any_rsa_pkcs1signature.java

来自「jpeg2000编解码」· Java 代码 · 共 494 行 · 第 1/2 页

     *              been generated with.
     * @exception InvalidKeyException
     *      If the key class does not implement java.security.interfaces.RSAPrivateKey
     *      or
     *      If the size of the minimal PKCS#1 frame generated by the
     *      engineSign() method will be larger than the public key modulus.
     */
    protected void engineInitVerify (PublicKey key) throws InvalidKeyException {
        if (!(key instanceof CryptixRSAPublicKey))
            throw new InvalidKeyException(getAlgorithm() +
                ": Not an RSA public key");

        CryptixRSAPublicKey rsa = (CryptixRSAPublicKey) key;
        n = rsa.getModulus();
        exp = rsa.getExponent();

        // It is unusual for an RSAPublicKey class to implement RSAFactors,
        // because knowing p and q implies knowing the private key. Still,
        // occasionally it is useful to verify a signature that you created,
        // and this can be used to make that more efficient.
        if (key instanceof RSAFactors) {
            RSAFactors factors = (RSAFactors) key;
            p = factors.getP();
            q = factors.getQ();
            u = factors.getInverseOfQModP();
        }
        md.reset();

        // result will have as many bytes as the public modulus n
        int mdl = md.digest().length;
        int length = (n.bitLength() + 7) / 8;
        int aidl = getAlgorithmEncoding().length;
        int padLen = length - 3 - aidl - mdl;
        if (padLen < 0) throw new
            InvalidKeyException("Signer's public key modulus too short.");
    }

    /**
     * Updates the data to be signed or verified, using one byte.
     *
     * @param  b  the byte to use for the update process.
     * @exception SignatureException if the engine is not initialised properly.
     */ 
    protected void engineUpdate (byte b)
    throws SignatureException {
        if (state != VERIFY && state != SIGN)
            throw new SignatureException(getAlgorithm() + ": Not initialized");

        md.update(b);
    }

    /**
     * Updates the data to be signed or verified, using the specified
     * sub-array of bytes, starting at the specified offset.
     *
     * @param  in      the array of bytes.
     * @param  offset  the offset to start from in <i>in</i>.
     * @param  length  the number of bytes to use, starting at <i>offset</i>.
     * @exception SignatureException if the engine is not initialised properly.
     */          
    protected void engineUpdate (byte[] in, int offset, int length)
    throws SignatureException {
        if (state != VERIFY && state != SIGN)
            throw new SignatureException(getAlgorithm() + ": Not initialized");

        md.update(in, offset, length);
    }

    /**
     * Terminates the update process and returns the signature bytes of
     * all the data signed so far.
     * <p>
     * <b>NOTES:</b> Sun's documentation talks about the bytes returned
     * being X.509-encoded. For this RSA/PKCS#1 implementation, they
     * conform to PKCS#1 section 10. Practically, the return value will
     * be formed by concatenating a leading <i>NULL</i> byte, a block type
     * <i>BT</i>, a padding block <i>PS</i>, another <i>NULL</i>byte, and
     * finally a data block <i>D</i>;
     * ie:
     * <pre>
     *     return = 0x00 || BT || PS || 0x00 || D.
     * </pre>
     * For signing, <i>PKCS#1 block type 01</i> encryption-block formatting
     * scheme is employed. The block type <i>BT</i> is a single byte valued
     * 0x01 and the padding block <i>PS</i> is enough 0xFF bytes to make the
     * length of the complete RSA Multi Precision Integer equal to the length
     * of the public modulus. The data block <i>D</i> consists of the MIC --
     * Message Integrity Check, or message digest value-- and the MIC
     * algorithm ASN.1 encoded identifier. The formal syntax in ASN.1
     * notation is:
     * <pre>
     *   SEQUENCE {
     *     digestAlgorithm  AlgorithmIdentifier,
     *     digest           OCTET STRING
     *   }
     *
     *   AlgorithmIdentifier ::= SEQUENCE {
     *     algorithm        OBJECT IDENTIFIER,
     *     parameters       ANY DEFINED BY algorithm OPTIONAL
     *   }
     * </pre>
     *
     * @return  the signature bytes of the signing operation's result.
     * @exception  SignatureException
     *     if the engine is not initialised properly.
     */
    protected byte[] engineSign()
    throws SignatureException {
        if (state != SIGN) throw new SignatureException(
            getAlgorithm() + ": Not initialized for signing");

        long t = 0;
if (DEBUG && debuglevel >= 7) t = System.currentTimeMillis();

        BigInteger pkcs = makePKCS1();
        BigInteger result = RSAAlgorithm.rsa(pkcs, n, exp, p, q, u);

if (DEBUG && debuglevel >= 7) {
    t = System.currentTimeMillis() - t;
    debug(" ...engineSign() completed in "+t+" ms.");
}
        return result.toByteArray();
    }

    /**
     * Terminates the update process and verifies that the passed signature
     * equals that of a generated one based on the updated data so far.
     * <p>
     * <b>NOTES:</b> Sun's documentation talks about the bytes received
     * being X.509-encoded. For this RSA/PKCS#1 implementation, the bytes
     * received are assumed to conform to PKCS#1 section 10, or have
     * been generated by a previous invocation of the <code>engineSign</code>
     * method.
     *
     * @param  signature    the signature bytes to be verified.
     * @return true if the signature was verified successfully, false
     *                      otherwise.
     * @exception SignatureException if the engine is not initialised
     *                      properly, the received signature data is improperly
     *                      encoded or of the wrong type, etc.
     */
    protected boolean engineVerify(byte[] signature)
    throws SignatureException {
        if (state != VERIFY) throw new SignatureException(
            getAlgorithm() + ": Not initialized for verification");

        long t = 0;
if (DEBUG && debuglevel >= 7) t = System.currentTimeMillis();

        // if we generated it, it's a positive BI
        BigInteger M = new BigInteger(1,signature);
        BigInteger computed = RSAAlgorithm.rsa(M, n, exp, p, q, u);
        BigInteger actual = makePKCS1();
        boolean ok = computed.equals(actual);

if (DEBUG && debuglevel >= 7) {
    t = System.currentTimeMillis() - t;
    debug(" ...engineVerify() completed in "+t+" ms.");
    if (!ok) {
        debug("   Computed: " + Hex.dumpString(computed.toByteArray()));
        debug("     Actual: " + Hex.dumpString(actual.toByteArray()));
    }
}
        return ok;
    }

    protected void engineSetParameter(String param, Object value)
    throws InvalidParameterException {
        throw new InvalidParameterException(getAlgorithm() + ": " + param);
    }

    protected Object engineGetParameter(String param)
    throws InvalidParameterException {
        throw new InvalidParameterException(getAlgorithm() + ": " + param);
    }


// Own methods
//...........................................................................

    /**
     * Returns a byte array consisting of a padded message digest value,
     * previously computed. This packet will be RSA-encrypted with the
     * private key of this object to act as an authentication for whatever
     * was digested.
     * <p>
     * As described in the <i>engineSign()</i> method above, the return
     * array will consist of:
     * <pre>
     *    MSB                                                            LSB
     *    00  01   FF-1 ... FF-n  00   AID-1 ... AID-n   04 LL MD-1 ... MD-n
     *      | BT |----- PS -----|    |-- AlgorithmId --|------ digest ------|
     * </pre>
     * <p>
     * The <i>AID<i> bytes form the <i>AlgorithmIdentifier</i> token.
     * The OCTET STRING tag is <i>04</i> and <i>LL</i> is the length byte
     * (the number of bytes in the message digest proper, i.e. <i>n</i>).
     * <p>
     * Bytes <i>MD-1</i> to <i>MD-n</i> are the message digest value
     * of the material updated so far, thus completing the <i>digest</i>
     * token in the SEQUENCE described in <i>engineSign()</i> above.
     *
     * @return the result of the updating process framed in a PKCS#1
     *         type 01 block structure as a BigInteger.
     * @exception SignatureException If the length of the minimal PKCS#1 frame
     *      generated by this method will be longer than the public key modulus.
     */
    private BigInteger makePKCS1() throws SignatureException {
        byte[] theMD = md.digest();                           // stop hashing
        int mdl = theMD.length;

        // result has as many bytes as the public modulus
        int length = (n.bitLength() + 7) / 8;
        byte[] r = new byte[length];

        r[1] = 0x01;                          // PKCS#1 encryption block type

        byte[] aid = getAlgorithmEncoding();             // get the AID bytes
        int aidl = aid.length;

//        int padLen = length - 3 - aidl - mdl - 2;        // put padding bytes
        int padLen = length - 3 - aidl - mdl;            // put padding bytes
        if (padLen < 0)
            throw new SignatureException("Signer's public key modulus too short.");

        for (int i = 0; i < padLen;) r[2 + i++] = (byte) 0xFF;

        System.arraycopy(aid, 0, r, padLen + 3, aidl);   // copy the AID bytes
        // the next 2 bytes are now part of the subclass
//        r[length - mdl - 2] = 0x04;              // tag it as an OCTET STRING
//        r[length - mdl - 1] = (byte) mdl;           // and say how long it is
        System.arraycopy(theMD, 0, r, length - mdl, mdl); // now the md per se

if (DEBUG && debuglevel >= 4) debug("PKCS#1 frame = " + Hex.dumpString(r));

        return new BigInteger(r);        // always positive because r[0] is 0
    }

    /**
     * Returns the ASN.1 bytes of the <i>AlgorithmIdentifier</i> token described
     * in <code>engineSign()</code> method above.
     *
     * @return the <i>AlgorithmIdentifier</i> bytes.
     */
    protected abstract byte[] getAlgorithmEncoding();
}