mpathsenser (version 1.2.3)

decrypt_gps: Decrypt GPS data from a curve25519 public key

Description

By default, the latitude and longitude of the GPS data collected by m-Path Sense are encrypted using an asymmetric curve25519 key to provide extra protection for these highly sensitive data. This function takes a character vector and decrypts its longitude and latitude columns using the provided key.

Usage

decrypt_gps(data, key, ignore = ":")

Value

A vector of doubles of the decrypted GPS coordinates.

Arguments

data

A character vector containing hexadecimal (i.e. encrypted) data.

key

A curve25519 private key.

ignore

A string with characters to ignore from data. See sodium::hex2bin().

Parallel

This function supports parallel processing in the sense that it is able to distribute it's computation load among multiple workers. To make use of this functionality, run future::plan("multisession") before calling this function.

Examples

if (FALSE) { # rlang::is_installed("sodium")
library(dplyr)
library(sodium)
# Create some GPS  coordinates.
data <- data.frame(
  participant_id = "12345",
  time = as.POSIXct(c(
    "2022-12-02 12:00:00",
    "2022-12-02 12:00:01",
    "2022-12-02 12:00:02"
  )),
  longitude = c("50.12345", "50.23456", "50.34567"),
  latitude = c("4.12345", "4.23456", "4.345678")
)

# Generate keypair
key <- sodium::keygen()
pub <- sodium::pubkey(key)

# Encrypt coordinates with pubkey
# You do not need to do this for m-Path Sense
# as this is already encrypted
encrypt <- function(data, pub) {
  data <- lapply(data, charToRaw)
  data <- lapply(data, function(x) sodium::simple_encrypt(x, pub))
  data <- lapply(data, sodium::bin2hex)
  data <- unlist(data)
  data
}
data$longitude <- encrypt(data$longitude, pub)
data$latitude <- encrypt(data$latitude, pub)

# Once the data has been collected, decrypt it using decrypt_gps().
data |>
  mutate(longitude = decrypt_gps(longitude, key)) |>
  mutate(latitude = decrypt_gps(latitude, key))
}