RE: Action 06-05-22-01 on CG: Proposal for verification time and signing time issues found in DSS Core plus editorial instructions

Carlos 
et all,

 

I was 
considering putting in a choice so that the signingTime could be dateTime 
or an explicit indicator <unknown> but looking further into this the 
non-presence of the optional output is equally good.  So propose we leave 
this as below.

 

Nick

  
-----Original Message-----
From: Carlos González-Cadenas 
  [mailto:]
Sent: 01 June 2006 
  10:24
To: 'Juan Carlos Cruellas'; 'Nick Pope'
Cc: 'DSS TC 
  List'
Subject: Action 06-05-22-01 on CG: Proposal for verification 
  time and signing time issues found in DSS Core plus editorial 
  instructions

  

  
All,

  
 

  
Here’s 
  the last draft of the proposal including latest JC and NP’s comments (latest 
  changes in a different colour). The only proposed change that is not included 
  at the moment is the one by Nick suggesting to change “When there's no way for the server 
  to determine the signing time, the server MUST omit the <SigningTimeInfo> output.” by a 
  protocol error in (4). Nick, please replace that by the corresponding 
  Major/Minor combination (as I can’t find any good choice with existing 
  Major/Minor combinations…).

  
 

  
The 
  rest of changes are incorporated, so, in my opinion, when this pending change 
  is done, we’re ready to incorporate all the changes in 
  DSS.

  
 

  
Stefan,

  
 

  
Here 
  goes my proposal for incorporation of the text below in the 
  core,

  
 

  
1.       
  Append the 
  text at (1) to the end of  chapter 4.3 item 
  3.

  
2.       
  Replace 
  optional input <dss:VerificationTime> in 4.6.2 
  by the optional input <dss:UseVerificationTime> using the text included in 
  (2)

  
3.       
  Create a new 
  optional input /output 4.6.3 <dss:ReturnVerificationTimeInfo> / <dss:VerificationTimeInfo> (shifting actual 4.6.3 to 
  4.6.4 and so on)  using the text 
  included in (3).

  
4.       
  Replace 
  optional input/output <dss:ReturnSigningTime> / <dss:SigningTime> in 4.6.5 by the optional input/output 
  <dss:ReturnSigningTimeInfo> / <dss:SigningTimeInfo> using the text included in 
  (4).

  
 

  
Kind 
  regards,

  

Carlos

  
 

  
Carlos 
  González-Cadenas
Chief 
  Security Officer

Diagonal 188-198 Planta 
  2
08018 Barcelona
tel: 902 303 393
fax: 902 303 
  394

www.netfocus.es 

  
 

  
 

  
------------------

  
 

  
1) 4.3 item 3 (line 
  1481):

  
 

  
"The server shall verify the 
  validity of the signature at a particular time (i.e. current time, assumed 
  signing time or other time), depending on the server policy. This behaviour 
  MAY be altered by using the optional input <UseVerificationTime> (see 
  section 4.6.2)"

  
 

  
 

  
2) 4.6.2 Optional Input 
  <UseVerificationTime>

  
 

  
This element instructs the 
  server to attempt to determine the signature’s validity at the specified time, 
  instead of a time determined by the 
  server policy.

  
 

  
Note: In order to perform the verification of 
  the signature at a certain time, the server MUST obtain the information 
  necessary to carry out this verification (e.g. CA certificates, CRLs) 
  applicable at that time.

  
 

  
<CurrentTime> 
  [Optional]

  
      Instructs the 
  server to use its current time (normally the time associated with the 
  server-side request processing).

  
 

  
<SpecificTime> 
  [Optional]

  
Allows the client to manage 
  manually the time instant used in the verification process. It SHOULD be 
  expressed as UTC time (Coordinated Universal Time) to reduce confusion with 
  the local time zone use.

  
 

  
Profiles MAY define new 
  child elements associated to other different 
  behaviours.

  
 

  
      <xs:element 
  name="UseVerificationTime"/>

  
      
  <xs:complexType 
  name="UseVerificationTimeType">

  
            
  <xs:choice>

  
                  
  <xs:element name="CurrentTime"/>

  
                  
  <xs:element name="SpecificTime" 
  type="xs:dateTime"/>

  
                  
  <xs:any namespace="##other"/>

  
            
  </xs:choice>

  
      
  </xs:complexType>

  
 

  
If the verification time is 
  a significant period in the past the server MAY need to take specific steps 
  for this, and MAY need to ensure

  
that any cryptographic 
  weaknesses over the period do not affect the validation. 
  

  
 

  
This optional input is 
  allowed in multi-signature verification.

  
 

  
3) New optional input/output 
  <ReturnVerificationTimeInfo> / 
  <VerificationTimeInfo>

  
 

  
This element allows the 
  client to obtain the time instant used by the server to validate the 
  signature.

  
 

  
      <xs:element 
  name="ReturnVerificationTimeInfo"/>

  
 

  
Optionally, in addition to 
  the verification time, the server MAY include in the 
  <VerificationTimeInfo> response any other relevant time instants that 
  may have been used when determining the verification time or that may be 
  useful for its qualification.

  
 

  
<VerificationTime> 
  [Required]

  
The 
  time instant used by the server when verifying the signature. It SHOULD be 
  expressed as UTC time (Coordinated Universal Time) to reduce confusion with 
  the local time zone use.    
  

  
 

  
<AdditionalTimeInfo> 
  [Optional]

  
      Any other time 
  instant(s) relevant in the context of the verification time 
  determination.

  
 

  
The 
  Type attribute qualifies the kind of time information included in the 
  response. The Ref attribute allows to establish references to the source of 
  the time information, and SHOULD be used when there is a need to disambiguate 
  several <AdditionalTimeInfo> elements with the same Type 
  attribute.

  
 

  
      This 
  specification defines the following base types, whose values MUST      be of type 
  xs:dateTime and SHOULD be expressed as UTC time      (Coordinated 
  Universal Time). Profiles MAY include 
  and define new values for the Type attribute.

  
 

  
      
  urn:oasis:names:tc:dss:1.0:additionaltimeinfo:signatureTimestamp

  
 

  
      The time 
  carried inside a timestamp applied over the signature value. 
  

  
 

  
      
  urn:oasis:names:tc:dss:1.0:additionaltimeinfo:signatureTimemark

  
 

  
      The time 
  instant associated to the signature stored in a secure record      in the 
  server.

  
 

  
      
  urn:oasis:names:tc:dss:1.0:additionaltimeinfo:signedObjectTimestamp

  
 

  
      The time 
  carried inside a timestamp applied over a signed 
  object.

  
 

  
Note 
  that XML Signatures can be produced       over multiple 
  objects (via multiple ds:Reference elements), and therefore it's possible to 
  have      multiple 
  timestamps, each one applied over each object. In this case, the Ref attribute 
  MUST include the value of the Id attribute of the ds:Reference element.     
  

  
 

  
      
  urn:oasis:names:tc:dss:1.0:additionaltimeinfo:claimedSigningTime

  
 

  
      The time 
  claimed by the signer to be the signature creation 
  time.

  
 

  
<xs:element name="AdditionalTimeInfo">

  
            <xs:complexType>

  
            
        
  <xs:complexContent>

  
                  
        
  <xs:extension base="xs:dateTime">

  
                             
  <xs:attribute name="Type" type="xs:anyURI" use="required"/>

  
                             
  <xs:attribute 
  name="Ref" type="xs:string" use="optional"/>                                    
  

  
                        
  </xs:extension>

  
                  
  </xs:complexContent>

  
            
  </xs:complexType>

  
      </xs:element>

  
 

  
      
  <xs:element name="VerificationTimeInfo" type="VerificationTimeInfoType"/>

  
      
  <xs:complexType 
  name="VerificationTimeInfoType">

  
            
  <xs:sequence>

  
                  
  <xs:element name="VerificationTime" 
  type="xs:dateTime"/>

  
                  
  <xs:element 
  ref=”dss:AditionalTimeInfo” minOccurs="0" maxOccurs="unbounded"/>      
  

  
            
  </xs:sequence>

  
      </xs:complexType>

  
 

  
In 
  the case of multi-signature verification, it’s a matter of server policy as to 
  whether this element is supported.

  
 

  
4) 4.6.5 Optional Input 
  <ReturnSigningTimeInfo> and Output 
  <SigningTimeInfo>

  
 

  
This element allows the 
  client to obtain the time instant associated to the signature creation. 
  

  
 

  
Note: 
  The signing time may be derived, for example, from a claimed signing time 
  signed signature attribute.

  
 

  
      <xs:element name="ReturnSigningTimeInfo"/>

  
 

  
Sometimes, depending on the 
  applicable server policy, this signing time needs to be qualified, in order to 
  avoid unacceptable measurement errors or false claims, using time boundaries 
  associated to trustworthy time values (based on timestamps or time-marks 
  created using trusted time sources). In this case, the server MAY include 
  these values in the <LowerBoundary> and <UpperBoundary> elements, 
  respectively.

  
 

  
Criteria for determining 
  when a time instant can be considered trustworthy and for determining the 
  maximum acceptable delays between the signing time and their boundaries (if 
  any) is outside the scope of this 
  specification.

  
 

  
When there's no way for the 
  server to determine the signing time, the server MUST omit the 
  <SigningTimeInfo> output.

  
 

  
<SigningTime> 
  [Required]

  
      The time value 
  considered by the server to be the signature creation 
  time.

  
 

  
<SigningTimeBoundaries> 
  [Optional]

  
      The trusted 
  time values considered as lower and upper limits for the signing time. If this 
  element is present, at least one of the   
  <LowerBoundary> and <UpperBoundary> elements MUST be 
  present.

  
 

  
 

  
      <xs:element 
  name="SigningTimeInfo" 
  type="SigningTimeInfoType"/>

  
      
  <xs:complexType 
  name="SigningTimeInfoType">

  
            
  <xs:sequence>

  
                  
  <xs:element name="SigningTime" 
  type="xs:dateTime"/>

  
                  
  <xs:element name="SigningTimeBoundaries" 
  minOccurs="0">

  
                        
  <xs:complexType>

  
                             
  <xs:sequence>

  
                                   
  <xs:element name="LowerBoundary" minOccurs="0" 
  type="xs:dateTime"/>

  
                                   
  <xs:element name="UpperBoundary" minOccurs="0" 
  type="xs:dateTime"/>

  
                             
  </xs:sequence>

  
                        
  </xs:complexType>

  
                  
  </xs:element>

  
            
  </xs:sequence>

  
      
  </xs:complexType>

  
 

  
This optional input is not 
  allowed in multi-signature verification.