예제 #1
0
  /**
   * Call to save the public key (value B in the docs) when received from the server
   *
   * @param publicKey_B B
   * @throws SRPAuthenticationFailedException if B is invalid
   */
  public void setServerPublicKey_B(BigInteger publicKey_B) throws SRPAuthenticationFailedException {
    if (fPublicKey_A == null) {
      throw new IllegalStateException("setSalt_s() has not been called yet.");
    }

    if (publicKey_B.mod(fConstants.largePrime_N).equals(BigInteger.ZERO)) {
      throw new SRPAuthenticationFailedException("B%N == 0");
    }

    BigInteger SRP6_u = SRPUtils.calc_u(fPublicKey_A, publicKey_B);
    if (SRP6_u.mod(fConstants.largePrime_N).equals(BigInteger.ZERO)) {
      throw new SRPAuthenticationFailedException("u%N == 0");
    }

    // S = (B - 3(g^x))^(a + ux)
    BigInteger three_g_pow_x =
        fConstants.srp6Multiplier_k.multiply(
            fConstants.primitiveRoot_g.modPow(fPrivateKey_x, fConstants.largePrime_N));
    BigInteger B_minus_g_pow_x = publicKey_B.subtract(three_g_pow_x);
    BigInteger ux = SRP6_u.multiply(fPrivateKey_x);
    fCommonValue_S =
        B_minus_g_pow_x.modPow(fRandom_a.add(ux), fConstants.largePrime_N)
            .mod(fConstants.largePrime_N);
    fEvidenceValue_M1 = SRPUtils.calcM1(fPublicKey_A, publicKey_B, fCommonValue_S);

    // the MD5 output is the same as the AES key length
    fSessionKey_K = SRPUtils.hashToBytesMD5(fCommonValue_S);
  }
예제 #2
0
  /** Call to calculate the common session key (S/K in the docs) */
  public void computeCommonValue_S() {
    if (fPublicKey_A == null) {
      throw new IllegalStateException("setClientPublicKey_A() has not been called yet.");
    }

    fCommonValue_S =
        fPublicKey_A
            .multiply(fVerifier.verifier_v.modPow(fSRP6_u, fConstants.largePrime_N))
            .modPow(fRandom_b, fConstants.largePrime_N);
    fEvidenceValue_M1 = SRPUtils.calcM1(fPublicKey_A, fPublicKey_B, fCommonValue_S);

    // the MD5 output is the same as the AES key length
    fSessionKey_K = SRPUtils.hashToBytesMD5(fCommonValue_S);
  }