From 009aa08ad528ae40e5878126c7df16827cba6f8d Mon Sep 17 00:00:00 2001 From: Florian Dold Date: Mon, 28 Oct 2019 15:05:19 +0100 Subject: ebics crypto --- libeufin/ebics.rst | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) diff --git a/libeufin/ebics.rst b/libeufin/ebics.rst index 605bd971..731882fe 100644 --- a/libeufin/ebics.rst +++ b/libeufin/ebics.rst @@ -342,6 +342,21 @@ The following order types are, for now, not relevant for LibEuFin: HAC order type. +EBICS Message Format +==================== + +The following elements are the allowed root elements of EBICS request/response messages: + +* ``ebicsHEVRequest`` / ``ebicsHEVResponse``: Always unauthenticated and unencrypted. Used + **only** for query/response of the host's EBICS version. +* ``ebicsKeyManagementResponse``: Unauthenticated response. Used for key management responses and + sometimes **also** to deliver error messages that are not signed by the bank (such as "invalid request"). +* ``ebicsNoPubKeyDigestsRequest``: Signed request that *does not* contain the hash of the bank's + public key that the client expects. Used for key management, specifically only the HPB order type. +* ``ebicsRequest`` / ``ebicsResponse`` + + + EBICS Transaction ================= @@ -491,6 +506,43 @@ HypoVereinsbank See `this document `__. + +Cryptography +============ + +EBICS uses the XML Signature standard for signatures. It does *not* use XML encryption. + +The EBICS specification doesn't directly reference the standardized URIs for the various +signing algorithms. Some of these URIs are defined in ``__. + +* A005 is http://www.w3.org/2001/04/xmldsig-more#rsa-sha256 + + * the ``RSASSA-PKCS1-v1_5`` signature scheme contains the ``EMSA-PKCS1-v1_5`` encoding scheme + mentioned in the EBICS spec. + +* A006 is ``__ as defined in RFC 6931. + +XML Signatures +-------------- + +XML Signatures can be a combination of: + +* detached (referencing another document) +* enveloping (signs over ``Object`` tags *within* the ``Signature`` elements) +* enveloped (signs over arbitrary data (via XPath expression) in other parts of the document + that contains the signature). + +In EBICS, only **enveloped** signatures are used. + +In the XML Signature standard, the element for a signature is ``Signature``. EBICS violates this +standard by always mandating ``AuthSignature`` as the name. ``AuthSignature`` is an alias to +the ``SignatureType`` xsd type in the XML Schema. + +Canonicalization vs transforms: + * Canonicalization refers to the processing of the ``SignedInfo`` element. + * Transformations apply to the data that ``Reference`` elements reference. Canonicalization + algorithms can be used as a transformation on referenced data. + Standards and Resources ======================= -- cgit v1.2.3