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The Bouncy Castle Java APIs for the OpenPGP Protocol. The APIs are designed primarily to be used in conjunction with the BC FIPS provider. The APIs may also be used with other providers although if being used in a FIPS context it is the responsibility of the user to ensure that any other providers used are FIPS certified and used appropriately.

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package org.bouncycastle.bcpg;

import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;

import org.bouncycastle.bcpg.sig.EmbeddedSignature;
import org.bouncycastle.bcpg.sig.Exportable;
import org.bouncycastle.bcpg.sig.Features;
import org.bouncycastle.bcpg.sig.IntendedRecipientFingerprint;
import org.bouncycastle.bcpg.sig.IssuerFingerprint;
import org.bouncycastle.bcpg.sig.IssuerKeyID;
import org.bouncycastle.bcpg.sig.KeyExpirationTime;
import org.bouncycastle.bcpg.sig.KeyFlags;
import org.bouncycastle.bcpg.sig.NotationData;
import org.bouncycastle.bcpg.sig.PolicyURI;
import org.bouncycastle.bcpg.sig.PreferredAlgorithms;
import org.bouncycastle.bcpg.sig.PrimaryUserID;
import org.bouncycastle.bcpg.sig.RegularExpression;
import org.bouncycastle.bcpg.sig.Revocable;
import org.bouncycastle.bcpg.sig.RevocationKey;
import org.bouncycastle.bcpg.sig.RevocationReason;
import org.bouncycastle.bcpg.sig.SignatureCreationTime;
import org.bouncycastle.bcpg.sig.SignatureExpirationTime;
import org.bouncycastle.bcpg.sig.SignatureTarget;
import org.bouncycastle.bcpg.sig.SignerUserID;
import org.bouncycastle.bcpg.sig.TrustSignature;
import org.bouncycastle.util.Arrays;
import org.bouncycastle.util.io.Streams;

/**
 * reader for signature sub-packets
 */
public class SignatureSubpacketInputStream
    extends InputStream
    implements SignatureSubpacketTags
{
    private final InputStream in;
    private final int limit;

    public SignatureSubpacketInputStream(
        InputStream in)
    {
        this(in, StreamUtil.findLimit(in));
    }

    public SignatureSubpacketInputStream(
        InputStream in,
        int limit)
    {
        this.in = in;
        this.limit = limit;
    }

    public int available()
        throws IOException
    {
        return in.available();
    }

    public int read()
        throws IOException
    {
        return in.read();
    }

    public SignatureSubpacket readPacket()
        throws IOException
    {
        int l = this.read();
        int bodyLen = 0;

        if (l < 0)
        {
            return null;
        }

        boolean isLongLength = false;

        if (l < 192)
        {
            bodyLen = l;
        }
        else if (l <= 223)
        {
            bodyLen = ((l - 192) << 8) + (in.read()) + 192;
        }
        else if (l == 255)
        {
            isLongLength = true;
            bodyLen = (in.read() << 24) | (in.read() << 16) | (in.read() << 8) | in.read();
        }
        else
        {
            throw new IOException("unexpected length header");
        }

        int tag = in.read();

        if (tag < 0)
        {
            throw new EOFException("unexpected EOF reading signature sub packet");
        }

        // see below about miscoding... we'll try not to panic about anything under 2K.
        if (bodyLen <= 0 || (bodyLen > limit && bodyLen > 2048))
        {
            throw new EOFException("out of range data found in signature sub packet");
        }

        byte[] data = new byte[bodyLen - 1];

        //
        // this may seem a bit strange but it turns out some applications miscode the length
        // in fixed length fields, so we check the length we do get, only throwing an exception if
        // we really cannot continue
        //
        int bytesRead = Streams.readFully(in, data);

        boolean isCritical = ((tag & 0x80) != 0);
        int type = tag & 0x7f;

        if (bytesRead != data.length)
        {
            switch (type)
            {
            case CREATION_TIME:
                data = checkData(data, 4, bytesRead, "Signature Creation Time");
                break;
            case ISSUER_KEY_ID:
                data = checkData(data, 8, bytesRead, "Issuer");
                break;
            case KEY_EXPIRE_TIME:
                data = checkData(data, 4, bytesRead, "Signature Key Expiration Time");
                break;
            case EXPIRE_TIME:
                data = checkData(data, 4, bytesRead, "Signature Expiration Time");
                break;
            default:
                throw new EOFException("truncated subpacket data.");
            }
        }

        switch (type)
        {
        case CREATION_TIME:
            return new SignatureCreationTime(isCritical, isLongLength, data);
        case EMBEDDED_SIGNATURE:
            return new EmbeddedSignature(isCritical, isLongLength, data);
        case KEY_EXPIRE_TIME:
            return new KeyExpirationTime(isCritical, isLongLength, data);
        case EXPIRE_TIME:
            return new SignatureExpirationTime(isCritical, isLongLength, data);
        case REVOCABLE:
            return new Revocable(isCritical, isLongLength, data);
        case EXPORTABLE:
            return new Exportable(isCritical, isLongLength, data);
        case FEATURES:
            return new Features(isCritical, isLongLength, data);
        case ISSUER_KEY_ID:
            return new IssuerKeyID(isCritical, isLongLength, data);
        case TRUST_SIG:
            return new TrustSignature(isCritical, isLongLength, data);
        case PREFERRED_COMP_ALGS:
        case PREFERRED_HASH_ALGS:
        case PREFERRED_SYM_ALGS:
        case PREFERRED_AEAD_ALGORITHMS:
            return new PreferredAlgorithms(type, isCritical, isLongLength, data);
        case KEY_FLAGS:
            return new KeyFlags(isCritical, isLongLength, data);
        case POLICY_URL:
            return new PolicyURI(isCritical, isLongLength, data);
        case PRIMARY_USER_ID:
            return new PrimaryUserID(isCritical, isLongLength, data);
        case SIGNER_USER_ID:
            return new SignerUserID(isCritical, isLongLength, data);
        case NOTATION_DATA:
            return new NotationData(isCritical, isLongLength, data);
        case REG_EXP:
            return new RegularExpression(isCritical, isLongLength, data);
        case REVOCATION_REASON:
            return new RevocationReason(isCritical, isLongLength, data);
        case REVOCATION_KEY:
            return new RevocationKey(isCritical, isLongLength, data);
        case SIGNATURE_TARGET:
            return new SignatureTarget(isCritical, isLongLength, data);
        case ISSUER_FINGERPRINT:
            return new IssuerFingerprint(isCritical, isLongLength, data);
        case INTENDED_RECIPIENT_FINGERPRINT:
            return new IntendedRecipientFingerprint(isCritical, isLongLength, data);
        }

        return new SignatureSubpacket(type, isCritical, isLongLength, data);
    }

    private byte[] checkData(byte[] data, int expected, int bytesRead, String name)
        throws EOFException
    {
        if (bytesRead != expected)
        {
            throw new EOFException("truncated " + name + " subpacket data.");
        }

        return Arrays.copyOfRange(data, 0, expected);
    }
}




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