Module access_key 

Access key (chave de acesso) generation for NF-e/NFC-e.

An access key is a 44-digit numeric string that uniquely identifies a Brazilian fiscal document. Layout:

cUF(2) + AAMM(4) + CNPJ(14) + mod(2) + serie(3) + nNF(9)
+ tpEmis(1) + cNF(8) + cDV(1) = 44 digits

Functions

build_access_key

Build the 44-digit access key from its component parts.

calculate_mod11

Calculate the mod-11 check digit used in Brazilian fiscal documents.

format_year_month

Format a DateTime<FixedOffset> as YYMM for the access key.

generate_numeric_code

Generate an 8-digit random numeric code for the access key.