I've read a bit about signing a transaction using openSSL, I've tried implementing it but it seems like the signatures generated are not accepted. So I'm wondering if the following commands provide a valid signature.

Let's create a private key: dd1cd59c4de2fa92e363dac282afe790a5193177d413b38e206b2b86b879ffbf And generate a testnet public address: mhZQtrhzjqkDmm8yp8jR2D84AagCdL4YzM And send some testnet btc to it: a05f60a9679a1ad0ef57b092006b6c01886291a2ff696f5e2ac107b349594cf6

We will create a transaction that sends the BTC to 2N8hwP1WmJrFF5QWABn38y63uYLhnJYJYTF.

Okay, so the unsigned raw transaction is: 01000000 01 f64c5949b307c12a5e6f69ffa2916288016c6b0092b057efd01a9a67a9605fa0 00000000 19 166749c16df955750990623397be66e965863611 ffffffff 01 70508e0600000000 1976a914a9974100aeee974a20cda9a2f545704a0ab54fdc88ac 00000000 01000000

We double hash the raw transaction: 372f7f092abc73c2bcd357ec2b0dab4a9fdbb956771c676cf92a899feedcda0a. And create a PEM key for openSSL (30740201010420 . private_key . a00706052b8104000aa144034200 . public_key and base64 it): -----BEGIN EC PRIVATE KEY----- MHQCAQEEIN0c1ZxN4vqS42PawoKv55ClGTF31BOzjiBrK4a4ef+/oAcGBSuBBAAK oUQDQgAEnQ9w7thTRcpcHARWO+0ZYIViw31kQGF4WoNujxmRVfKBih4mYfntUB2P kGYRiSCZqd5afqn2Qey03XW7tjwtWg== -----END EC PRIVATE KEY-----

And then I use the following command to create the DER sig: echo "372f7f092abc73c2bcd357ec2b0dab4a9fdbb956771c676cf92a899feedcda0a" | openssl dgst -sha256 -hex -sign key.pem.

Adding the length byte and public key, we end up with the following scriptSig: 46 304402203c8aaa41ae647149f70ce24f73109e99d59d7e54a5d854239943358d581e9f8302206336cb57c00bb78f46c881b3d6bb2ed76dc652eedf36064ae022ea4ae3ba3b100141049d0f70eed85345ca5c1c 04 563bed19608562c37d644061785a836e8f199155f2818a1e2661f9ed501d8f906611892099a9de5a7ea9f641ecb4dd75bbb63c2d5a .

Great. This leaves us with the following raw transaction: 01000000 01 f64c5949b307c12a5e6f69ffa2916288016c6b0092b057efd01a9a67a9605fa0 00000000 8a 46304402203c8aaa41ae647149f70ce24f73109e99d59d7e54a5d854239943358d581e9f8302206336cb57c00bb78f46c881b3d6bb2ed76dc652eedf36064ae022ea4ae3ba3b100141049d0f70eed85345ca5c1c04563bed19608562c37d644061785a836e8f199155f2818a1e2661f9ed501d8f906611892099a9de5a7ea9f641ecb4dd75bbb63c2d5a ffffffff 01 70508e0600000000 1976a914a9974100aeee974a20cda9a2f545704a0ab54fdc88ac 00000000

Which is unfortunately not a valid transaction (error received: PUSH TRANSACTION ERROR: 16: MANDATORY-SCRIPT-VERIFY-FLAG-FAILED (OPCODE MISSING OR NOT UNDERSTOOD)).

Using a transaction tool, I get the following (valid) raw transaction, which I was able to redeem: 01000000 01 f64c5949b307c12a5e6f69ffa2916288016c6b0092b057efd01a9a67a9605fa0 00000000 8a 47304402204cdb6499578276106748c4877bf2a3381ba484fb621ce8d3faa2161254bdeec902205e3536aeaa65f8f0f55b3eb31a9bf8959b70e247c0ebd9da485e586370a25b900141 049d0f70eed85345ca5c1c04563bed19608562c37d644061785a836e8f199155f2818a1e2661f9ed501d8f906611892099a9de5a7ea9f641ecb4dd75bbb63c2d5a ffffffff 01 70508e0600000000 1976a914a9974100aeee974a20cda9a2f545704a0ab54fdc88ac 00000000

All the fields are correct besides the signature. How come the openSSL signing command I used was incorrect?

Is the signature generated valid? Is the openSSL command valid? Can we even use openSSL to sign a transaction?