CIF (.cif)

.cif file signature | application/octet-stream

Crystallographic Information File (CIF) is a text-based data format developed and maintained by the International Union of Crystallography for storing standardized crystallographic information. It is used in chemistry, materials science, and structural biology to exchange unit-cell parameters, atomic coordinates, symmetry data, and related experimental results. CIF is generally safe because it is plain text, although applications that interpret embedded links or scripts should still treat files from untrusted sources with care.

Safe

Magic Bytes

Offset 2


              5B 56 65 72 73 69 6F 6E

Sources: Gary Kessler

Extension

.cif

MIME Type

application/octet-stream

Byte Offset

Risk Level

Safe

Validation Code

How to validate .cif files in Python

Python

def is_cif(file_path: str) -> bool:
    """Check if file is a valid CIF by magic bytes at offset 2."""
    signature = bytes([0x5B, 0x56, 0x65, 0x72, 0x73, 0x69, 0x6F, 0x6E])
    with open(file_path, "rb") as f:
        f.seek(2)
        return f.read(8) == signature

How to validate .cif files in Node.js

Node.js

function isCIF(buffer: Buffer): boolean {
  const signature = Buffer.from([0x5B, 0x56, 0x65, 0x72, 0x73, 0x69, 0x6F, 0x6E]);
  if (buffer.length < 10) return false;
  return buffer.subarray(2, 10).equals(signature);
}

How to validate .cif files in Go

func IsCIF(data []byte) bool {
    signature := []byte{0x5B, 0x56, 0x65, 0x72, 0x73, 0x69, 0x6F, 0x6E}
    if len(data) < 10 {
        return false
    }
    return bytes.Equal(data[2:10], signature)
}

API Endpoint

GET /api/v1/cif


              curl https://filesignature.org/api/v1/cif

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .cif file?

A .cif file is identified by the magic bytes 5B 56 65 72 73 69 6F 6E at byte offset 2. Crystallographic Information File (CIF) is a text-based data format developed and maintained by the International Union of Crystallography for storing standardized crystallographic information. It is used in chemistry, materials science, and structural biology to exchange unit-cell parameters, atomic coordinates, symmetry data, and related experimental results. CIF is generally safe because it is plain text, although applications that interpret embedded links or scripts should still treat files from untrusted sources with care.

What are the magic bytes for .cif files?

The magic bytes for CIF files are 5B 56 65 72 73 69 6F 6E at byte offset 2. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .cif file?

To validate a .cif file, read the first bytes of the file and compare them against the known magic bytes (5B 56 65 72 73 69 6F 6E) at offset 2. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .cif files?

There is no officially registered MIME type for .cif files. Systems typically use application/octet-stream as a generic fallback when handling this format.

Is it safe to open .cif files?

CIF (.cif) files are generally safe to open. They are classified as low risk because they primarily contain data rather than executable code. However, always ensure files come from a trusted source.