Overview
The purpose of this article is to explain how the “SSL Certificate” tool works; as its name suggests, it allows you to check the status of your website’s SSL certificate.
The Glossary contains explanations on multiple topics and can be consulted to clarify certain terms.
Prerequisite
Go to https://mg.n0c.com/en/.
What is a SSL Certificate?
An SSL (Secure Socket Layer) certificate is a data file that links a cryptographic key to the information of an individual or an organization.
The certificate is installed on the server and activates the padlock and HTTPS protocol, which secures data exchanges by encryption between a web server and the user’s browser.
How to Perform a SSL Checkup
- Go to Tools -> SSL.
- Enter the URL of the site in the field and click on the Analyze button to generate the SSL Report :
Certificate Information
Click on Certificate Information:
Common Name: refers to the main domain name or the exact URL that the certificate protects.
SAN: the Subject Alternative Name is an extension field that allows multiple domain names, subdomains or IP addresses to be secured with a single certificate.
Issued on: the date on which the validity period starts.1
Valid until: the end date of the validity period.
Certificate status: refers to the validity and security status of a digital security certificate at the time it was deemed valid. A certificate is considered valid when it meets the following conditions:
- its digital signature issued by the authority is intact and verifiable;
- it is issued by a recognised and trusted certification authority (CA);
- its expiry date has not passed (the current maximum validity period — as of October 2026 — is limited to 398 days, or approximately 13 months);
- the domain name of the website visited matches exactly the name recorded in the certificate.
Algorithm type: the main types of algorithms used by SSL/TLS certificates for asymmetric cryptography are RSA and ECC.
- RSA: a long-established and universal asymmetric algorithm that uses a pair of keys (public and private) based on the factorisation of large prime numbers. It offers maximum compatibility with all browsers and older devices.
- ECC (Elliptic Curve Cryptography): a more recent and efficient algorithm that provides security equivalent to RSA but with much shorter keys, thereby reducing the load on the server and speeding up the connection.
- Signature algorithm: enables the certification authority to sign the certificate (often SHA-256 with RSA or ECDSA).
- Symmetric session encryption: once the connection has been established via RSA or ECC, a symmetric algorithm such as AES (Advanced Encryption Standard) encrypts data exchanges in real time.
Certificate Chain
An SSL certificate chain is an ordered sequence of digital certificates that links a website’s certificate to a trusted root certificate authority to ensure the connection is authenticated.
Click on Is the certificate chain complete? to obtain the information:
Common name: refers to the primary domain name or the exact URL that the certificate protects.
Organisation: an organisation (field O or Organisation in a certificate’s X.509 metadata) refers to the legal entity that is the holder of the SSL certificate or the issuing certification authority within the chain of trust.
Valid until: the date on which the validity period of the digital certificate within the chain of trust expires.
Transmitter: the transmitter (or signatory) refers to the entity — a Certification Authority (CA) — which has verified the applicant’s identity and digitally signed the certificate at the relevant level.
- As of October 2026, the standard validity period for a certificate generated by Let’s Encrypt is 4 months. ↩︎