Hash digest functions for Google Sheets — uses Utilities.computeDigest() from Google App Scripts

gsheet-hashfunc.gs

/**
 * Returns the hash digest of a single cell or an array of cells.
 * 
 * @param {"Sample text"} input - Text to hash.
 * @param {"MD5"} algorithm - (optional) Hashing algorithm to use. Choose between MD2, MD5, SHA-1, SHA-256, SHA-384 and SHA-512. Defaults to MD5.
 * @customfunction
 */
function HASH(input, algorithm) {
  input = input || "" // what, nothing? FINE, you get nothing. Jerks.
  if (input.map) {    // check if it's an array, and make sure that the same damn algorithm is used.
    return input.map(
      function(input) {
        return singular_hash_(input, algorithm);} );
  }
  else {
    return singular_hash_(input, algorithm)
  }  
}

/** 
 * Private helper function for HASH(). Only deals with single strings.
 * 
 * @param {string} input - Text to hash.
 * @param {string} [opt_algo] - optional algorithm. Can only really use the algorithms provided by Utilities.DigestAlgorithm
 * @returns {string} a base64-encoded, web-safe hash.
 */
function singular_hash_(input, opt_algo) {
  var algorithm_to_use = {   "md2": Utilities.DigestAlgorithm.MD2,
                             "md5": Utilities.DigestAlgorithm.MD5,
                            "sha1": Utilities.DigestAlgorithm.SHA_1,
                          "sha256": Utilities.DigestAlgorithm.SHA_256,
                          "sha384": Utilities.DigestAlgorithm.SHA_384,
                          "sha512": Utilities.DigestAlgorithm.SHA_512 };
  
  old_opt_algo = opt_algo      // in case shit goes wrong
  opt_algo = opt_algo || "md5" // default to MD5 if no algorithm specified
  
  opt_algo = opt_algo.replace(/[^a-z0-9]+/i, "").toLowerCase();  //strip out anything that aren't letters and numbers, and smash everything to lower case.
  
  if(algorithm_to_use[opt_algo] == undefined) {
    throw new Error("Unknown hashing algorithm (What's " + old_opt_algo + "?"); // good thing we saved the original text before we mangled it half to death.
  }
  else {
    return Utilities.base64EncodeWebSafe(Utilities.computeDigest(algorithm_to_use[opt_algo], input));
  }
}