Can't replicate hashing of string

I need to reproduce a JS function that hashes a string with SHA-256 in r.
The said function is:

function hashPhrase (phrase) {
  const buf = new ArrayBuffer(phrase.length * 2)
  const bufView = new Uint16Array(buf)
  const strLen = phrase.length
  for (let i = 0; i < strLen; i++) {
    bufView[i] = phrase.charCodeAt(i)
  }
  return window.crypto.subtle.digest('SHA-256', buf)
    .then(hashArrayBuffer => {
      let binary = ''
      const bytes = new Uint8Array(hashArrayBuffer)
      const len = bytes.byteLength
      for (let i = 0; i < len; i++) {
        binary += String.fromCharCode(bytes[i])
      }
      return Promise.resolve(window.btoa(binary))
    })
}

Calling the function:

hashPhrase('test').then(x => { console.log(x) })

gives me:

/lIGdrGh2T2rqyMZ7qA2dPNjLq7rFj0eiCRPXrHeEOs=

as output.

I load openssl and try to use sha256 as function to hash the string.

library(openssl)

phrase = "test"
phraseraw = charToRaw(phrase)
base64_encode(sha256(phraseraw))

and the output is:

[1] "n4bQgYhMfWWaL+qgxVrQFaO/TxsrC4Is0V1sFbDwCgg="

Don't know if the problem is the uint16 because in both cases I guess that the variable is being passed as raw.

I'll appreciate very much any help.

Solution

Because you created an Uint16Array, you are using two bytes per character and those values are presumably being stored in little-endian byte order. By default in R, since you just have ASCII characters, it is just using one byte per character. So with javascript you are digesting the bytes

[116, 0, 101, 0, 115, 0, 116, 0]

But with the R code you are digesting the bytes.

[116, 101, 115, 116]

If you really want to include those padded values in R like you do in javascript, you can convert to UTF16-LE before the digest

phrase = "test"
phraseraw = iconv(phrase,from="ASCII", to="UTF-16LE",toRaw = TRUE)[[1]]
base64_encode(sha256(phraseraw))
# [1] "/lIGdrGh2T2rqyMZ7qA2dPNjLq7rFj0eiCRPXrHeEOs="

So really just make sure you are encoding your string into bytes in the exact same way in both languages.