Method generateKeys

src/main/java/com/thealgorithms/ciphers/RSA.java:104–118

Generates a new RSA key pair (public and private keys) with the specified bit length. Steps: 1. Generate two large prime numbers p and q. 2. Compute the modulus n = p q. 3. Compute Euler's totient function: φ(n) = (p-1) (q-1). 4. Choose a public key e (starting from 3) that is coprime with φ(n). 5.

(int bits)

     * @param bits The bit length of the keys to be generated.
     */
    public final synchronized void generateKeys(int bits) {
        SecureRandom random = new SecureRandom();
        BigInteger p = new BigInteger(bits / 2, 100, random);
        BigInteger q = new BigInteger(bits / 2, 100, random);
        modulus = p.multiply(q);

        BigInteger phi = (p.subtract(BigInteger.ONE)).multiply(q.subtract(BigInteger.ONE));

        publicKey = BigInteger.valueOf(3L);
        while (phi.gcd(publicKey).intValue() > 1) {
            publicKey = publicKey.add(BigInteger.TWO);
        }

        privateKey = publicKey.modInverse(phi);
    }
}