add syft attest command to produce an attestation as application/vnd.in-toto+json to standard out using on disk PKI
Signed-off-by: Christopher Phillips <christopher.phillips@anchore.com>
* use named pipe bit when checking for piped input
Signed-off-by: Alex Goodman <alex.goodman@anchore.com>
Co-authored-by: Christopher Angelo Phillips <christopher.phillips@anchore.com>
* fixed piped input
Signed-off-by: Alex Goodman <alex.goodman@anchore.com>
* allow pipedinput helper to raise an error
Signed-off-by: Alex Goodman <alex.goodman@anchore.com>
* factor out verbosity check to function
Signed-off-by: Alex Goodman <alex.goodman@anchore.com>