[OFFICE-3027] Public Comment: ODF 1.2 Part 3 Encryption Process and Default Concerns - OASIS Technical Committees Issue Tracker

Details

Type: Sub-task
Status: Applied
Priority: Major
Resolution: Fixed
Affects Version/s: ODF 1.2 CD 05
Fix Version/s: ODF 1.2 CD 06
Component/s: Part 2 (Packages) [1.2: 3], Public Review, Security
Labels:
None

Proposal:
Hide

1. Rename section 3.4.2 to "Encryption Process"

2. Replace the first paragraph of 3.4.2
"""
The encryption process for file entries using the default digest and encryption algorithms has three steps:
"""
with the paragraph
"""
The three stages of the encryption process proceed as follows, using the legacy algorithms to illustrate each stage:
"""

3. In section 4.5 <manifest:algorithm>, replace the second and third (the last two) paragraphs to read
"""
When the manifest:algorithm-name attribute value matches one of those defined in section §3.2 of [xmlenc-core], the <manifest:algorithm> element shall not have child elements except those permitted as child elements of the [xmlenc-core] <EncryptionMethod> element whose Algorithm attribute value is the same as the <manifest:algorithm> manifest:algorithm attribute value.

When the value of the manifest:algorithm attribute identifies the legacy Blowfish algorithm, <manifest:algorithm> shall be an empty element.
"""

4. In section 4.8.1 manifest:algorithm-name

Replace the the first pagraph with

"""
The manifest:algorithm name attribute identifies the algorithm and mode used to encrypt a file entry.
"""

Move the third bullet to the beginning of the bulleted list. Change it to read
"""

An IRI listed in §5.2 of [xmlenc-core]: The algorithm and mode specified in §5.2 of [xmlenc-core]: for this IRI.
"""

The last parapgraph of 4.8.1 is not a list item. Make it a final paragraph and reword it as follows:
"""
Package producers and consumers shall support the AES-128 CBC algorithm and mode identified by value http://www.w3.org/2001/04/xmlenc#aes128-cbc. The legacy Blowfish algorithm need not be supported. [Note: Suport of the Blowfish algorithm by package consumers provides compatibility with existing applications and documents conforming to earlier versions of this specification.]
"""

5. In 3.4.1 General, Delete the following sentences from the second paragraph:
"""
Package consumers and producers that support encryption shall support the digest and encryption algorithms defined in 3.4.2. They may support additional algorithms.
"""
Show
1. Rename section 3.4.2 to "Encryption Process" 2. Replace the first paragraph of 3.4.2 """ The encryption process for file entries using the default digest and encryption algorithms has three steps: """ with the paragraph """ The three stages of the encryption process proceed as follows, using the legacy algorithms to illustrate each stage: """ 3. In section 4.5 <manifest:algorithm>, replace the second and third (the last two) paragraphs to read """ When the manifest:algorithm-name attribute value matches one of those defined in section §3.2 of [xmlenc-core] , the <manifest:algorithm> element shall not have child elements except those permitted as child elements of the [xmlenc-core] <EncryptionMethod> element whose Algorithm attribute value is the same as the <manifest:algorithm> manifest:algorithm attribute value. When the value of the manifest:algorithm attribute identifies the legacy Blowfish algorithm, <manifest:algorithm> shall be an empty element. """ 4. In section 4.8.1 manifest:algorithm-name Replace the the first pagraph with """ The manifest:algorithm name attribute identifies the algorithm and mode used to encrypt a file entry. """ Move the third bullet to the beginning of the bulleted list. Change it to read """ An IRI listed in §5.2 of [xmlenc-core] : The algorithm and mode specified in §5.2 of [xmlenc-core] : for this IRI. """ The last parapgraph of 4.8.1 is not a list item. Make it a final paragraph and reword it as follows: """ Package producers and consumers shall support the AES-128 CBC algorithm and mode identified by value http://www.w3.org/2001/04/xmlenc#aes128-cbc . The legacy Blowfish algorithm need not be supported. [Note: Suport of the Blowfish algorithm by package consumers provides compatibility with existing applications and documents conforming to earlier versions of this specification.] """ 5. In 3.4.1 General, Delete the following sentences from the second paragraph: """ Package consumers and producers that support encryption shall support the digest and encryption algorithms defined in 3.4.2. They may support additional algorithms. """
Resolution:
Hide

1. Rename section 3.4.2 to "Encryption Process"

2. Replace the first paragraph of 3.4.2
"""
The encryption process for file entries using the default digest and encryption algorithms has three steps:
"""
with the paragraph
"""
The three stages of the encryption process proceed as follows, using the legacy algorithms to illustrate each stage:
"""

3. In section 4.5 <manifest:algorithm>, replace the second and third (the last two) paragraphs to read
"""
When the manifest:algorithm-name attribute value matches one of those defined in section §3.2 of [xmlenc-core], the <manifest:algorithm> element shall not have child elements except those permitted as child elements of the [xmlenc-core] <EncryptionMethod> element whose Algorithm attribute value is the same as the <manifest:algorithm> manifest:algorithm attribute value.

When the value of the manifest:algorithm attribute identifies the legacy Blowfish algorithm, <manifest:algorithm> shall be an empty element.
"""

4. In section 4.8.1 manifest:algorithm-name

Replace the the first pagraph with

"""
The manifest:algorithm name attribute identifies the algorithm and mode used to encrypt a file entry.
"""

Move the third bullet to the beginning of the bulleted list. Change it to read
"""

An IRI listed in §5.2 of [xmlenc-core]: The algorithm and mode specified in §5.2 of [xmlenc-core]: for this IRI.
"""

The last parapgraph of 4.8.1 is not a list item. Make it a final paragraph and reword it as follows:
"""
Package producers and consumers shall support the AES-128 CBC algorithm and mode identified by value http://www.w3.org/2001/04/xmlenc#aes128-cbc. The legacy Blowfish algorithm need not be supported. [Note: Suport of the Blowfish algorithm by package consumers provides compatibility with existing applications and documents conforming to earlier versions of this specification.]
"""

5. In 3.4.1 General, Delete the following sentences from the second paragraph:
"""
Package consumers and producers that support encryption shall support the digest and encryption algorithms defined in 3.4.2. They may support additional algorithms.
"""
Show
1. Rename section 3.4.2 to "Encryption Process" 2. Replace the first paragraph of 3.4.2 """ The encryption process for file entries using the default digest and encryption algorithms has three steps: """ with the paragraph """ The three stages of the encryption process proceed as follows, using the legacy algorithms to illustrate each stage: """ 3. In section 4.5 <manifest:algorithm>, replace the second and third (the last two) paragraphs to read """ When the manifest:algorithm-name attribute value matches one of those defined in section §3.2 of [xmlenc-core] , the <manifest:algorithm> element shall not have child elements except those permitted as child elements of the [xmlenc-core] <EncryptionMethod> element whose Algorithm attribute value is the same as the <manifest:algorithm> manifest:algorithm attribute value. When the value of the manifest:algorithm attribute identifies the legacy Blowfish algorithm, <manifest:algorithm> shall be an empty element. """ 4. In section 4.8.1 manifest:algorithm-name Replace the the first pagraph with """ The manifest:algorithm name attribute identifies the algorithm and mode used to encrypt a file entry. """ Move the third bullet to the beginning of the bulleted list. Change it to read """ An IRI listed in §5.2 of [xmlenc-core] : The algorithm and mode specified in §5.2 of [xmlenc-core] : for this IRI. """ The last parapgraph of 4.8.1 is not a list item. Make it a final paragraph and reword it as follows: """ Package producers and consumers shall support the AES-128 CBC algorithm and mode identified by value http://www.w3.org/2001/04/xmlenc#aes128-cbc . The legacy Blowfish algorithm need not be supported. [Note: Suport of the Blowfish algorithm by package consumers provides compatibility with existing applications and documents conforming to earlier versions of this specification.] """ 5. In 3.4.1 General, Delete the following sentences from the second paragraph: """ Package consumers and producers that support encryption shall support the digest and encryption algorithms defined in 3.4.2. They may support additional algorithms. """

Description

There are clarifications requested for portions of the Encryption process, with objection to the Blowfish default and proposal of an AES default.

The full text is in the second attachment to the public comment posting at
<http://lists.oasis-open.org/archives/office/201006/msg00071.html>.

Here is the Complete Text extracted from the Microsoft Word Format document linked in the original comment:

"""
Forslag til ændringer i ODF 1.2 Part 3:

For

Section 2.4.2 [CD05 3.4.2] Default Encryption algorithm:

Since the section deals with the steps involved in encrypting and not
so much the encryption algorithm itself, I suggest changing the name
of the section to "Encryption process".

Section 2.8 [CD05 3.8] Preview Image

Simply editorial, but the last sentence should start with the word
"They" and not "The". Also, there seems to be an extra [space] between
the words "is" and "independant".

Section 3.5 [CD05 4.5] <manifest:algorithm>

I propose to change section 3.5 [CD05 4.5] to the following:

[Section 3.5 [CD05 4.5] start]

The <manifest:algorithm> element specifies the algorithm used to encrypt data.

The <manifest:algorithm>-element SHALL only contain child elements
that are permitted child elements of an <EncryptionMethod> element as
defined in §3.2 of [xmlenc-core], whose Algorithm-attribute has the
value of the manifest:algorithm-name attribute.

If the value of the manifest:algorithm-name attribute is Blowfish CFB
the <manifest:algorithm> element shall not have child elements.

(section describing schema at the end of the section remains the same)

[Section 3.5 [CD05 4.5] end]

Justification:

The idea is basically to promote "standard" algorithms and XML
constructs as those mentioned in [xmlenc-core] to "first class
citizens" of ODF while making usage of Blowfish a second class citizen

while acknowledging that there are documents and applications out
there using Blowfish.

I have specifically chosen to substitute " SHOULD only contain child
elements" with " SHALL only contain child elements" since I see no
need for the more lose "should"-term. The definition of
EncryptionMethod from xmlenc-core consists of optional child elements,
so this fits nicely with "no child elements" when dealing with
Blowfish. I believe a more strict set of element rules would
facilitate interop better than the current lax way of specifying
elements.

Section 3.8.1 [CD05 4.8.1] manifest:algorithm-name

I like the idea of reusing already standardised functionality in "XML
Encryption Syntax and Processing". Especially the reusage of the
xmlenc-core way of specifiying algorithms look really good and
facilitate interoperability and reuse of existing implementations of
encryption algorithms in the best possible way.

However, I do not understand the need to persist Blowfish as the
preferred, default algorithm. I also do not understand the need to
include usage of Blowfish in the list of possible algorithms complying
with "standard OpenDocument conformance" (and not making it extended
conformance) - especially since the creator of Blowfish (Bruce
Schneier) himself discourages the usage of Blowfish today to other
alternatives.

I therefore propose the entire paragraph to be changed to:

[Section 3.8.1 [CD05 4.8.1] start]

The manifest:algorithm-name attribute specifies the name of the
algorithm used to encrypt a file entry, and also specifies in which
mode this algorithm was used.

Defined values for the manifest:algorithm-name attribute are:

An IRI listed in §5.2 or §5.3 of [xmlenc-core]: The algorithm
specified in §5.2 or §5.3 of [xmlenc-core] for this IRI, or
The IRI of an alternative algorithm as specified in §5.1 of [xmlenc-core].

To maintain compatibility with existing applications and documents
conforming to earlier versions of this specification, an application
may support Blowfish in CBC-code. The defined values for this
algorithm are "Blowfish CBC" or
"urn:oasis:names:tc:opendocument:xmlns:manifest:1.0#blowfish" See
[Blowfish].

Package producers and package consumers that support encryption shall
support AES-128 CBC using the value
http://www.w3.org/2001/04/xmlenc#aes128-cbc.

Alternative algorithms other than an IRI listed in §5.2 or §5.3 of
[xmlenc-core] may be specified by extended conforming documents only.
They shall not be specified by conforming documents.

(section describing schema at the end of the section remains the same)

[Section 3.8.1 [CD05 4.8.1] end]

Public Comment: ODF 1.2 Part 3 Encryption Process and Default Concerns

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