Merge pull request metafy-social#433 from shubhajitroy123/master

Adding script for Checksum

Author: advaita-saha

scripts/checksum/README.md

@@ -0,0 +1,29 @@
+# Checksum
+
+This script can generate checksums from md5, sha1, sha224, sha256, sha384, and sha512. 
+Additionally, for another layer of secret it can create signed checksums using HMAC and a provided secret.
+Lastly, to provide actual value to the script it can also verify if a checksum matches the file it was generated from.
+
+Examples:
+
+Generate a sha1 checksum
+```
+python checksum.py -H sha1 -f test.txt -g
+# b29d28bc5239dbc2689215811b2a73588609f301
+```
+
+Generate a signature
+```
+python checksum.py -f test.txt -s secret
+# 3YYMCthY4hFxQj1wPF3uAg==
+```
+
+Verify a checksum
+```
+python -H sha1 -f test.txt -v b29d28bc5239dbc2689215811b2a73588609f301
+```
+
+Verify a signature
+```
+python -f test.txt -s secret -v 3YYMCthY4hFxQj1wPF3uAg==
+```

scripts/checksum/checksum.py

@@ -0,0 +1,92 @@
+import os
+import sys
+import hmac
+import base64
+import hashlib
+import argparse
+
+def checksum(hash, seed=None):
+    hashs = {
+        "md5": hashlib.md5,
+        "sha1": hashlib.sha1,
+        "sha224": hashlib.sha224,
+        "sha256": hashlib.sha256,
+        "sha384": hashlib.sha384,
+        "sha512": hashlib.sha512
+        }
+    method = hashs.get(hash, hashlib.md5)()
+    if seed is not None:
+        method.update(seed.encode("utf-8"))
+    else:
+        method.update(os.urandom(32))
+    return method.hexdigest()
+
+def sign(hash, message, secret):
+    hashs = {
+        "md5": hashlib.md5,
+        "sha1": hashlib.sha1,
+        "sha224": hashlib.sha224,
+        "sha256": hashlib.sha256,
+        "sha384": hashlib.sha384,
+        "sha512": hashlib.sha512
+        }
+    method = hashs.get(hash, hashlib.md5)()
+    digest = hmac.new(secret.encode("utf-8"), 
+                msg=message.encode(),
+                digestmod=hashs.get(hash, hashlib.md5)).digest()
+    signature = base64.b64encode(digest).decode("utf-8")
+    return signature
+
+def verify(hash, input, check, secret=None):
+    challenge = None
+    if secret is not None:
+        challenge = sign(hash, input, secret)
+    else:
+        challenge = checksum(hash, input)
+    return "Valid! :D" if challenge == check else "Invalid :("
+
+def main():
+    description = "Checksum tool to generate, sign, and verify"
+    parser = argparse.ArgumentParser(description=description)
+    parser.add_argument("-g", "--generate", dest="generate", 
+        action="store_true", help="Generates checksum")
+    parser.add_argument("-s", "--sign", dest="sign", default=None, 
+        help="Signs input using HMAC")
+    parser.add_argument("-H", "--hash", dest="hash", default="md5",
+        help="Hash method (md5, sha1, sha224, sha256, sha384, sha512)")
+    parser.add_argument("-v", "--verify", dest="verify", default=None,
+        help="Checksum or signature used to verify against file / stdin")
+    parser.add_argument("-f", "--file", dest="file", 
+        type=argparse.FileType("r"), default=sys.stdin,
+        help="File / stdin to create checksum, make signature, or verify from")
+    arguments = parser.parse_args()
+
+    if arguments.verify is not None:
+        if not arguments.file:
+            print("Missing input to generate checksum from")
+            sys.exit(1)
+        if arguments.sign is not None:
+            print(verify(arguments.hash, arguments.file.read(),
+                         arguments.verify, arguments.sign))
+            return
+        else:
+            print(verify(arguments.hash, arguments.file.read(),
+                         arguments.verify))
+            return
+    elif arguments.generate:
+        if not arguments.file:
+            print("Missing input to generate checksum from")
+            sys.exit(1)
+        print(checksum(arguments.hash, arguments.file.read()))
+        return
+    elif arguments.sign is not None:
+        if not arguments.file:
+            print("Missing input to generate checksum from")
+            sys.exit(1)
+        print(sign(arguments.hash, arguments.file.read(), arguments.sign))
+        return
+    print("Missing function (-g, -s, -v)")
+    sys.exit(1)
+
+if __name__ == "__main__":
+    main()