OCC authorizes a US bank to provide bitcoin custody services

This letter is addressed to an un-named bank providing an interpretation of existing laws. It interprets these laws as permitting banks to provide custodial services for bitcoin:

Providing such services is permissible in both non-fiduciary and fiduciary capacities. A bank that provides custody for cryptocurrency in a non-fiduciary capacity would essentially provide safekeeping for the cryptographic key that allows for control and transfer of the customer’s cryptocurrency