secure data transmission

Secure Data TransmissionEDI-INT AS1, AS2, AS3

Kevin Grant

Goals of this Presentation

• Understanding Security Mechanisms

• Understanding Applicability Statements– MDNs– Secure Transmission Loop– AS1, AS2, AS3

• Product Certification

AS1/AS2/AS3 Standards

• Applicability Statements 1 (AS1), 2 (AS2), & 3 (AS3) are the current specifications developed by EDI-INT for transporting data via the Internet.

• AS Standards specify how to exchange data, not how to process data.

– AS1 defines how to perform secure file transfers via SMTP– AS2 defines how to perform secure file transfers via HTTP– AS3 defines how to perform secure file transfers via FTP

• Specify Security Services over a Specific Communication protocol with the introduction of Message Disposition Notifications (MDNs) to complete the Secure Transmission Loop

AS1/AS2/AS3 Options

• Encrypted or not encrypted

• Signed or unsigned

• Receipt or no receipt

• Receipt signed, or not signed

AS1/AS2/AS3 Message Flow

Outgoing Message

SMTP/HTTP/FTP

Recipient

Signed MDN back to

sender with hash

Message Encrypted

with Recipient’s Public Key

Signature/Hash Applied and

Encrypted with Sender’s

Private Key

Signature/hash Decrypted with

Sender’s Public Key

Message Decrypted

with Recipient’s Private Key

Document hash is

computed

Computed hash compared with

transmitted hash

Incoming MessageValidated

Security Mechanisms

Three basic building blocks are used:• Encryption is used to provide confidentiality, can provide

authentication and integrity protection• Hash algorithms are used to provide integrity protection,

can provide authentication• Digital signatures are used to provide authentication,

integrity protection, and non-repudiation

One or more security mechanisms are combined to provide a security service

Security Protocol• A typical security protocol provides one or

more services• Services are built from mechanisms

• Mechanisms are implemented using algorithms

Hash Functions• Hashing is the transformation of a string of

characters into a shorter fixed-length value or key that represents the original string.

• It is used to index and retrieve items in a database because it is faster to find the item using the shorter hashed key than to find it using the original value.

Hash Functions• It is also used in many encryption algorithms.

– Creates a unique “fingerprint” or message digest.

– Anyone can alter the data and calculate a new hash value

– Message digest has to be protected in some way

Public-key Encryption• Uses matched public/private key pairs

(Asymmetric)

• Anyone can encrypt with the public key, only one person can decrypt with the private key

Cryptography – Digital Signatures

Here’s where the public-key algorithm and the hashing algorithm work together:

Certificates

• A certificate is a public key that has been digitally signed by a trusted third party– Certificate Authority (CA).

• A Certification Authority (CA) guarantees a public key’s authenticity

MDNs (Message Disposition Notifications)

• Document acknowledgment– Non-repudiation of delivery (confirms the document WAS received

and by whom)– Confirms that the recipient was able to decrypt– Gives a status message, as appropriate

• Contains the receiver’s computed hash for comparison against the one originally sent with the message

• MDN may be signed by the recipient of the original message

• Defined by your trading partner (optional)

MDN Request HeadersThe MDN is requested by the “Disposition-Notification-To” field found in the message header:

From: mrAS2@as2.comAS2-Version: 1.1AS2-From: AS2SENDERAS2-To: AS2RECEIVERSubject: G1 Test CaseMessage-Id: <200207310834482A70BF63@\"~~foo~~\">Disposition-Notification-To: mrAS2@as2.comReceipt-Delivery-Option: mailto:AS2@as2.comDisposition-Notification-Options: signed-receipt-protocol=optional,pkcs7-signature; signed-receipt-micalg=optional,sha1Content-Type: multipart/signed; boundary="as2BouNdary1as2"; protocol="application/pkcs7-signature"; micalg=sha1

MDN Request HeadersThe “Receipt-Delivery-Option” field is used to request MDNs in an asynchronous manner. If this field is not present, the MDN is returning via the active HTTP session (AS2):

From: mrAS2@as2.comAS2-Version: 1.1AS2-From: AS2SENDERAS2-To: AS2RECEIVERSubject: G1 Test CaseMessage-Id: <200207310834482A70BF63@\"~~foo~~\">Disposition-Notification-To: mrAS2@as2.comReceipt-Delivery-Option: mailto:AS2@as2.comDisposition-Notification-Options: signed-receipt-protocol=optional,pkcs7-signature; signed-receipt-micalg=optional,sha1Content-Type: multipart/signed; boundary="as2BouNdary1as2"; protocol="application/pkcs7-signature"; micalg=sha1

MDN Request HeadersThe “Disposition-Notification-Options” field determines whether the MDN is to be signed and identifies the preferred hash algorithm (SHA-1 or MD5):

From: mrAS2@as2.comAS2-Version: 1.1AS2-From: AS2SENDERAS2-To: AS2RECEIVERSubject: G1 Test CaseMessage-Id: <200207310834482A70BF63@\"~~foo~~\">Disposition-Notification-To: mrAS2@as2.comReceipt-Delivery-Option: mailto:AS2@as2.comDisposition-Notification-Options: signed-receipt-

protocol=optional,pkcs7-signature; signed-receipt-micalg=optional,sha1

Content-Type: multipart/signed; boundary="as2BouNdary1as2"; protocol="application/pkcs7-signature"; micalg=sha1

The “Secure Transmission Loop” (STL)

• The originator sends a signed and encrypted document with a request for a signed receipt.

• The recipient decrypts the document, verifies the signature, and returns a signed receipt to the sender.

The “STL” In More Detail

• Sender signs and encrypts the data using S/MIME and sends requesting a signed receipt.

• Receiver decrypts the message and verifies the signature, resulting in verified integrity of the data and authenticity of the sender.

• The receiving organization returns a signed receipt (message disposition notification). This signed receipt contains the hash of the message from the received message, so sender knows message was verified and/or decrypted properly.

Receiving via AS1/AS2/AS3(Inbound Documents)

1. Signed/encrypted document is received

2. Document is decrypted (using receiver’s private key)

and hash is computed

3. Digital signature is checked to validate sender

4. Transmitted hash is decrypted (using sender’s public

key) and compared to the “computed” hash

5. If the hashes are the same, the document is identical to the one transmitted

6. MDN is sent to confirm message status

Sending via AS1/AS2/AS3(Outbound Documents)

1. Document is encrypted (using receiver’s public key)

and hash is computed

2. Hash is encrypted (using sender’s private key) and attached to the digital signature block (which may or may not be encrypted)

3. Message (document + signature) is transmitted

4. Partner receives message and attempts to decrypt and validate

5. MDN is received confirming message status

AS1/AS2/AS3 Message Flow

Outgoing Message

SMTP/HTTP/FTP

Recipient

Signed MDN back to

sender with hash

Message Encrypted

with Recipient’s Public Key

Signature/Hash Applied and

Encrypted with Sender’s

Private Key

Signature/hash Decrypted with

Sender’s Public Key

Message Decrypted

with Recipient’s Private Key

Document hash is

computed

Computed hash compared with

transmitted hash

Incoming MessageValidated

AS1 - SampleReceived: from gw.somecompany.com (gw.somecompany.com [10.1.1.2])

by mail.softshare.com (8.9.1/8.9.1) with ESMTP id RAA29018

for <AS1@softshare.com>; Wed, 25 Feb 2004 17:56:50 -0800 (PST)

Message-ID: <1077760571490.12345686869@somecompany.com>

Date: Thu, 26 Feb 2004 01:56:11 GMT

Subject: 850:ORDERNO-12345678

From: edi@somecompany.com

To: AS1@softshare.com

Disposition-Notification-To: somecompanyprodedi1@somecompany.com

Disposition-Notification-Options: signed-receipt-protocol=optional, pkcs7-signature; signed-receipt-micalg=optional, sha1, md5

Content-Type: application/pkcs7-mime; smime-type=enveloped-data; name=smime.p7m

Content-Transfer-Encoding: base64

Content-Disposition: attachment; filename=smime.p7m

AS2 - SamplePOST /invoke/wm.EDIINT/receive HTTP/1.0

Host: 208.234.160.12:80

User-Agent: AS2 Company Server

Date: Wed, 31 Jul 2002 13:34:50 GMT

From: mrAS2@as2.com

AS2-Version: 1.1

AS2-From: "\" as2Name \""

AS2-To: 0123456780000

Subject: G1 Test Case

Message-Id: <200207310834482A70BF63@\"~~foo~~\">

Disposition-Notification-To: mrAS2@as2.com

Disposition-Notification-Options: signed-receipt-protocol=optional,pkcs7-signature; signed-receipt-micalg=optional,sha1

Content-Type: multipart/signed; boundary="as2BouNdary1as2";

protocol="application/pkcs7-signature"; micalg=sha1

Content-Length: 2464

AS3 - SampleDate: Wed, 31 Jul 2002 13:34:50 GMT

AS3-Version: 1.0

AS3-From: cyclone

AS3-To: "trading partner"

Message-Id: <200207310834482A70BF63@host.com>

Disposition-Notification-To: ftp://host:port/mdnbox

Disposition-Notification-Options: signed-receipt-

protocol=optional,pkcs7-signature; signed-receipt-micalg=optional,sha1

Content-Type: multipart/signed; boundary="as3BouNdary1as3";

protocol="application/pkcs7-signature"; micalg=sha1

Content-Length: 3075

--as3BouNdary1as3

Content-Type: application/edi-x12

Content-Disposition: Attachment; filename=rfc1767.dat

[ISA ...EDI transaction data...IEA...]

--as3BouNdary1as3

Content-Type: application/pkcs7-signature

[omitted binary pkcs7 signature data]

--as3BouNdary1as3

AS2 Certification

• All ‘standards’ created equal?

• Based on clear public specifications that enjoy wide usage because of this

• Certifying commonly-used and well-documented standards causes time delays in implementation and adds unnecessary costs to the end product

Drummond Certification

• Founded in 1999

• Drummond Group Inc. (DGI) is a privately held company that conducts interoperability and conformance testing

• DGI’s role is to administer the test

Open AS2

• The OpenAS2 project is a collaborative effort to develop an open source application that implements the EDIINT AS2 Standard

• Self-paced, performed in-house, and the project itself does not profit from the testing process

Questions?