Hash a Vector with a Salted Pre-Image

Returns a hash of the same length as the input vector. Each element is first coerced to character, upper-cased, trimmed, and stripped of internal whitespace, then concatenated with key and hashed with digest::digest(). The transformation is one-way and deterministic: the same (value, key) pair always produces the same hash, and the original value cannot be recovered from the hash alone.

Usage

crypt_vector(vector, key, algo)

Arguments

vector

Atomic vector of values to hash. Non-character inputs are coerced to character before normalization.

key

Character scalar. The salt prepended to each value before hashing. Choose a value with enough entropy that rainbow-table attacks are impractical.

algo

Character scalar. Any algorithm accepted by the algo argument of digest::digest() ("md5", "sha1", "sha256", …).

Value

Character vector of upper-case hexadecimal hashes, same length as vector. NA at every position where the input was NA or empty.

Details

NA values and empty strings are preserved as NA in the output — they are not hashed.

Examples

# Three IDs, a missing value, an empty string. The non-empty values
# come back as upper-case MD5 hashes; `NA` and "" stay `NA`.
crypt_vector(
  vector = c("1234", "5678", "9101112", NA, ""),
  key = "123456",
  algo = "md5"
)
#> [1] "B38E2BF274239FF5DD2B45EE9AE099C9" "D71B95E05E2208136FEA6F9052FD6F9B"
#> [3] "3F9A1DBCC3C016DE3DC05F247F23D01D" NA                                
#> [5] NA                                

# Determinism: same value + same key + same algo => same hash.
identical(
  crypt_vector("Alice",  key = "k", algo = "md5"),
  crypt_vector("alice ", key = "k", algo = "md5")
)
#> [1] TRUE