15.8 Using a lookup table

Rather than storing the ciphertext in the working data frame, a lookup table can be used as an alternative. Using lookup = TRUE has the following effects:

  • returns the data frame / tibble with encrypted columns removed and a key column included;
  • returns the lookup table as an object in the R environment;
  • creates a lookup table .csv file in the active directory.
gp_encrypt = gp %>% 
  select(-c(name, address1, address2, address3)) %>% 
  encrypt(postcode, telephone, lookup = TRUE)
#> Lookup table object created with name 'lookup'
#> Lookup table written to file with name 'lookup.csv'


#> A tibble: 1,212 x 7
#>   key   organisation_code city      county     opendate   
#>   <int> <chr>             <chr>     <chr>      <date>     
#> 1 1     S10002            DUNDEE    ANGUS      1995-05-01 
#> 2 2     S10017            CRIEFF    PERTHSHIRE 1996-04-06 

The file creation can be turned off with write_lookup = FALSE and the name of the lookup can be changed with lookup_name = "anyNameHere". The created lookup file should be itself encrypted using the method below.

Decryption is performed by passing the lookup object or file to the decrypt() function.

gp_encrypt %>%  
  decrypt(postcode, telephone, lookup_object = lookup)

# Or
gp_encrypt %>%  
  decrypt(postcode, telephone, lookup_path = "lookup.csv")

#> A tibble: 1,212 x 8
#>   postcode telephone    organisation_code city    county     opendate   
#>   <chr>    <chr>        <chr>             <chr>   <chr>      <date>     
#>  1 DD2 5NH 01382 580264 S10002            DUNDEE  ANGUS      1995-05-01 
#>  2 PH7 3SA 01764 652283 S10017            CRIEFF  PERTHSHIRE 1996-04-06