Unable to parse blocks from blk*.dat for testnet (3 and 4)

For the Bitcoin mainnet, I can easily fetch one block by following steps:

  1. Open the LevelDB database at <bitcoind-dir>/data/blocks/index

  2. Get by key: 629986b32020caeb48a421956936dd88dc8d7825441bbc96fec10e98b800000000(hex)

    Just as an example. This is block #12345 with block hash 00000000b8980ec1fe96bc1b4425788ddc88dd36699521a448ebca2020b38699. Transform it into the internal representation in bitcoin-core and prepend ASCII 'b' to it.

  3. Follow this answer and parse the value.

I'm able to get:

8eed3c -- client_version (259900)
df39 -- block_height (12345)
1d -- block_status (29)
01 -- tx_number (1)
00 -- blk_file (0)
80afc145 -- blk_start (2892101)
9fd565 -- rev_start (not care about this)

01000000 -- block_version
df9c748f06fcb1e7a4152e76b974e8a5c51c235afb6044388260877600000000 -- prev_blockhash
5731362967a95ffbce2027abf78111e87e804aa8ad6b5b483bb96e827ac91dfd -- merkle_root
5cdff449 -- time
ffff001d -- bits
1f35c72e -- nonce

Open <bitcoind-dir>/blocks/blocks/blk00000.dat and go to offset 2892101, there's 01000000 df9c748f06fcb1..., which is the correct block header and is the same as one decoded above.

File dump:

002C2140   D9 D8 00 00  00 01 00 00  00 DF 9C 74  8F 06 FC B1  ...........t....
002C2150   E7 A4 15 2E  76 B9 74 E8  A5 C5 1C 23  5A FB 60 44  ....v.t....#Z.`D
....

But it's just broken for testnet3 and testnet4. For example, use the exactly same approach above, also with block #12345, I got:

8eed3c -- client_version
df39 -- block_height (12345)
801d -- block_status
01 -- tx_number
00 -- blk_file (0)
9cf0ff70 -- blk_start (62668912)
83f19804 -- rev_start

00600720 -- version
39905ba030a61e45209006737dc9dc4cfbe2f077919b01cbc7a20a0000000000 -- prev_blockhash
8cf89e0e3a833718dc0b05da4ad7b5faeff63507ed5d02b66a0b2ce7bb82f12d -- merkle_root
734c3e66 -- time
f0ff0f1b -- bits
924847df -- nonce

Consult file blocks/testnet4/blocks/blk00000.dat at position 9cf0ff70, it says

03BC4070   73 73 15 A8  83 AE 8E 19  A5 F9 1D E0  A6 0D FC 9E  ss..............
03BC4080   BE 3C 81 74  E4 F3 57 14  B7 31 3A D0  C4 4C EF E2  .<.t..W..1:..L..
03BC4090   9D 14 53 14  0A A1 8E 19  65 4C 3D 5A  43 8D 38 AE  ..S.....eL=ZC.8.
03BC40A0   50 A5 8A B8  83 B4 E8 17  02 B6 C3 32  E9 AB 20 C8  P..........2.. .
03BC40B0   8F 0C 90 9F  F8 19 FC 50  5C 4D 38 E8  CE 90 E8 E9  .......P\M8.....
03BC40C0   9A 43 26 4D  DA 73 83 18  64 4C 3D 85  82 AF 8F 19  .C&M.s..dL=.....
03BC40D0   65 4C 3D 85  82 AE 8E 19  65 4C 3D 85  82 AE 8E 19  eL=.....eL=.....
03BC40E0   65 4C 3D 85  82 AE 8E 19  65 4C 3D 85  82 AE 8E E6  eL=.....eL=.....

Obviously it's not a block data.

I tried searching the testnet4 genesis block signature 03/May/2024 0000000... in the testnet4/blocks folder, with no result either.

❯ rg --binary -uuu '03/May/2024 0000'

Is there some obfuscation or something applied for the testnet blk* file data? Or I missed something? Thanks!

My Bitcoin Core version: v28.99.0-0ca1d1bf69ca



from Recent Questions - Bitcoin Stack Exchange https://ift.tt/vRAzWBL
via IFTTT

Popular posts from this blog

Do Kwon’s Detention Prolonged Until 2024 As Montenegro Responds To Extradition Requests

Image
According to an International Business Times report , Montenegro’s Supreme Court decided to extend the detention of TerraForm Labs founder and CEO Do Kwon until February 2024, following extradition requests from the United States and South Korea. Closed-Door Discussions Reveal Montenegro’s Plan For Do Kwon Initially set to be extradited to the US on December 15, Do Kwon’s fate turned when the Montenegrin High Court ruled to prolong his stay until February 15, 2024. The decision stems from charges related to the collapse of the TerraUSD stablecoin, which led to significant financial losses. The High Court had previously ordered Kwon’s extradition by Friday, but his defense team appealed the decision in the appellate court in Podgorica, the capital of Montenegro. The Montenegrin Court of Appeal confirmed that Kwon contested the High Court’s ruling, vehemently stating, “I do not submit to the court’s decision.” Recent reports indicate that Montenegro’s Justice Minister, Andrej Mil
Read more

Sam Bankman-Fried Trial Begins Tomorrow: 3 Reasons Ex-SEC Official Foresees Conviction

Image
The trial of Sam Bankman-Fried, the founder of cryptocurrency exchange FTX and hedge fund Alameda Research, is set to commence in New York on Tuesday, October 3.  This comes almost a year after the collapse of both FTX and Alameda Research. The events leading up to the trial paint a picture of alleged fraudulent activities and money laundering that caused significant damage to the businesses involved. Ex-SEC Official’s Bleak Prediction As Sam Bankman-Fried Trial Commences In a nutshell, Alameda Research purportedly took customer deposits from FTX and invested them in fictitious crypto tokens, which derived their value from the confidence in FTX’s operations.  When this confidence waned, FTX and Alameda Research suffered substantial losses, which many argue contributed to a broader disillusionment in the cryptocurrency industry.  Following an investigation, federal authorities uncovered numerous alleged crimes, leading to seven federal fraud and money-laundering charges against B
Read more

April’s Crypto Game-Changers: 7 Events Set To Drastically Impact The Course Of Digital Currencies

Image
As the crypto market ended March positively, the industry gears up for an eventful April, marked by crucial developments and milestones that could significantly impact the digital asset landscape.  Crypto Halvings And Regulatory Deadlines The month starts with the Bitcoin Cash (BCH) halving event scheduled for April 2nd. Similar to Bitcoin (BTC), BCH undergoes a halving approximately every four years, which reduces mining profits for BCH miners.  On April 10, the US is scheduled to announce March’s Consumer Price Index (CPI), a vital indicator that measures the average price change paid by urban consumers for a basket of goods and services.  The Federal Reserve closely monitors the CPI as it influences inflation and, consequently, the central bank’s decisions regarding interest rates. Any changes in interest rates can ripple effect on the overall crypto market performance. April 19 marks the deadline for the US Securities and Exchange Commission (SEC) and US crypto exchange Coin
Read more