Make PyCryptodome an optional dependency

README.md

@@ -46,6 +46,7 @@ The mandatory dependencies of this library are:
 Optional dependencies are:
 
 * [mpmath](https://mpmath.org/), for *beta_ratio* and *beta_oddsratio*
+* [PyCryptodome](https://www.pycryptodome.org/), for *pickle_write_encrypted* and *pickle_read_encrypted*
 * [rpy2](https://rpy2.github.io/), with R packages:
 	* [BFpack](https://cran.r-project.org/web/packages/BFpack/index.html), for *bayesfactor_afbf* (*RegressionResult.bayesfactor_beta_zero*)
 	* [logistf](https://cran.r-project.org/web/packages/logistf/index.html), for *PenalisedLogit*

yli/io.py

@@ -14,10 +14,6 @@
 #   You should have received a copy of the GNU Affero General Public License
 #   along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
-from Crypto.Cipher import AES
-from Crypto.Protocol.KDF import scrypt
-from Crypto.Random import get_random_bytes
-
 import getpass
 import io
 import lzma
@@ -32,6 +28,10 @@ def pickle_write_encrypted(df, fname):
 	Password is derived using scrypt KDF
 	"""
 	
+	from Crypto.Cipher import AES
+	from Crypto.Protocol.KDF import scrypt
+	from Crypto.Random import get_random_bytes
+	
 	# Get random salt
 	salt = get_random_bytes(16)
 	
@@ -69,6 +69,9 @@ def pickle_read_encrypted(fname):
 	Read a DataFrame from an encrypted file
 	"""
 	
+	from Crypto.Cipher import AES
+	from Crypto.Protocol.KDF import scrypt
+	
 	# Read ciphertext data
 	with open(fname, 'rb') as f:
 		salt, nonce, ct_bytes = pickle.load(f)