I have been given an RSA public Key and an RSA private key with OAEP SHA-256 padding. I am attempting to simply encrypt a random string and then decrypt it to assert the result is equalt to the original.
This is the public key i have been given:
-----BEGIN RSA PUBLIC KEY----- MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAq8tiBtDmkeS/ruY3rrkq dz6Lc6XWFRbI/GjPtIokrtpM+Ujyv6wX8TBqY8e03gzh+eE7VUyEVPapDnceAqgJ ZQah2h+N5AEQKqNDM4/1to1V0F+m1ISR7CIUU8dvU+bPk67DU5VkEtLxf+mW8/es hy0u6oSB04WCDPNnh+9GDF7tN7lOzBH1FxKPWIb5Gqg6GoXS+KgvQhYEk0TajIBk +mefzTv1D4HJlhFYybgY+/p3k4P2kM5HnbEtoVpz/PL9+94YVp5RBHTQHmk/3SAX RkPP34IjY6LZqTJGWQGxc64Qci54ZJsq4wSTXvfdHgUWz7eX+v1jA+GLjFExNcYZ nQIDAQAB -----END RSA PUBLIC KEY----- This is the private key I have been given:
-----BEGIN PRIVATE KEY----- MIIEvQIBADANBgkqhkiG9w0BAQEFAASCBKcwggSjAgEAAoIBAQDAUQiHdHuMBCnF P/7RQoRWrp62dGWQLDLP9l+3KUMlSPheN2R5jHDZ/WEGJGF2WYKxaQvv5XCocdnt uxVZTNM1PVyduokJaJzrSIj+jGWDd4hTWvVoS3vhds8u6W0jD3M4ayrF6c7NYuHc tE5YLLIgK1DTn+ZZCr3VGbScISDJ/WPx3+1YTNQDvm+T7MfjhetJqqzWIsunMUiw nQOQvkdjCVWpk+L10SaMrezixtIS5wfpOTjGIZ0w5VunvtsPxg1TkuvGURa9S3rS 7D3uhDPY+V8UDMpBPso3j7TGD5axlBJcpavWeF8qde3sWztmqUFQ3JDypZWGSAe2 d8e4mY65AgMBAAECggEAal8nwYxbHZnb5L892U7aVfuly7Nbzb+0pzRVwsBu5DuV LL+kslpMvTYZqUUMJ2LhF/HLaXhVtMWsTYLSDx+gHu1+wbtAOtUDHlxzcaAEMhA2 dix0WqiNr6qAdCkmdWMBTu5vrSJigVW1KdcNElY+e+6ZeUQTK6L2Vt0t+cGVGkM4 K5PdHcGLR1BiAf3k4BguHE4TGGnqN9dF5Rn9nPP6C7QihWzGn15efD2dAXn3Kbho dMIRgyYiO7uXPm2LrIjtldYb8tPus+V9SWT4hcgnJZrtd9atkqZrJ3dhQf9ZetGs UwTCzHJ169NNbVyrjCbcy4Uht8Na+t/94Im9hI8n0QKBgQDO6tYnwh1hPg3E+4DY xCiDAp7v3afJIvC9a1sBtif8KkzZTYH31ww+PRcfDPQUlk/MIDie0u6xIawnBYkC oN1u9erojcvQbBP0GFylP5hNxYZbI7gPA/7AiGRxyezZPOiVMwdd5fCM7Wv4kucr c1JCcvtPoDQcFFZOfI+wqqdWnQKBgQDt745Pvckt7/XL7wbfv4BV+cwpLNjc4/3k ajOLtasgpT8mc0gUH2ejHhpkuhjSUpSTrlFB8EN1kAwmBYy0GOoO9967hm6twmqk Q5L3OHJ96pYkf1rbyXNE1N7inh5Z3M1H5ONIaliAYLHXOzKsZvI5eUdKAJdSqFLo uvVCwr4PzQKBgG6W3rzDJ9a4Rr24OgYg2RIkTXQgALQko4xpm2tPwxEoPoiJv2QK ILYHCpuC3dU+/Qk5U2m3jPFI8OyuLask9RSABPwkBQGxMfztJF8BnVI7tvJxJceI uBiJDT4v0RHOVvSfIFnUMnvvzRw+z6TObvGq6JyHIDK9v98U/etLWkKVAoGAIIxF lmjqzUrm/8ep1A+5OYmbQQKug8D4aTeR54mpaCTSt6rLcF0/axPiHmdKn/LF+lG9 MdzxDXLwBn952OUTl4qWwGZKW6Cdv+yyfPkOyGS/tyxovGoZR5ArESr6Eebfefc4 lB5gDuerTDr/2o+WkQAjHV9pU9hMxyNUC5biMv0CgYEAiDlw8lBf3cQs6FxNXs9t whWpfL0yY7WAONvhfFB0Dpsz52gGDCYRvJekGRz6jOlKDuXJ+Mm1AX4BaufMETI5 QseZxtVPIn+BXm0A1x8w/DifmE1JqQZmPCQPOh3eLx5nSn9LKGIbMgd17mfH3HhU 8WX2mzWjmRA3C/CzdGfCKSk= -----END PRIVATE KEY----- I am reading this key from a pem file "crypt_pkcs8.pem" but recive the public key as a byte array from a gRPC call.
Here is my Java code:
public class Encryption{ public static void main(String args){ ByteString publicKey = client.getPublicKey(nonce).getRSAEncryptionKey(); String strKeyPEM = ""; BufferedReader br = new BufferedReader(new FileReader("crypt_pkcs8.pem")); String line; while ((line = br.readLine()) != null) { strKeyPEM += line+"\n"; } br.close(); byte[] pt; try { pt = "h".getBytes("UTF-8"); byte[] ct =encrypt(publicKey, pt); byte[] response= decrypt(strKeyPEM, ct); assertEquals(pt, response); } catch (UnsupportedEncodingException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public static byte[] encrypt(ByteString rawKey ,byte[] message){ String strippedKey=stripKey(rawKey.toStringUtf8()); byte[] keyBytes = Base64.getDecoder().decode(strippedKey); System.out.println(keyBytes.length); Cipher cipher_RSA; try { cipher_RSA = Cipher.getInstance("RSA/ECB/OAEPWITHSHA-256ANDMGF1PADDING"); KeyFactory keyFactory = KeyFactory.getInstance("RSA"); X509EncodedKeySpec spec = new X509EncodedKeySpec(keyBytes); PublicKey pk = keyFactory.generatePublic(spec); System.out.println(pk.getAlgorithm()+" format : "+pk.getFormat()); cipher_RSA.init(Cipher.ENCRYPT_MODE, pk); return cipher_RSA.doFinal(message); } catch (NoSuchAlgorithmException | NoSuchPaddingException | IllegalBlockSizeException | BadPaddingException | InvalidKeyException | InvalidKeySpecException e) { // TODO Auto-generated catch block e.printStackTrace(); return null; } } public static byte[] decrypt(String rawKey ,byte[] message){ String strippedKey=stripPrivateKey(rawKey); byte[] keyBytes = Base64.getDecoder().decode(strippedKey); System.out.println(keyBytes.length); Cipher cipher_RSA; try { cipher_RSA = Cipher.getInstance("RSA/ECB/OAEPWITHSHA-256ANDMGF1PADDING"); KeyFactory keyFactory = KeyFactory.getInstance("RSA"); PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes); PrivateKey pk = keyFactory.generatePrivate(spec); System.out.println(pk.getAlgorithm()+" format : "+pk.getFormat()); cipher_RSA.init(Cipher.DECRYPT_MODE, pk); return cipher_RSA.doFinal(message); } catch (NoSuchAlgorithmException | NoSuchPaddingException | IllegalBlockSizeException | BadPaddingException | InvalidKeyException | InvalidKeySpecException e) { // TODO Auto-generated catch block e.printStackTrace(); return null; } } public static String stripKey(String key){ key = key.replace("-----BEGIN RSA PUBLIC KEY-----\n", ""); key = key.replace("-----END RSA PUBLIC KEY-----", ""); key = key.replace("\n", ""); return key; } public static String stripPrivateKey(String key){ key = key.replace("-----BEGIN PRIVATE KEY-----", ""); key = key.replace("-----END PRIVATE KEY-----", ""); key = key.replace("\n", ""); return key; } } I cannot find anything obviously wrong with my actaul code so I believe this is to do with the keys not matching.
I also notice the header/footer is different on the public key and private key. From looking online this is because the public key is in PKCS#8 format.
Will I need to change the public key to pkcs#8 format as well? If so what is the easiest way to do this?
I have also been told I should be able to extract the public key (in pkcs8 format) from the private key given above. Can this be done easily?
