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I'm having trouble understanding how the following transaction was valided (Block 364845 July 2015) :

2c6c27639e79038cf446e795e267dc8abbe96d1f21cdd17518cc6b57ad2d86d9

It has one input, and is redeeming a P2PKH output.

It's ScriptSig is (95 bytes):

3c303902153b78ce563f89a0ed9414f5aa28ad0d96d6795f9c6302207cb21ff771e841b5706df6f7e26bbea177d05129b1fe1ec49af65f4bb0ba744a03210265939df6b81b4d5ecb3b913d7013efda1498349b65b61847825c37bfde5b87fe

The bold bytes are data-pushes. The second data-push is the public key, it is the first one that I'm having a problem with. It is supposed to be the signature, but I don't understand it, it doesn't even seem to be DER encoded. The s-value seems to be 0x7cb21ff771e841b5706df6f7e26bbea177d05129b1fe1ec49af65f4bb0ba744a and the sighash x03, but I can't read the r-value.

1 Answer 1

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I think you got confused because you changed the order of signature and public key in scriptSig which consumes P2PKH output.

First comes the signature, then the public key. Here you can see the complete list for all standard transactions.

Since the signature is the first data-push in scriptSig, the DER format of the signature in the transaction you specified is as follows:

DER sequence:30
sequence_length:39
integer_value:02
length:15
R:3b78ce563f89a0ed9414f5aa28ad0d96d6795f9c63
integer_value:02
length:20
S:7cb21ff771e841b5706df6f7e26bbea177d05129b1fe1ec49af65f4bb0ba744a
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    Thanks, actually what destabilized me was the unusually low value for r
    – mathboi
    Sep 26, 2023 at 22:41
  • @mathboi You're welcome
    – dassd
    Sep 26, 2023 at 22:44

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