The Cisco ASA remote access VPN server must be configured to use SHA-2 or greater for hashing to protect the integrity of IPsec remote access sessions.
Without strong cryptographic integrity protections, information can be altered by unauthorized users without detection.
SHA-1 is considered a compromised hashing standard and is being phased out of use by industry and Government standards. DoD systems must not be configured to use SHA-1 for integrity of remote access sessions.
The remote access VPN provides access to DoD non-public information systems by an authorized user (or an information system) communicating through an external, non-organization-controlled network.