diff --git a/challenge4.py b/challenge4.py
new file mode 100644
index 0000000..7bdec65
--- /dev/null
+++ b/challenge4.py
@@ -0,0 +1,43 @@
+import requests
+from binascii import unhexlify
+
+# get the list of strings (each string is 60 characters)
+request = requests.get('https://cryptopals.com/static/challenge-data/4.txt')
+requestArray = request.text.splitlines()
+
+# here's the code used in challenge 3, which is said to be useful
+def xor_SingleByte(hexed):
+    alphabet = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']
+    unHexed = unhexlify(hexed)
+    # generate a dict of possible answers and their decryption keys
+    
+    tableOfPossibleAnswers = {}
+    for code in range(256):
+        possibleAnswer = ''.join(chr(byte ^ code) for byte in unHexed)
+        if possibleAnswer.isprintable():
+            tableOfPossibleAnswers[code] = possibleAnswer
+
+    # weight the answers using a simple english alphabet list
+    if tableOfPossibleAnswers:
+        weightedCodes = {}
+        for key,value in tableOfPossibleAnswers.items():
+            weightedCodes[value] = 0
+            for letter in alphabet:
+                if letter in value:
+                    weightedCodes[value] += 1
+
+        # find the highest value and return it and its corresponding key
+        maxValue = max(weightedCodes.values())
+        answerValue = []
+        for key in weightedCodes:
+            if weightedCodes[key] == maxValue:
+                answerValue = key
+        
+        # now i need to use that to key into the original tableOfPossibleAnswers to return the answer and the decryption key.
+        for key,value in tableOfPossibleAnswers.items():
+            if tableOfPossibleAnswers[key] == answerValue:
+                print(key, tableOfPossibleAnswers[key])
+
+
+for string in requestArray:
+    xor_SingleByte(string)
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