inital commit, already did quite a few things.

mastering_bitcoin_notes.md

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+# Mastering Bitcoin notes
+
+So, after years of messing around with Bitcoin, the time has finally come to 
+reach the bottom of the rabbit hole and understand things down to the code 
+level.
+
+I'm going to use this document to keep my notes and thoughts while going 
+through the book.
+
+----------
+
+"There's a lot more to Bitcoin than first meets the eye." Joder, ya te digo.
+
+----------
+
+Finally, I get to discover what the hell is an `SPV`: simplified payment 
+verification, which is fancy pants language for a client that keeps keys and
+performs operations but relies on another full-node for following the protocol
+and getting the blockchain data from other peers. So, if I understand 
+correctly, an Electrum Personal Server fits the definition of an SPV.
+
+----------
+
+Andreas mentions that we should talk about "mnemonic phrase", and not a "seed 
+phrase", because "even though common, its use is incorrect". But, why? -> So
+it works this way: technically, the seed is a 512-bit piece of data, which is 
+the actual piece of information used to generate the keys of a wallet. The 
+mnemonic is just a human-readeable proxy to this seed, hence why mnemonic != 
+seed.
+
+This sparked my curiosity and I have been reading more low level details on how
+seed generation works.
+
+The first thing that's required is randomness. To get this, a series of bits is
+generated. Specifically, the entropy should be between 128 and 256 bits (that 
+means, 128 to 256 random zeros and ones).
+
+The checksum for this entropy is computed the following way:
+
+- Generate the SHA256 hash of the entropy.
+- Starting from the left, grab one bit of the hash for every 32 bits of length
+in the original entropy (if the entropy is 128 bits, 128/32 = 4, you grab the 4
+first bits of the hash).
+
+```python
+
+entropy = "01000010011111001011100101101111001010010110101011011111000001101000110111111001010000101000000110011010110011110110010000011001"
+entropy_len = len(entropy)
+
+import hashlib 
+
+hash_of_entropy = hashlib.sha256(entropy)
+
+print(hash_of_entropy)
+
+
+
+
+```
+
+----------
+
+Another interesting fact: miner fees for a transaction are not explicitly
+specified anywhere, but are simply calculated as the difference between the
+inputs and the outputs of the transaction.