<?xml version="1.0" encoding="UTF-8"?>
<xs:schema 
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  elementFormDefault="qualified"
  version="2.0">

  <xs:annotation>
    <xs:documentation>
      Document identifier: saml-schema-authn-context-types-2.0
      Location: http://docs.oasis-open.org/security/saml/v2.0/
      Revision history:
          V2.0 (March, 2005):
          New core authentication context schema types for SAML V2.0. 
    </xs:documentation>
  </xs:annotation>

  <xs:element name="AuthenticationContextDeclaration" type="AuthnContextDeclarationBaseType">
    <xs:annotation>
      <xs:documentation>
        A particular assertion on an identity
        provider's part with respect to the authentication
        context associated with an authentication assertion.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="Identification" type="IdentificationType">
    <xs:annotation>
      <xs:documentation>
        Refers to those characteristics that describe the
        processes and mechanisms
        the Authentication Authority uses to initially create
        an association between a Principal
        and the identity (or name) by which the Principal will
        be known
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="PhysicalVerification">
    <xs:annotation>
      <xs:documentation>
        This element indicates that identification has been
        performed in a physical
        face-to-face meeting with the principal and not in an
        online manner.
      </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:attribute name="credentialLevel">
        <xs:simpleType>
          <xs:restriction base="xs:NMTOKEN">
            <xs:enumeration value="primary"/>
            <xs:enumeration value="secondary"/>
          </xs:restriction>
        </xs:simpleType>
      </xs:attribute>
    </xs:complexType>
  </xs:element>

  <xs:element name="WrittenConsent" type="ExtensionOnlyType"/>

  <xs:element name="TechnicalProtection" type="TechnicalProtectionBaseType">
    <xs:annotation>
      <xs:documentation>
        Refers to those characterstics that describe how the
        'secret' (the knowledge or possession
        of which allows the Principal to authenticate to the
        Authentication Authority) is kept secure
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="SecretKeyProtection" type="SecretKeyProtectionType">
    <xs:annotation>
      <xs:documentation>
        This element indicates the types and strengths of
        facilities
        of a UA used to protect a shared secret key from
        unauthorized access and/or use.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="PrivateKeyProtection" type="PrivateKeyProtectionType">
    <xs:annotation>
      <xs:documentation>
        This element indicates the types and strengths of
        facilities
        of a UA used to protect a private key from
        unauthorized access and/or use.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="KeyActivation" type="KeyActivationType">
    <xs:annotation>
      <xs:documentation>The actions that must be performed
        before the private key can be used. </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="KeySharing" type="KeySharingType">
    <xs:annotation>
      <xs:documentation>Whether or not the private key is shared
        with the certificate authority.</xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="KeyStorage" type="KeyStorageType">
    <xs:annotation>
      <xs:documentation>
        In which medium is the key stored.
        memory - the key is stored in memory.
        smartcard - the key is stored in a smartcard.
        token - the key is stored in a hardware token.
        MobileDevice - the key is stored in a mobile device.
        MobileAuthCard - the key is stored in a mobile
        authentication card.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="SubscriberLineNumber" type="ExtensionOnlyType"/>
  <xs:element name="UserSuffix" type="ExtensionOnlyType"/>

  <xs:element name="Password" type="PasswordType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that a password (or passphrase)
        has been used to
        authenticate the Principal to a remote system.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="ActivationPin" type="ActivationPinType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that a Pin (Personal
        Identification Number) has been used to authenticate the Principal to
        some local system in order to activate a key.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="Token" type="TokenType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that a hardware or software
        token is used
        as a method of identifying the Principal.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="TimeSyncToken" type="TimeSyncTokenType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that a time synchronization
        token is used to identify the Principal. hardware -
        the time synchonization
        token has been implemented in hardware. software - the
        time synchronization
        token has been implemented in software. SeedLength -
        the length, in bits, of the
        random seed used in the time synchronization token.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="Smartcard" type="ExtensionOnlyType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that a smartcard is used to
        identity the Principal.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="Length" type="LengthType">
    <xs:annotation>
      <xs:documentation>
        This element indicates the minimum and/or maximum
        ASCII length of the password which is enforced (by the UA or the
        IdP). In other words, this is the minimum and/or maximum number of
        ASCII characters required to represent a valid password.
        min - the minimum number of ASCII characters required
        in a valid password, as enforced by the UA or the IdP.
        max - the maximum number of ASCII characters required
        in a valid password, as enforced by the UA or the IdP.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="ActivationLimit" type="ActivationLimitType">
    <xs:annotation>
      <xs:documentation>
        This element indicates the length of time for which an
        PIN-based authentication is valid.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="Generation">
    <xs:annotation>
      <xs:documentation>
        Indicates whether the password was chosen by the
        Principal or auto-supplied by the Authentication Authority.
        principalchosen - the Principal is allowed to choose
        the value of the password. This is true even if
        the initial password is chosen at random by the UA or
        the IdP and the Principal is then free to change
        the password.
        automatic - the password is chosen by the UA or the
        IdP to be cryptographically strong in some sense,
        or to satisfy certain password rules, and that the
        Principal is not free to change it or to choose a new password.
      </xs:documentation>
    </xs:annotation>

    <xs:complexType>
      <xs:attribute name="mechanism" use="required">
        <xs:simpleType>
          <xs:restriction base="xs:NMTOKEN">
            <xs:enumeration value="principalchosen"/>
            <xs:enumeration value="automatic"/>
          </xs:restriction>
        </xs:simpleType>
      </xs:attribute>
    </xs:complexType>
  </xs:element>

  <xs:element name="AuthnMethod" type="AuthnMethodBaseType">
    <xs:annotation>
      <xs:documentation>
        Refers to those characteristics that define the
        mechanisms by which the Principal authenticates to the Authentication
        Authority.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="PrincipalAuthenticationMechanism" type="PrincipalAuthenticationMechanismType">
    <xs:annotation>
      <xs:documentation>
        The method that a Principal employs to perform
        authentication to local system components.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="Authenticator" type="AuthenticatorBaseType">
    <xs:annotation>
      <xs:documentation>
        The method applied to validate a principal's
        authentication across a network
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="ComplexAuthenticator" type="ComplexAuthenticatorType">
    <xs:annotation>
      <xs:documentation>
        Supports Authenticators with nested combinations of
        additional complexity.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="PreviousSession" type="ExtensionOnlyType">
    <xs:annotation>
      <xs:documentation>
        Indicates that the Principal has been strongly
        authenticated in a previous session during which the IdP has set a
        cookie in the UA. During the present session the Principal has only
        been authenticated by the UA returning the cookie to the IdP.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="ResumeSession" type="ExtensionOnlyType">
    <xs:annotation>
      <xs:documentation>
        Rather like PreviousSession but using stronger
        security. A secret that was established in a previous session with
        the Authentication Authority has been cached by the local system and
        is now re-used (e.g. a Master Secret is used to derive new session
        keys in TLS, SSL, WTLS).
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="ZeroKnowledge" type="ExtensionOnlyType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that the Principal has been
        authenticated by a zero knowledge technique as specified in ISO/IEC
        9798-5.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="SharedSecretChallengeResponse" type="SharedSecretChallengeResponseType"/>

  <xs:complexType name="SharedSecretChallengeResponseType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that the Principal has been
        authenticated by a challenge-response protocol utilizing shared secret
        keys and symmetric cryptography.
      </xs:documentation>
    </xs:annotation>
    <xs:sequence>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
    <xs:attribute name="method" type="xs:anyURI" use="optional"/>
  </xs:complexType>

  <xs:element name="DigSig" type="PublicKeyType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that the Principal has been
        authenticated by a mechanism which involves the Principal computing a
        digital signature over at least challenge data provided by the IdP.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="AsymmetricDecryption" type="PublicKeyType">
    <xs:annotation>
      <xs:documentation>
        The local system has a private key but it is used
        in decryption mode, rather than signature mode. For example, the
        Authentication Authority generates a secret and encrypts it using the
        local system's public key: the local system then proves it has
        decrypted the secret.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="AsymmetricKeyAgreement" type="PublicKeyType">
    <xs:annotation>
      <xs:documentation>
        The local system has a private key and uses it for
        shared secret key agreement with the Authentication Authority (e.g.
        via Diffie Helman).
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:complexType name="PublicKeyType">
    <xs:sequence>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
    <xs:attribute name="keyValidation" use="optional"/>
  </xs:complexType>

  <xs:element name="IPAddress" type="ExtensionOnlyType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that the Principal has been
        authenticated through connection from a particular IP address.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="SharedSecretDynamicPlaintext" type="ExtensionOnlyType">
    <xs:annotation>
      <xs:documentation>
        The local system and Authentication Authority
        share a secret key. The local system uses this to encrypt a
        randomised string to pass to the Authentication Authority.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="AuthenticatorTransportProtocol" type="AuthenticatorTransportProtocolType">
    <xs:annotation>
      <xs:documentation>
        The protocol across which Authenticator information is
        transferred to an Authentication Authority verifier.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="HTTP" type="ExtensionOnlyType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that the Authenticator has been
        transmitted using bare HTTP utilizing no additional security
        protocols.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="IPSec" type="ExtensionOnlyType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that the Authenticator has been
        transmitted using a transport mechanism protected by an IPSEC session.
      </xs:documentation>
    </xs:annotation>
  </xs:element>
  
  <xs:element name="WTLS" type="ExtensionOnlyType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that the Authenticator has been
        transmitted using a transport mechanism protected by a WTLS session.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="MobileNetworkNoEncryption" type="ExtensionOnlyType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that the Authenticator has been
        transmitted solely across a mobile network using no additional
        security mechanism.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="MobileNetworkRadioEncryption" type="ExtensionOnlyType"/>
  <xs:element name="MobileNetworkEndToEndEncryption" type="ExtensionOnlyType"/>

  <xs:element name="SSL" type="ExtensionOnlyType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that the Authenticator has been
        transmitted using a transport mechnanism protected by an SSL or TLS
        session.
      </xs:documentation>
    </xs:annotation>
  </xs:element>
  
  <xs:element name="PSTN" type="ExtensionOnlyType"/>
  <xs:element name="ISDN" type="ExtensionOnlyType"/>
  <xs:element name="ADSL" type="ExtensionOnlyType"/>

  <xs:element name="OperationalProtection" type="OperationalProtectionType">
    <xs:annotation>
      <xs:documentation>
        Refers to those characteristics that describe
        procedural security controls employed by the Authentication Authority.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="SecurityAudit" type="SecurityAuditType"/>
  <xs:element name="SwitchAudit" type="ExtensionOnlyType"/>
  <xs:element name="DeactivationCallCenter" type="ExtensionOnlyType"/>

  <xs:element name="GoverningAgreements" type="GoverningAgreementsType">
    <xs:annotation>
      <xs:documentation>
        Provides a mechanism for linking to external (likely
        human readable) documents in which additional business agreements,
        (e.g. liability constraints, obligations, etc) can be placed.
      </xs:documentation>
    </xs:annotation>
  </xs:element>

  <xs:element name="GoverningAgreementRef" type="GoverningAgreementRefType"/>

  <xs:simpleType name="nymType">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="anonymity"/>
      <xs:enumeration value="verinymity"/>
      <xs:enumeration value="pseudonymity"/>
    </xs:restriction>
  </xs:simpleType>

  <xs:complexType name="AuthnContextDeclarationBaseType">
    <xs:sequence>
      <xs:element ref="Identification" minOccurs="0"/>
      <xs:element ref="TechnicalProtection" minOccurs="0"/>
      <xs:element ref="OperationalProtection" minOccurs="0"/>
      <xs:element ref="AuthnMethod" minOccurs="0"/>
      <xs:element ref="GoverningAgreements" minOccurs="0"/>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
    <xs:attribute name="ID" type="xs:ID" use="optional"/>
  </xs:complexType>
  
  <xs:complexType name="IdentificationType">
    <xs:sequence>
      <xs:element ref="PhysicalVerification" minOccurs="0"/>
      <xs:element ref="WrittenConsent" minOccurs="0"/>
      <xs:element ref="GoverningAgreements" minOccurs="0"/>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
    <xs:attribute name="nym" type="nymType">
      <xs:annotation>
        <xs:documentation>
          This attribute indicates whether or not the
          Identification mechanisms allow the actions of the Principal to be
          linked to an actual end user.
        </xs:documentation>
      </xs:annotation>
    </xs:attribute>
  </xs:complexType>

  <xs:complexType name="TechnicalProtectionBaseType">
    <xs:sequence>
      <xs:choice minOccurs="0">
        <xs:element ref="PrivateKeyProtection"/>
        <xs:element ref="SecretKeyProtection"/>
      </xs:choice>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>

  <xs:complexType name="OperationalProtectionType">
    <xs:sequence>
      <xs:element ref="SecurityAudit" minOccurs="0"/>
      <xs:element ref="DeactivationCallCenter" minOccurs="0"/>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>

  <xs:complexType name="AuthnMethodBaseType">
    <xs:sequence>
      <xs:element ref="PrincipalAuthenticationMechanism" minOccurs="0"/>
      <xs:element ref="Authenticator" minOccurs="0"/>
      <xs:element ref="AuthenticatorTransportProtocol" minOccurs="0"/>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>

  <xs:complexType name="GoverningAgreementsType">
    <xs:sequence>
      <xs:element ref="GoverningAgreementRef" maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>

  <xs:complexType name="GoverningAgreementRefType">
    <xs:attribute name="governingAgreementRef" type="xs:anyURI" use="required"/>
  </xs:complexType>

  <xs:complexType name="PrincipalAuthenticationMechanismType">
    <xs:sequence>
      <xs:element ref="Password" minOccurs="0"/>
      <xs:element ref="RestrictedPassword" minOccurs="0"/>
      <xs:element ref="Token" minOccurs="0"/>
      <xs:element ref="Smartcard" minOccurs="0"/>
      <xs:element ref="ActivationPin" minOccurs="0"/>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
    <xs:attribute name="preauth" type="xs:integer" use="optional"/>
  </xs:complexType>
  
  <xs:group name="AuthenticatorChoiceGroup">
    <xs:choice>
      <xs:element ref="PreviousSession"/>
      <xs:element ref="ResumeSession"/>
      <xs:element ref="DigSig"/>
      <xs:element ref="Password"/>
      <xs:element ref="RestrictedPassword"/>
      <xs:element ref="ZeroKnowledge"/>
      <xs:element ref="SharedSecretChallengeResponse"/>
      <xs:element ref="SharedSecretDynamicPlaintext"/>
      <xs:element ref="IPAddress"/>
      <xs:element ref="AsymmetricDecryption"/>
      <xs:element ref="AsymmetricKeyAgreement"/>
      <xs:element ref="SubscriberLineNumber"/>
      <xs:element ref="UserSuffix"/>
      <xs:element ref="ComplexAuthenticator"/>
    </xs:choice>
  </xs:group>
  
  <xs:group name="AuthenticatorSequenceGroup">
    <xs:sequence>
      <xs:element ref="PreviousSession" minOccurs="0"/>
      <xs:element ref="ResumeSession" minOccurs="0"/>
      <xs:element ref="DigSig" minOccurs="0"/>
      <xs:element ref="Password" minOccurs="0"/>
      <xs:element ref="RestrictedPassword" minOccurs="0"/>
      <xs:element ref="ZeroKnowledge" minOccurs="0"/>
      <xs:element ref="SharedSecretChallengeResponse" minOccurs="0"/>
      <xs:element ref="SharedSecretDynamicPlaintext" minOccurs="0"/>
      <xs:element ref="IPAddress" minOccurs="0"/>
      <xs:element ref="AsymmetricDecryption" minOccurs="0"/>
      <xs:element ref="AsymmetricKeyAgreement" minOccurs="0"/>
      <xs:element ref="SubscriberLineNumber" minOccurs="0"/>
      <xs:element ref="UserSuffix" minOccurs="0"/>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:group>

  <xs:complexType name="AuthenticatorBaseType">
    <xs:sequence>
      <xs:group ref="AuthenticatorChoiceGroup"/>
      <xs:group ref="AuthenticatorSequenceGroup"/>
    </xs:sequence>
  </xs:complexType>
  
  <xs:complexType name="ComplexAuthenticatorType">
    <xs:sequence>
      <xs:group ref="AuthenticatorChoiceGroup"/>
      <xs:group ref="AuthenticatorSequenceGroup"/>
    </xs:sequence>
  </xs:complexType>
  
  <xs:complexType name="AuthenticatorTransportProtocolType">
    <xs:sequence>
      <xs:choice minOccurs="0">
        <xs:element ref="HTTP"/>
        <xs:element ref="SSL"/>
        <xs:element ref="MobileNetworkNoEncryption"/>
        <xs:element ref="MobileNetworkRadioEncryption"/>
        <xs:element ref="MobileNetworkEndToEndEncryption"/>
        <xs:element ref="WTLS"/>
        <xs:element ref="IPSec"/>
        <xs:element ref="PSTN"/>
        <xs:element ref="ISDN"/>
        <xs:element ref="ADSL"/>
      </xs:choice>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>

  <xs:complexType name="KeyActivationType">
    <xs:sequence>
      <xs:element ref="ActivationPin" minOccurs="0"/>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>

  <xs:complexType name="KeySharingType">
    <xs:attribute name="sharing" type="xs:boolean" use="required"/>
  </xs:complexType>

  <xs:complexType name="PrivateKeyProtectionType">
    <xs:sequence>
      <xs:element ref="KeyActivation" minOccurs="0"/>
      <xs:element ref="KeyStorage" minOccurs="0"/>
      <xs:element ref="KeySharing" minOccurs="0"/>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>

  <xs:complexType name="PasswordType">
    <xs:sequence>
      <xs:element ref="Length" minOccurs="0"/>
      <xs:element ref="Alphabet" minOccurs="0"/>
      <xs:element ref="Generation" minOccurs="0"/>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
    <xs:attribute name="ExternalVerification" type="xs:anyURI" use="optional"/>
  </xs:complexType>

  <xs:element name="RestrictedPassword" type="RestrictedPasswordType"/>

  <xs:complexType name="RestrictedPasswordType">
    <xs:complexContent>
      <xs:restriction base="PasswordType">
        <xs:sequence>
          <xs:element name="Length" type="RestrictedLengthType" minOccurs="1"/>
          <xs:element ref="Generation" minOccurs="0"/>
          <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
        </xs:sequence>
        <xs:attribute name="ExternalVerification" type="xs:anyURI" use="optional"/>
      </xs:restriction>
    </xs:complexContent>
  </xs:complexType>
  
  <xs:complexType name="RestrictedLengthType">
    <xs:complexContent>
      <xs:restriction base="LengthType">
        <xs:attribute name="min" use="required">
          <xs:simpleType>
            <xs:restriction base="xs:integer">
              <xs:minInclusive value="3"/>
            </xs:restriction>
          </xs:simpleType>
        </xs:attribute>
        <xs:attribute name="max" type="xs:integer" use="optional"/>
      </xs:restriction>
    </xs:complexContent>
  </xs:complexType>

  <xs:complexType name="ActivationPinType">
    <xs:sequence>
      <xs:element ref="Length" minOccurs="0"/>
      <xs:element ref="Alphabet" minOccurs="0"/>
      <xs:element ref="Generation" minOccurs="0"/>
      <xs:element ref="ActivationLimit" minOccurs="0"/>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>
  
  <xs:element name="Alphabet" type="AlphabetType"/>
  <xs:complexType name="AlphabetType">
    <xs:attribute name="requiredChars" type="xs:string" use="required"/>
    <xs:attribute name="excludedChars" type="xs:string" use="optional"/>
    <xs:attribute name="case" type="xs:string" use="optional"/>
  </xs:complexType>
  
  <xs:complexType name="TokenType">
    <xs:sequence>
      <xs:element ref="TimeSyncToken"/>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>
  
  <xs:simpleType name="DeviceTypeType">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="hardware"/>
      <xs:enumeration value="software"/>
    </xs:restriction>
  </xs:simpleType>
  
  <xs:simpleType name="booleanType">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="true"/>
      <xs:enumeration value="false"/>
    </xs:restriction>
  </xs:simpleType>
  
  <xs:complexType name="TimeSyncTokenType">
    <xs:attribute name="DeviceType" type="DeviceTypeType" use="required"/>
    <xs:attribute name="SeedLength" type="xs:integer" use="required"/>
    <xs:attribute name="DeviceInHand" type="booleanType" use="required"/>
  </xs:complexType>
  
  <xs:complexType name="ActivationLimitType">
    <xs:choice>
      <xs:element ref="ActivationLimitDuration"/>
      <xs:element ref="ActivationLimitUsages"/>
      <xs:element ref="ActivationLimitSession"/>
    </xs:choice>
  </xs:complexType>
  
  <xs:element name="ActivationLimitDuration" type="ActivationLimitDurationType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that the Key Activation Limit is
        defined as a specific duration of time.
      </xs:documentation>
    </xs:annotation>
  </xs:element>
  
  <xs:element name="ActivationLimitUsages" type="ActivationLimitUsagesType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that the Key Activation Limit is
        defined as a number of usages.
      </xs:documentation>
    </xs:annotation>
  </xs:element>
  
  <xs:element name="ActivationLimitSession" type="ActivationLimitSessionType">
    <xs:annotation>
      <xs:documentation>
        This element indicates that the Key Activation Limit is
        the session.
      </xs:documentation>
    </xs:annotation>
  </xs:element>
  
  <xs:complexType name="ActivationLimitDurationType">
    <xs:attribute name="duration" type="xs:duration" use="required"/>
  </xs:complexType>
  
  <xs:complexType name="ActivationLimitUsagesType">
    <xs:attribute name="number" type="xs:integer" use="required"/>
  </xs:complexType>
  
  <xs:complexType name="ActivationLimitSessionType"/>
  
  <xs:complexType name="LengthType">
    <xs:attribute name="min" type="xs:integer" use="required"/>
    <xs:attribute name="max" type="xs:integer" use="optional"/>
  </xs:complexType>

  <xs:simpleType name="mediumType">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="memory"/>
      <xs:enumeration value="smartcard"/>
      <xs:enumeration value="token"/>
      <xs:enumeration value="MobileDevice"/>
      <xs:enumeration value="MobileAuthCard"/>
    </xs:restriction>
  </xs:simpleType>

  <xs:complexType name="KeyStorageType">
    <xs:attribute name="medium" type="mediumType" use="required"/>
  </xs:complexType>

  <xs:complexType name="SecretKeyProtectionType">
    <xs:sequence>
      <xs:element ref="KeyActivation" minOccurs="0"/>
      <xs:element ref="KeyStorage" minOccurs="0"/>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>

  <xs:complexType name="SecurityAuditType">
    <xs:sequence>
      <xs:element ref="SwitchAudit" minOccurs="0"/>
      <xs:element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>

  <xs:complexType name="ExtensionOnlyType">
    <xs:sequence>
      <xs:element ref="Extension" minOccurs="0"  maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>
  
  <xs:element name="Extension" type="ExtensionType"/>

  <xs:complexType name="ExtensionType">
    <xs:sequence>
      <xs:any namespace="##other" processContents="lax" maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>

</xs:schema>