F.6 XML schema for integrity protection of MIME bodies

24.3793GPPMission Critical Push To Talk (MCPTT) call controlProtocol specificationRelease 18TS

F.6.1 General

This clause defines the XML schema and the MIME type vnd.3gpp.mcptt-signed+xml, for integrity protection of MIME bodies used in the present document.

F.6.2 XML schema

<?xml version="1.0" encoding="UTF-8"?>

<xs:schema

xmlns:xs="http://www.w3.org/2001/XMLSchema"

targetNamespace="urn:3gpp:ns:mcpttSignedDoc:1.0"

xmlns:mcpttsigneddoc="urn:3gpp:ns:mcpttSignedDoc:1.0"

elementFormDefault="qualified"

attributeFormDefault="unqualified"

xmlns:xmldsig="http://www.w3.org/2000/09/xmldsig#">

<xs:import namespace="http://www.w3.org/2000/09/xmldsig#"
schemaLocation="http://www.w3.org/TR/xmldsig-core/xmldsig-core-schema.xsd"/>

<xs:complexType name="signaturesType">

<xs:sequence>

<xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>

<xs:element name="anyExt" type="mcpttsigneddoc:anyExtType" minOccurs="0"/>

</xs:sequence>

<xs:anyAttribute namespace="##any" processContents="lax"/>

</xs:complexType>

<!– root XML element when creating a signed XML document –>

<xs:element name="signatures" type="mcpttsigneddoc:signaturesType"/>

<xs:complexType name="anyExtType">

<xs:sequence>

<xs:any namespace="##any" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>

</xs:sequence>

</xs:complexType>

</xs:schema>

F.6.3 Semantic

When integrity protection is turned on, the vnd.3gpp.mcptt-signed+xml MIME body is included when sending MIME bodies containing XML content in SIP requests and SIP responses.

The <signatures> element is the root element of the XML document.

NOTE 1: The subelements of the <signatures> element are validated by the <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/> particle of the <signatures> element

An instance of the <signatures> element contains one or more instances of the <xmldsig:Signature> element from the http://www.w3.org/2000/09/xmldsig# namespace. The <xmldsig:Signature> element validates against the <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/> element.

Each <xmldsig:Signature> element contains the following child elements:

1) a <xmldsig:SignatureValue> element is included with a signature value;

2) a <xmldsig:SignedInfo> element can be included and can contain the following child elements:

a) a <xmldsig:CanonicalizationMethod> element can be included with an "Algorithm" attribute containing an appropriate canonicalisation method to be applied to the signed information;

b) a <xmldsig:SignatureMethod> element can be included with an "Algorithm" attribute containing an appropriate algorithm for the signature; and

NOTE 2: For signatures, it is assumed that HMAC-SHA256 is supported by the sender and the receiver.

c) a <xmldsig:Reference> element can be included and can contain the following child elements:

i) a "URI" attribute can be included with a "cid-URL" referring to an XML MIME body containing a Content-ID set to the "cid-URL"

ii) a <xmldsig:DigestMethod> element can be included referring to an appropriate method for hashing the content; and

NOTE 3: For hashing of the content, it is assumed that SHA-256 is supported by the sender and the receiver.

iii) a <xmldsig:DigestValue> element can be included containing the hashed content; and

3) a <xmldsig:KeyInfo> element can be included with a <xmldsig:KeyName> element containing the base 64 encoded XPK-ID.

NOTE 4: When the optional attributes and elements are not included within the <xmldsig:Signature> element, the information they contain is known to sender and the receiver by other means.

F.6.4 IANA registration template

Your Name:

<MCC name>

Your Email Address:

<MCC email address>

Media Type Name:

Application

Subtype name:

vnd.3gpp.mcptt-signed+xml

Required parameters:

None

Optional parameters:

"charset" the parameter has identical semantics to the charset parameter of the "application/xml" media type as specified in section 9.1 of IETF RFC 7303.

Encoding considerations:

binary.

Security considerations:

Same as general security considerations for application/xml media type as specified in section 9.1 of IETF RFC 7303. In addition, this media type provides a format for exchanging information in SIP, so the security considerations from IETF RFC 3261 apply.

The information transported in this media type does not include active or executable content.

Mechanisms for privacy and integrity protection of protocol parameters exist. Those mechanisms as well as authentication and further security mechanisms are described in 3GPP TS 24.229.

This media type does not include provisions for directives that institute actions on a recipient’s files or other resources.

This media type does not include provisions for directives that institute actions that, while not directly harmful to the recipient, may result in disclosure of information that either facilitates a subsequent attack or else violates a recipient’s privacy in any way.

This media type does not employ compression.

Interoperability considerations:

Same as general interoperability considerations for application/xml media type as specified in section 9.1 of IETF RFC 7303. Any unknown XML elements and any unknown XML attributes are to be ignored by recipient of the MIME body.

Published specification:

3GPP TS 24.379 "Mission Critical Push To Talk (MCPTT) call control" version 13.1.0, available via http://www.3gpp.org/specs/numbering.htm.

Applications which use this media type:

Applications supporting the mission critical push to talk as described in the published specification.

Fragment identifier considerations:

The handling in section 5 of IETF RFC 7303 applies.

Restrictions on usage:

None

Provisional registration? (standards tree only):

N/A

Additional information:

1. Deprecated alias names for this type: none

2. Magic number(s): none

3. File extension(s): none

4. Macintosh File Type Code(s): none

5. Object Identifier(s) or OID(s): none

Intended usage:

Common

Person to contact for further information:

– Name: <MCC name>

– Email: <MCC email address>

– Author/Change controller:

i) Author: 3GPP CT1 Working Group/3GPP_TSG_CT_WG1@LIST.ETSI.ORG

ii) Change controller: <MCC name>/<MCC email address>