private RespondToAuthChallengeRequest userSrpAuthRequest()

in java/src/main/java/com/alexa/awisapi/AuthenticationHelper.java [240:289]
43 lines of code
3 McCabe index (conditional complexity)

    private RespondToAuthChallengeRequest userSrpAuthRequest(InitiateAuthResult challenge,
                                                             String password
    ) {
        String userIdForSRP = challenge.getChallengeParameters().get("USER_ID_FOR_SRP");
        String usernameInternal = challenge.getChallengeParameters().get("USERNAME");

        BigInteger B = new BigInteger(challenge.getChallengeParameters().get("SRP_B"), 16);
        if (B.mod(AuthenticationHelper.N).equals(BigInteger.ZERO)) {
            throw new SecurityException("SRP error, B cannot be zero");
        }

        BigInteger salt = new BigInteger(challenge.getChallengeParameters().get("SALT"), 16);
        byte[] key = getPasswordAuthenticationKey(userIdForSRP, password, B, salt);

        Date timestamp = new Date();
        byte[] hmac = null;
        try {
            Mac mac = Mac.getInstance("HmacSHA256");
            SecretKeySpec keySpec = new SecretKeySpec(key, "HmacSHA256");
            mac.init(keySpec);
            mac.update(this.userPoolID.split("_", 2)[1].getBytes(StringUtils.UTF8));
            mac.update(userIdForSRP.getBytes(StringUtils.UTF8));
            byte[] secretBlock = Base64.decode(challenge.getChallengeParameters().get("SECRET_BLOCK"));
            mac.update(secretBlock);
            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("EEE MMM d HH:mm:ss z yyyy", Locale.US);
            simpleDateFormat.setTimeZone(new SimpleTimeZone(SimpleTimeZone.UTC_TIME, "UTC"));
            String dateString = simpleDateFormat.format(timestamp);
            byte[] dateBytes = dateString.getBytes(StringUtils.UTF8);
            hmac = mac.doFinal(dateBytes);
        } catch (Exception e) {
            System.out.println(e);
        }

        SimpleDateFormat formatTimestamp = new SimpleDateFormat("EEE MMM d HH:mm:ss z yyyy", Locale.US);
        formatTimestamp.setTimeZone(new SimpleTimeZone(SimpleTimeZone.UTC_TIME, "UTC"));

        Map<String, String> srpAuthResponses = new HashMap<>();
        srpAuthResponses.put("PASSWORD_CLAIM_SECRET_BLOCK", challenge.getChallengeParameters().get("SECRET_BLOCK"));
        srpAuthResponses.put("PASSWORD_CLAIM_SIGNATURE", new String(Base64.encode(hmac), StringUtils.UTF8));
        srpAuthResponses.put("TIMESTAMP", formatTimestamp.format(timestamp));
        srpAuthResponses.put("USERNAME", usernameInternal);

        RespondToAuthChallengeRequest authChallengeRequest = new RespondToAuthChallengeRequest();
        authChallengeRequest.setChallengeName(challenge.getChallengeName());
        authChallengeRequest.setClientId(clientId);
        authChallengeRequest.setSession(challenge.getSession());
        authChallengeRequest.setChallengeResponses(srpAuthResponses);

        return authChallengeRequest;
    }