Sign computes a new signature for an environment (env) combined with an object containing values (sf) using a given key.

sign adds signatures to each command step (and recursively to any command steps that are within group steps.

Verify verifies an existing signature against environment (env) combined with an object containing values (sf) using keys from a keySet.

EnvNamespacePrefix is the string that prefixes all fields in the "env" namespace.

SignedFielder describes types that can be signed and have signatures verified.