Added IAM/account_id_from_access_key.py (#498)

CHANGELOG.md

@@ -2,6 +2,13 @@
 
 All notable changes to this project will be documented in this file.
 
+## 2023-11-03
+
+### Added
+
+   * Added IAM/account_id_from_access_key.py
+
+
 ## 2023-10-25
 
 ### Changed

IAM/account_id_from_access_key.py

@@ -0,0 +1,34 @@
+"""
+Retrieve account ID from the given AWS access key ID(s).
+
+Modified from https://medium.com/@TalBeerySec/a-short-note-on-aws-key-id-f88cc4317489
+"""
+import base64
+import binascii
+
+import click
+
+
+def get_account_id_from_access_key_id(key_id):
+    # Remove ID prefix and do base32 decode
+    x = base64.b32decode(key_id[4:])
+
+    # The account ID is 5 bytes but data is shifted by one bit
+    y = x[0:6]
+
+    z = int.from_bytes(y, byteorder="big", signed=False)
+
+    mask = int.from_bytes(binascii.unhexlify(b"7fffffffff80"), byteorder="big", signed=False)
+
+    return (z & mask) >> 7
+
+
+@click.command()
+@click.option("--key", "-k", multiple=True, required=True, help="AWS access key ID")
+def main(key):
+    for k in key:
+        print("{:012d}".format(get_account_id_from_access_key_id(k)))
+
+
+if __name__ == "__main__":
+    main()