My friend has an idea about protecting the stored cookies in browser with adding an encryption on them using library such as Stanford Javascript Crypto Library.
Meanwhile i believe such actions are not possible because, javascript has no access to file system.
The question is:
what would be the functionality the said library?
What does it encrypt? I believe the encryption of it would be limited to variables of js application and not files on the host
You're asking
What kind of data could be encrypted using javascript?
and Bergi answered that in the comments:
In general, you can encrypt all data that can be represented in binary
That's true, but this is not what you're actually trying to ask. I believe you're looking for scenarios where crypto libraries are useful in the browser. But more on that a little further down.
I believe the encryption of it would be limited to variables of js application and not files on the host
Yes and no. Anything that can be accessed by JavaScript, can be encrypted. Whether this encryption adds any security is a whole other issue. Values that are accessible through variables in JavaScript code can be encrypted. The same goes to user input which includes files that the user explicitly opened in order to upload in a file dialog (example).
Additionally, your JavaScript code has access to the whole file system in Chrome if you really want it.
Here are some scenarios where using Cryptography in JavaScript could make sense, but not all of them are recommended (not exhaustive, but common):
File storage (i.e. Mega) where the symmetric encryption key is never sent to the server but kept on the client or is directly entered by the user. Its security depends on your trust that the service provider doesn't change their own JavaScript and log the key that was used for encryption.
Password-manager (i.e. clipperz) is similar to file storage, but its code is injected to other sites and it must be resilient to not blurt out all its secrets. It can use many different cryptographic primitives.
Poor-man's HTTPS (i.e. too many Stack Overflow questions) where the server has its RSA private key and sends the RSA public key over HTTP (sic!) to the browser. The browser can encrypt any data and send it back to the server (maybe also establishing a symmetric key in the process). The server can decrypt the message with its private key and respond. This is sort-of secure as long as there is no man-in-the-middle attacker that simply injects its own JavaScript that copies any browser data to the attacker's server. SJCL implements ElGamal encryption instead of RSA for this use case.
Hashing data before uploading in order to check for transmission errors or achieve deduplication (no need to upload file, because somebody else already did so). Hashing is technically in the realm of cryptography and many libraries to that.
Online calculators (i.e. my authenticated encryption tests) where valid and easy to use implementations or algorithms can be used directly when implementing the same algorithms in another language. The data is never sent to the server and is encrypted purely in the browser. My "calculator" can be used to test ones own implementation, because it is verified by various test vectors. Others are there to help friends pass hidden messages without proper e-mail encryption.
These should not be done with browser-based crypto:
If you're using only symmetric encryption over HTTP and the exact same key is present at the server and the client, then you have a problem, because the key must be sent in some way for the client to the server or back. If you send the encryption key from the server to the client or the other way around you need to encrypt your symmetric encryption key. The easiest way to do this would be to use TLS. If you use TLS, then the data as well as key are encrypted, so you don't need to encrypt it yourself. This doesn't provide any security, just a little bit of obfuscation. Any passive attacker (observer) can read your messages. You should read: Javascript Cryptography Considered Harmful
Hashing a password for log in is a bad practice. The general consensus is that you need to hash a password many times (PBKDF2, bcrypt, scrypt, Argon2) in order to check whether a user has sent the correct username and password. Some think that if we hash on the client, the password is not sent in the clear over the network and everything is secure. The problem is that if they think that, they are not using HTTPS (which they need). At the same time, the hashed password is their new password. If the server doesn't implement a constant-time comparison, it is trivial to use a timing side-channel attack to log in as any person which you know the username of.
JWT for sessions: Part 1 and part 2
Cookies are in fact accessible via JavaScript, just like the DOM is.
You could encrypt them by running the value you want to store through the encryption algorithm.
Depending on what you want to store and how the encryption/decryption mechanism works this may or may not be a good idea.
Is there any solution for secure user registration and authentication without SSL?
With "secure" I mean safe from passive eavesdropping, not from man-in-the-middle (I'm aware that only SSL with signed certificate will reach this degree of security).
The registration (password setup, i.e. exchanging of pre-shared keys) must be also secured without SSL (this will be the hardest part I guess).
I prefer established and well tested solution. If possible, I don't want to reinvent the wheel and make up my own cryptographic protocols.
Thanks in advance.
For logging in you could try SRP from clipperz:
I'm not sure how strong the random number generator they use is. You might want to try and use the Crypto API to get stronger values. I'm not sure how you can get secure seed values in javascript without using Crypto API.
For sending initial password to server you could use public key encryption. So the server sends the client its public key (ok under the no mitm assumption) and the client encrypts the whole registration request when registering. Cipperz has support for public key encryption but in a very raw form. Often you use public key encryption to encrypt a randomly generated symmetric key and use the symmetric key to encrypt the payload. You have to be quite careful with padding/etc to make public encryption properly secure. I don't know of any robust public key crypto libraries for javascript.
You may want to check out jsbn for public key encryption because it looks like it does padding correctly. Though, I suspect it suffers from insecure random number generation. It would be a good idea to use Crypto API or make the user bang the keyboard to generate some entropy. Snippet from rng.js
// For best results, put code like
// <body onClick='rng_seed_time();' onKeyPress='rng_seed_time();'>
// in your main HTML document.
My security knowledge is kind of limited but I might learn something.I´m planning to create an ajax application where I encrypt/decrypt passwords client-side with a typed master password
using a javascript AES library and then send/retrieve the encrypted data to/from Google App Engine(user authenticated). I actually found a project with the same idea: http://code.google.com/p/safety-vault/
In my mind as long as I keep my local computer secure (keyloggers) this should be quite secure or am I missing something?
As long as you use SSL for the webapp, this should be fine. Without SSL, an attacker could modify the page to insert some Javascript that sends them your password when you type it.
You might want to reconsider your threat model, though. Do you trust the server? If not, you shouldn't trust it to not send you a page that captures your master password when you enter it. If you do, you shouldn't have any qualms in sending your master password to the server.
There is a problem here, as I assume at some point you're going to have to send your master password to the browser client? If you have the master password, then you can decrypt the stream you send...
Use HTTPS, it's what it was designed for.
You effectively are trusting Google App Engine employees, and transitively, the entire trust chain behind them, to not steal your passwords. Encrypting client side doesn't mean anything if you are executing JavaScript code the server sends you, furthermore if you have no HTTPS implemented properly, it's trivial for someone to do a man in the middle attack and steal your passwords as they are transmitted. Just store the passwords locally or encrypt them with a well known tool like GPG and upload them.
I'm wondering what the serious issues are with the following setup:
Username/password login scheme
Javascript/ajax requests the salt value from the server (we have established in previous questions salt is not a secret value)
Javascript preforms an SHA1 (or otherwise) of the password and salt.
Javascript/ajax return the hash to the server
The server applies another salt/hash on-top of the the one sent via ajax.
Transactions are over HTTPS.
I'm concerned about problems that may exist but can't convince myself that this is that bad of a setup. Assume that all users need javascript enabled as jQuery is heavily used on the site. It's basically attempting to add an additional layer of security to the plain-text of a password.
As always: be very careful about designing cryptographic protocols yourself.
But that being said, I can see the advantage in the scheme. It will protect against the password being revealed through a man-in-the-middle-attack and it will ensure that the server never sees the actual password, thus preventing some inside attacks. On the other hand it does not protect against man-in-the-browser, fishing etc.
You might want to read through RFC 2617 about HTTP Digest access authentication. That scheme is similar to what you propose.
All that effort of passing salts and hashes between the client and server is already built into the underlying HTTPS/SSL protocol. I would be very surprised if a security layer in javascript is going to help very much. I recommend keeping it simple and use plaintext over SSL on the client-side. Worry about encryption on the server-side.
This doesn't add any additional security. The JavaScript code is present in the client, so the hashing algorithm is known. You gain nothing from doing a client-side hash in this case.
Also, there's no reason why the client should know about the hashing salt. It actually should be a secret value, especially if you're using a shared salt.
I'll 100% disagree with the accepted answer and say that under no circumstances should an original password ever Ever EVER leave the client. It should always be salted and hashed. Always, without exception.
Two reasons...
. The client should not be relying that all the server components and internal networks are TSL. It is quite common for the TSL endpoint to be a load balancing reverse proxy, which communicates with app servers using plaintext because devops can't be bothered to generate server certs for all their internal servers.
. Many users are pathologically inclined to use a common password for all of their services. The fact that a server has plaintext passwords, even if only in memory, makes it an attractive target for external attack.
You're not gaining anything. There's no point to a salt if Joe Public can see it by clicking View > Source, and the old maxim about never trusting client input goes double for password hashing.
If you really want to increase security, use a SHA-2 based hash (SHA-224/256/384/512), as SHA-1 has potential vulnerabilities. NIST no longer recommends SHA-1 for applications that are vulnerable to collision attacks (like password hashes).
I am using the basic-auth twitter API (no longer available) to integrate twitter with my blog's commenting system. The problem with this and many other web APIs out there is that they require the user's username and password to do anything useful. I don't want to deal with the hassle and cost of installing a SSL certificate, but I also don't want passwords passed over the wire in clear text.
I guess my general question is: How can I send sensitive data over an insecure channel?
This is my current solution and I'd like to know if there are any holes in it:
Generate a random key on the server (I'm using php).
Save the key in a session and also output the key in a javascript variable.
On form submit, use Triple DES in javascript with the key to encrypt the password.
On the server, decrypt the password using the key from the session and then destroy the session.
The end result is that only the encrypted password is sent over the wire and the key is only used once and never sent with the password. Problem solved?
Generate a random key on the server (I'm using php).
Save the key in a session and also output the key in a javascript variable.
On form submit, use Triple DES in javascript with the key to encrypt the password.
This avoids sending the password in the clear over the wire, but it requires you to send the key in the clear over the wire, which would allow anyone eavesdropping to decode the password.
It's been said before and I'll say it again: don't try to make up your own cryptographic protocols! There are established protocols out there for this kind of thing that have been created, peer reviewed, beat on, hacked on, poked and prodded by professionals, use them! No one person is going to be able to come up with something better than the entire cryptographic and security community working together.
Your method has a flaw - if someone were to intercept the transmission of the key to the user and the user's encrypted reply they could decrypt the reply and obtain the username/password of the user.
However, there is a way to securely send information over an unsecure medium so long as the information is not capable of being modified in transit known as the Diffie-Hellman algorithm. Basically two parties are able to compute the shared key used to encrypt the data based on their conversations - yet an observer does not have enough information to deduce the key.
Setting up the conversation between the client and the server can be tricky though, and much more time consuming than simply applying SSL to your site. You don't even have to pay for it - you can generate a self-signed certificate that provides the necessary encryption. This won't protect against man-in-the-middle attacks, but neither will the Diffie-Hellman algorithm.
You don't have to have a certificate on your server; it's up to the client whether they are willing to talk to an unauthenticated server. Key agreement can still be performed to establish a private channel. It wouldn't be safe to send private credentials to an unauthenticated server though, which is why you don't see SSL used this way in practice.
To answer your general question: you just send it. I think your real general question is: “How do I send sensitive data over an insecure channel—and keep it secure?” You can't.
It sounds like you've decided that security isn't worth the $10–20 per month a certificate would cost, and to protect Twitter passwords, that's probably true. So, why spend time to provide the illusion of security? Just make it clear to your users that their password will be sent in the clear and let them make their own choice.
So how is this any more secure? Even though you might have secured browser<>your server, what about the rest of the Internet (your server<>twitter)?
IMHO, it's unacceptable to ask for a username and password of another service and expect people to enter that. And if you care that much - don't integrate them until they get their act straight and re-enable OAuth. (They supported it for a while, but disabled it a few months ago.)
In the mean time, why not offer OpenID? Every Google, Yahoo!, VOX etc. account has one. People might not be aware of it but chances are really, really high that they already have OpenID. Check this list to see what I mean.
When the key is sent between the client and the server it is clear text and subject to interception. Combine that with the encrypted text of the password and the password is decrypted.
Diffie-Hellman is a good solution. If you only need to authenticate them, and not actually transmit the password (because the password is already stored on the server) then you can use HTTP Digest Authentication, or some variation there of.
APIs and OAuth
Firstly, as others have said, you shouldn't be using a user's password to access the API, you should be getting an OAuth token. This will allow you to act on that user's behalf without needing their password. This is a common approach used by many APIs.
Key Exchange
If you need to solve the more general problem of exchanging information over insecure connections, there are several key exchange protocols as mentioned by other answers.
In general key exchange algorithms are secure from eavesdroppers, but because they do not authenticate the identity of the users, they are vulnerable to man-in-the-middle attacks.
From the Wikipedia page on Diffie Hellman:
In the original description, the
Diffie–Hellman exchange by itself does not provide authentication of
the communicating parties and is thus vulnerable to a
man-in-the-middle attack. A person in the middle may establish two
distinct Diffie–Hellman key exchanges, one with Alice and the other
with Bob, effectively masquerading as Alice to Bob, and vice versa,
allowing the attacker to decrypt (and read or store) then re-encrypt
the messages passed between them. A method to authenticate the
communicating parties to each other is generally needed to prevent
this type of attack. Variants of Diffie-Hellman, such as STS, may be
used instead to avoid these types of attacks.
Even STS is insecure in some cases where an attacker is able to insert their own identity (signing key) in place of either the sender or receiver.
Identity and Authentication
This is exactly the problem SSL is designed to solve, by establishing a hierarchy of 'trusted' signing authorities which have in theory verified who owns a domain name, etc, someone connecting to a website can verify that they are indeed communicating with that domain's server, and not with a man-in-the-middle who has placed themselves in between.
You can create a self-signed certificate which will provide the necessary configuration to encrypt the connection, but will not protect you from man in the middle attacks for the same reason that unauthenticated Diffie-Hellman key exchange will not.
You can get free SSL certificates valid for 1 year from https://www.startssl.com/ - I use them for my personal sites. They're not quite as 'trusted' whatever that means, since they only do automatic checks on people who apply for one, but it's free. There are also services which cost very little (£10/year from 123-Reg in the UK).
I've implemented a different approach
Server: user name and password-hash stored in the database
Server: send a challenge with the form to request the password, store it in the session with a timestamp and the client's IP address
Client: hash the password, concat challenge|username|passwordhash, hash it again and post it to the server
Server: verify timestamp, IP, do the same concatenation/hashing and compare it
This applies to a password transmission. Using it for data means using the final hash as the encryption key for the plain text and generating a random initialization vector transmitted with the cipher text to the server.
Any comments on this?
The problem with client-side javascript security is that the attacker can modify the javascript in transit to a simple {return input;} thereby rendering your elaborate security moot. Solution: use browser-provided (ie. not transmitted) RSA. From what I know, not available yet.
How can I send sensitive data over an
insecure channel
With a pre-shared secret key. This is what you attempt in your suggested solution, but you can't send that key over the insecure channel. Someone mentioned DH, which will help you negotiate a key. But the other part of what SSL does is provide authentication, to prevent man-in-the-middle attacks so that the client knows they are negotiating a key with the person they intend to communicate with.
Chris Upchurch's advice is really the only good answer there is for 99.99% of engineers - don't do it. Let someone else do it and use their solution (like the guys who wrote the SSL client/server).
I think the ideal solution here would be to get Twitter to support OpenID and then use that.
An ssl certificate that is self-signed doesn't cost money. For a free twitter service, that is probably just fine for users.
TO OLI
In your approch for example i'm in the same subnet with same router, so i get the same ip as my collegues in my work. I open same url in browser, so server generates the timestamp with same ip, then i use tcp/ip dump to sniff the hashed or non hashed password from my collegues connection. I can sniff everything he sends. So i have all hashes from his form also you have timestamp(my) and same ip. So i send everything using post tool and hey i'm loggen in.
If you don't want to use SSL, why not try some other protocol, such as kerberos?
A basic overview is here:
http://www.kerberos.org/software/tutorial.html
Or if you want to go somewhat more in depth, see
http://www.hitmill.com/computers/kerberos.html
I have a similar issue(wanting to encrypt data in forms without paying for an ssl certificate) so I did some hunting and found this project: http://www.jcryption.org/
I haven't used it yet but it looks easy to implement and thought I'd share it here in-case anyone else is looking for something like it and finds themselves on this page like I did.