An OpenSSL-based file encryption and decryption utility
filecrypt - OpenSSL file encryption
Author M. Massenzio
Version 0.7.2 Updated 2020-04-30 Code bitbucket.org
Uses OpenSSL library to encrypt a file using a private/public key pair and a one-time secret.
A full description of the process can be found here.
See also this blog entry for more details.
Install directly from PyPi:
pip install crytto
Please note the package name (
filecrypt was conflicting with the
FileCrypt package name, and
crypto was already taken).
This requires OpenSSL to be installed on your machine:
sudo apt-get install openssl
Alternatively, clone the project from github and follow the instructions below:
git clone firstname.lastname@example.org:marco/filecrypt.git
Once cloned, you can try out functionality by packaging it as a
self-contained executable: use the
package.sh script to generate a
filecrypt.pyz self-extracting executable (make sure to set the
permission on *nix systems) and then you can encrypt/decrpyt files (see
the configuration section first).
```shell script # To encrypt ./filecrypt.pyz -o test.enc /path/to/my_plaintext.txt
./filecrypt.pyz -d -o /path/to/whatever.txt test.enc ```
Once all dependencies are installed:
pip install -r requirements.txt
tests can be run via:
See both the
package scripts for examples of how to
This uses a YAML file to describe the configuration; by default it
assumes it is in
/etc/filecrypt/conf.yml but its location can be
specified using the
The structure of the
conf.yml file is as follows:
keys: private: sample.pem public: sample.pub secrets: . store: keys.csv ## # Any option below is optional and can be omitted. # # Where to store the encrypted file; the folder MUST already exist and the user # have write permissions. Defaults to the current directory; can be overridden # using --out on the command line. # #out: /data/store/file # Whether to securely delete the original plaintext file; by default it is kept. # It can be overridden by using `--keep` when running `filecrypt`. True by default. shred: true # Optional logging configuration - mostly useful to # diagnose issues. Default is WARN level. logging: format: "%(asctime)s [%(levelname)-5s] %(message)s" level: WARN
public keys are a key-pair generated using the
openssl genrsa command; the encryption key used to actually encrypt
the file will be created in the
secrets folder, and afterward
encrypted using the
public key and stored in the location provided.
The name will be
nnnn will be a random
9999, that has not been already used for a
file in that folder.
The name of the secret passphrase can also be defined by the user, using
--secret option (it will be left unmodified):
if it does not exist a random secure one will be created, used for encryption, then encrypted and saved with the given path, while the plain-text temporary version securely destroyed; OR
if it is the name of an already existing file, it will be decrypted, used to encrypt the file, then left unchanged on disk.
NOTE we recommend NOT to re-use encryption passphrases, but always generate a new secret.
NOTE it is currently not possible to specify a plain-text
passphrase: we always assume that the given file has been encrypted
store file is a CSV list of:
"Original archive","Encryption key","Encrypted archive" 201511_data.tar.gz,/opt/store/pass-key-001.enc,201511_data.tar.gz.enc
a new line will be appended at the end; any comments will be left unchanged.
We do not provide the means to generate them (this will be done at a later stage), but for now they can be generated using:
openssl genrsa -out ./key.pem 2048 openssl rsa -in key.pem -out key.pub -outform PEM -pubout
their path can then be specified in the
Always use the
--help option to see the most up-to-date options
available; anyway, the basic usage is:
which will create a
my_secret.txt.enc file in the current directory,
unless a different one has been specified using the
out option in
A completely random and cryptographically secure key will have been
created; used; and then encrypted to the
secrets location, its full
path stored in the CSV keystore named in the
store option of the YAML
Finally, the plaintext version of this key will have been safely destroyed.
A more elaborate one (see the example configuration in
filecrypt --conf example_conf.yaml -s secret-key.enc plaintext.txt
will create an encrypted copy of the file to be stored as
/data/store/plaintext.txt.enc; the original file will not be
securely destroyed (using
shred); and the encryption key name and
location (the current directory, and
secret-key.enc) to be stored in
# Fragment of example_conf.yaml ... store: keys.csv out: /data/store shred: false
Specifying the encryption destination
By default, the encrypted filename has the same name as the plaintext
file, with the
.enc extension appended; and it is saved to either the
current directory or the
out location specified in the configuration
By using the
-o) option, it is possible to specify the
location of the output encrypted file, either absolute, or relative to
the current directory:
filecrypt -o mysecret.ser my_secret.doc
filecrypt -o secret/files/mysecret.ser my_secret.doc
Regardless of the means of specifying the input/outpup files, the full path to both files will always be used in the CSV keystore, regardless of whether a relative or absolute path was specified on the command line.
IMPORTANT >We recommend testing your configuration and command-line
options on test files:
shred erases files in a terminal way that is
not recoverable: if you mess up, you will lose data. > >You
have been warned.
To decrypt a file that has been encrypted using this utility, use the
decrypt -o example_conf.yaml -d plaintext.txt
If the encryption key (
-s) is not specified, then the
application will try and locate the plaintext file in the keystore
specified in the
conf.yaml using the
store: keys.csv ...
and derive the location of the encryption key from the entry, if one is found.
Please note that only the filename is used to lookup the key and so
two encrypted filenames in different directories but with the same
name will be assumed to have been encrypted with the same
passphrase file, is stored with its full path: if you move the
keys, or rename any of the folder in their path, you will have to update
keystore (or use the
-s flag when decrypting).
As with encryption, the
--out flag can be used to specify the output
file; otherwise, the current directory will be used.
The encrypted file will be left untouched: the
--keep flag may be
used, but will have no effect and the value of the
shred: option will
As the encrypted file is already cryptographically secure a simple
rm my_secret.doc.enc will be sufficient to guarantee privacy.
crytto supports encrypting a file using solely a Public
Key, and then the resulting ecnrypted file can be securely decrypted by
the owner of the Secret Key.
The main use case is to enable Alice to send Bob an encrypted file, once
Bob has given her a copy of his Public key; call the latter
and the file to share
my_secret.txt, then Alice can execute:
filecrypt --send --key bob.pub --out my-secret.ser my_secret.txt
after encryption, in the current directory there will be the following two new files:
the former is the encrypted contents of
my_secret.txt and the latter
the encrypted passphrase (leaving out the
--out argument would have
made the encrypted file's name
Those files can be both sent to Bob or, even better, provided to him
separately for added security; either way, upon receiving them, Bob can
run the following (we assume the
bob.pub was the private half of the
configured key pair that he keeps in his configuration
filecrypt -s pass-key-000854.enc --out alice_secret.txt -d my-secret.ser
(again, leaving out the
--out is useful when using the defaults, as
my_secret.txt.enc would have turned back into
in this case, the plaintext decrypted file would have been called
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