I am trying to encode a message with SH1 RSA
but I have no experience with security subject except some base information about RSA
. I have been given a private key as String
. I have managed to write following code block to do the job but I am not sure if I am doing the job securely and correctly.
I am not an expert but putting my private key as String in code is not secure I guess. Can anyone guide me?
String privateKeyString = "mykeyhere...";
byte[] privateKeyBytes = privateKeyString.getBytes();
String encodedPrivateKey = Base64.encodeToString(privateKeyBytes, Base64.URL_SAFE);
KeyFactory factory = KeyFactory.getInstance(RSA);
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(encodedPrivateKey.getBytes());
RSAPrivateKey privateKey = (RSAPrivateKey) factory.generatePrivate(keySpec);
Signature instance = Signature.getInstance(ALGORITHM);
instance.initSign(privateKey);
instance.update(content.getBytes());
return new String(instance.sign());
My private key is in form as:
"-----BEGIN PRIVATE KEY-----\n"+
"MIIE...\n"+
"cH0iRj...\n"+
"O0Hhj...\n"+
.
.
.
"fG6...\n"+
"B6/hF...\n"+
"3Mq38...\n"+
"-----END PRIVATE KEY-----\n"
Your key format is an unencrypted base64-encoded PKCS8-encoded private key. Here is an example of how to decode it into a private key. (Don't worry about the security of the private key in this example, it is just a throwaway for the example).
import java.io.*;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.spec.PKCS8EncodedKeySpec;
import android.util.Base64;
public class ReadPKCS8Pem {
private final static String PRIVATE_KEY =
"-----BEGIN PRIVATE KEY-----\n"
+ "MIICdQIBADANBgkqhkiG9w0BAQEFAASCAl8wggJbAgEAAoGBAM7t8Ub1DP+B91NJ\n"
+ "nC45zqIvd1QXkQ5Ac1EJl8mUglWFzUyFbhjSuF4mEjrcecwERfRummASbLoyeMXl\n"
+ "eiPg7jvSaz2szpuV+afoUo9c1T+ORNUzq31NvM7IW6+4KhtttwbMq4wbbPpBfVXA\n"
+ "IAhvnLnCp/VyY/npkkjAid4c7RoVAgMBAAECgYBcCuy6kj+g20+G5YQp756g95oN\n"
+ "dpoYC8T/c9PnXz6GCgkik2tAcWJ+xlJviihG/lObgSL7vtZMEC02YXdtxBxTBNmd\n"
+ "upkruOkL0ElIu4S8CUwD6It8oNnHFGcIhwXUbdpSCr1cx62A0jDcMVgneQ8vv6vB\n"
+ "/YKlj2dD2SBq3aaCYQJBAOvc5NDyfrdMYYTY+jJBaj82JLtQ/6K1vFIwdxM0siRF\n"
+ "UYqSRA7G8A4ga+GobTewgeN6URFwWKvWY8EGb3HTwFkCQQDgmKtjjJlX3BotgnGD\n"
+ "gdxVgvfYG39BL2GnotSwUbjjce/yZBtrbcClfqrrOWWw7lPcX1d0v8o3hJfLF5dT\n"
+ "6NAdAkA8qAQYUCSSUwxJM9u0DOqb8vqjSYNUftQ9dsVIpSai+UitEEx8WGDn4SKd\n"
+ "V8kupy/gJlau22uSVYI148fJSCGRAkBz+GEHFiJX657YwPI8JWHQBcBUJl6fGggi\n"
+ "t0F7ibceOkbbsjU2U4WV7sHyk8Cei3Fh6RkPf7i60gxPIe9RtHVBAkAnPQD+BmND\n"
+ "By8q5f0Kwtxgo2+YkxGDP5bxDV6P1vd2C7U5/XxaN53Kc0G8zu9UlcwhZcQ5BljH\n"
+ "N24cUWZOo+60\n"
+ "-----END PRIVATE KEY-----";
public static void main(String[] args) throws Exception {
// Read in the key into a String
StringBuilder pkcs8Lines = new StringBuilder();
BufferedReader rdr = new BufferedReader(new StringReader(PRIVATE_KEY));
String line;
while ((line = rdr.readLine()) != null) {
pkcs8Lines.append(line);
}
// Remove the "BEGIN" and "END" lines, as well as any whitespace
String pkcs8Pem = pkcs8Lines.toString();
pkcs8Pem = pkcs8Pem.replace("-----BEGIN PRIVATE KEY-----", "");
pkcs8Pem = pkcs8Pem.replace("-----END PRIVATE KEY-----", "");
pkcs8Pem = pkcs8Pem.replaceAll("\\s+","");
// Base64 decode the result
byte [] pkcs8EncodedBytes = Base64.decode(pkcs8Pem, Base64.DEFAULT);
// extract the private key
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(pkcs8EncodedBytes);
KeyFactory kf = KeyFactory.getInstance("RSA");
PrivateKey privKey = kf.generatePrivate(keySpec);
System.out.println(privKey);
}
}