The full electronic invoice key is a key string that uses a cryptographic encryption algorithm to digitally sign and encrypt electronic invoices.

The fully electronic invoice key, also known as the electronic invoice password, is an important piece of information to ensure the authenticity and security of electronic invoices. It is usually issued by the tax department or its authorized agency. Full electronic invoice keys include two types: interface secret key and CA certificate.

The fully electronic invoice key is confidential information assigned by the tax department or its authorized agency when an enterprise applies for electronic invoice issuance qualifications. It involves the enterprise's core data and key business information and must be properly kept to avoid leakage or lost. No unit or individual may use, rent or transfer electronic invoice passwords without permission.