static byte[] buildRSA(RSAPublicKey key) {
DataByteOutputStream out = new DataByteOutputStream();
BigInteger exponent = key.getPublicExponent();
BigInteger modulus = key.getModulus();
int exponentLength = BigIntegerLength(exponent);
if (exponentLength < 256) out.writeByte(exponentLength);
else {
out.writeByte(0);
out.writeShort(exponentLength);
}
out.writeBigInteger(exponent);
out.writeBigInteger(modulus);
return out.toByteArray();
}
