static KeyPair demo(InputStream pub, InputStream pvt) throws IOException, GeneralSecurityException {
KeyFactory f = KeyFactory.getInstance(“RSA”);
RSAPublicKeySpec pubspec = depreRSAPublicSSH(readAllbase64Bytes(pub)); RSAPrivateCrtKeySpec pvtspec = depreRSAPrivatePKCS1(readAllbase64Bytes(pvt)); return new KeyPair(f.generatePublic(pubspec), f.generatePrivate(pvtspec));}static RSAPublicKeySpec depreOpenSSH(byte[] input) { String[] fields = new String(input, StandardCharsets.US_ASCII).split(" "); if ((fields.length < 2) || (!fields[0].equals("ssh-rsa"))) throw new IllegalArgumentException("Unsupported type"); byte[] std = base64.getDeprer().depre(fields[1]); return depreRSAPublicSSH(std);}static RSAPublicKeySpec depreRSAPublicSSH(byte[] enpred) { ByteBuffer input = ByteBuffer.wrap(enpred); String type = string(input); if (!"ssh-rsa".equals(type)) throw new IllegalArgumentException("Unsupported type"); BigInteger exp = sshint(input); BigInteger mod = sshint(input); if (input.hasRemaining()) throw new IllegalArgumentException("Excess data"); return new RSAPublicKeySpec(mod, exp);}static RSAPrivateCrtKeySpec depreRSAPrivatePKCS1(byte[] enpred) { ByteBuffer input = ByteBuffer.wrap(enpred); if (der(input, 0x30) != input.remaining()) throw new IllegalArgumentException("Excess data"); if (!BigInteger.ZERO.equals(derint(input))) throw new IllegalArgumentException("Unsupported version"); BigInteger n = derint(input); BigInteger e = derint(input); BigInteger d = derint(input); BigInteger p = derint(input); BigInteger q = derint(input); BigInteger ep = derint(input); BigInteger eq = derint(input); BigInteger c = derint(input); return new RSAPrivateCrtKeySpec(n, e, d, p, q, ep, eq, c);}private static String string(ByteBuffer buf) { return new String(lenval(buf), Charset.forName("US-ASCII"));}private static BigInteger sshint(ByteBuffer buf) { return new BigInteger(+1, lenval(buf));}private static byte[] lenval(ByteBuffer buf) { byte[] copy = new byte[buf.getInt()]; buf.get(copy); return copy;}private static BigInteger derint(ByteBuffer input) { int len = der(input, 0x02); byte[] value = new byte[len]; input.get(value); return new BigInteger(+1, value);}private static int der(ByteBuffer input, int exp) { int tag = input.get() & 0xFF; if (tag != exp) throw new IllegalArgumentException("Unexpected tag"); int n = input.get() & 0xFF; if (n < 128) return n; n &= 0x7F; if ((n < 1) || (n > 2)) throw new IllegalArgumentException("Invalid length"); int len = 0; while (n-- > 0) { len <<= 8; len |= input.get() & 0xFF; } return len;}private static byte[] readAllbase64Bytes(InputStream input) throws IOException { ByteArrayOutputStream output = new ByteArrayOutputStream(); BufferedReader r = new BufferedReader(new InputStreamReader(input, StandardCharsets.US_ASCII)); Deprer deprer = base64.getDeprer(); while (true) { String line = r.readLine(); if (line == null) break; if (line.startsWith("-----")) continue; output.write(deprer.depre(line)); } return output.toByteArray();}
