add script to validate keys

check_key.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+
+# Input file containing the SSH public keys
+key_file=$1
+
+# Read the file line by line
+while IFS= read -r line; do
+    # Skip empty lines
+    if [ -z "$line" ]; then
+        continue
+    fi
+
+    # Trim leading/trailing whitespace (preserving the key and comment structure)
+    trimmed_line=$(echo "$line" | xargs)
+
+    # Validate the SSH key format:
+    # Starts with ssh-<type>, followed by base64-encoded data, and an optional comment
+    echo $key_file
+    if ! echo "$trimmed_line" | grep -Eq '^ssh-(rsa|ed25519|dss|ecdsa) [A-Za-z0-9+/=]+ ?.*$'; then
+        echo "Invalid key format: $line"
+        exit 1
+    fi
+
+    # Ensure there is only one key on the line: a valid key should only have one space separating key data from the comment
+    space_count=$(echo "$trimmed_line" | grep -o ' ' | wc -l)
+    if [ "$space_count" -gt 2 ]; then
+        echo "Invalid: Multiple keys found on the same line"
+        exit 1
+    fi
+
+done < "$key_file"
+
+echo "All keys are valid and correctly formatted."