org.bouncycastle.gpg.SXprUtils Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of bcpg-lts8on Show documentation

The Bouncy Castle Java APIs for the OpenPGP Protocol. The APIs are designed primarily to be used in conjunction with the BC LTS provider but may also be used with other providers providing cryptographic services.

The newest version!

package org.bouncycastle.gpg;

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

import org.bouncycastle.bcpg.HashAlgorithmTags;
import org.bouncycastle.bcpg.S2K;
import org.bouncycastle.util.io.Streams;

/**
 * Utility functions for looking a S-expression keys. This class will move when it finds a better home!
 * 
 * Format documented here:
 * https://git.gnupg.org/cgi-bin/gitweb.cgi?p=gnupg.git;a=blob;f=agent/keyformat.txt;h=42c4b1f06faf1bbe71ffadc2fee0fad6bec91a97;hb=refs/heads/master
 * 
 */
class SXprUtils
{
    private static int readLength(InputStream in, int ch)
        throws IOException
    {
        int len = ch - '0';

        while ((ch = in.read()) >= 0 && ch != ':')
        {
            len = len * 10 + ch - '0';
        }

        return len;
    }

    static String readString(InputStream in, int ch)
        throws IOException
    {
        int len = readLength(in, ch);

        char[] chars = new char[len];

        for (int i = 0; i != chars.length; i++)
        {
            chars[i] = (char)in.read();
        }

        return new String(chars);
    }

    static byte[] readBytes(InputStream in, int ch)
        throws IOException
    {
        int len = readLength(in, ch);

        byte[] data = new byte[len];

        Streams.readFully(in, data);

        return data;
    }

    static S2K parseS2K(InputStream in)
        throws IOException
    {
        skipOpenParenthesis(in);

        String alg = readString(in, in.read());
        byte[] iv = readBytes(in, in.read());
        final long iterationCount = Long.parseLong(readString(in, in.read()));

        skipCloseParenthesis(in);

        // we have to return the actual iteration count provided.
        S2K s2k = new S2K(HashAlgorithmTags.SHA1, iv, (int)iterationCount)
        {
            public long getIterationCount()
            {
                return iterationCount;
            }
        };

        return s2k;
    }

    static void skipOpenParenthesis(InputStream in)
        throws IOException
    {
        int ch = in.read();
        if (ch != '(')
        {
            throw new IOException("unknown character encountered: " + (char)ch);
        }
    }

    static void skipCloseParenthesis(InputStream in)
        throws IOException
    {
        int ch = in.read();
        if (ch != ')')
        {
            throw new IOException("unknown character encountered");
        }
    }
}