CNT
application/octet-stream
Magic Bytes
Offset: 0
3A 42 61 73 65 20
Microsoft Help Workshop Content (CNT) is a legacy navigation file format developed by Microsoft for its WinHelp documentation system. These files define the hierarchical structure, book icons, and topic links used to navigate compiled help documentation in 16-bit and 32-bit Windows environments. While the format is now obsolete and superseded by HTML Help, it remains essential for maintaining legacy software documentation and is generally considered safe as it contains plain text instructions.
Validation Code
How to validate .cnt files in Python
Python
def is_cnt(file_path: str) -> bool:
"""Check if file is a valid CNT by magic bytes."""
signature = bytes([0x3A, 0x42, 0x61, 0x73, 0x65, 0x20])
with open(file_path, "rb") as f:
return f.read(6) == signatureHow to validate .cnt files in Node.js
Node.js
function isCNT(buffer: Buffer): boolean {
const signature = Buffer.from([0x3A, 0x42, 0x61, 0x73, 0x65, 0x20]);
return buffer.subarray(0, 6).equals(signature);
}
Go
func IsCNT(data []byte) bool {
signature := []byte{0x3A, 0x42, 0x61, 0x73, 0x65, 0x20}
if len(data) < 6 {
return false
}
return bytes.Equal(data[:6], signature)
}API Endpoint
GET
/api/v1/cnt
curl https://filesignature.org/api/v1/cnt