Find XMSS signature indices used twice

Lists every XMSS signature in the capsule bundles under a directory, and in seen-logs, and marks an index that one key signed with two different signatures. An XMSS index must sign once: two signatures at one index let anyone forge a third message, so a reused index means the key's state was copied or rolled back (RFC 10033, section 4: a verifier that sees all of a signer's signatures can detect reuse, since each carries its index).

Usage

xmssidxseen(path = ".", seenlog = NULL)

Arguments

path

A directory (every capsule_bundle.json under it) or one bundle file.

seenlog

Seen-log files to read as well, or NULL. A file that does not exist yet is an empty log; a directory, or a log with a malformed line, is refused.

Value

A data frame, one row per signature seen: key (the key fingerprint, the first 16 hex characters of SHA-256 over the public key), index, sig (a digest of the signature), where (the file) and reused (TRUE when this key signed this index with another signature too).

Details

A seen-log is the text file rmbl sign --seen-log FILE appends to: one line per signature it made, with the key fingerprint, the index, a digest of the signature and the bundle it went into, tab-separated; lines starting with # are comments. The same signature found twice (one bundle copied to two places, or a bundle and its log line) is not a reuse.

See also

cpsbndlvrf() (its seen argument), blcli() (rmbl sign --seen-log), pqckg().

Examples

# keep this example's
op <- options(rmoriebricklayer.xmssidxfile = tempfile())
# one-time index record out of your configuration directory
root <- tempfile("capsules-")
d <- file.path(root, "one")
dir.create(d, recursive = TRUE)
writeLines("x\n1", file.path(d, "data.csv"))
key <- pqckg(height = 2)
b <- cpsbndl(d, mkmnf(list(), env = FALSE), key)
xmssidxseen(root)
#>                key index              sig
#> 1 ca1b86e99fb3d1bf     0 1154fc5e5065a208
#>                                                           where reused
#> 1 /tmp/RtmpZpRdcE/capsules-1e6a3f532e8b/one/capsule_bundle.json  FALSE

# the same index signed again from a stale copy of the key: reused
e <- file.path(root, "two")
dir.create(e)
writeLines("x\n2", file.path(e, "data.csv"))
# forget the record, as a copy on another machine would
invisible(xmssfgt(key))
b2 <- cpsbndl(e, mkmnf(list(), env = FALSE), key)
xmssidxseen(root)[, c("index", "reused")]
#>   index reused
#> 1     0   TRUE
#> 2     0   TRUE

try(xmssidxseen(tempfile()))
#> Error : xmssidxseen: `path` is not an existing directory or bundle file: /tmp/RtmpZpRdcE/file1e6a7639c5c8
options(op)