I am currently developing an MQ application client-side, that is meant to establish connection between a machine and a distant server, and I need to implement SSL connection between them. The server was already configured with a given certificate that I was sent. The problem is : I can't understand what exactly needs to be done with the key repository part.
It looks like the MQCONNX call is expecting not only a certificate name (label), but also a key database (kdb) file, which I don't have. Thus I have several question, because it seems like I don't understand every aspect of the certificate part:
How can I get the kdb file linked to the certificate? Is it supposed to be generated by the person who made the certificate?
Where is it supposed to be stored? Can I use any folder/name?
A little background : I am working on Windows and developping with C MQ libraries. Before the SSL requirement was added, everything was working properly : I could connect to the queue manager and post messages into a given queue. Now I get error 2381 MQRC_KEY_REPOSITORY_ERROR, which will probably be gone after this key repository part is solved.
Thanks a lot for all your answers.
Cheers,
I think between them the comments to your question provide the answer. In essence your client application (or the underlying MQ C layer) needs to trust the certificate that the server is sending.
If the certificate you have was signed by a trusted certificate authority,
then your app needs to be told to trust the public key of the certificate authority. If it is self-signed, then your app needs to be told to trust the public certificate.
Either way, you will need a keystore. The keystore holds all the public keys and public keys of certificate signers that you trust.
To create the keystore, follow the "Create a client keystore" section of https://developer.ibm.com/tutorials/mq-secure-msgs-tls/
These steps will create a keystore containing the certificate that you have been sent.
You then tell your application where to find the trusted keys keystore by setting the environment variable MQSSLKEYR
// MQSSLKEYR is need so that the MQ client knows what keystore to use..
// note it is the full path, including the base file name but not the .kdb extension
// my keystore file is user.kdb in the C:\tmp subdirectory..
set MQSSLKEYR=C:\tmp\user
see - https://www.ibm.com/docs/en/ibm-mq/9.0?topic=wsulw-specifying-key-repository-location-mq-mqi-client-unix-linux-windows
and
https://www.ibm.com/support/pages/how-do-i-configure-mq-client-c-based-application-amqsputc-amqsgetc-connect-mq-server-ssl
So, I'm trying to understand how certificates really, really work - I haven't been able to find what exactly I'm looking for on google so I'm phrasing it my way... If there's a straightforward link that you think might help me - please post it and I will delete this question.
I understand that when the client(say, a browser) makes a request to a website, it verifies the identity of the website by checking its certificate. Self signed certificates are discouraged and certificates from the Certificate Authority (and its branches) are the real deal. Now that the identity has been verified, the request is processed by the server and the response is sent to the client and now the user (a human being) can see that green lock sign on their browser next to the URL. Did I sum this up correctly? And this response is encrypted and will be decrypted by the browser/client?
In the case of SSO (single sign on) flows - when SAML assertions are "digitally signed" - what exactly does this mean? And how does the above mentioned certificates help in that?
I've just got too many concepts all mixed up in my head and was looking for clarity understanding systems and security and TLS.
First of all this is all about asymmetric cryptography. This allows to encrypt the message with one key and decrypt with another. Why is this helpful.
Secure interaction
You can send a message to your server using the public key of that server. Thus you can be sure that nobody else (except of that server) would be able to decrypt that message
Digital signing
You can encrypt a digest of a message with your private key and anyone will be able to check if that was you by decrypting your "signature" with your public key.
At what stage the certificate is involved
Both above cases have a pitfall. You cannot be really sure that the public key that the server provides you is really a key of the party you trust to. The same with signatures. You cannot be sure that the public key you have just successfully used to verify a signature is really a key of a person you expect to sign your contract.
Certificate is a bundle of a public key and the information about the holder of the key pair. This bundle is digitally signed with the private key of CA.
What is the end to end process
Let's consider https case. Your client says to a server "Hey I want to use https protocol". This is the point where asymmetric cryptography is involved. You use server's public key to encrypt a symmetric key (since the asymmetric cryptography is somewhat expensive, it is used only when symmetric key is being negotiated) that will be used for encrypting traffic.
But how can you be sure you can trust that server. Actually what server sends you is not just a key but a certificate. You take the certificate and verify that the server name specified in the cert is actually what you used in your address bar. You also verify the signature of CA using that CA's public key.
Certification chain
Public key of CA that has signed the server certificate might also require verification. Such verification is performed in the same way as explained above. The chain has to eventually stop at the certificate that you absolutely trust. Such certificates are stored at so called trust store.
So this is how ssl works. Digitally signed SAML assertions work in the very similar way. They deliver certificates which you can validate and use the public keys extracted from them for validating the signature of assertions.
I am new to digital certificates and it's various types and applications. What I know/assume as of now is in https communication, a CA will issue a certificate which will basically contain a public-private key pair which the Server and Client will use to communicate securely. And authentication will be through conventional password like mechanisms. Please correct me.
Now in the context of device certificates, does it serve the purpose of authentication only, if yes, then how? or it also serves the purpose of secure communication by means of public-private keys. How it is used.
How does a server determine the authenticity of device?
And in https there is only one certificate that a Server/Host and it's Clients will have, whereas, in device based it's issued per device. Am I right?
Thanks
I have another question to security in the web world.
So I read (and ask :P) about certificates and think I got what it is and how it works. My next question is putty specific. When I open a connection with putty to a new server with ssh (port: 22) I get a PuTTY Security Alert:
The server's host key is not chacked in the registry. You have to guarantee that the server is the computer you think it is.
The server's xxxx key fingerprint is:
yyyyyyyyyyyyyyyyyyyyyyyyyyy
If you trust this host, hit Yes... etc.
Now I am wondering what a key fingerprint means.
Is that just a certificate which putty hasn't in is cache yet?
thanks.
SCBoy
Those are the first bytes of the server certificate public key. The idea is that the key is a random number, so the first bytes are random too and therefore knowing that those first bytes are the same for two keys would likely mean that the keys are actually the same.
You can use this to validate the server. You could for example call the administrator of that server and ask him for the fingerprint of the key to validate that it's indeed the key of that server, not some man-in-the-middle server belonging to a malicious party.
What is the series of steps needed to securely verify a ssl certificate? My (very limited) understanding is that when you visit an https site, the server sends a certificate to the client (the browser) and the browser gets the certificate's issuer information from that certificate, then uses that to contact the issuerer, and somehow compares certificates for validity.
How exactly is this done?
What about the process makes it immune to man-in-the-middle attacks?
What prevents some random person from setting up their own verification service to use in man-in-the-middle attacks, so everything "looks" secure?
Here is a very simplified explanation:
Your web browser downloads the web server's certificate, which contains the public key of the web server. This certificate is signed with the private key of a trusted certificate authority.
Your web browser comes installed with the public keys of all of the major certificate authorities. It uses this public key to verify that the web server's certificate was indeed signed by the trusted certificate authority.
The certificate contains the domain name and/or ip address of the web server. Your web browser confirms with the certificate authority that the address listed in the certificate is the one to which it has an open connection.
Your web browser generates a shared symmetric key which will be used to encrypt the HTTP traffic on this connection; this is much more efficient than using public/private key encryption for everything. Your browser encrypts the symmetric key with the public key of the web server then sends it back, thus ensuring that only the web server can decrypt it, since only the web server has its private key.
Note that the certificate authority (CA) is essential to preventing man-in-the-middle attacks. However, even an unsigned certificate will prevent someone from passively listening in on your encrypted traffic, since they have no way to gain access to your shared symmetric key.
You said that
the browser gets the certificate's issuer information from that
certificate, then uses that to contact the issuerer, and somehow
compares certificates for validity.
The client doesn't have to check with the issuer because two things :
all browsers have a pre-installed list of all major CAs public keys
the certificate is signed, and that signature itself is enough proof that the certificate is valid because the client can make sure, on his own, and without contacting the issuer's server, that that certificate is authentic. That's the beauty of asymmetric encryption.
Notice that 2. can't be done without 1.
This is better explained in this big diagram I made some time ago
(skip to "what's a signature ?" at the bottom)
It's worth noting that in addition to purchasing a certificate (as mentioned above), you can also create your own for free; this is referred to as a "self-signed certificate". The difference between a self-signed certificate and one that's purchased is simple: the purchased one has been signed by a Certificate Authority that your browser already knows about. In other words, your browser can easily validate the authenticity of a purchased certificate.
Unfortunately this has led to a common misconception that self-signed certificates are inherently less secure than those sold by commercial CA's like GoDaddy and Verisign, and that you have to live with browser warnings/exceptions if you use them; this is incorrect.
If you securely distribute a self-signed certificate (or CA cert, as bobince suggested) and install it in the browsers that will use your site, it's just as secure as one that's purchased and is not vulnerable to man-in-the-middle attacks and cert forgery. Obviously this means that it's only feasible if only a few people need secure access to your site (e.g., internal apps, personal blogs, etc.).
I KNOW THE BELOW IS LONG, BUT IT IS DETAILED, YET SIMPLIFIED ENOUGH. READ CAREFULLY AND I GUARANTEE YOU'LL START FINDING THIS TOPIC IS NOT ALL THAT COMPLICATED.
First of all, anyone can create 2 keys. One to encrypt data, and another to decrypt data. The former can be a private key, and the latter a public key, AND VICERZA.
Second of all, in simplest terms, a Certificate Authority (CA) offers the service of creating a certificate for you. How? They use certain values (the CA's issuer name, your server's public key, company name, domain, etc.) and they use their SUPER DUPER ULTRA SECURE SECRET private key and encrypt this data. The result of this encrypted data is a SIGNATURE.
So now the CA gives you back a certificate. The certificate is basically a file containing the values previously mentioned (CA's issuer name, company name, domain, your server's public key, etc.), INCLUDING the signature (i.e. an encrypted version of the latter values).
Now, with all that being said, here is a REALLY IMPORTANT part to remember: your device/OS (Windows, Android, etc.) pretty much keeps a list of all major/trusted CA's and their PUBLIC KEYS (if you're thinking that these public keys are used to decrypt the signatures inside the certificates, YOU ARE CORRECT!).
Ok, if you read the above, this sequential example will be a breeze now:
Example-Company asks Example-CA to create for them a certificate.
Example-CA uses their super private key to sign this certificate and gives Example-Company the certificate.
Tomorrow, internet-user-Bob uses Chrome/Firefox/etc. to browse to https://example-company.com. Most, if not all, browsers nowadays will expect a certificate back from the server.
The browser gets the certificate from example-company.com. The certificate says it's been issued by Example-CA. It just so happens to be that Bob's OS already has Example-CA in its list of trusted CA's, so the browser gets Example-CA's public key. Remember: this is all happening in Bob's computer/mobile/etc., not over the wire.
So now the browser decrypts the signature in the certificate. FINALLY, the browser compares the decrypted values with the contents of the certificate itself. IF THE CONTENTS MATCH, THAT MEANS THE SIGNATURE IS VALID!
Why? Think about it, only this public key can decrypt the signature in such a way that the contents look like they did before the private key encrypted them.
How about man in the middle attacks?
This is one of the main reasons (if not the main reason) why the above standard was created.
Let's say hacker-Jane intercepts internet-user-Bob's request, and replies with her own certificate. However, hacker-Jane is still careful enough to state in the certificate that the issuer was Example-CA. Lastly, hacker-Jane remembers that she has to include a signature on the certificate. But what key does Jane use to sign (i.e. create an encrypted value of the certificate main contents) the certificate?????
So even if hacker-Jane signed the certificate with her own key, you see what's gonna happen next. The browser is gonna say: "ok, this certificate is issued by Example-CA, let's decrypt the signature with Example-CA's public key". After decryption, the browser notices that the certificate contents don't match at all. Hence, the browser gives a very clear warning to the user, and it says it doesn't trust the connection.
The client has a pre-seeded store of SSL certificate authorities' public keys. There must be a chain of trust from the certificate for the server up through intermediate authorities up to one of the so-called "root" certificates in order for the server to be trusted.
You can examine and/or alter the list of trusted authorities. Often you do this to add a certificate for a local authority that you know you trust - like the company you work for or the school you attend or what not.
The pre-seeded list can vary depending on which client you use. The big SSL certificate vendors insure that their root certs are in all the major browsers ($$$).
Monkey-in-the-middle attacks are "impossible" unless the attacker has the private key of a trusted root certificate. Since the corresponding certificates are widely deployed, the exposure of such a private key would have serious implications for the security of eCommerce generally. Because of that, those private keys are very, very closely guarded.
if you're more technically minded, this site is probably what you want: http://www.zytrax.com/tech/survival/ssl.html
warning: the rabbit hole goes deep :).