Add Lesson 8 Task e1900ba2

Lesson_8/We know/sha256_crack.py

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+# Lesson 8 Task e1900ba2: SHA-256 crack (?)
+# Author: Stanislav Mykhailenko
+# License: Unlicense
+
+# Return codes:
+# 0 - OK
+# 1 - Invalid hash
+# 2 - Not cracked
+
+import hashlib, itertools, sys
+
+def hashError():
+	print("Invalid SHA-256 hash.")
+	sys.exit(1)
+
+crackedHash = input("Enter SHA-256 hash: ")
+
+if len(crackedHash) != 64:
+	hashError()
+
+try:
+	int(crackedHash, 16)
+except ValueError:
+	hashError()
+
+for product in itertools.product('abcdefghijklmnopqrstuvwxyz', repeat=4):
+	string = ''
+	for i in range(len(product)):
+		string += product[i]
+	if crackedHash == hashlib.sha256(string.encode('utf-8')).hexdigest():
+		print("Cracked: " + string)
+		sys.exit(0)
+
+print("Not cracked.")
+sys.exit(2)