maybe just use ssh-keygen

.forgejo/workflows/validate-keys.yaml

@@ -12,7 +12,7 @@ jobs:
       image: 'code.forgejo.org/oci/ci:1'
     steps:
       - uses: actions/checkout@v4
-      - run: for i in *.pub; do ./check_key.sh $i; done
+      - run: for i in *.pub; do ssh-keygen -l -f $i; done
       - run: |
           echo assembeling authorized keys &&
           cat *.pub > authorized_keys

byte.pub

@@ -1 +1,2 @@
-ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIDWcYvzMXydV3n3S5DfT5C0TGQROKC2OUr/WLo+ohqZ7ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAICYfR9R1unNcDxCiS9lIYG1xEgZHF9/1zHrOn/Gn9tqB
+ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIDWcYvzMXydV3n3S5DfT5C0TGQROKC2OUr/WLo+ohqZ7
+ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAICYfR9R1unNcDxCiS9lIYG1xEgZHF9/1zHrOn/Gn9tqB

check_key.sh

@@ -1,33 +0,0 @@
-#!/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."