The appendix is part of the digital invoice, that the SAT has been made available to the companies, so they can add to the voucher data that are not relevant in terms of taxation, but in commercial terms is so important, for example key supplier, number purchase order, serial numbers of the products, the delivery location, etc. The content of the Appendix is not considered in the generation of the original string neither in the digital seal. The content of Appendix not "participate" in the processing of information that gives validity to CFD.
It´s the sequence of data stream is formed with CFD information. It is lay down by the Item C of Annex 20 of Miscellany Tax Rules.
Digital Tax Receipt (CFD by the initial in Spanish)
Is an electronically mechanism for checking tax revenues, expenses and transfer ownership of goods, which is incorporated into existing traditional schemes. Its peculiarity is the use of information technology for the generation, processing, transmission and receipt of tax documents 100% digital. The digital tax receipts (CFD) are electronic documents that show transactions between taxpayers, under technological and safety standards recognized internationally.
It is a file with *.CER extension. It associate a public key with the identity of its owner. There are two types of digital certificates: electronic signature certificate and certificate of digital seal.
Electronic Signature Certificates
It´s a kind of digital certificate that identifies individuals or corporations and ability for obtain Digital Certificates and sign the monthly report, among other services.
Digital stamp certificates
It´s a kind of digital certificate for the exclusive use of digital invoices. Used to sign and seal the Digital Tax Voucher.
Spanish initial of electronic signature. The name was changed by FIEL
Spanish initial of electronic signature
* An electronic signature or "FIEL" is a set of data that is attached to an electronic message, which purpose is to identify
the sender of the message as legitimate author it as if like a signature.
* Due to its technological features, the FIEL is a tool that provides security for electronic transactions between SAT and
taxpayers because it let to verify that the received messages are unchanged and identify at the author of the message.
* The design is based on international standards of public key infrastructure (PKI by its acronym: Public Key
Infrastructure) where use two keys mathematically related, for sending messages. One of them is only known by the
holder of the FIEL and used to encrypt data. That’s the reason why is known by the term of "private key." The other key,
called "public key", is available online for consultation.
Digital Stamp Seal
Is a text string with a sequence of signs. This chain is formed as a result of encrypting the information of the original string of Proof, which makes impossible to forge the proof because any change in data generates a different stamp.
Secure Sockets Layer (SSL) and Transport Layer Security (TLS). Both are cryptographic protocols that provide secure communications over a network, typically the Internet. There are slight differences between SSL 3.0 and TLS 1.0, but the protocol remains substantially the same. The term "SSL" as used herein, applies to both protocols unless the context indicates otherwise.