Declassified 310 BTC (2)

The $14 million Bitcoin puzzle game has just been on fire for a few days, the prize was taken away by a master, 310 BTC cracking process is not yet public, but there have been hackers released the second level solution video, the process is very complex, I am ready to use a few articles, slowly unravel these mysterious content, can be regarded as the end of one. A Cryptography Course in the US.
Let's take a look back at that picture:

The original image is in PNG format, and the PNG format can hold transparent colors, that is, with alpha layers, which can be viewed with a well-known hacker tool, called stegsolve.

Download address:
Http://www.caesum.com/handbook/Stegsolve.jar

This tool needs to run in the JAVA environment, please install the JRE environment, after running, open the original picture, look at the layer information, you can find a two-dimensional code in alpha plane 1, which is a common method of picture steganography.

Sweep with WeChat. This two-dimensional code is a website address:
Https://bitcoinchallenge.codes/register-310/
If you break the puzzle, you can register your information on this web page. When you register information, you need to use SHA256 to prove that you really cracked the problem.

It is also noteworthy that there is a dotted line above the two-dimensional code, where important information appears to be hidden. 310 BTC puzzle, which looks like this one is on line 310, tries to write a C# program that reads the alpha color information in line 310 of this picture.

It can be seen that color is mainly composed of two values of 254 and 253.

Take only the lowest bit of this number of binary digits, you can get a long string of binary digits, this string at the end of a lot of 1, abandon do not.

Convert binary to sixteen hexadecimal integer and convert it to ASCII code. Source program:

Operation results:

If you are familiar with all kinds of codes, you can guess from the last = = symbol that this is the base64 encoding.

U2FsdGVkX19Q3I//VCH0U3c
VtITZ3ckILJnUcdPX3Gs5qjdF
1UjZ3mAftGivtFYDN5ZCSkB
YnnVqBawl4p8wKO0O8zI6D0
A1+VEVCUyEvEeNoUfGcS0
El9d93vsPxbg7D5avufQsScg
Sk3QEtq9/M4Do32OKFeq00/
Lonely with dream sleep
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Pay attention to the public address
3NrxWOsMmh3AXmDzuuZ0
QmZaI7re16FcXIrmPPiQDO
HRc7wt0ng6qLiNz7VqESR
TdxPOahKFRkWT8sT+Ur2y
+2iZ2LEaxNM7UZqcPwYg
M6FoKOVjnqdeg30R27jc6
AoFPyRZ2g8+EJMp3n/
Pf94oSCLEWkc0osjH9D
QbM6DUptu3HJbAVwXQ==

Find a Base64 decoding website at random.
Https://www.base64decode.org/

Try to decode it, it's not very good, it's scrambled, but you can see from the previous letters "Salted_uuuuuuuuuuuuuuuuuuuuuu Password.

The key to unlock this mess comes from a few letters and curves scattered in the picture, which I'll write next.