X.509 is just the format of the data. Certificates include a public key and a signature from a certificate authority (CA). On the web, typically web sites have a server cert that is issued (signed) by Verisign or some other well-known CA.

2014年11月19日 · Edit #3: Ok, I figured the relationship between PEM and DER formats. The Base64 encoded payload of the PEM file is actually data in DER format. So initially the X.509 certificate is encoded in DER format and then optionally you can encode the resulted 'DER encoded certificate' to 'PEM encoded certificate'.

X.509 certificates are a generic, highly flexible format. SSL (now known as "TLS") uses X.509 certificates. A "SSL certificate" is a certificate whose contents make it usable for SSL (usually, usable for a SSL server).

2020年9月25日 · X.509 was initially issued on July 3, 1988 and was begun in association with the X.500 standard. X.500 is a series of computer networking standards covering electronic directory services. The X.500 series was developed by the Telecommunication Standardization Sector of the International Telecommunications Union (ITU-T).

Encoding must comply to the X.509 ASN.1 specification: the Common Name is limited to 64 characters (64 code points if using UTF8String, as you should, per the standard). The IssuerDN of a certificate must be equal to the SubjectDN of its issuer. Equality rules are theoretically case-insensitive, but the rules can be complex to implement in a ...

2013年2月19日 · Thus, X.509 is a way to distribute public keys, by which I mean: a method which allows various actors (e.g. you) to know, with some guarantee of non alteration by malicious third parties (i.e. "attackers") the public keys of other actors. OpenPGP is …

2016年2月16日 · In X.509 certificates, the signature algorithm is protected because it is duplicated in the TBSCertificate.signature field with the proviso that the validator is to compare both fields as part of the signature validation process. I think it's exactly what you are looking for :) Cheers ! Edit: Edited to add the "I think".

2022年7月11日 · I understand how Key Usage Extension of x.509 certificate works. I have gone through the Key Usage section of RFC5280 and I know of all the valid values and what they mean. But what I don't understand is the usage; Why it was deem necessary to add Key Usage extension to x.509 certificate?

2019年3月22日 · Is the serial number attribute of an X509 certificate Issuer or Subject, as defined in RFC5280, required to be the same as the Serial Number of the issuing or subject certificate?

2015年7月24日 · How can we identify which root CA client used when there are multiple root CAs on the server? We can compare the public keys of the client certificate and the root certificate but if we have many ...