Certificates --digitally signed statement

Certificates Overview

A public key certificate, usually just called a certificate, is a digitally signed statement that binds the value of a public key to the identity of the person, device, or service that holds the corresponding private key. One of the main benefits of certificates is that hosts no longer have to maintain a set of passwords for individual subjects who need to be authenticated as a prerequisite to access. Instead, the host merely establishes trust in a certificate issuer.
Most certificates in common use are based on the X.509 v3 certificate standard.
Typically, certificates contain the following information:

• The subject's public key value.
  
  
• The subject's identifier information, such as the name and e-mail address.
  
  
• The validity period (the length of time that the certificate is considered valid).
  
  
• Issuer identifier information.
  
  
• The digital signature of the issuer, which attests to the validity of the binding between the subject's public key and the subject's identifier information.
  

A certificate is valid only for the period of time specified within it; every certificate contains Valid From and Valid To dates, which set the boundaries of the validity period. Once a certificate's validity period has passed, a new certificate must be requested by the subject of the now-expired certificate.

• Using Certificates
  
  
• Public and Private Keys
  
  
• Certificate File Formats

https://en.wikipedia.org/wiki/Meltdown_(security_vulnerability)

Meltdown (security vulnerability)

Meltdown is a hardware vulnerability affecting Intel x86 microprocessors and some ARM-based microprocessors.^[1][2][3] It allows a rogue process to read any physical, kernel or other process's mapped memory, regardless of whether or not it should be able to do so.

Meltdown affects a wide range of systems. At the time of disclosure, this included all iOS and Mac devices,^[4] in addition to machines with affected hardware running any not yet patched version of Microsoft Windows, or any but very recent versions of Linux. Accordingly, many servers and cloud services were impacted,^[5] as well as a potential majority of smart devices and embedded devices using ARM based processors (mobile devices, smart TVs and others), including a wide range of networking equipment. A purely software workaround to Meltdown has been assessed as slowing computers between five and 30 percent in certain workloads.^[6] Companies responsible for software correction of the exploit are reporting minimal impact from benchmark testing.^[7]

Meltdown was issued a Common Vulnerabilities and Exposures ID of CVE-2017-5754, also known as Rogue Data Cache Load,^[2] in January 2018. It was disclosed in conjunction with another exploit, Spectre, with which it shares some but not all characteristics.