source: java/net/deterlab/abac/GENICredential.java

package net.deterlab.abac;

import java.io.*;
import java.math.*;
import java.text.*;

import java.util.*;

import java.security.*;
import java.security.cert.*;

import javax.xml.parsers.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.*;
import javax.xml.transform.stream.*;

import javax.xml.crypto.*;
import javax.xml.crypto.dsig.*;
import javax.xml.crypto.dsig.dom.*;
import javax.xml.crypto.dsig.keyinfo.*;
import javax.xml.crypto.dsig.spec.*;

import org.xml.sax.*;
import org.w3c.dom.*;

/**
 * Abstract Base class from which GENI credentials are derived.
 * @author <a href="http://abac.deterlab.net">ISI ABAC team</a>
 * @version 1.5
 */
public abstract class GENICredential extends Credential implements Comparable {
    /** The signed XML representing this credential */
    protected Document doc;
    /** The GENI credential suffix */
    private static final String fileSuffix = ".xml";

    /**
     * X509KeySelector implementation from
     * http://www.outsourcingi.com/art-271-Programming-With-the-Java-XML-Digital-Signature-API.html
     * .
     *
     * Straight ahead extraction of a key from an X509 cert, but it is their
     * code and hard to improve on.
     */
    static protected class X509KeySelector extends KeySelector {
        public KeySelectorResult select(KeyInfo keyInfo,
                                        KeySelector.Purpose purpose,
                                        AlgorithmMethod method,
                                        XMLCryptoContext context)
            throws KeySelectorException {
            Iterator ki = keyInfo.getContent().iterator();
            while (ki.hasNext()) {
                XMLStructure info = (XMLStructure) ki.next();
                if (!(info instanceof X509Data))
                    continue;
                X509Data x509Data = (X509Data) info;
                Iterator xi = x509Data.getContent().iterator();
                while (xi.hasNext()) {
                    Object o = xi.next();
                    if (!(o instanceof X509Certificate))
                        continue;
                    final PublicKey key = ((X509Certificate)o).getPublicKey();
                    // Make sure the algorithm is compatible
                    // with the method.
                    if (algEquals(method.getAlgorithm(), key.getAlgorithm())) {
                        return new KeySelectorResult() {
                            public Key getKey() { return key; }
                        };
                    }
                }
            }
            throw new KeySelectorException("No key found!");
        }

        boolean algEquals(String algURI, String algName) {
            if ((algName.equalsIgnoreCase("DSA") &&
                algURI.equalsIgnoreCase(SignatureMethod.DSA_SHA1)) ||
                (algName.equalsIgnoreCase("RSA") &&

                algURI.equalsIgnoreCase(SignatureMethod.RSA_SHA1))) {
                return true;
            } else {
                return false;
            }
        }
    }

    /**
     * Create an empty Credential.
     */
    public GENICredential() {
        super();
        doc = null;
        setSuffix(fileSuffix);
    }
    /**
     * Create a credential from a head and tail role.  This credential has no
     * underlying certificate, and cannot be exported or used in real proofs.
     * make_cert can create a certificate for a credential initialized this
     * way.
     * @param head the Role at the head of the credential
     * @param tail the Role at the tail of the credential
     */
    public GENICredential(Role head, Role tail) {
        super(head, tail);
        doc = null; 
        setSuffix(fileSuffix);
    }

    /**
     * Do the credential extraction from an input stream.  This parses the
     * certificate from the input stream and saves it. The contents must be
     * validated and parsed later.
     * @param stream the InputStream to read the certificate from.
     * @return the parsed XML document
     * @throws IOException if the stream is unparsable
     */
    static protected Document read_certificate(InputStream stream) 
            throws IOException {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = null;
        Document ldoc = null;

        if ( dbf == null ) 
            throw new IOException("Cannot get DocumentBuilderFactory!?");
        try {
            /* Note this setting is required to find the properly
             * namespace-scoped signature block in the credential.
             */
            dbf.setNamespaceAware(true);
            if ( (db = dbf.newDocumentBuilder()) == null ) 
                throw new IOException("Cannot get DocumentBuilder!?");
            ldoc = db.parse(stream);
            ldoc.normalizeDocument();
            return ldoc;
        }
        catch (IllegalArgumentException ie) {
            throw new IOException("null stream", ie);
        }
        catch (SAXException se) {
            throw new IOException(se.getMessage(), se);
        }
        catch (Exception e) {
            throw new IOException(e.getMessage(), e);
        }

    }

    /**
     * Walk the document and set all instances of an xml:id attribute to be ID
     * attributes in terms of the java libraries.  This is needed for the
     * signature code to find signed subsections.  The "xml:id" is treated as
     * both a namespace free ID with a colon and as an "id" identifier in the
     * "xml" namespace so we don't miss it.
     * @param n the root of the document to mark
     */
    static protected void setIDAttrs(Node n) {
        if ( n.getNodeType() == Node.ELEMENT_NODE) {
            Element e = (Element) n;
            String id = e.getAttribute("xml:id");

            if ( id != null && id.length() > 0 )
                e.setIdAttribute("xml:id", true);

            id = e.getAttributeNS("xml", "id");
            if ( id != null && id.length() > 0 )
                e.setIdAttributeNS("xml", "id", true);
        }

        for (Node nn = n.getFirstChild(); nn != null; nn = nn.getNextSibling())
            setIDAttrs(nn);
    }

    /**
     * Return the child of Node n  that has the given name, if there is one.
     * @param n a Node to search
     * @param name the name to search for
     * @return a Node with the name, may be null
     */
    static protected Node getChildByName(Node n, String name) {
        if (name == null ) return null;

        for (Node nn = n.getFirstChild(); nn != null; nn = nn.getNextSibling())
            if ( nn.getNodeType() == Node.ELEMENT_NODE && 
                    name.equals(nn.getNodeName())) return nn;
        return null;
    }

    /**
     * Find the X509Certificate in the Signature element and convert it to an
     * ABAC identity.  This assumes a KeyInfo in that section holding an
     * X509Data section containing the certificate in an X509Certificate
     * section.  Any of that not being found will cause a failure.  If the
     * Identity cannot be created a Gignature exception is thrown.
     * @param n a Node pointing to a Signature section
     * @return an Identity constructed frm the X509 Certificate
     * @throws MissingIssuerException if the Identity cannot be created from the
     * certificate.
     */
    static protected Identity getIdentity(Node n) 
        throws MissingIssuerException {
        Identity rv = null;
        Node nn = getChildByName(n, "KeyInfo");
        String certStr = null;

        if ( nn == null ) return null;
        if ( ( nn = getChildByName(nn, "X509Data")) == null ) return null;
        if ( ( nn = getChildByName(nn, "X509Certificate")) == null ) return null;
        if ( ( certStr = nn.getTextContent()) == null ) return null;
        try {
            certStr = "-----BEGIN CERTIFICATE-----\n" + 
                certStr + 
                "\n-----END CERTIFICATE-----";
            return new Identity(new StringReader(certStr));
        } 
        catch (Exception e) {
            throw new MissingIssuerException(e.getMessage(), e);
        }
    }

    static protected Date getTime(Document d, String field) 
            throws ABACException {
        Node root = null;
        Node n = null;
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssz");
        Date date = null;
        String dstr = null;

        if ( (root = getChildByName(d, "signed-credential")) == null)
            throw new CertInvalidException("No signed-credential element");
        if ( (n = getChildByName(root, "credential")) == null )
            throw new CertInvalidException("No credential element");
        if ( (n = getChildByName(n, field)) == null )
            throw new CertInvalidException("No " + field + " element");

        if ( ( dstr = n.getTextContent()) == null ) 
            throw new CertInvalidException("No expires content");

        dstr = dstr.replace("Z", "GMT");
        if ((date = df.parse(dstr, new ParsePosition(0))) == null)
            throw new CertInvalidException("Cannot parse date: "+
                    n.getTextContent());

        return date;
    }

    /**
     * Initialize a credential from parsed certificate.  Validiate it against
     * the given identities and parse out the roles.  Note that catching
     * java.security.GeneralSecurityException catches most of the exceptions
     * this throws.
     * @param ids a Collection of Identities to use in validating the cert
     * @throws CertInvalidException if the stream is unparsable
     * @throws MissingIssuerException if none of the Identities can validate the
     *                              certificate
     * @throws BadSignatureException if the signature check fails
     */
    protected void init(Collection<Identity> ids) 
            throws ABACException {

        XMLSignatureFactory fac = XMLSignatureFactory.getInstance("DOM");
        NodeList nl = doc.getElementsByTagNameNS(XMLSignature.XMLNS, 
                "Signature");
        DOMValidateContext valContext = null;
        XMLSignature signature = null;

        try {

            if (nl.getLength() == 0) 
                throw new CertInvalidException("Cannot find Signature element");

            setIDAttrs(doc);
            valContext = new DOMValidateContext(new X509KeySelector(),
                    nl.item(0));
            if ( valContext == null )
                throw new ABACException("No validation context!?");

            signature = fac.unmarshalXMLSignature(valContext);
            if (signature == null) 
                throw new BadSignatureException("Cannot unmarshal signature");

            if (!signature.validate(valContext))
                throw new BadSignatureException("bad signature");

            m_expiration = getTime(doc, "expires");

            if ( m_expiration.before(new Date()))
                throw new CertInvalidException("Certificate Expired " + 
                        m_expiration);

            load_roles();

            // Load the issuer identity from the credential. If the identity in
            // the credential is invalid throw out the credential (the
            // getIdentity call will throw an exception)
            id = getIdentity(nl.item(0));

            if ( !ids.contains(id) ) ids.add(id);

            if (!id.getKeyID().equals(m_head.principal()))
                throw new MissingIssuerException("Issuer ID and left hand " +
                        "side principal disagree");
        }
        catch (ABACException ae) {
            throw ae;
        }
        catch (Exception e) {
            throw new BadSignatureException(e.getMessage(), e);
        }
    }

    /**
     * Parse a credential from an InputStream and initialize the role from it.
     * Combine read_credential(stream) and init(ids).  Note that catching
     * java.security.GeneralSecurityException catches most of the exceptions
     * this throws.
     * @param stream the InputStream to read the certificate from.
     * @param ids a Collection of Identities to use in validating the cert
     * @throws CertInvalidException if the stream is unparsable
     * @throws MissingIssuerException if none of the Identities can validate the
     *                              certificate
     * @throws BadSignatureException if the signature check fails
     */
    protected void init(InputStream stream, Collection<Identity> ids) 
            throws ABACException {
         try {
            doc = read_certificate(stream);
         }
         catch (IOException e) {
             throw new CertInvalidException("Cannot parse cert", e);
         }
        if (doc == null) throw new CertInvalidException("Unknown Format");
        init(ids);
    }

    /**
     * Create a credential from an attribute cert in a file. Throws an
     * exception if the cert file can't be opened or if there's a format
     * problem with the cert.  Note that catching
     * java.security.GeneralSecurityException catches most of the exceptions
     * this throws.
     * @param filename a String containing the filename to read
     * @param ids a Collection of Identities to use in validating the cert
     * @throws CertInvalidException if the stream is unparsable
     * @throws MissingIssuerException if none of the Identities can validate the
     *                              certificate
     * @throws BadSignatureException if the signature check fails
     */
    GENICredential(String filename, Collection<Identity> ids) 
        throws ABACException { 
        super();
        setSuffix(fileSuffix);
        try {
            init(new FileInputStream(filename), ids);
        }
        catch (FileNotFoundException e) {
            throw new CertInvalidException("Bad filename", e);
        }
    }

    /**
     * Create a credential from an attribute cert in a file. Throws an
     * exception if the cert file can't be opened or if there's a format
     * problem with the cert.  Note that catching
     * java.security.GeneralSecurityException catches most of the exceptions
     * this throws.
     * @param file the File to read
     * @param ids a Collection of Identities to use in validating the cert
     * @throws CertInvalidException if the stream is unparsable
     * @throws MissingIssuerException if none of the Identities can validate the
     *                              certificate
     * @throws BadSignatureException if the signature check fails
     */
    GENICredential(File file, Collection<Identity> ids) 
            throws ABACException {
        super();
        setSuffix(fileSuffix);
        try {
            init(new FileInputStream(file), ids);
        }
        catch (FileNotFoundException e) {
            throw new CertInvalidException("Bad filename", e);
        }
    }

    /**
     * Create a credential from an InputStream.  Throws an exception if the
     * stream can't be parsed or if there's a format problem with the cert.
     * Note that catching java.security.GeneralSecurityException catches most
     * of the exceptions this throws.
     * @param s the InputStream to read
     * @param ids a Collection of Identities to use in validating the cert
     * @throws CertInvalidException if the stream is unparsable
     * @throws MissingIssuerException if none of the Identities can validate the
     *                              certificate
     * @throws BadSignatureException if the signature check fails
     */
    GENICredential(InputStream s, Collection<Identity> ids) 
            throws ABACException { 
        super();
        setSuffix(fileSuffix);
        init(s, ids);
    }

    /**
     * Encode the abac credential's XML and set the validity. Overload this to
     * build a real credential.
     * @param validity a long holding the number of seconds that the credential
     * is valid for.
     * @return a Node, the place to attach signatures
     * @throws ABACException if any of the XML construction fails
     */
    abstract protected Node make_rt0_content(long validity) 
        throws ABACException;

    /**
     * Create a certificate from this credential issued by the given identity
     * valid for the given time (in seconds).  This is the signed XML ABAC
     * credential.
     * @param i the Identity that will issue the certificate
     * @param validity a long holding the number of seconds that the credential
     * is valid for.
     * @throws ABACException if xml creation fails
     * @throws MissingIssuerException if the issuer is bad
     * @throws BadSignatureException if the signature creation fails
     */
    public void make_cert(Identity i, long validity) 
            throws ABACException {
        X509Certificate cert = i.getCertificate();
        KeyPair kp = i.getKeyPair();
        PublicKey pubKey = null;
        PrivateKey privKey = null;
        if ( cert == null ) 
            throw new MissingIssuerException("No credential in identity?");
        if ( kp == null ) 
            throw new MissingIssuerException("No keypair in identity?");

        pubKey = kp.getPublic();
        if ((privKey = kp.getPrivate()) == null ) 
            throw new MissingIssuerException("No private ket in identity");

        XMLSignatureFactory fac = XMLSignatureFactory.getInstance("DOM");
        Reference ref = null;
        SignedInfo si = null;
        KeyInfoFactory kif = fac.getKeyInfoFactory();

        /* The <Object> doesn't say much, but shuts the compiler up about
         * unchecked references.  The lists are polymorphyc and the signature
         * libs expect that, so <Object> is the best we can do.
         */
        List<Object> x509Content = new ArrayList<Object>();
        List<Object> keyInfo = new ArrayList<Object>();
        x509Content.add(cert.getSubjectX500Principal().getName());
        x509Content.add(cert);
        X509Data xd = kif.newX509Data(x509Content);
        KeyValue kv = null;

        try {
            kv = kif.newKeyValue(pubKey);
        } 
        catch (KeyException ke) {
            throw new ABACException("Unsupported key format " + 
                    ke.getMessage(), ke);
        }

        Collections.addAll(keyInfo, kv, xd);

        KeyInfo ki = kif.newKeyInfo(keyInfo);
        Node sig = make_rt0_content(validity);

        try {
            ref = fac.newReference("#ref0", 
                    fac.newDigestMethod(DigestMethod.SHA1, null),
                    Collections.singletonList(
                        fac.newTransform(Transform.ENVELOPED, 
                            (TransformParameterSpec) null)),
                    null, null);

            si = fac.newSignedInfo(
                    fac.newCanonicalizationMethod(
                        CanonicalizationMethod.INCLUSIVE,
                        (C14NMethodParameterSpec) null),
                    fac.newSignatureMethod(SignatureMethod.RSA_SHA1, null),
                    Collections.singletonList(ref));

            DOMSignContext dsc = new DOMSignContext(privKey, sig);
            XMLSignature signature = fac.newXMLSignature(si, ki);
            signature.sign(dsc);
        }
        catch (Exception me) {
            throw new BadSignatureException(me.getMessage(), me);
        }

    }

    /**
     * Create a certificate from this credential issued by the given identity
     * valid for the default validity period.  This is the signed XML ABAC
     * credential.
     * @param i the Identity that will issue the certificate
     * @throws ABACException if xml creation fails
     * @throws MissingIssuerException if the issuer is bad
     * @throws BadSignatureException if the signature creation fails
     */
    public void make_cert(Identity i) 
            throws ABACException {
        make_cert(i, defaultValidity);
    }

    /**
     * Load the roles off the attribute cert. Overload it to make a real
     * credential.
     * @throws CertInvalidException if the certificate is badly formatted
     */
    abstract protected void load_roles() throws CertInvalidException;
    /**
     * Output the signed GENI ABAC certificate associated with this
     * Credential to the OutputStream.
     * @param s the OutputStream on which to write
     * @throws IOException if there is an error writing.
     */
    public void write(OutputStream s) throws IOException {
        if ( doc == null ) 
            return;
        try {
            TransformerFactory tf = TransformerFactory.newInstance();
            Transformer t = tf.newTransformer();
            DOMSource source = new DOMSource(doc);
            StreamResult result = new StreamResult(s);

            t.transform(source, result);
            s.flush();
        } 
        catch (Exception e) {
            throw new IOException(e.getMessage(), e);
        }
    }
    /**
     * Output the signed GENI ABAC certificate associated with this
     * Credential to the OutputStream.
     * @param fn a String, the file name on which to write
     * @throws IOException if there is an error writing.
     */
    public void write(String fn) throws IOException {
        write(new FileOutputStream(fn));
    }

    /**
     * Return true if this Credential has a certificate associated.  A jabac
     * extension.
     * @return true if this Credential has a certificate associated.
     */
    public boolean hasCertificate() { return doc != null; }

}