Path in CC5: System settings - Access control - User groups
The access control contains an own user group section for Digital Signatures (read more below). But you can also give access to this module from within each other user group via the tabs Access control - Files - Digital signature.
Read only + Digital signature
There is an own user group section for digital signing: Users in this group can get full access to this module, but only read access to contracts, etc.
Read also: