B4J Question [Closed] Using X.509 digital certificate

[aeric]

Hi guys,

I have been studying about how to use digital certificate in B4J for 1 week and still unclear what I was doing is correct.
I have read a lot of articles but none giving me a clear picture.
Before I purchase an expensive digital certificate which valid for 1 year or getting a trial certificate valid for 1 month, I want to know:

1. how to retrieve any information from the certificate?
2. what information I need to retrieve or could I retrieve?
   I think I need serial number, issuer, subject, cert in base64, cert digest and validity from the certificate
3. can I use JavaObject only without calling/exporting the certificate with keytool or openssl?
4. if #3 above is no, meaning I must export them from DER format to .cer, .crt or .pem file?
5. is there any method to read the properties of a certificate using JavaObject?
   If no then meaning I need to "trim" the unwanted text from the plain .pem file?
6. can I use keytool and/or openssl to create a selfsigned certificate that valid for signing a document?
   I notice that the output certificate doesn't contain information such as Organization identifier and Email as required.
7. I need to create a PKCS#12 (.p12 or .pfx file) is it a keystore or is it also a digital certificate?
   I think it is a certificate which embeded with a keystore inside it, am i right?
8. does this certificate store public and private keys?
9. if #7 above is yes, how do I retrieve them?
10. what is digital signature algorithm XAdES (XML Advanced Electronic Signature)?
    Isn't it just suppose to be hashing by a "normal" algorithm such as SHA256?

Thanks to anyone who can help me to understand better.

 

[aeric]

1. how to retrieve any information from the certificate?
2. what information I need to retrieve or could I retrieve?
   I think I need serial number, issuer, subject, cert in base64, cert digest and validity from the certificate

I found a solution using Java JDK 11/14. I was using java 17/19 that doesn't work.

 

[aeric]

I create another question.

[Closed] cannot access class sun.security.x509.X509CertImpl because module java.base does not export sun.security.x509 to unnamed module

I created an example. https://www.b4x.com/android/forum/threads/create-and-read-pkcs12-keystore.163171/ It works in Debug and Release but if I call the jar in command prompt, I get errors. C:\Users\aeric\Desktop\readp12\Objects>C:\Java\jdk-19.0.2\bin\java -jar readp12.jar MyPassword...

www.b4x.com

 

[aeric]

I have written a code snippet: Create and Read PKCS12 Keystore and have better understanding now.
If I am wrong, please point to me. Thanks.

1. how to retrieve any information from the certificate?
   answer: code snippet
   
   
2. what information I need to retrieve or could I retrieve?
   I think I need serial number, issuer, subject, cert in base64, cert digest and validity from the certificate
   answer: code snippet
   
   
3. can I use JavaObject only without calling/exporting the certificate with keytool or openssl?
   answer: yes, except for creating the keystore file, I need to use keytool
   
   
4. if #3 above is no, meaning I must export them from DER format to .cer, .crt or .pem file?
   answer: no
   
   
5. is there any method to read the properties of a certificate using JavaObject?
   If no then meaning I need to "trim" the unwanted text from the plain .pem file?
   answer: yes, there are many methods that can be used as listed in the link in first post of the code snippet
   
   
6. can I use keytool and/or openssl to create a selfsigned certificate that valid for signing a document?
   I notice that the output certificate doesn't contain information such as Organization identifier and Email as required.
   answer: yes, but the additional information mentioned above are not available. I think still need to refer to local CA.
   
   
7. I need to create a PKCS#12 (.p12 or .pfx file) is it a keystore or is it also a digital certificate?
   I think it is a certificate which embeded with a keystore inside it, am i right?
   answer: It seems this keystore file contains a combination of keypair and certificate.
   
   
8. does this certificate store public and private keys?
   answer: yes
   
   
9. if #7 above is yes, how do I retrieve them?
   answer: it can be retrieved using JavaObject calling methods getPublicKey and getKey
   
   
10. what is digital signature algorithm XAdES (XML Advanced Electronic Signature)?
    Isn't it just suppose to be hashing by a "normal" algorithm such as SHA256?
    answer: https://www.w3.org/TR/XAdES/#Introduction-Definitions_of_Terms