Java does not come with out-of-the-box support for PKCS1 keys. You can however use Bouncycastle PEMParser pemParser = new PEMParser(new FileReader(privateKeyFile)); JcaPEMKeyConverter converter = new JcaPEMKeyConverter().setProvider(“BC”); Object object = pemParser.readObject(); KeyPair kp = converter.getKeyPair((PEMKeyPair) object); PrivateKey privateKey = kp.getPrivate();
To hash a string, use the built-in MessageDigest class: import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.nio.charset.StandardCharsets; import java.math.BigInteger; public class CryptoHash { public static void main(String[] args) throws NoSuchAlgorithmException { MessageDigest md = MessageDigest.getInstance(“SHA-256”); String text = “Text to hash, cryptographically.”; // Change this to UTF-16 if needed md.update(text.getBytes(StandardCharsets.UTF_8)); byte[] digest = md.digest(); String hex = … Read more
First a disclaimer: DO NOT ever use SecureRandom to derive a key! This is broken and doesn’t make sense! The following block of code from the question tries to deterministically derive a key from a password, called the “seed” as the password is used to “seed” the random number generator. KeyGenerator keygen = KeyGenerator.getInstance(“AES”); SecureRandom … Read more
RSA + SHA256 can and will work… Your later example may not work all the time, it should use the hash algorithm’s OID, rather than it’s name. As per your first example, this is obtained from a call to CryptoConfig.MapNameToOID(AlgorithmName) where AlgorithmName is what you are providing (i.e. “SHA256”). First you are going to need … Read more