From 5d826f409b1bdda606d90d4a91fcdde611f16d5e Mon Sep 17 00:00:00 2001
From: RubenCGomes <rlcg@ua.pt>
Date: Tue, 12 Nov 2024 10:41:18 +0000
Subject: [PATCH] encryption functions added (may require adaptation)

---
 delivery1/cryptLib/decryptionFuncts.py | 26 ++++++++++++++++++
 delivery1/cryptLib/encryptionFuncts.py | 23 ++++++++++++++++
 delivery1/cryptLib/keyPair.py          | 38 ++++++++++++++++++++++++++
 3 files changed, 87 insertions(+)
 create mode 100644 delivery1/cryptLib/decryptionFuncts.py
 create mode 100644 delivery1/cryptLib/encryptionFuncts.py
 create mode 100644 delivery1/cryptLib/keyPair.py

diff --git a/delivery1/cryptLib/decryptionFuncts.py b/delivery1/cryptLib/decryptionFuncts.py
new file mode 100644
index 0000000..5d7379a
--- /dev/null
+++ b/delivery1/cryptLib/decryptionFuncts.py
@@ -0,0 +1,26 @@
+import sys
+
+from cryptography.hazmat.primitives import serialization, hashes
+from cryptography.hazmat.primitives.asymmetric import rsa, padding
+
+
+def decryptFile(private_key, cipher_text):
+	plain_text = private_key.decrypt(
+		cipher_text,
+		padding.OAEP(
+			mgf=padding.MGF1(algorithm=hashes.SHA256()),
+			algorithm=hashes.SHA256(),
+			label=None
+		)
+	)
+	return plain_text
+
+
+def load_private_key(file, paswd=None):
+	with open(file, 'rb') as key_file:
+		private_key = serialization.load_pem_private_key(
+			key_file.read(),
+			password=paswd,
+		)
+
+	return private_key
diff --git a/delivery1/cryptLib/encryptionFuncts.py b/delivery1/cryptLib/encryptionFuncts.py
new file mode 100644
index 0000000..4531dcc
--- /dev/null
+++ b/delivery1/cryptLib/encryptionFuncts.py
@@ -0,0 +1,23 @@
+import sys
+
+from cryptography.hazmat.primitives import serialization, hashes
+from cryptography.hazmat.primitives.asymmetric import rsa, padding
+
+def encryptFile(public_key, text):
+	ciphertext = public_key.encrypt(
+		text,
+		padding.OAEP(
+			mgf=padding.MGF1(algorithm=hashes.SHA256()),
+			algorithm=hashes.SHA256(),
+			label=None
+		)
+	)
+	return ciphertext
+
+def load_public_key(file):
+	with open(file, 'rb') as key_file:
+		public_key = serialization.load_pem_public_key(
+			key_file.read(),
+		)
+
+	return public_key
diff --git a/delivery1/cryptLib/keyPair.py b/delivery1/cryptLib/keyPair.py
new file mode 100644
index 0000000..fe7c7e4
--- /dev/null
+++ b/delivery1/cryptLib/keyPair.py
@@ -0,0 +1,38 @@
+import sys
+
+from cryptography.hazmat.primitives import serialization, hashes
+from cryptography.hazmat.primitives.asymmetric import rsa, padding
+
+
+def generate_key_pair(passwd=None):
+	pub_name, priv_name, key_size = sys.argv[1:]
+
+	private_key = rsa.generate_private_key(
+		public_exponent=65537,
+		key_size=int(key_size)
+	)
+	public_key = private_key.public_key()
+
+	with open(pub_name, 'wb') as f:
+		f.write(public_key.public_bytes(
+			encoding=serialization.Encoding.PEM,
+			format=serialization.PublicFormat.SubjectPublicKeyInfo
+		))
+
+	if not passwd:
+		with open(priv_name, 'wb') as f:
+			f.write(private_key.private_bytes(
+				encoding=serialization.Encoding.PEM,
+				format=serialization.PrivateFormat.TraditionalOpenSSL,
+				encryption_algorithm=serialization.NoEncryption()
+			))
+	else:
+		with open(priv_name, 'wb') as f:
+			f.write(private_key.private_bytes(
+				encoding=serialization.Encoding.PEM,
+				format=serialization.PrivateFormat.TraditionalOpenSSL,
+				encryption_algorithm=serialization.BestAvailableEncryption(passwd.encode())
+			))
+
+	return pub_name, priv_name
+