file.txt to file.txt.pegh with password SUPER_SECRET_1942
pegh -e SUPER_SECRET_1942 <file.txt >file.txt.pegh

# decrypt file.txt.pegh to file.txt with password SUPER_SECRET_1942
pegh -d SUPER_SECRET_1942 <file.txt.pegh >file.txt

The easiest way to scale cost/time it takes for bruteforcing is simply to continue doubling -s, on both encryption and decryption commands.

full help:

$ pegh -h
usage: pegh [-demNrpshV] password
 -e            encrypt stdin to stdout, default mode
 -d            decrypt stdin to stdout
 -m <max_mb>   maximum megabytes of ram to use when deriving key from password
               with scrypt, applies for encryption AND decryption, must
               almost linearly scale with -N, if too low operation will fail,
               default: 64
 -N <num>      scrypt parameter N, only applies for encryption, default 32768
               this is rounded up to the next highest power of 2
 -r <num>      scrypt parameter r, only applies for encryption, default 8
 -p <num>      scrypt parameter p, only applies for encryption, default 1
 -s <num>      multiplication factor to apply to both -N and -m for easy
               work scaling, rounded up to the next highest power of 2,
               default: 1
 -h            print this usage text
 -V            show version number and format version support then quit

For additional info on scrypt params refer to:
    https://blog.filippo.io/the-scrypt-parameters/
    https://tools.ietf.org/html/rfc7914#section-2

pegh file format

pegh implements a simple versioned file format so encryption parameters can change in the future. Numbers here are inclusive 0-based byte array indices, 0th byte is always version number, everything else depends on version number, currently only version 0 exists.

Version 0, scrypt key derivation, aes-256-gcm encryption, 51 byte header, 16 byte footer:

indices	format	value interpretation
0	8 bit unsigned byte	pegh file format version
1-4	32 bit unsigned integer in big endian order	scrypt N parameter
5	8 bit unsigned byte	scrypt r parameter
6	8 bit unsigned byte	scrypt p parameter
7-38	32 randomly generated bytes	scrypt key derivation seed
39-50	12 randomly generated bytes	AES-256-GCM IV
51-X	any number of bytes	AES-256-GCM encrypted data
(X+1)-(X+16)	16 bytes, always last 16 bytes in file	AES-256-GCM authentication tag

License

AGPLv3 for now, message me if you have a problem with this