inst/doc/cose-webauthn.R

In zucbor: Deterministic and Secure CBOR Encoding and Decoding

## ----include = FALSE----------------------------------------------------------
knitr::opts_chunk$set(collapse = TRUE, comment = "#>")

## -----------------------------------------------------------------------------
library(zucbor)
hex <- function(h) as.raw(strtoi(substring(h, seq(1, nchar(h), 2), seq(2, nchar(h), 2)), 16L))

## -----------------------------------------------------------------------------
att <- hex(paste0(
  "a363666d74646e6f6e656761747453746d74a068617574684461746158a4bfabc374",
  "32958b063360d3ad6461c9c4735ae7f8edd46592a5e0f01452b2e4b5590000000084",
  "46ccb9ab1db374750b2367ff6f3a1f0020f91f391db4c9b2fde0ea70189cba3fb63f",
  "579ba6122b33ad94ff3ec330084be4a5010203262001215820afefa16f97ca9b2d23",
  "eb86ccb64098d20db90856062eb249c33a9b672f26df61225820930a56b87a2fca66",
  "334b03458abf879717c12cc68ed73290af2e2664796b9220"))
ao <- cbor_decode(att)
str(ao)

## -----------------------------------------------------------------------------
ad <- ao$authData
id_len <- as.integer(ad[54]) * 256L + as.integer(ad[55])
rest <- ad[-seq_len(55 + id_len)]
key <- cbor_decode_prefix(rest)
key$value

## -----------------------------------------------------------------------------
cbor_diagnose(rest[seq_len(key$consumed)])

## -----------------------------------------------------------------------------
flags <- as.integer(ad[33])
bitwAnd(flags, 0x80L) != 0L        # extensions?
length(rest) - key$consumed        # bytes after the key

## -----------------------------------------------------------------------------
identical(cbor_encode(ao), att)

## -----------------------------------------------------------------------------
cwt <- hex(paste0(
  "d28443a10126a104524173796d6d657472696345434453413235365850a70175636f",
  "61703a2f2f61732e6578616d706c652e636f6d02656572696b77037818636f61703a",
  "2f2f6c696768742e6578616d706c652e636f6d041a5612aeb0051a5610d9f0061a56",
  "10d9f007420b7158405427c1ff28d23fbad1f29c4c7c6a555e601d6fa29f9179bc3d",
  "7438bacaca5acd08c8d4d4f96131680c429a01f85951ecee743a52b9b63632c57209",
  "120e1c9e30"))
msg <- cbor_decode(cwt)
msg$tag
str(msg$value, max.level = 1)

## -----------------------------------------------------------------------------
cbor_decode(msg$value[[1]])        # protected header: {1: -7}, ES256
claims <- cbor_decode(msg$value[[3]])
claims

## -----------------------------------------------------------------------------
to_be_signed <- cbor_encode(list("Signature1", msg$value[[1]], raw(), msg$value[[3]]))
cbor_diagnose(to_be_signed)