What’s the Actual Quantum Threat?
ECDSA Vulnerability:
ECDSA security relies on the hardness of the elliptic curve discrete logarithm problem. Large-scale, fault-tolerant quantum computers running Shor’s algorithm could theoretically solve this problem efficiently, breaking ECDSA and exposing private keys.

Timeline Uncertainty:
While some estimates suggest that powerful quantum computers capable of breaking ECDSA could emerge by 2030 or later, there is significant uncertainty about when exactly such quantum hardware will be built and become practically usable against Bitcoin’s 256-bit curve.

What Are Bitcoin Developers Doing?
Active Research on Post-Quantum Cryptography (PQC):
The Bitcoin community and cryptographers are investigating quantum-resistant signature schemes like Lamport signatures, hash-based signatures (e.g., XMSS), lattice-based cryptography, and others.

Layered and Gradual Transition:
Transitioning Bitcoin to quantum-safe cryptography is non-trivial. It would require protocol changes and careful migration strategies to avoid compromising security during the upgrade.

Focus on Wallet Hygiene:
Since reuse of public keys is a major risk if a quantum adversary can break ECDSA, best practices like avoiding address reuse and using new addresses for each transaction reduce exposure.

Monitoring Quantum Computing Progress:
The ecosystem closely follows advances in quantum hardware, error correction, and algorithms to adjust timelines and plans accordingly.

What Can Users Do Today?
Use wallets and addresses that avoid reusing public keys (HD wallets help here).
Stay informed about developments in quantum resistance in Bitcoin protocols.
Support open discussions and development efforts on quantum-resistant upgrades.

Old Wallet.dat Model: Individual Keys, Separate Backups
In the early Bitcoin Core wallets (pre-HD wallets), your wallet.dat stored each private key separately, independently generated and backed up. This approach meant:

Pros:

Each key is unique and unrelated to others—no master seed.
Compromise of one key doesn't expose others.
No risk of deriving all keys from a single master key.

Cons:

You had to back up your wallet frequently, because new receiving addresses were newly generated keys not derived from any seed.
Backup management was tedious and error-prone—missing a backup meant losing some funds.
No hierarchical deterministic structure, so no easy way to recover all keys from one backup.
Modern HD Wallets: Seed-Based, Hierarchical Keys
Modern wallets use BIP32/BIP39/BIP44 HD wallets, where:
One master seed (typically represented as 12 or 24 mnemonic words) generates a master private key (xprv).
From this, all private keys are derived deterministically via a hierarchical tree structure.
A single backup of the seed can restore the entire wallet and all derived addresses.

1. Can a transaction with nLockTime be replaced by a new one that has a different nLockTime value? What happens if it gets replaced?

Yes, a transaction with an nLockTime can be replaced by another transaction via RBF, even if the replacement has a different nLockTime value—as long as the replacement transaction follows RBF rules:

It must spend the same inputs.

It must pay a higher fee.

It must be valid according to consensus rules, including the new nLockTime.

Effectively:
If the original transaction had an nLockTime set in the future, but you replace it with a transaction that has an earlier nLockTime (or even no nLockTime), miners can include the replacement immediately, speeding confirmation.

On the other hand, if the replacement has a later nLockTime, it will still only be valid after that time is reached, so confirmation will be delayed accordingly.

Summary: RBF replacement overwrites the old transaction in the mempool with the new one, and miners treat the new nLockTime as the rule for when to confirm.

2. If a transaction with nLockTime is stuck in the mempool due to low fees, can I use RBF to replace it with a new transaction that has a higher fee?

Absolutely. That’s exactly one of the main use cases of RBF.

If your transaction is stuck because the fee is too low, and it has an nLockTime set that allows immediate or near-future inclusion (meaning the nLockTime has already passed or will soon pass), you can broadcast a replacement transaction:

Using the same inputs.

With a higher fee.

Possibly with the same or updated nLockTime.

Miners will then prioritize the new transaction over the old one, helping your payment confirm faster.

However, if the nLockTime has not yet been reached, neither the original nor the replacement can be mined until the locktime condition is met. So you can replace the transaction to increase the fee, but miners will still wait for nLockTime to pass before confirming.

How do developers of non-custodial Bitcoin wallets make profits?

First, let’s be clear: a true Bitcoiner doesn’t create a non-custodial wallet to chase profits. We build wallets because we believe in freedom, privacy, and financial sovereignty. It’s about giving people full control over their own money—no middlemen, no custodians, no gatekeepers. That spirit is the core of Bitcoin itself.

That said, developers who dedicate their time and skills to building these wallets do need sustainable ways to support their work and keep improving the software. Non-custodial wallets don’t hold users’ funds, so they can’t make money like exchanges do with trading fees or interest on deposits. Instead, their revenue models are built around adding value, convenience, and enhanced features while respecting user control.

Here are some common ways non-custodial Bitcoin wallet developers generate revenue:

1..Affiliate and Referral Programs:
Many wallets integrate with fiat-to-crypto gateways or cryptocurrency exchanges inside the app. When users buy or sell crypto through these partners, the wallet developers earn a referral or affiliate commission. This helps bridge traditional finance with crypto in a user-friendly way while providing a revenue stream.

2..Transaction Fee Markups or Service Fees:
Some wallets help users by optimizing transaction fees or providing privacy features like CoinJoin. They may charge a small, transparent fee on top of the network fee for these value-added services. This fee supports ongoing development without compromising user sovereignty.

3..Premium Features and Subscriptions:
While basic wallet functionality remains free and open, developers offer advanced tools—like multi-signature support, hardware wallet integrations, portfolio analytics, or enhanced privacy options—as premium features behind subscriptions or one-time payments.

4..In-App Token Swaps and DeFi Integrations:
Wallets that support decentralized finance often let users swap tokens or participate in liquidity pools directly inside the app. Developers take a small cut from swap fees or liquidity provision, creating revenue while empowering users to access DeFi easily and securely.

5..Donations, Grants, and Sponsorships:
Many wallets are open source and rely on community support through donations or grants from blockchain foundations and sponsors who share the mission of promoting financial freedom.

6..White-Label Solutions and Enterprise SDKs:
Some teams offer their wallet software or development kits to businesses looking to build their own wallets. This B2B approach brings licensing fees and consulting revenue.

At the end of the day, building a non-custodial Bitcoin wallet is more about the mission than the money. It’s about empowering users to hold their own keys, secure their own wealth, and participate in a truly permissionless financial system. The revenue models are designed to support this mission sustainably without compromising trust or decentralization.
 

This is also a nice address : 1FuckiSraeLNoBiteNetanyahuxuHxjgT

https://bitcoindata.science/api/addressbalance.php?address=1FuckiRGCTerroristsNoBiTEXXXaAovLX&currency=USD&hex=a51d2d

A lot better could've been done with that money, in my opinion. A shame the coins are literally destroyed.

Great! Hope to get more speed in future

How can I actually create another testnet blockchain for bitcoin

How can I actually create another testnet blockchain for bitcoin

WOw! are they centralized ?

Now continue ur blockchain

u could use sparrow 3 of 4 multisig wallet , native segwit, 24 words and passphrase for every bip39, use in 3 different air gapped device and import the watch only to a online device to make tx

Nice, but need more advance

What if Bitcoin was reimagined today, under modern cryptographic assumptions, using a principled minimalist architecture designed for long-term auditability and zero-trust adversarial environments?

That's Amazing

שלום לכולם,
רציתי לפתוח דיון על נושא שלא מדברים עליו מספיק – כריית ביטקוין בישראל.

בזמן שבעולם כולו מוקמים חוות כרייה ענקיות במדינות כמו קזחסטן, ארה"ב וסין (לשעבר), אצלנו בישראל – מדינה עם טכנולוגיה מתקדמת אך מחירי חשמל מהגבוהים בעולם – התחום הזה עדיין נמצא יחסית בחיתוליו.

❓ אז מה המצב כיום?
🔌 מחירי החשמל בישראל מקשים על כרייה ביתית. בלי גישה לחשמל תעשייתי מוזל או אנרגיה ירוקה, הרווחיות על כרייה עצמאית נמוכה מאוד.
💻 רוב הכורים הרציניים עוברים לשימוש בציוד ASIC כמו Antminer S19, אבל גם כאן – הרווח נטו תלוי במחיר החשמל וברשת החום.
🧠 למרות זאת, יש כמה מיזמים מעניינים, כולל שימוש באנרגיה סולארית בקיבוצים או באזורי תעשייה, וניסיונות לחוות כרייה קטנות בפריפריה.

🌱 הזדמנויות לעתיד
שימוש באנרגיה מתחדשת בישראל – השמש הישראלית היא משאב עצום. חוות סולאריות יכולות להפוך את הכרייה ליעילה ואקולוגית.

שיתופי פעולה בין קהילת הקריפטו – אולי הגיע הזמן להקים מיזם קואופרטיבי לכרייה משותפת.

חדשנות ישראלית בתחום ה-HW וה-FW לכרייה – יש כאן פוטנציאל אדיר לחברות סטארטאפ לפתח פתרונות אופטימליים לחומרה ותוכנה.

⚠ אתגרים
רגולציה לא ברורה, במיוחד בתחום צריכת חשמל והצהרת הכנסות.

הבנה ציבורית לקויה – כרייה עדיין נתפסת אצל רבים כ"פשע סביבתי", מה שלא תמיד נכון.

מחסור באינפרה מקומית – רוב הציוד נרכש מחו"ל, עם מיסוי לא זול.

אני מזמין את כל מי שכורה בישראל או התנסה בכרייה לשתף –
🔹 איך אתם מתמודדים עם העלויות?
🔹 האם לדעתכם יש פוטנציאל לכרייה רווחית בארץ?
🔹 והאם ראיתם מיזמים מעניינים בתחום?

אם יהיו מספיק תגובות – אולי נארגן קבוצת טלגרם של כורי ביטקוין בישראל 🇮🇱

I vote for: #9, #15, #94, #99, #121

I don't know the k , I Know only rs , the private key of the public key Q , R (rx , ry)
I want to compute the corresponding z of the rs
Is it possible ?

is it possible to compute z with rs , priv key and the public key? 

how to delete