simple R implementation of "optimus" algorithm for obfuscating numeric IDs. Original PHP implementation at https://github.com/jenssegers/optimus

optimus.R

## Super simple implementation of "optimus" algorithm. Easy and fast way to
## encrypt/decrypt numbers. To make it more user-friendly, the `.settings`
## function generates a prime number and mask from a supplied key string. This
## depends on a stable hash of the string, so it's probably a good idea to jot
## down the underlying numbers (prime and mask) in case something changes with
## the hash internals. You'll always be able to decrypt if you know the prime
## and mask.

library(digest)
library(gmp)

.key <- "myPassword"
.MAX_ID <- 2147483647L

.settings <- function(key = .key){
  x <- readBin(digest(key, serialize = FALSE, raw = TRUE), 
               what = "integer", n = 2)
  x <- abs(x)
  p <- nextprime(x[1])
  modulus(p) <- .MAX_ID
  i <- inv.bigz(p, .MAX_ID)
  mask <- x[2]
  out <- list(p = p, i = i, mask = mask)
  message("Encryption settings (keep these somewhere safe):")
  message(stringr::str_glue("Prime: {as.integer(out$p)}"))
  message(stringr::str_glue("Mask: {as.integer(out$mask)}"))
  out
}

encrypt <- function(settings, ids){
  bitwXor(as.integer(ids * settings$p), settings$mask)
}

decrypt <- function(settings, x){
  as.integer(bitwXor(x, settings$mask) * settings$i)
}

## Usage:
# s <- .settings("mySuperSecretKey")
# y <- encrypt(s, 1:10)
# x <- decrypt(s, y)