To ensure a high level of security, HelseID uses a profile of the technical protocols that our core services are based on. This is a profile that is customized for high risk domains such as health, finance, eGov and banking etc. The HelseID security profile is based on the FAPI 2.0 Baseline profile, which is maintained by OpenID Foundation (OIDF). Be aware that there might be some minor differences between the FAPI 2.0 standard and HelseIDs profile due to practical considerations.

This security profile assumes that the reader is familiar with the roles and underlying protocols and specifications as described in the OAuth 2.1 framework and OpenID Connect.

Absolute requirements for clients using HelseID

All clients:

• shall only establish connections to servers, including HelseID, using TLS. All TLS connections shall be set up using TLS version 1.2 or later, and follow RFC 7525.

• shall use Authorization Code flow, as described by IETF in OAuth 2.0 and by OIDF in OpenID Connect for interactive sessions (end-user sessions), OR

• shall use the Client Credentials flow as described in RFC 6749.

• shall be confidential clients, meaning that the client secrets used to authenticate the clients are known to HelseID prior to the authentication.

• shall pass request parameters as JWT as described by OIDF in OpenID Connect, and as detailed by HelseID.

• shall support client authentication usin:

  • “private_key_jwt”, as described by OpenID Connect for interactive sessions.

  • Client Assertions as described by RFC 7521 and RFC 7523

  • The requirements for client authentication are further detailed by HelseID

• shall support sender-constrained tokens using

  • Demonstrating Proof-of-Possession at the Application Layer (DPoP) as described by draft-ietf-oauth-dpop.

• shall use PKCE, as defined by IETF in RFC 76936 - Proof Key for Code Exchange, to mitigate against code interception and other attacks.

• shall send access tokens in http authorization headers, as described by RFC 6750.

• shall use the “authorization_details” structure, as defined by IETF in the specification Rich Authorization Requests, to convey fine grained authorization requirements to HelseID.

  • These requirements are further detailed by HelseID.

• shall check the the validity of the “iss” parameter in the authorization response to prevent mix-up attacks.

• shall implement protection against XSS and CSRF attacks. Please refer to external sources as OWASP for details about how to test and secure a client.

• shall not expose to open redirectors where the client is vulnerable to malicious redirections . Please refer to external sources to find descriptions of mitigations to these types of attacks.

  • the client shall protect against attacks via HTTP Header

  • the client shall protect against attacks via Javascript (e.g. XSS attacks)

Cryptography and secrets

Cryptography

The following algorithms are supported when using “private_key_jwt” and request objects.

• It is recommended to use PS256 or PS512

• RSA shall have a minimum length of 2048 bits

• Elliptic curve shall have a minimum length of 160 bits

References

The OAuth 2.0 Authorization Framework: https://tools.ietf.org/html/rfc6749

OAuth 2.0 for Native Apps: https://tools.ietf.org/html/rfc8252

The OAuth 2.0 Authorization Framework - Bearer Token usage: https://tools.ietf.org/html/rfc6750

Proof Key for Code Exchange: https://tools.ietf.org/html/rfc7636

OpenID Connect: https://openid.net/specs/openid-connect-core-1_0.html

FAPI 2.0: https://openid.bitbucket.io/fapi/fapi-2_0-security-profile

OAuth 2.1: https://tools.ietf.org/html/draft-ietf-oauth-v2-1-00

OAuth DPoP: https://www.ietf.org/archive/id/draft-ietf-oauth-dpop-13