Warning
This document summarizes and clarifies some aspects of the EBICS protocol that are important to LibEuFin. Both version 3.0 and 2.5 are discussed here.
It is not a specification, and it does not replace the official EBICS specification.
Table of Contents
Electronic Signature. This abbreviation is commonly used in the context of EBICS.
The following signature classes are defined (in descending order from strongest to weakest):
In H004 and H005, the ES of the bank is specified as a “planned feature” that is not actually implemented yet. Thus banks in practice only use their encryption key pair and authentication/identity key pair.
ISO 20022: Financial Services - Universal financial industry message scheme. Rather important standard for financial industry business-related messages. In contrast, EBICS takes care of message transmission, segmentation, authentication, key management, etc.
The full catalogue of messages is available gratis.
Interchangeably called “Order ID”.
Each upload transaction gets a unique order number assigned by the bank server.
The Order Number is used to match VEUs in a second upload to the original order.
An Order Number matches the format [A-Z][A-Z0-9]{3} (and is not really a number!).
Must be unique per customer ID and per order type.
In German, this is called “Kunden ID” (= Customer ID). One partner can have multiple “participants”, which are identified by user IDs.
Practical example: A company has one Partner ID. Each person at the company that can access the company’s bank accounts gets their own User ID. When the person is indirectly accessing the bank server (for example via a client server application), an additional “System ID” is created for this “technical subscriber”. When there is no technical subscriber, the System ID must be the same as the User ID. Usually the System ID is optional though.
The (partner, user, system) triple uniquely identifies a subscriber.
EBICS implements its own protocol-level segmentation of business-related messages.
The segmentation can be seen as an alternative to the HTTP facilities of Accept-Ranges.
The order data of an EBICS message may not exceed 1 MB. The segmentation applies both to requests and responses.
Entity that wishes to communicate with the financial institution via EBICS.
Subscribers can be technical or human. Technical subscribers are typically a server in client-server applications, where the server talks to a financial institution via EBICS.
Requests from technical subscribers have a SystemID in addition to a PartnerID
and UserId. A technical subscriber cannot sign a bank-technical request.
A transaction ID is a 128-bit cryptographically strong random number. It is assigned by the bank server for every transaction, i.e. upload or download of an order.
The transaction ID must not be guessable, as it would allow a potential attacker to upload segments of an upload that do not match the whole message’s digest.
By convention, order types beginning with “H” are administrative order types, and other ones are bank-technical order types. This convention isn’t always followed consistently by EBICS.
Type: Upload.
Send SEPA Credit Transfer Initiation (pain.001) via XML container. This is the DFÜ variant (Appendix 3 DFÜ-Agreement).
Type: Upload.
Send SEPA Credit Transfer Initiation (pain.001) directly. This is the DFÜ variant (Appendix 3 DFÜ-Agreement).
Type: Download.
Payment Status Report for Credit Transfer Instant.
Type: Download.
Fetch payment status report (pain.002).
Type: Download, Optional.
Download order types for which there is new data available.
K_SIG, K_IA and K_ENC).Type: Download, Optional.
Download information about a customer (=partner). From German “Kundendaten”.
Type: Download.
Download information about a subscriber. From German “Teilnehmerdaten”.
The following order types are, for now, not relevant for LibEuFin:
Type: Upload.
From German “Auslandszahlungsverkehr”. Used to submit cross-border payments in a legacy format.
Type: Upload.
German “Eilüberweisung”.
Type: Download.
Download payment status report for direct debit.
Type: Upload.
Send all three RSA key pairs for initialization at once, accompanied by a CA certificate for the keys. This is (as far as we know) used in France, but not used by any German banks. When initializing a subscriber with H3K, no INI and HIA letters are required.
Type: Upload.
Change the identification and authentication key as well as the encryption key (K_IA and K_ENC).
Superseded by HCS.
Type: Optional
Order to migrate from FTAM to EBICS. Removed in EBICS 3.0.
Type: Download.
Retrieve VEU state.
Type: Upload.
Host Verification of Electronic Signature. Used to submit an electronic signature separately from a previously uploaded order.
Type: Upload.
Cancel Previous Order (from German “Storno”). Used to submit an electronic signature separately from a previously uploaded order.
Type: Download.
Retrieve VEU overview.
Type: Download.
Retrieve VEU extra information. From German “Zusatzinformationen”.
Type: Download.
Download a human-readable protocol of operations done via EBICS. Mandatory for German banks. Superseded by the machine-readable HAC order type.
Type: Upload.
Change of the bank-technical key (K_SIG).
Superseded by HSA.
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.ebicsUnsecuredRequest: Request without signature or encryption (beyond TLS). Used for INI and HIA.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 / ebicsResponseebicsUnsignedRequest: Not used anymore. Was used in FTAM migration with the HSA order type.In practice, the Order ID seems to be allocated via number of counters at the level of the PartnerID.
A transaction in EBICS simply refers to the process of uploading or downloading a file. Whether it is an upload or download transaction depends on the order type. Each transaction is either an upload transaction or a download transaction, neither both.
Uploads and downloads must proceed in segments of at most 1 MB. The
segmentation happens after (1) encryption, (2) zipping, and (3) base64-encoding
of the order data.
The number of segments is always fixed starting from the first message sent (for uploads) or received (for downloads) by the subscriber. The digest of the whole message is also sent/received with the first message of a transaction. The EBICS host generates a 128-bit transaction ID. This ID is used to correlate uploads/downloads of segments for the same transaction.
If an attacker would be able to guess the transaction ID, they could upload a bogus segment. This would only be detected after the whole file has been transmitted.
An upload transaction is finished when the subscriber has sent the last segment. A download transaction is only finished when the subscriber has sent an additional acknowledgement message to the EBICS host.
When upload/download of a segment fails, the client can always re-try. There are some conditions for that:
n can only be downloaded/uploaded when segments [0..n-1] have
been downloaded/uploaded.ISO 20022 is XML-based and defines the message format for many finance-related activities.
ISO 20022 messages are identified by a message identifier in the following format:
<business area> . <message identifier> . <variant> . <version>
Some financial instututions (such as the Deutsche Kreditwirtschaft) have decided to use
a subset of elements/attributes in a message, this is what the <variant> part is for.
“Standard” ISO20022 have variant 001.
The most important message types for LibEuFin are:
SWIFT Proprietary messages are in a custom textual format. The relevant messages are MT940 and MT942.
SWIFT will eventually transition from MT messages to ISO20022, but some banks might still only give us account statements in the old SWIFT format.
RSA key pairs are used for three purposes:
K_SIG.K_IA.K_ENC.One subscriber may use three different key pairs for these purposes. The identification and authentication key pair may be the same as the encryption key pair. The bank-technical key pair may not be used for any other purpose.
Real-time transactions will be supported with EBICS starting November 2019. That’s the earliest date, some banks may offer it later or not at all.
For us, CIZ is the relevant order type that we need to ask banks for.
It looks like there is no way to “reject” payments, unless you are the bank.
There is a concept of payment reversal (with pain.007 for direct debit and camt.055 for SEPA Credit Transfer),
but they are a way for the payer / sender to reverse a payment before it is finalized.
All German banks that are part of the Deutsche Kreditwirtschaft must support EBICS.
The exact subset of EBICS order types must be agreed on contractually by the bank and customer. The following subsections list the message types that we know are supported by particular banks.
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 RFC 6931.
RSASSA-PKCS1-v1_5 signature scheme contains the EMSA-PKCS1-v1_5 encoding scheme
mentioned in the EBICS spec.XML Signatures can be a combination of:
Object tags within the Signature elements)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.
SignedInfo element.Reference elements reference. Canonicalization
algorithms can be used as a transformation on referenced data.The EBICS standard documents are available at http://www.ebics.org.
EBICS 3.0:
2017-03-29-EBICS_V_3.0-FinalVersion.pdf).2017-03-29-EBICS_V_3.0_Annex1_ReturnCodes-FinalVersion.pdf) .The DFÜ Agreement is the set of standards used by the German Banking Industry Committee (Deutsche Kreditwirtschaft).
The following Annexes (also see the DK Website) are relevant for implementing EBICS:
The EBICS Compendium has some additional info on EBICS. It is published by a company that sells a proprietary EBICS server implementation.