We are writing a new server/client app and need to Verify self-signed certificates in OpenSSL 1.1.0 where CN field isn't important.
I tried to do the following but it doesn't seem to have an effect:
X509_VERIFY_PARAM *param = NULL;
param = SSL_get0_param(sslo.ssl);
X509_VERIFY_PARAM_set1_host(param, nullptr, 0);
How can I effectivly ignore all verification of this field?
Update after Shane's answer:
I tried setting verify_callback with SSL_CTX_set_verify .
In the callback I called X509_STORE_CTX_get_error_depth . The resulting error code was X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT, which according to documentation means "the passed certificate is self signed and the same certificate cannot be found in the list of trusted certificates."
This error is very generic and not related specifically to CN, if I only change the CN field in the cert to appropriate value it doesn't happen.
Use the SSL_CTX_set_verify call to specify your own verification callback function where you can OK anything you wish about the certificate.
Read that page carefully and it should tell you everything you need to know, the page also includes a example you can base your handler on if you wish.
Related
I am working on Linux embedded application which acts as client and receives data from https server using libCurl. My application's requirement is to accept expired certificate and continue to connection establishment.
I could not find any such option that can be set using curl_easy_setopt as we can ignore -
- verification of the certificate's name against host => setting CURLOPT_SSL_VERIFYHOST to 0
- verification of the authenticity of the peer's certificate => setting CURLOPT_SSL_VERIFYPEER to FALSE
Any there any other way out I can try to make it work.
You can set a callback using CURLOPT_SSL_CTX_FUNCTION (see example at https://curl.haxx.se/libcurl/c/cacertinmem.html) where you can manipulate the SSL context, clear errors, etc.
This will probably not be enough, you can experiment with setting some options of openssl itself, see https://www.openssl.org/docs/man1.1.0/ssl/SSL_CTX_set_verify.html.
I'm not sure if it is enough to set SSL_VERIFY_NONE or if you actually have to supply a validation callback function that says yes to everything.
I haven't tested this and I'm not sure it will actually work, but you can certainly try.
I am in process of verifying a client certificate on server.
I have used the SSL_CTX_set_verify and have a valid callback API inside which i am validating the client certificate for expiry date and few other parameters.I need to extract the 'Issued By' and 'Issued To' values of the client certificate.
The call back function is like this
int certificateVerificationCallBack(int preverify_ok, X509_STORE_CTX *ctx)
{
X509* cert = X509_STORE_CTX_get_current_cert(ctx);
}
I am getting the client certificate details filled into the X509 pointer and am able to get the expiry date too(straight forward access). But i am not able to figure out what OpenSSL API to use to get the 'issued by' and 'issued to'.
If you want the subject name and issuer name of the certificate, you need to use the X509_get_subject_name() and X509_get_issuer_name() APIs. These take the X509 pointer and return the respective names.
More Info can be obtained here and here
I have a form that users can enter in a copy of their SSL certificate. Users tend to just enter comments instead of the actual certificate. What would the regex syntax be that I can use to ensure they are entering a valid certificate?
The below regular expression will help you to validate a custom field in WHMCS that requires a valid certificate structure.
/^(?:(?!-{3,}(?:BEGIN|END) CERTIFICATE)[\s\S])*(-{3,}BEGIN CERTIFICATE(?:(?!-{3,}END CERTIFICATE)[\s\S])*?-{3,}END CERTIFICATE-{3,})(?![\s\S]*?-{3,}BEGIN CERTIFICATE[\s\S]+?-{3,}END CERTIFICATE[\s\S]*?$)/
Simply paste that in to the Validation field.
I modified the regular expression found on the answer to this question.
The regular expression from that question can also be used if you have a custom field requiring a Certificate Signing Request:
/^(?:(?!-{3,}(?:BEGIN|END) NEW CERTIFICATE REQUEST)[\s\S])*(-{3,}BEGIN NEW CERTIFICATE REQUEST(?:(?!-{3,}END NEW CERTIFICATE REQUEST)[\s\S])*?-{3,}END NEW CERTIFICATE REQUEST-{3,})(?![\s\S]*?-{3,}BEGIN NEW CERTIFICATE REQUEST[\s\S]+?-{3,}END NEW CERTIFICATE REQUEST[\s\S]*?$)/
What would the regex syntax be that I can use to ensure they are entering a valid certificate?
There isn't one. Certificate validity depends on expiry date, the integrity of a digital signature, and the validity of the signer's own certificate. No regular expression can check all that.
If on the other hand you just want to reject outright garbage, see my comments under your question.
I'm writing a script that loads IAM certificate to some ELB in order to check if it's valid.
When I tested it, I used an invalid private key on purpose to see if I could load it to the ELB.... and the problem - it gets loaded!
So my questions are-
How is this possible? I know for a fact that if you use AWS console you can't do something like that.
Is there a boto way to check if a cert is valid? (not using openssl, this is what I'm trying to avoid).
What exactly do you mean when you say "check if it's valid"? If you try to upload a malformed PEM file (the text of the cert isn't valid) then it will definitely throw an error since it can't decode the file. Also, if you try to upload a mismatched public & private key it will also throw an error. I just tested these sorts of cases myself and got the following error:
The private key did not match the public key provided. Please verify the key material and try again.
If you're referring to testing that a certificate is signed, authentic, and not expired, then the ELB isn't going to do any of that. According to the AWS documentation for ELBs it's perfectly fine to make use of self-signed certificates, and certs will also continue to work (whether CA signed or self-signed) even if expired. Both self-signed certs and expired certs are "valid" as far as operation of a secure SSL connection goes. Whether the cert is signed and unexpired or not is really just a means of providing authentication that it's a legitimate certificate.
If you are asking about testing if a certificate is properly signed and not expired then you would need to test for these sorts of things yourself, typically by leveraging something like openssl.
I am using openssl in c to verify a certificate. Is there any way i can skip the self signed certificate error? I am getting that error for all the sites that has invalid/expired/mismatched url certificates and i am unable to detect any of the other errors.
And I use the function
SSL_CTX_load_verify_locations(ctx,0,CA_LIST)) to load CA_LIST. What does it exactly do?
The error self-signed certificate in certificate chain comes, when the root or self-signed certificate is present in the certificate list sent by the peer, but, the same is not loaded in your Trust Store.
The SSL_CTX_load_verify_locations(ctx,0,CA_LIST)) will try to load the CAs present in the path mentioned in CA_LIST.
The function prototype is int SSL_CTX_load_verify_locations(SSL_CTX *ctx, const char *CAfile, const char *CApath);
The OpenSSL Help Page Says:
"If CApath is not NULL, it points to a directory containing CA certificates in PEM format. The files each contain one CA certificate. The files are looked up by the CA subject name hash value, which must hence be available. If more than one CA certificate with the same name hash value exist, the extension must be different (e.g. 9d66eef0.0, 9d66eef0.1 etc). The search is performed in the ordering of the extension number, regardless of other properties of the certificates. Use the c_rehash utility to create the necessary links.
The certificates in CApath are only looked up when required, e.g. when building the certificate chain or when actually performing the verification of a peer certificate."
You can get more information from the OpenSSL Page here.