package org.bouncycastle.cms;

import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;

import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1Encoding;
import org.bouncycastle.asn1.ASN1ObjectIdentifier;
import org.bouncycastle.asn1.ASN1OctetString;
import org.bouncycastle.asn1.ASN1Primitive;
import org.bouncycastle.asn1.ASN1Set;
import org.bouncycastle.asn1.DERNull;
import org.bouncycastle.asn1.DERSet;
import org.bouncycastle.asn1.cms.Attribute;
import org.bouncycastle.asn1.cms.AttributeTable;
import org.bouncycastle.asn1.cms.CMSAlgorithmProtection;
import org.bouncycastle.asn1.cms.CMSAttributes;
import org.bouncycastle.asn1.cms.IssuerAndSerialNumber;
import org.bouncycastle.asn1.cms.SignerIdentifier;
import org.bouncycastle.asn1.cms.SignerInfo;
import org.bouncycastle.asn1.cms.Time;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.asn1.x509.DigestInfo;
import org.bouncycastle.cert.X509CertificateHolder;
import org.bouncycastle.operator.ContentVerifier;
import org.bouncycastle.operator.DigestCalculator;
import org.bouncycastle.operator.OperatorCreationException;
import org.bouncycastle.operator.RawContentVerifier;
import org.bouncycastle.util.Arrays;
import org.bouncycastle.util.io.TeeOutputStream;

an expanded SignerInfo block from a CMS Signed message
/**
 * an expanded SignerInfo block from a CMS Signed message
 */
public class SignerInformation
{
    private final SignerId                sid;
    private final CMSProcessable          content;
    private final byte[]                  signature;
    private final ASN1ObjectIdentifier    contentType;
    private final boolean                 isCounterSignature;

    // Derived
    private AttributeTable                signedAttributeValues;
    private AttributeTable                unsignedAttributeValues;
    private byte[]                        resultDigest;

    protected final SignerInfo            info;
    protected final AlgorithmIdentifier   digestAlgorithm;
    protected final AlgorithmIdentifier   encryptionAlgorithm;
    protected final ASN1Set               signedAttributeSet;
    protected final ASN1Set               unsignedAttributeSet;

    SignerInformation(
        SignerInfo          info,
        ASN1ObjectIdentifier contentType,
        CMSProcessable      content,
        byte[]              resultDigest)
    {
        this.info = info;
        this.contentType = contentType;
        this.isCounterSignature = contentType == null;

        SignerIdentifier   s = info.getSID();

        if (s.isTagged())
        {
            ASN1OctetString octs = ASN1OctetString.getInstance(s.getId());

            sid = new SignerId(octs.getOctets());
        }
        else
        {
            IssuerAndSerialNumber   iAnds = IssuerAndSerialNumber.getInstance(s.getId());

            sid = new SignerId(iAnds.getName(), iAnds.getSerialNumber().getValue());
        }

        this.digestAlgorithm = info.getDigestAlgorithm();
        this.signedAttributeSet = info.getAuthenticatedAttributes();
        this.unsignedAttributeSet = info.getUnauthenticatedAttributes();
        this.encryptionAlgorithm = info.getDigestEncryptionAlgorithm();
        this.signature = info.getEncryptedDigest().getOctets();

        this.content = content;
        this.resultDigest = resultDigest;
    }

    
Protected constructor. In some cases clients have their own idea about how to encode
the signed attributes and calculate the signature. This constructor is to allow developers
to deal with that by extending off the class and overridng methods like getSignedAttributes().
Params:
baseInfo – the SignerInformation to base this one on./**
     * Protected constructor. In some cases clients have their own idea about how to encode
     * the signed attributes and calculate the signature. This constructor is to allow developers
     * to deal with that by extending off the class and overridng methods like getSignedAttributes().
     *
     * @param baseInfo the SignerInformation to base this one on.
     */
    protected SignerInformation(SignerInformation baseInfo)
    {
        this.info = baseInfo.info;
        this.contentType = baseInfo.contentType;
        this.isCounterSignature = baseInfo.isCounterSignature();
        this.sid = baseInfo.getSID();
        this.digestAlgorithm = info.getDigestAlgorithm();
        this.signedAttributeSet = info.getAuthenticatedAttributes();
        this.unsignedAttributeSet = info.getUnauthenticatedAttributes();
        this.encryptionAlgorithm = info.getDigestEncryptionAlgorithm();
        this.signature = info.getEncryptedDigest().getOctets();
        this.content = baseInfo.content;
        this.resultDigest = baseInfo.resultDigest;
        this.signedAttributeValues = baseInfo.signedAttributeValues;
        this.unsignedAttributeValues = baseInfo.unsignedAttributeValues;
    }

    public boolean isCounterSignature()
    {
        return isCounterSignature;
    }

    public ASN1ObjectIdentifier getContentType()
    {
        return this.contentType;
    }

    private byte[] encodeObj(
        ASN1Encodable    obj)
        throws IOException
    {
        if (obj != null)
        {
            return obj.toASN1Primitive().getEncoded();
        }

        return null;
    }

    public SignerId getSID()
    {
        return sid;
    }

    
return the version number for this objects underlying SignerInfo structure.
/**
     * return the version number for this objects underlying SignerInfo structure.
     */
    public int getVersion()
    {
        return info.getVersion().getValue().intValue();
    }

    public AlgorithmIdentifier getDigestAlgorithmID()
    {
        return digestAlgorithm;
    }

    
return the object identifier for the signature.
/**
     * return the object identifier for the signature.
     */
    public String getDigestAlgOID()
    {
        return digestAlgorithm.getAlgorithm().getId();
    }

    
return the signature parameters, or null if there aren't any.
/**
     * return the signature parameters, or null if there aren't any.
     */
    public byte[] getDigestAlgParams()
    {
        try
        {
            return encodeObj(digestAlgorithm.getParameters());
        }
        catch (Exception e)
        {
            throw new RuntimeException("exception getting digest parameters " + e);
        }
    }

    
return the content digest that was calculated during verification.
/**
     * return the content digest that was calculated during verification.
     */
    public byte[] getContentDigest()
    {
        if (resultDigest == null)
        {
            throw new IllegalStateException("method can only be called after verify.");
        }
        
        return Arrays.clone(resultDigest);
    }
    
    
return the object identifier for the signature.
/**
     * return the object identifier for the signature.
     */
    public String getEncryptionAlgOID()
    {
        return encryptionAlgorithm.getAlgorithm().getId();
    }

    
return the signature/encryption algorithm parameters, or null if
there aren't any.
/**
     * return the signature/encryption algorithm parameters, or null if
     * there aren't any.
     */
    public byte[] getEncryptionAlgParams()
    {
        try
        {
            return encodeObj(encryptionAlgorithm.getParameters());
        }
        catch (Exception e)
        {
            throw new RuntimeException("exception getting encryption parameters " + e);
        }
    }  

    
return a table of the signed attributes - indexed by
the OID of the attribute.
/**
     * return a table of the signed attributes - indexed by
     * the OID of the attribute.
     */
    public AttributeTable getSignedAttributes()
    {
        if (signedAttributeSet != null && signedAttributeValues == null)
        {
            signedAttributeValues = new AttributeTable(signedAttributeSet);
        }

        return signedAttributeValues;
    }

    
return a table of the unsigned attributes indexed by
the OID of the attribute.
/**
     * return a table of the unsigned attributes indexed by
     * the OID of the attribute.
     */
    public AttributeTable getUnsignedAttributes()
    {
        if (unsignedAttributeSet != null && unsignedAttributeValues == null)
        {
            unsignedAttributeValues = new AttributeTable(unsignedAttributeSet);
        }

        return unsignedAttributeValues;
    }

    
return the encoded signature
/**
     * return the encoded signature
     */
    public byte[] getSignature()
    {
        return Arrays.clone(signature);
    }

    
Return a SignerInformationStore containing the counter signatures attached to this
signer. If no counter signatures are present an empty store is returned.
/**
     * Return a SignerInformationStore containing the counter signatures attached to this
     * signer. If no counter signatures are present an empty store is returned.
     */
    public SignerInformationStore getCounterSignatures()
    {
        // TODO There are several checks implied by the RFC3852 comments that are missing

        /*
        The countersignature attribute MUST be an unsigned attribute; it MUST
        NOT be a signed attribute, an authenticated attribute, an
        unauthenticated attribute, or an unprotected attribute.
        */        
        AttributeTable unsignedAttributeTable = getUnsignedAttributes();
        if (unsignedAttributeTable == null)
        {
            return new SignerInformationStore(new ArrayList(0));
        }

        List counterSignatures = new ArrayList();

        /*
        The UnsignedAttributes syntax is defined as a SET OF Attributes.  The
        UnsignedAttributes in a signerInfo may include multiple instances of
        the countersignature attribute.
        */
        ASN1EncodableVector allCSAttrs = unsignedAttributeTable.getAll(CMSAttributes.counterSignature);

        for (int i = 0; i < allCSAttrs.size(); ++i)
        {
            Attribute counterSignatureAttribute = (Attribute)allCSAttrs.get(i);            

            /*
            A countersignature attribute can have multiple attribute values.  The
            syntax is defined as a SET OF AttributeValue, and there MUST be one
            or more instances of AttributeValue present.
            */
            ASN1Set values = counterSignatureAttribute.getAttrValues();
            if (values.size() < 1)
            {
                // TODO Throw an appropriate exception?
            }

            for (Enumeration en = values.getObjects(); en.hasMoreElements();)
            {
                /*
                Countersignature values have the same meaning as SignerInfo values
                for ordinary signatures, except that:

                   1. The signedAttributes field MUST NOT contain a content-type
                      attribute; there is no content type for countersignatures.

                   2. The signedAttributes field MUST contain a message-digest
                      attribute if it contains any other attributes.

                   3. The input to the message-digesting process is the contents
                      octets of the DER encoding of the signatureValue field of the
                      SignerInfo value with which the attribute is associated.
                */
                SignerInfo si = SignerInfo.getInstance(en.nextElement());

                counterSignatures.add(new SignerInformation(si, null, new CMSProcessableByteArray(getSignature()), null));
            }
        }

        return new SignerInformationStore(counterSignatures);
    }
    
    
return the DER encoding of the signed attributes.
Throws:
IOException – if an encoding error occurs./**
     * return the DER encoding of the signed attributes.
     * @throws IOException if an encoding error occurs.
     */
    public byte[] getEncodedSignedAttributes()
        throws IOException
    {
        if (signedAttributeSet != null)
        {
            return signedAttributeSet.getEncoded(ASN1Encoding.DER);
        }

        return null;
    }

    private boolean doVerify(
        SignerInformationVerifier verifier)
        throws CMSException
    {
        String          encName = CMSSignedHelper.INSTANCE.getEncryptionAlgName(this.getEncryptionAlgOID());
        ContentVerifier contentVerifier;

        try
        {
            contentVerifier = verifier.getContentVerifier(encryptionAlgorithm, info.getDigestAlgorithm());
        }
        catch (OperatorCreationException e)
        {
            throw new CMSException("can't create content verifier: " + e.getMessage(), e);
        }

        try
        {
            OutputStream sigOut = contentVerifier.getOutputStream();

            if (resultDigest == null)
            {
                DigestCalculator calc = verifier.getDigestCalculator(this.getDigestAlgorithmID());
                if (content != null)
                {
                    OutputStream      digOut = calc.getOutputStream();

                    if (signedAttributeSet == null)
                    {
                        if (contentVerifier instanceof RawContentVerifier)
                        {
                            content.write(digOut);
                        }
                        else
                        {
                            OutputStream cOut = new TeeOutputStream(digOut, sigOut);

                            content.write(cOut);

                            cOut.close();
                        }
                    }
                    else
                    {
                        content.write(digOut);
                        sigOut.write(this.getEncodedSignedAttributes());
                    }

                    digOut.close();
                }
                else if (signedAttributeSet != null)
                {
                    sigOut.write(this.getEncodedSignedAttributes());
                }
                else
                {
                    // TODO Get rid of this exception and just treat content==null as empty not missing?
                    throw new CMSException("data not encapsulated in signature - use detached constructor.");
                }

                resultDigest = calc.getDigest();
            }
            else
            {
                if (signedAttributeSet == null)
                {
                    if (content != null)
                    {
                        content.write(sigOut);
                    }
                }
                else
                {
                    sigOut.write(this.getEncodedSignedAttributes());
                }
            }

            sigOut.close();
        }
        catch (IOException e)
        {
            throw new CMSException("can't process mime object to create signature.", e);
        }
        catch (OperatorCreationException e)
        {
            throw new CMSException("can't create digest calculator: " + e.getMessage(), e);
        }

        // RFC 3852 11.1 Check the content-type attribute is correct
        {
            ASN1Primitive validContentType = getSingleValuedSignedAttribute(
                CMSAttributes.contentType, "content-type");
            if (validContentType == null)
            {
                if (!isCounterSignature && signedAttributeSet != null)
                {
                    throw new CMSException("The content-type attribute type MUST be present whenever signed attributes are present in signed-data");
                }
            }
            else
            {
                if (isCounterSignature)
                {
                    throw new CMSException("[For counter signatures,] the signedAttributes field MUST NOT contain a content-type attribute");
                }

                if (!(validContentType instanceof ASN1ObjectIdentifier))
                {
                    throw new CMSException("content-type attribute value not of ASN.1 type 'OBJECT IDENTIFIER'");
                }

                ASN1ObjectIdentifier signedContentType = (ASN1ObjectIdentifier)validContentType;

                if (!signedContentType.equals(contentType))
                {
                    throw new CMSException("content-type attribute value does not match eContentType");
                }
            }
        }

        AttributeTable signedAttrTable = this.getSignedAttributes();

        // RFC 6211 Validate Algorithm Identifier protection attribute if present
        {
            AttributeTable unsignedAttrTable = this.getUnsignedAttributes();
            if (unsignedAttrTable != null && unsignedAttrTable.getAll(CMSAttributes.cmsAlgorithmProtect).size() > 0)
            {
                throw new CMSException("A cmsAlgorithmProtect attribute MUST be a signed attribute");
            }
            if (signedAttrTable != null)
            {
                ASN1EncodableVector protectionAttributes = signedAttrTable.getAll(CMSAttributes.cmsAlgorithmProtect);
                if (protectionAttributes.size() > 1)
                {
                    throw new CMSException("Only one instance of a cmsAlgorithmProtect attribute can be present");
                }

                if (protectionAttributes.size() > 0)
                {
                    Attribute attr = Attribute.getInstance(protectionAttributes.get(0));
                    if (attr.getAttrValues().size() != 1)
                    {
                        throw new CMSException("A cmsAlgorithmProtect attribute MUST contain exactly one value");
                    }

                    CMSAlgorithmProtection algorithmProtection = CMSAlgorithmProtection.getInstance(attr.getAttributeValues()[0]);

                    if (!CMSUtils.isEquivalent(algorithmProtection.getDigestAlgorithm(), info.getDigestAlgorithm()))
                    {
                        throw new CMSException("CMS Algorithm Identifier Protection check failed for digestAlgorithm");
                    }

                    if (!CMSUtils.isEquivalent(algorithmProtection.getSignatureAlgorithm(), info.getDigestEncryptionAlgorithm()))
                    {
                        throw new CMSException("CMS Algorithm Identifier Protection check failed for signatureAlgorithm");
                    }
                }
            }
        }

        // RFC 3852 11.2 Check the message-digest attribute is correct
        {
            ASN1Primitive validMessageDigest = getSingleValuedSignedAttribute(
                CMSAttributes.messageDigest, "message-digest");
            if (validMessageDigest == null)
            {
                if (signedAttributeSet != null)
                {
                    throw new CMSException("the message-digest signed attribute type MUST be present when there are any signed attributes present");
                }
            }
            else
            {
                if (!(validMessageDigest instanceof ASN1OctetString))
                {
                    throw new CMSException("message-digest attribute value not of ASN.1 type 'OCTET STRING'");
                }

                ASN1OctetString signedMessageDigest = (ASN1OctetString)validMessageDigest;

                if (!Arrays.constantTimeAreEqual(resultDigest, signedMessageDigest.getOctets()))
                {
                    throw new CMSSignerDigestMismatchException("message-digest attribute value does not match calculated value");
                }
            }
        }

        // RFC 3852 11.4 Validate countersignature attribute(s)
        {
            if (signedAttrTable != null
                && signedAttrTable.getAll(CMSAttributes.counterSignature).size() > 0)
            {
                throw new CMSException("A countersignature attribute MUST NOT be a signed attribute");
            }

            AttributeTable unsignedAttrTable = this.getUnsignedAttributes();
            if (unsignedAttrTable != null)
            {
                ASN1EncodableVector csAttrs = unsignedAttrTable.getAll(CMSAttributes.counterSignature);
                for (int i = 0; i < csAttrs.size(); ++i)
                {
                    Attribute csAttr = Attribute.getInstance(csAttrs.get(i));
                    if (csAttr.getAttrValues().size() < 1)
                    {
                        throw new CMSException("A countersignature attribute MUST contain at least one AttributeValue");
                    }

                    // Note: We don't recursively validate the countersignature value
                }
            }
        }

        try
        {
            if (signedAttributeSet == null && resultDigest != null)
            {
                if (contentVerifier instanceof RawContentVerifier)
                {
                    RawContentVerifier rawVerifier = (RawContentVerifier)contentVerifier;

                    if (encName.equals("RSA"))
                    {
                        DigestInfo digInfo = new DigestInfo(new AlgorithmIdentifier(digestAlgorithm.getAlgorithm(), DERNull.INSTANCE), resultDigest);

                        return rawVerifier.verify(digInfo.getEncoded(ASN1Encoding.DER), this.getSignature());
                    }

                    return rawVerifier.verify(resultDigest, this.getSignature());
                }
            }

            return contentVerifier.verify(this.getSignature());
        }
        catch (IOException e)
        {
            throw new CMSException("can't process mime object to create signature.", e);
        }
    }

    
Verify that the given verifier can successfully verify the signature on
this SignerInformation object.
Params:
verifier – a suitably configured SignerInformationVerifier.
Throws:
CMSVerifierCertificateNotValidException – if the provider has an associated certificate and the certificate is not valid at the time given as the SignerInfo's signing time.
CMSException – if the verifier is unable to create a ContentVerifiers or DigestCalculators.
Returns:
true if the signer information is verified, false otherwise./**
     * Verify that the given verifier can successfully verify the signature on
     * this SignerInformation object.
     *
     * @param verifier a suitably configured SignerInformationVerifier.
     * @return true if the signer information is verified, false otherwise.
     * @throws org.bouncycastle.cms.CMSVerifierCertificateNotValidException if the provider has an associated certificate and the certificate is not valid at the time given as the SignerInfo's signing time.
     * @throws org.bouncycastle.cms.CMSException if the verifier is unable to create a ContentVerifiers or DigestCalculators.
     */
    public boolean verify(SignerInformationVerifier verifier)
        throws CMSException
    {
        Time signingTime = getSigningTime();   // has to be validated if present.

        if (verifier.hasAssociatedCertificate())
        {
            if (signingTime != null)
            {
                X509CertificateHolder dcv = verifier.getAssociatedCertificate();

                if (!dcv.isValidOn(signingTime.getDate()))
                {
                    throw new CMSVerifierCertificateNotValidException("verifier not valid at signingTime");
                }
            }
        }

        return doVerify(verifier);
    }

    
Return the underlying ASN.1 object defining this SignerInformation object.
Returns:
a SignerInfo./**
     * Return the underlying ASN.1 object defining this SignerInformation object.
     *
     * @return a SignerInfo.
     */
    public SignerInfo toASN1Structure()
    {
        return info;
    }

    private ASN1Primitive getSingleValuedSignedAttribute(
        ASN1ObjectIdentifier attrOID, String printableName)
        throws CMSException
    {
        AttributeTable unsignedAttrTable = this.getUnsignedAttributes();
        if (unsignedAttrTable != null
            && unsignedAttrTable.getAll(attrOID).size() > 0)
        {
            throw new CMSException("The " + printableName
                + " attribute MUST NOT be an unsigned attribute");
        }

        AttributeTable signedAttrTable = this.getSignedAttributes();
        if (signedAttrTable == null)
        {
            return null;
        }

        ASN1EncodableVector v = signedAttrTable.getAll(attrOID);
        switch (v.size())
        {
            case 0:
                return null;
            case 1:
            {
                Attribute t = (Attribute)v.get(0);
                ASN1Set attrValues = t.getAttrValues();
                if (attrValues.size() != 1)
                {
                    throw new CMSException("A " + printableName
                        + " attribute MUST have a single attribute value");
                }

                return attrValues.getObjectAt(0).toASN1Primitive();
            }
            default:
                throw new CMSException("The SignedAttributes in a signerInfo MUST NOT include multiple instances of the "
                    + printableName + " attribute");
        }
    }

    private Time getSigningTime() throws CMSException
    {
        ASN1Primitive validSigningTime = getSingleValuedSignedAttribute(
            CMSAttributes.signingTime, "signing-time");

        if (validSigningTime == null)
        {
            return null;
        }

        try
        {
            return Time.getInstance(validSigningTime);
        }
        catch (IllegalArgumentException e)
        {
            throw new CMSException("signing-time attribute value not a valid 'Time' structure");
        }
    }

    
Return a signer information object with the passed in unsigned
attributes replacing the ones that are current associated with
the object passed in.
Params:
signerInformation – the signerInfo to be used as the basis.
unsignedAttributes – the unsigned attributes to add.
Returns:
a copy of the original SignerInformationObject with the changed attributes./**
     * Return a signer information object with the passed in unsigned
     * attributes replacing the ones that are current associated with
     * the object passed in.
     * 
     * @param signerInformation the signerInfo to be used as the basis.
     * @param unsignedAttributes the unsigned attributes to add.
     * @return a copy of the original SignerInformationObject with the changed attributes.
     */
    public static SignerInformation replaceUnsignedAttributes(
        SignerInformation   signerInformation,
        AttributeTable      unsignedAttributes)
    {
        SignerInfo  sInfo = signerInformation.info;
        ASN1Set     unsignedAttr = null;
        
        if (unsignedAttributes != null)
        {
            unsignedAttr = new DERSet(unsignedAttributes.toASN1EncodableVector());
        }
        
        return new SignerInformation(
                new SignerInfo(sInfo.getSID(), sInfo.getDigestAlgorithm(),
                    sInfo.getAuthenticatedAttributes(), sInfo.getDigestEncryptionAlgorithm(), sInfo.getEncryptedDigest(), unsignedAttr),
                    signerInformation.contentType, signerInformation.content, null);
    }

    
Return a signer information object with passed in SignerInformationStore representing counter
signatures attached as an unsigned attribute.
Params:
signerInformation – the signerInfo to be used as the basis.
counterSigners – signer info objects carrying counter signature.
Returns:
a copy of the original SignerInformationObject with the changed attributes./**
     * Return a signer information object with passed in SignerInformationStore representing counter
     * signatures attached as an unsigned attribute.
     *
     * @param signerInformation the signerInfo to be used as the basis.
     * @param counterSigners signer info objects carrying counter signature.
     * @return a copy of the original SignerInformationObject with the changed attributes.
     */
    public static SignerInformation addCounterSigners(
        SignerInformation        signerInformation,
        SignerInformationStore   counterSigners)
    {
        // TODO Perform checks from RFC 3852 11.4

        SignerInfo          sInfo = signerInformation.info;
        AttributeTable      unsignedAttr = signerInformation.getUnsignedAttributes();
        ASN1EncodableVector v;

        if (unsignedAttr != null)
        {
            v = unsignedAttr.toASN1EncodableVector();
        }
        else
        {
            v = new ASN1EncodableVector();
        }

        ASN1EncodableVector sigs = new ASN1EncodableVector();

        for (Iterator it = counterSigners.getSigners().iterator(); it.hasNext();)
        {
            sigs.add(((SignerInformation)it.next()).toASN1Structure());
        }

        v.add(new Attribute(CMSAttributes.counterSignature, new DERSet(sigs)));

        return new SignerInformation(
                new SignerInfo(sInfo.getSID(), sInfo.getDigestAlgorithm(),
                    sInfo.getAuthenticatedAttributes(), sInfo.getDigestEncryptionAlgorithm(), sInfo.getEncryptedDigest(), new DERSet(v)),
                    signerInformation.contentType, signerInformation.content, null);
    }
}