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Public half of a signing key

Source: R/sign.R
signpubkey.Rd

Strips the secret seeds from an XMSS signing key, leaving only what a verifier needs. Publish this, or hand it to whoever must check your signatures; never the object returned by pqckg(), which lets its holder sign in your name. The public key does not change as the signing key is used, so it is made once.

Usage

signpubkey(key)

Arguments

key

A bricklayer_signing_key from pqckg().

Value

A list of class bricklayer_public_key: root and pubseed (64 hex characters each), height and scheme.

Details

The public key is the Merkle root and the public seed that masks the hashes (RFC 8391's root || SEED), with the tree height and scheme name. skseed, skprf and next_index are dropped. For a standardised key from fipskg() use fipspubkey() instead: this function refuses any key that is not a bricklayer_signing_key ("key must come from pqckg()").

See also

cpsvrf(), which takes it.

Examples

# keep this example's
op <- options(rmoriebricklayer.xmssidxfile = tempfile())
# one-time index record out of your configuration directory; leave the
# default in use
key <- pqckg(height = 2)
pub <- signpubkey(key)

# The secret seed is gone.
is.null(pub$skseed)
#> [1] TRUE

# And verification works from the public half alone.
sig <- cpssign("manifest-digest", key)
cpsvrf("manifest-digest", sig, pub)
#> [1] TRUE

# A standardised key has its own function.
try(signpubkey(fipskg("ML-DSA-44")))
#> Error : `key` must come from pqckg()
options(op)