lemma

README

lemma

lemma is a command-line utility that uses lemma to provide authenticated symmetric cryptography for small files on disk.

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Usage

Usage:
    lemmacmd command [flags]

The commands are:
    encrypt     encrypt a file on disk
    decrypt     decrypt a file on disk

The flags are: 
    in          path to file to be read in
    out         path to file to be written out
    keypath     path to base64-encoded 32-byte key on disk, if no path is given, a passphrase is used
    itercount   if a passphrase is used, iteration count for PBKDF#2, the default is 524288

Example

lemmacmd encrypt -in foo.txt -out foo.txt.enc
lemmacmd decrypt -in foo.txt.enc -out foo.txt

Performance

The following benchmarks were run to calculate wall-clock time to encrypt files of various sizes. The benchmarks were run on a machine with the following specs: 2x Intel Xeon E5-2680 2.8Ghz and 32GB RAM.

	1 MB	10 MB	100 MB
Time	0.98s	1.33s	4.85s

Technical Details

• Can be used with either a randomly generated key on disk or a passpharse.
• When used with a passphrase, the key derivation function (KDF) is HMAC-SHA-256 based PBKDF#2 with a randomly generated 128-bit salt and 524,288 iterations (tunable).
• The symmetric cipher used is Salsa20 with Poly1305 as the message authentication code (MAC) from the Networking and Cryptography (NaCl) library.