What’s a quick test to see if an $n \times n$ matrix is diagonal and/or proporitional to the identity matrix?

As the title indicates, I want to test whether an $ n \times n$ matrix (numeric, symbolic,..) is diagonal and/or proportional to the $ n \times n$ identity matrix. I, of course, can test whether the $ n^2-n$ individual off-diagonal entries are zero–but that’s, it would seem, is inefficient.

What’s the difference between product security and vulnerability research?

I am trying to understand what is the difference between these two. I know both roles are some quite similar, because as vulnerability research, and product security finds flaws in popular apps, nonpopular, but however in VR it may involve reverse engineering to find more vulnerabilities, but it also sees VR from product security

case 1 product security I find an overflow, and check it with overwriting the EIP, and product security stop there, and patch it, but what about VR? finds the flaw > develop the exploit, and report?

Application Security/product security Vulnerability Research service is an attack simulation to expose critical vulnerabilities of an application. This service is completely based on manual and technical audits. We perform vulnerability research service for client-based, server-based and web-based applications.  The detailed vulnerability research service will cover the following top critical vulnerabilities: Buffer Overflow Input Validation Dangling Pointers Remote Code Execution SQL Injection Authentication Bypass Code Injection 

vulnerability research

  • fuzzing
  • reverse engineering
  • target application binary analysis and debugging
  • exploit development

What’s the algorithm behind MySQL’s sha256_password hashing scheme?

MySQL’s old mysql_native_password hashing scheme was the equivalent of this in PHP:

sha1(sha1('password', true)); 

That’s a hex-encoded SHA-1 hash of a binary SHA-1 hash of the password, without any salting.

MySQL 8.0 introduced a two variants of a new hashing scheme based on SHA256 called caching_sha2_password and sha256_password, the former being the default (docs. Despite their name, neither appears to be vanilla SHA256.

Yes, I know SHA256 is not a great choice for password hashing, but it’s a lot better than SHA-1 and it wasn’t up to me!

Can anyone tell me the actual algorithms for these new schemes, in PHP or similar code?

What’s the correct way to apply Thorn Whip pull effect on a mounted target?

The thorn whip cantrip description is:

You create a long, vine-like whip covered in thorns that lashes out at your command toward a creature in range. Make a melee spell attack against the target. If the attack hits, the creature takes 1d6 piercing damage, and if the creature is Large or smaller, you pull the creature up to 10 feet closer to you.

If the cantrip is directed to a target riding a mount and hits, should both mount and rider be pulled?

What’s my most efficient use of spell slots to help my AC?

I’ve got a wizard with 11 Dex and I’m trying to figure out what my most efficient use of spell slots is to help me from getting hit.

We typically have 2-4 very difficult encounters per day and I want to balance my spell slot uses where I can provide as much firepower as needed. The monsters are generally higher CR as opposed to mobs. It’s usually approximately 1:1 in terms of PCs:NPCs and if it isn’t, it’s fairly close. Mob fights have been much less common.

Spending slots on defense with potentially diminishing returns due to the actual AC values is where I am looking to be most efficient.

Currently 5th level and have the following spells available:

1st level – mage armor and shield
2nd level – mirror image

Scenario A is casting mage armor in the morning and having AC 13 throughout the day. The difference between 10 and 13 seems minimal and that i’m likely going to get hit no matter what. But casting shield will boost to 18 which is legitimate. But then I’ve burned 2 spell slots on this method.

Scenario B is casting mirror image in a fight I think I’ll need it. Leave my AC at 10 and hope the images take the hits. Can still use shield if AC 15 will save me at some point.

I’m open to other scenarios as well, just trying to figure out the optimal strategy to get the best return on my spell slot usage for defense vs offense.

My offensive strategy

Most of my offensive spells are evocation and that’s where I’m mostly going to spending my spell slots. I’ll have a couple of control type spells that aren’t, but a lot of the instant-damage I do will be evocation.

While I try to stay away from enemies and not be in melee range, it’s going to happen at times. It’s those times (and ranged attacks), that I’m most concerned about keeping myself alive after.

What’s the safest password type?

I’ve used Dashline (password manager) with random generated passwords, but I forgot the master password and there is no way to get it back. I read that password managers and random generated passwords aren’t that safe as I thought they are. So what type of a password should I have that is the safest?

What’s in a Dead God?

On pages 46-47 of the DMG, under the section regarding the Astral Plane, it states:

Visitors occasionally stumble across the petrified corpse of a dead god.

Is there any lore about the composition of a dead god and the potential uses for it. Homebrew suggestions would be welcome too.

What’s the significance of different Laser Types in Starfinder

As the title says, What is up with all the different types of lasers, there’s Zenith, Parallax, Corona and others. But I can’t seem to find the significance of these subtypes of laser? I am assuming there are maybe certain armors or something that resist say a zenith laser, but not a corona laser?

using crtl+f doesn’t seem to be picking up any relevant info in my PDF. The index is of equal uselessness.

Any help on determining what all these types mean and what i should be looking for in arming myself with a laser weapon would be highly appreciated.