bip 32 hd wallets – Is there a simpler form of BIP32-like key derivation?

I’ve read about BIP32 key derivation functions, and also:

Any Elliptic Curve could work in the BIP32 scheme. The only property
of a Curve that BIP32 relies on is that a * G + b *G = (a + b mod N) *
G, which is true for any Elliptic Curve.

(from Is BIP 32 Technology Cryptographic Curve Agnostic?.)

Are there simpler forms of weak-child-only key derivations? (I’m guessing that the HMAC, splitting and concatenation is unneeded for a simpler/weaker scheme. Such a scheme would just have a large number of weak children and no layers/tree.)

Is a simpler scheme possible? (I’m asking about cryptography generally, not whether it’s a good idea for Bitcoin.)

public key infrastructure – How is the digital certificate sent alongside digital signatures?

Most tutorials on the net only mention sending the digital signature attached to the document, but without the digital signature certificate, it’ll be impossible for receivers to verify the signature. I’m assuming that the digital certificate is somehow sent alongside the signature but I can’t seem to find any source mentioning that.

sql server – Como eliminar FOREIGN KEY Sql

Estoy haciendo una consulta y necesito eliminar una tabla pero como tiene FOREIGN KEY no me deja no hay ningunan sentencia sql que elimine todas sus foreign key



What is the probability of different public key hash that produce the same checksum value

checksum = 1st4byte(sha256(sha256(PubKeyHash)))

checksum1 = 1st4byte(sha256(sha256(PubKeyHash1)))

What is the P(checksum == checksum1)? where PubKeyHash != PubKeyHash1

Is it 1/(2^^32)?

Best approach for UNIQUE ( not UUID ) primary key for a mult tenant with schemas on Postgresql

I’m working on some projects and I always have this doubt and I don’t know if I’m doing it in the wrong way or in the right way.

I have 2 new applications one is a MarketPlace and the other is a SAAS software. For both, I will need to make a global search feature on the application, so I make a multi tenant with schemas on PostgreSQL where each of my clients will have a schema like:


and goes on…

I have a table called product when each of my clients will store a product and i want to make a global QUERY for each of the product tables from all my tenants.

I use Inheritance from PostgreSQL following this topic:

And now all is working fine but with one problem, I make a simple sequence for all my schemas and I need to make it GLOBAL. So I using 2 approaches to make this work


I store in each tenant table the tableoid and I make a JOIN with tableoid and primary key

SELECT  tableoid, tableoid::regclass, * FROM master.bra_product LIMIT 10


I create a GLOBAL SEQUENCE on public schema on PostgreSQL for each new tables on the database

CREATE TABLE tenant3.bra_product (
        product_id integer DEFAULT nextval('public.product_global_seq'),
        description varchar


Create a composite primary key with SEQUENCE + UUID ( this for me I have a bad experience with UUID my QUERIES take so long to retrieve ), that if I need to make a tenant select I use SEQUENCE if I need a global I make a JOIN with UUID

Please give some light to move on

encryption – Does PGP passphrase necessary if I store private key and passphrase in the same place?

The benefit of a passphrase is an added layer of protection for your keys assuming that the attacker has no way of associating the passphrase and the key.

Let’s assume an attacker gained access to this vault.

If it has both the passphrase and the key, then it matters not if the passphrase was randomly generated or what, they key is essentially (for lack of a better word) ‘breached’.

If it has only the key with no passphrase, then the same result applies. Your keys are ‘breached’.

If this vault has the keys with a passphrase (which isn’t stored in the same vault), then your keys are a lot safe, and if generated properly, secured.

magento2.3 – Integrity constraint violation: 1062 Duplicate entry for key ‘EAV_ATTRIBUTE_GROUP_ATTRIBUTE_SET_ID_ATTRIBUTE_GROUP_NAME’

I’ve created a custom module that includes a script (InstallData.php) that adds a new attribute to an existing attribute group (Product Label):

'group' => 'Product Label'

However, when I enable the module and run setup:upgrade, I receive the following error:

Installing data... SQLSTATE(23000): Integrity constraint violation: 1062 Duplicate entry '10-Product Label' for key 'EAV_ATTRIBUTE_GROUP_ATTRIBUTE_SET_ID_ATTRIBUTE_GROUP_NAME', query was: INSERT INTO `eav_attribute_group` (`attribute_set_id`, `attribute_group_name`, `sort_order`, `attribute_group_code`) VALUES (?, ?, ?, ?)

If I run the following database query I can see that there are two records with the group name ‘Product Label’, however I don’t see these
as duplicates as they belong to attribute set 10, and 4 respectively.

MariaDB (max)> select attribute_group_name, attribute_set_id from eav_attribute_group where attribute_group_name = 'Product Label';
| attribute_group_name | attribute_set_id |
| Product Label        |                4 |
| Product Label        |               10 |
2 rows in set (0.00 sec)

Furthermore, I’m unable to delete these records as it will cause the attributes that are currently under those attribute labels to lose their current values.

Does anyone know what may be causing this issue? I have verified that the InstallData.php script works, by adding the attribute to the default group, this issue only occurs when adding the attribute to the attribute group ‘Product Label’.

network – Should Group Key Update Interval be Off or On?

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I want to hold a key (1), and for it to repeat every 0.5 seconds until I release it using ‘Automator’ or ‘AppleScript’?

When I was on Windows, I used AutoHotKey to allow me to hold down the “1” key, and for it to simulate pressing it every 0.5 seconds until I let go.

I managed to do something in Automator (or AppleScript) on my old Mac to give me the same functionality, however I forgot to write down how I did it.

I am now on a new Mac and cannot fathom how I did it (Google doesn’t really help).

Any suggestions?

When importing a wallet from private key or seed phrase, how do you guess the correct address format

I am building a bitcoin wallet, i can derive addresses using the derivation paths. how do i determine the derivation path for the seed when importing it.