The encryptr package provides functions to simply
encrypt and decrypt columns of data. It also includes functions to
encrypt and decrypt files.
The motivation is around sensitive healthcare data, but the
applications are wide. There are a number of packages providing similar
functions. However, they tend to be complex and are not designed with
tidyverse functions in mind. The package wraps
openssl and is intended to be safe and straightforward for
non-experts. Strong RSA (2048 bit) encryption using a public/private key
pair is used.
It is designed to work in tidyverse piped functions.
You can install encryptr from GitHub:
devtools::install_github("SurgicalInformatics/encryptr")Documentation is maintained at encrypt-r.org.
The basis of RSA encryption is a public/private key pair and is the method used of many modern encryption applications. The public key can be shared and is used to encrypt the information.
The private key is sensitive and should not be shared. The private key requires a password to be set. This password should follow modern rules on password complexity. You know what you should do. If lost, it cannot be recovered.
The genkeys() function generates a public and private
key pair. A password is required to be set in the dialogue box for the
private key. Two files are written to the active directory.
The default name for the private key is:
id_rsaAnd for the public key name is generated by default:
id_rsa.pubIf the private key file is lost, nothing encrypted with the public key can be recovered. Keep this safe and secure. Do not share it without a lot of thought on the implications.
genkeys()
> Private key written with name 'id_rsa'
> Public key written with name 'id_rsa.pub'An example dataset containing the addresses general practioners (family doctors) in Scotland is included in the package.
data(gp)
# A tibble: 1,212 x 12
organisation_code name address1 address2 address3 city county postcode opendate closedate telephone practice_type
<chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <date> <date> <chr> <dbl>
1 S10002 MUIRHE… LIFF RO… MUIRHEAD NA DUND… ANGUS DD2 5NH 1995-05-01 NA 01382 58… 4
2 S10017 THE BL… CRIEFF … KING ST… NA CRIE… PERTH… PH7 3SA 1996-04-06 NA 01764 65… 4Encrypting columns to a ciphertext is straightforward. An important principle is dropping sensitive data which is never going to be required.
library(dplyr)
gp_encrypt = gp %>%
select(-c(name, address1, address2, address3)) %>%
encrypt(postcode, telephone)
gp_encrypt
# A tibble: 1,212 x 10
organisation_code name address1 city county postcode opendate closedate telephone practice_type
<chr> <chr> <chr> <chr> <chr> <chr> <date> <date> <chr> <dbl>
1 S10002 619057f99… 54c39b3fa200… DUND… ANGUS 796284eb46ca… 1995-05-01 NA 5fcc30b04e260… 4
2 S10017 371aa33c3… a996d07a84d2… CRIE… PERTH… 639dfc076ae3… 1996-04-06 NA 715909615a6ae… 4Decryption requires the private key generated using
genkeys() and the password set at the time. The password
and file are not replaceable so need to be kept safe and secure.
gp_encrypt %>%
decrypt(postcode, telephone)
# A tibble: 1,212 x 8
organisation_code city county postcode opendate closedate telephone practice_type
<chr> <chr> <chr> <chr> <date> <date> <chr> <dbl>
1 S10002 DUNDEE ANGUS DD2 5NH 1995-05-01 NA 01382 580264 4
2 S10017 CRIEFF PERTHSHIRE PH7 3SA 1996-04-06 NA 01764 652283 4Rather than storing the ciphertext in the working dataframe, a lookup
table can be used as an alternative. Using lookup = TRUE
has the following effects:
key column included;.csv file in the active
directory. file of the lookupgp_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'
gp_encrypt
# A tibble: 1,212 x 7
key organisation_code city county opendate closedate practice_type
<int> <chr> <chr> <chr> <date> <date> <dbl>
1 1 S10002 DUNDEE ANGUS 1995-05-01 NA 4
2 2 S10017 CRIEFF PERTHSHIRE 1996-04-06 NA 4The file creation can be turned off with
write_lookup = FALSE and the name of the lookup can be
changed with lookup_name = "anyNameHere".
Decryption is performed by passing the lookup object or file to the
decrypt() function.
gp_encrypt %>%
decrypt(postcode, telephone, lookup_object = lookup)
# A tibble: 1,212 x 8
postcode telephone organisation_code city county opendate closedate practice_type
<chr> <chr> <chr> <chr> <chr> <date> <date> <dbl>
1 DD2 5NH 01382 580264 S10002 DUNDEE ANGUS 1995-05-01 NA 4
2 PH7 3SA 01764 652283 S10017 CRIEFF PERTHSHIRE 1996-04-06 NA 4gp_encrypt %>%
decrypt(postcode, telephone, lookup_path = "lookup.csv")
# A tibble: 1,212 x 8
postcode telephone organisation_code city county opendate closedate practice_type
<chr> <chr> <chr> <chr> <chr> <date> <date> <dbl>
1 DD2 5NH 01382 580264 S10002 DUNDEE ANGUS 1995-05-01 NA 4
2 PH7 3SA 01764 652283 S10017 CRIEFF PERTHSHIRE 1996-04-06 NA 4
The ciphertext produced for a given input will change with each encryption. This is a feature of the RSA algorithm. Ciphertexts should not therefore be attempted to be matched between datasets encrypted using the same public key. This is a conscious decision given the risks associated with sharing the necessary details (a salt).
Encryption and decryption with asymmetric keys is computationally
expensive. This is how encrypt above works. This makes it
easy for each piece of data in a data frame to be decrypted without
compromise of the whole data frame. This works on the presumption that
each cell contains less than 245 bytes of data.
File encryption requires a different approach as files are often
larger in size. encrypt_file encrypts a file using a
symmetric “session” key and the AES-256 cipher. This key is itself then
encrypted using a public key generated using genkeys. In OpenSSL this
combination is referred to as an envelope.
genkeys()
> Private key written with name 'id_rsa'
> Public key written with name 'id_rsa.pub'To demonstrate, the included dataset is written as a .csv file.
write.csv(gp, "gp.csv")
encrypt_file("gp.csv")
> Encrypted file written with name 'gp.csv.encryptr.bin'Check that the file can be decrypted prior to removing the original file from your system. Warning: it is strongly suggested that the original unencrypted data file is stored as a back-up in case unencryption is not possible, e.g., the private key file or password is lost
The decrypt_file function will not allow the original
file to be overwritten, therefore use the option to specify a new name
for the unencrypted file.
decrypt_file("gp.csv.encryptr.bin", file_name = "gp2.csv")
> Decrypted file written with name 'gp2.csv'In collaborative projects where data may be pooled, a public key can be made available by you via a link to enable collaborators to encrypt sensitive data, e.g.
gp_encrypt = gp %>%
select(-c(name, address1, address2, address3)) %>%
encrypt(postcode, telephone, public_key_path = "https://argonaut.is.ed.ac.uk/public/id_rsa.pub")All confidential information must be treated with the utmost care. Data should never be carried on removable devices or portable computers. Data should never be sent by open email. Encrypting data provides some protection against disclosure. But particularly in healthcare, data often remains potentially disclosive (or only pseudonymised) even after encryption of identifiable variables. Treat it with great care and respect.