Compute a File's SHA256 Digest — sha256

Returns the SHA256 digest of a file as a lowercase hex string, computed by the package's own compiled SHA-256 core (or, when the file is sourced standalone inside a capsule bundle, by the pure-R FIPS 180-4 implementation it ships). Used to record and verify data provenance.

Usage

sha256_file(path)

Arguments

path: Path to the file to hash.

Value

The SHA256 digest as a character string.

Examples

f <- tempfile()
writeLines("hello capsule", f)
sha256_file(f)
#> [1] "55d6110230c260319d580bb6274db530b7e751c4f687fc00d0736ec531260a02"

# Deterministic: the same bytes always yield the same digest.
identical(sha256_file(f), sha256_file(f))
#> [1] TRUE

# Any change to the file changes the digest (tamper-evidence).
before <- sha256_file(f)
writeLines("hello capsule (edited)", f)
after <- sha256_file(f)
before == after      # FALSE
#> [1] FALSE

# Provenance pin: record a digest, verify it later.
pinned <- sha256_file(f)
stopifnot(sha256_file(f) == pinned)