+ + Why Wright's proof is a fake + +
+ + 03 May 2016 + +I explained in my previous post (in italian) that the signature that Wright provided as a public proof is in fact invalid. +I want to explain briefly how you could check this claim. +The key in Wright's post is this:
+------------------------- Signature File -------------------------
+MEUCIQDBKn1Uly8m0UyzETObUSL4wYdBfd4ejvtoQfVcNCIK4AIgZmMsXNQWHvo6KDd2Tu6euEl1
+3VTC3ihl6XUlhcU+fM4=
+------------------------- End Signature --------------------------
+Now we can use some bash utilities:
+ +-
+
- base64, that translates encoded ASCII text; +
- hexdump, that displays hexadecimal contents from the input; +
- cut, used to remove the binary part of the input; +
- tr, used to delete spaces and carriage return from the input; +
base64 -d <<<'MEUCIQDBKn1Uly8m0UyzETObUSL4wYdBfd4ejvtoQfVcNCIK4AIgZmMsXNQWHvo6KDd2Tu6euEl13VTC3ihl6XUlhcU+fM4=' | hexdump -C| cut -b 11-60| tr -d ' \n'
+
+3045022100c12a7d54972f26d14cb311339b5122f8c187417dde1e8efb6841f55c34220ae0022066632c5cd4161efa3a2837764eee9eb84975dd54c2de2865e9752585c53e7cce
+Let's analyze the command one by one:
+ +-
+
base64 -ddecodes the redirected string, the output is some gibberish characters so I won't display them here;
+hexdump -Cis used with a pipe to convert to hexadecimal:
+
00000000 30 45 02 21 00 c1 2a 7d 54 97 2f 26 d1 4c b3 11 |0E.!..*}T./&.L..|
+00000010 33 9b 51 22 f8 c1 87 41 7d de 1e 8e fb 68 41 f5 |3.Q"...A}....hA.|
+00000020 5c 34 22 0a e0 02 20 66 63 2c 5c d4 16 1e fa 3a |\4"... fc,\....:|
+00000030 28 37 76 4e ee 9e b8 49 75 dd 54 c2 de 28 65 e9 |(7vN...Iu.T..(e.|
+00000040 75 25 85 c5 3e 7c ce |u%..>|.|
+-
+
- cut -b 11-60 displays only the character from column 11 to 60: +
30 45 02 21 00 c1 2a 7d 54 97 2f 26 d1 4c b3 11
+33 9b 51 22 f8 c1 87 41 7d de 1e 8e fb 68 41 f5
+5c 34 22 0a e0 02 20 66 63 2c 5c d4 16 1e fa 3a
+28 37 76 4e ee 9e b8 49 75 dd 54 c2 de 28 65 e9
+75 25 85 c5 3e 7c ce
+-
+
tr -d ' \n'is used to delete spaces and carriage return from the output so that is shown in one line and gives us the final result:
+
3045022100c12a7d54972f26d14cb311339b5122f8c187417dde1e8efb6841f55c34220ae0022066632c5cd4161efa3a2837764eee9eb84975dd54c2de2865e9752585c53e7cce
+There is also another cleartext string at the beginning of Wright's post:
+$ base64 -d <<<'IFdyaWdodCwgaXQgaXMgbm90IHRoZSBzYW1lIGFzIGlmIEkgc2lnbiBDcmFpZyBXcmlnaHQsIFNhdG9zaGkuCgo='
+Wright, it is not the same as if I sign Craig Wright, Satoshi.
+Now let's head to blockchain.info. +Blockchain.info has a little utility to get hexadecimal informations out of a transaction on the blockchain, so let's use it to get the related info about this transaction:
+ +tx/828ef3b079f9c23829c56fe86e85b4a69d9e06e5b54ea597eef5fb3ffef509fe +tx/828ef3b079f9... in hexadecimal
+ +As you can see the entire output of the first bash command, that is
+
+3045022100c12a7d54972f26d14cb311339b5122f8c187417dde1e8efb6841f55c34220ae0022066632c5cd4161efa3a2837764eee9eb84975dd54c2de2865e9752585c53e7cce
+
+is contained in:
+
+"script":"483045022100c12a7d54972f26d14cb311339b5122f8c187417dde1e8efb6841f55c34220ae0022066632c5cd4161efa3a2837764eee9eb84975dd54c2de2865e9752585c53e7cce01"
+
+except for the 48 at the beginning and the 01 at the end.
That is a signature hash: +this page explains that the 48 is just a decimal prefix given to uncompressed transactions, and the 01 at the end is just a SIGHASH_ALL code that flags the end of the signature.
+ +So, is it a fake?
+ +Yes, indeed. +At the end, I ask, why would you choose anything else than the easiest and most conclusive way to prove something?
+ +
