packrat/lib/x86_64-pc-linux-gnu/3.2.2/openssl/doc/bignum.R

In etsakl/DasyMapR: Geographical ETRS-LAEA Grid Based Dasymetric Mapping

## ----setup, include=FALSE------------------------------------------------
library(openssl)
knitr::opts_chunk$set(echo = TRUE)

## ------------------------------------------------------------------------
# create a bignum
y <- bignum("123456789123456789")
z <- bignum("D41D8CD98F00B204E9800998ECF8427E", hex = TRUE)

# size grows
print(y * z)

# Basic arithmetic
div <- z %/% y
mod <- z %% y
z2 <- div * y + mod
stopifnot(z2 == z)
stopifnot(div < z)

## ------------------------------------------------------------------------
(key <- rsa_keygen(256))
(pubkey <- as.list(key)$pubkey)

## ------------------------------------------------------------------------
msg <- charToRaw("hello world")
ciphertext <- rsa_encrypt(msg, pubkey)
try(rawToChar(ciphertext))
rawToChar(rsa_decrypt(ciphertext, key))

## ------------------------------------------------------------------------
keydata <- as.list(key)$data
print(keydata)

## ------------------------------------------------------------------------
as.list(pubkey)$data

## ------------------------------------------------------------------------
m <- bignum(charToRaw("hello world"))
print(m)

## ------------------------------------------------------------------------
e <- as.list(pubkey)$data$e
n <- as.list(pubkey)$data$n
c <- (m ^ e) %% n
print(c)

## ------------------------------------------------------------------------
base64_encode(c)

## ------------------------------------------------------------------------
d <- as.list(key)$data$d
out <- bignum_mod_exp(c, d, n)
rawToChar(out)