Commit `99575d28c5`

99575d28c574803e78084ac5ce0eb499e0e8fdce

parent: 037a40e4a5

Unsigned

cmc <hello@cleberg.net> · 2025-07-07 14:30 UTC

fix: ignore draft posts when publishing

Layout: unified · split

build.py +14 −1

         "date": re.compile(r"^#\+date:\s*<(\d{4}-\d{2}-\d{2})"),
         "slug": re.compile(r"^#\+slug:\s*(.+)$", re.IGNORECASE),
         "filetags": re.compile(r"^#\+filetags:\s*(.+)$", re.IGNORECASE),
+        "draft": re.compile(r"^#\+draft:\s*(.+)$", re.IGNORECASE),
     }
     for org_path in Path(content_dir).glob("*.org"):
         date_str = None
         slug = None
         tags = []
+        is_draft = False
         with org_path.open("r", encoding="utf-8") as f:
             for line in f:
                         tags = [t for t in raw.split(":") if t]
                         continue
+                m = header_patterns["draft"].match(line)
+                if m:
+                    draft_value = m.group(1).strip().lower()
+                    if draft_value != "nil":
+                        is_draft = True
+                        break
+                    continue
                 # Stop scanning once we have all required fields
                 if title and date_str and slug and tags:
                     break
+        if is_draft:
+            continue
         if title and date_str and slug:
             try:
                 date_obj = datetime.strptime(date_str, "%Y-%m-%d")
             except ValueError:
                 # Skip files with invalid date format
                 continue
             posts.append(
                 {
                     "title": title,

content/blog/2025-06-27-how-blockchain-works.org added +197

@@ -0,0 +1,197 @@
	1	#+date: <2025-07-07 Mon 00:00:00>
	2	#+title: Blockchain Series #1: How Blockchain Works Under the Hood: Hashes, Keys, and Signatures Explained
	3	#+description: Dive into blockchain's cryptographic foundations. Explore how hash functions, Merkle trees, and digital signatures secure distributed, tamper-resistant ledgers.
	4	#+slug: how-blockchain-works
	5	#+filetags: :blockchain:encryption:
	6	#+draft: t
	7
	8	/This is Part 1 of a series I'm writing on blockchain. Stay tuned for further
	9	editions./
	10
	11	Blockchain is one of those technologies that seems to generate more marketing
	12	buzz than real understanding. Everywhere you look, people talk about
	13	decentralization, trustless systems, and the next big disruption. But beneath
	14	the hype, blockchain systems rely on well-understood cryptographic building
	15	blocks to do something very specific: maintain a secure, tamper-resistant ledger
	16	without needing a central authority.
	17
	18	If you're serious about understanding blockchain, it's critical to understand
	19	the cryptographic primitives that make it work. Hash functions, digital
	20	signatures, and public-key cryptography aren't just jargon—they're the core
	21	mechanisms that let a distributed network agree on a shared history no one can
	22	easily rewrite.
	23
	24	This post is Part 1 of a multi-part series on blockchain. Here, we'll focus on
	25	these fundamental building blocks—how they work, why they're used, and how they
	26	fit together to provide the security and trust that blockchain promises.
	27
	28	* What is Blockchain?
	29
	30	At its core, a blockchain is a distributed, append-only ledger shared among
	31	participants in a network.
	32
	33	What does this mean? Essentially, we can think of a standard, non-technical
	34	ledger (book of accounts where transactions are recorded against accounts). When
	35	introductin the idea of a blockchain, let's extend the idea of a standard ledger
	36	and make a few connections:
	37
	38	- Each block of transactions is connected cryptographically to the block before
	39	it, via a [[https://en.wikipedia.org/wiki/Cryptographic_hash_function][cryptographic hash]]. This is what forms a =chain= of blocks, or
	40	records.
	41	- Each block consists of:
	42	- A list of validated transactions
	43	- A timestamp
	44	- A cryptographic hash of the previous block (ensuring immutability)
	45	- Each transaction within a block is initiated between addresses, signed with
	46	cryptographic keys, and sent to the blockchain for validation (e.g.,
	47	proof-of-work, proof-of-staking, etc.).
	48	- The blockchain is shared amongst nodes in the network, who agree on the state
	49	of the blockchain through consensus mechanisms.
	50
	51	As we can see, the decentralized nature and cryptographic linking of
	52	transactions and blocks ensures that modifying the history is infeasible.
	53
	54	If you're more of a visual person, here's a very basic diagram of a standard
	55	blockchain structure.
	56
	57	#+begin_example
	58	+------------+ +------------+ +------------+
	59	\| Block 1 \| -> \| Block 2 \| -> \| Block 3 \|
	60	\|------------\| \|------------\| \|------------\|
	61	\| Data \| \| Data \| \| Data \|
	62	\| Prev Hash: \| \| Prev Hash: \| \| Prev Hash: \|
	63	\| 00000000 \| \| <hash1> \| \| <hash2> \|
	64	\| Hash: \| \| Hash: \| \| Hash: \|
	65	\| <hash1> \| \| <hash2> \| \| <hash3> \|
	66	+------------+ +------------+ +------------+
	67	#+end_example
	68
	69	* What Problems is Blockchain Trying to Solve?
	70
	71	I will be diving into the technical details of blockchains later in this post,
	72	but what exactly is the reason blockchain exists?
	73
	74	You may know of cryptocurrencies, such as Bitcoin, but that is only one of many
	75	use cases for blockchains.
	76
	77	As we learned in the section above, a blockchain can be equated to a ledger.
	78	With this in mind, let's dive into a few interesting use cases:
	79
	80	** Immutable record-keeping
	81
	82	If you simply need a ledger that cannot be modified easily and can establish a
	83	decentralized network to support that, blockchain is a great technology.
	84
	85	** Trust without central authority
	86
	87	The use of a decentralized system means that we do not need to rely on a
	88	centralized authority (e.g., Social Security, a bank, etc.) to store and provide
	89	access to information you need to record.
	90
	91	Think of the US Social Security Number (SSN) system. Each time you want to
	92	perform actions that require verifying your identify (e.g., opening bank
	93	accounts, investment accounts, child birth, etc.), you are currently required to
	94	provide your SSN.
	95
	96	However, this is a singular number - which means that if someone learns it, they
	97	can (essentially) now act as you.
	98
	99	Now imagine a scenario where the SSN system is a blockchain where you have both
	100	your private key for providing evidence to people that you are you. For example,
	101	you open a bank account and sign your form with your private key. Now, the bank
	102	can take that and use your public key to decrypt the message and verify that you
	103	are you, without needing to know your private key.
	104
	105	Another scenario is that, during a background check, a company could use your
	106	public key and consult the related blockchain to validate specific pieces of
	107	information. For example, if your identity alone is in one block, you could
	108	provide that information to your employer without providing your full SSN and
	109	all related personal information for as long as they keep your SSN on file.
	110
	111	** Double-spending problem
	112
	113	With the introduction of digital assets, such as cryptocurrencies and
	114	non-fungible tokens, a new risk is introduced: without control, these assets
	115	could be copied and reused at-will.
	116
	117	To solve this problem, digital assets are transacted on a blockchain to ensure
	118	that the decentralized system of nodes provide consensus on validating
	119	transactions, transactions are recorded in a transparent and tamper-resistant
	120	manner, and cryptographic functions are performed to order the transactions
	121	logically on chain.
	122
	123	* The Role of Cryptography in Blockchain
	124	- Why cryptography matters
	125	- Confidentiality vs. integrity/authenticity
	126	- Core goals:
	127	- Tamper-evidence
	128	- Secure identification
	129	- Non-repudiation
	130
	131	* Hash Functions
	132	- What is a cryptographic hash?
	133	- Properties:
	134	- Collision resistance
	135	- Pre-image resistance
	136	- How blockchain uses hashes:
	137	- Chaining blocks together
	138	- Block headers
	139	- Transactions
	140	- Example command:
	141	#+begin_src bash
	142	echo -n "Hello, Blockchain" \| sha256sum
	143	#+end_src
	144	- Optional diagram: chain of blocks with hashes
	145
	146	* Merkle Trees
	147	- Summarizing many transactions in a single root hash
	148	- Use case: efficient inclusion proofs
	149	- Example diagram (ASCII art if desired)
	150	- Why Merkle roots are in block headers
	151
	152	* Public Key Cryptography
	153	- Quick refresher
	154	- Public/private keypairs
	155	- Addresses derived from public keys
	156	- Importance of keeping private keys secret
	157
	158	* Digital Signatures
	159	- Purpose: proving authorship without revealing private key
	160	- Mention ECDSA / EdDSA
	161	- How transactions are signed
	162	- Example snippet:
	163	#+begin_example
	164	Alice signs transaction with her private key
	165	→ Anyone can verify with her public key
	166	#+end_example
	167	- Why signatures prevent forgery
	168
	169	* Bringing it All Together: Blockchain Data Structures
	170	- Block structure:
	171	- Block header with previous block's hash
	172	- Merkle root
	173	- Timestamp, nonce
	174	- How the chain ensures immutability
	175	- Example flow:
	176	1. User creates a transaction
	177	2. Signs it
	178	3. Transaction included in block
	179	4. Block hash links to previous block
	180
	181	* Proof of Work (Optional)
	182	- Hash puzzles to add blocks
	183	- Why it's hard to modify history
	184	- Keep this section simple
	185
	186	* Conclusion
	187	- Summarize how these primitives work together
	188	- Tease next post: "Next, we'll explore security threats and how blockchain
	189	networks mitigate them."
	190	- Optional links to further reading:
	191	- Bitcoin whitepaper
	192	- Ethereum docs
	193	- Cryptography references
	194
	195	* Optional Extras
	196	- Glossary box with terms (hash, signature, Merkle tree)
	197	- External references (e.g., NIST docs on hashes)

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