X.509
In cryptography, X.509 is an ITU-T standard for a public key infrastructure (PKI) and Privilege Management Infrastructure (PMI). X.509 specifies, amongst other things, standard formats for public key certificates, certificate revocation lists, attribute certificates, and a certification path validation algorithm.
History and usage
X.509 was initially issued on July 3, 1988 and was begun in association with the X.500 standard. It assumes a strict hierarchical system of certificate authorities (CAs) for issuing the certificates. This contrasts with web of trust models, like PGP, where anyone (not just special CAs) may sign and thus attest to the validity of others' key certificates. Version 3 of X.509 includes the flexibility to support other topologies like bridges and meshes. It can be used in a peer-to-peer, OpenPGP-like web of trust, but was rarely used that way as of 2004. The X.500 system has only ever been implemented by sovereign nations for state identity information sharing treaty fulfillment purposes, and the IETF's Public-Key Infrastructure (X.509), or PKIX, working group has adapted the standard to the more flexible organization of the Internet. In fact, the term X.509 certificate usually refers to the IETF's PKIX Certificate and CRL Profile of the X.509 v3 certificate standard, as specified in RFC 5280., commonly called PKIX for Public Key Infrastructure (X.509).
PEM
PEM may stand for:
- Photoelastic modulator
- Polyelectrolyte multilayer
- Positron emission mammography
- Proton exchange membrane or Polymer Electrolyte Membrane – as in "fuel cell", applications include use in proton-exchange fuel cells, used to manipulate hydrogen for energy conversion
- Professional Engineering Manager, a professional certification by the American Society for Engineering Management
- Professional Energy Manager, a professional certification by the Institute of Energy Professionals
- Power Entry Module
- PEM nut Self Clinching nut - commonly referred to as 'PEM'
- Porous European Mix – a type of asphalt used on roads and airport runways, commonly referred to as PEM
- Portable Emissions Measurement System (PEMS)
- Predictive Emission Monitoring System (PEMS)
- in computing
- PCI-Express mini, a computer bus standard
- Privacy Enhanced Mail, sometimes Privacy-Enhanced Electronic Mail
- The .pem filename extension is used for a Base64-encoded X.509 certificate
Podcasts:
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by Bim
Scream
by: BimMy heart won't stop, it beats for free
And common sense won't prevail with me
Overwhelming, to live on and breathe in
And I, I couldn't be all that I am
When I say I can't you just say you can
And without you I'd never be that strong
I was never enough for you
And I'll scream
I've been holding in this feeling forever
You promised that you'd never again
Scream
I guessed we'd always be there forever
You knew we'd never be there again
Scream out, I scream out
This time all my love won't break
It will smash you'll see
It's common sense to be hated by me
Overcomplicated to live on and take it
And I, I couldn't be all that I am
When I say I can't you just say you can
And without you I'd never be that strong
I was never enough for you
And I'll scream
I've been holding in this feeling forever
You promised that you'd never again
Scream
I guessed we'd always be there forever
You knew we'd never be there again
Scream out, I scream out
And I was proud to stand and love one another
Oh how it's changed
We swore we'd always stay the same