PixBrcode

Generate, parse and validate Pix "copia e cola" payloads (BR Code), the text behind every Pix QR code.

Static payloads (key, optional amount, txid, description)
Dynamic payloads (URL provided by the receiver's bank)
Parsing into a struct, with CRC16 check
Key validation and normalization (CPF, CNPJ including alphanumeric, phone, e-mail, random key/EVP)
Zero runtime dependencies

Installation

def deps do
  [
    {:pix_brcode, "~> 0.2.0"}
  ]
end

Usage

Static payload

PixBrcode.encode(%{
  key: "pix@bcb.gov.br",
  merchant_name: "Fulano de Tal",
  merchant_city: "Brasília",
  amount: 1050,        # integer cents, or the string "10.50"
  txid: "ORDER42",     # optional, defaults to "***"
  description: "Thanks" # optional
})
#=> {:ok, "00020126...6304XXXX"}

merchant_name (max 25 chars) and merchant_city (max 15 chars) have their accents removed ("Brasília" becomes "Brasilia"). Longer values return an error; they are never truncated.
amount never goes through floats: pass integer cents (1050) or a string with exactly two decimals ("10.50").

key is written in the canonical format of the Central Bank's DICT. Formatted input is accepted, so you can pass what the user typed:

Type	Input	Written as
CPF	`"123.456.789-09"`	`"12345678909"`
CNPJ	`"11.222.333/0001-81"`, `"12.ABC.345/01DE-35"`	`"11222333000181"`, `"12ABC34501DE35"`
Phone	`"+55 (11) 98765-4321"`, `"(11) 98765-4321"`, `"5511987654321"`	`"+5511987654321"`
E-mail	`" Fulano@Exemplo.com "`	`"fulano@exemplo.com"`
EVP	uppercase UUID	lowercase UUID

CPF and CNPJ must have valid check digits. An 11-digit number such as "11987654321" is read as a CPF; for a phone number without +55, pass key_type: :phone (also :cpf, :cnpj, :email, :evp).

Dynamic payload

PixBrcode.encode_dynamic(%{
  url: "pix.example.com/qr/v2/9d36b84f",  # without https://
  merchant_name: "Fulano de Tal",
  merchant_city: "Brasilia"
})

Parsing and validating

PixBrcode.decode("00020126580014br.gov.bcb.pix0136123e4567-e12b-12d1-a456-4266554400005204000053039865802BR5913Fulano de Tal6008BRASILIA62070503***63041D3D")
#=> {:ok,
#=>  %PixBrcode.Payload{
#=>    type: :static,
#=>    key: "123e4567-e12b-12d1-a456-426655440000",
#=>    merchant_name: "Fulano de Tal",
#=>    merchant_city: "BRASILIA",
#=>    txid: "***",
#=>    amount: nil, description: nil, url: nil
#=>  }}

PixBrcode.valid?("not a pix")
#=> false

decode/1 checks the CRC, the structure, the br.gov.bcb.pix GUI and the key format, and returns the key in canonical form. Check digits are not verified when decoding, since the CRC already guarantees the payload is intact. Leading/trailing whitespace is ignored.

Errors

All functions return {:ok, result} or {:error, reason}:

Reason	When
`:missing_required_fields`	a required field is missing or is not a string
`:invalid_key`	key does not match any DICT format, or CPF/CNPJ has wrong check digits
`:invalid_key_type`	`:key_type` is not one of `:cpf`, `:cnpj`, `:phone`, `:email`, `:evp`
`:invalid_merchant_name` / `:invalid_merchant_city`	empty, too long, or not printable ASCII after removing accents
`:invalid_description`	not a string, or not printable ASCII after removing accents
`:invalid_amount`	not positive integer cents nor a `"10.50"` string, or over 13 characters
`:invalid_txid`	not `"***"` nor 1–25 letters/digits
`:invalid_url`	empty or contains a protocol (`https://`)
`{:too_long, id}`	field `id` would exceed 99 characters
`:invalid_crc` / `:invalid_tlv` / `:invalid_format` / `:invalid_gui` / `:missing_key`	when decoding

QR code image

Generating the image is out of scope, so any QR code library works. With eqrcode:

{:ok, payload} = PixBrcode.encode(%{key: "pix@bcb.gov.br", merchant_name: "Fulano", merchant_city: "Brasilia"})

svg = payload |> EQRCode.encode() |> EQRCode.svg()

Specification

Based on the Central Bank of Brazil's Manual do BR Code (EMV QRCPS-MPM) and the key formats of the DICT API and the Manual Operacional do DICT (v8.5, alphanumeric CNPJ).

License

MIT — Igor Giamoniano.