Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;

import java.math.BigInteger;

public class Main {
    /**
     *  http://download.oracle.com/javase/1.5.0/docs/guide/security/CryptoSpec.html
     *  Signature Format   ASN.1 sequence of two INTEGER values: r and s, in that order:
     *                                SEQUENCE ::= { r INTEGER, s INTEGER }
     *
     *  http://en.wikipedia.org/wiki/Abstract_Syntax_Notation_One
     *  30 -- tag indicating SEQUENCE
     *  xx - length in octets
     *
     *  02 -- tag indicating INTEGER
     *  xx - length in octets
     *  xxxxxx - value
     *
     *  Convert to BigInteger and back so we have the minimum length representation, as required.
     *  r and s are always non-negative.
     *
     *  Only supports sigs up to about 252 bytes. See code to fix BER encoding for this before you
     *  add a SigType with bigger signatures.
     *
     *  @throws IllegalArgumentException if too big
     *  @since 0.8.7, moved to SigUtil in 0.9.9
     */
    private static byte[] sigBytesToASN1(byte[] sig) {
        //System.out.println("pre TO asn1\n" + net.i2p.util.HexDump.dump(sig));
        int len = sig.length;
        int sublen = len / 2;
        byte[] tmp = new byte[sublen];

        System.arraycopy(sig, 0, tmp, 0, sublen);
        BigInteger r = new BigInteger(1, tmp);
        byte[] rb = r.toByteArray();
        if (rb.length > 127)
            throw new IllegalArgumentException("FIXME R length > 127");
        System.arraycopy(sig, sublen, tmp, 0, sublen);
        BigInteger s = new BigInteger(1, tmp);
        byte[] sb = s.toByteArray();
        if (sb.length > 127)
            throw new IllegalArgumentException("FIXME S length > 127");
        int seqlen = rb.length + sb.length + 4;
        if (seqlen > 255)
            throw new IllegalArgumentException("FIXME seq length > 255");
        int totlen = seqlen + 2;
        if (seqlen > 127)
            totlen++;
        byte[] rv = new byte[totlen];
        int idx = 0;

        rv[idx++] = 0x30;
        if (seqlen > 127)
            rv[idx++] = (byte) 0x81;
        rv[idx++] = (byte) seqlen;

        rv[idx++] = 0x02;
        rv[idx++] = (byte) rb.length;
        System.arraycopy(rb, 0, rv, idx, rb.length);
        idx += rb.length;

        rv[idx++] = 0x02;
        rv[idx++] = (byte) sb.length;
        System.arraycopy(sb, 0, rv, idx, sb.length);

        //System.out.println("post TO asn1\n" + net.i2p.util.HexDump.dump(rv));
        return rv;
    }
}