How to get bitcoin in ghana
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This example is taken from http: Thanks to the Wizard of Ozzie who actually used some of his own Bitcoins to make a transaction and then published the private key used to make it the account is now empty, so there's no risk to him in publishing it. We can use the information on the blockchain page together with the private key to carry out some of the raw calculations involved in the transaction. The transaction can be viewed at blockchain. From this page we can get both the signature value and the public key used to sign it.
These are under the Input Scripts heading. Normally we don't have the corresponding private key for a transaction, but in this case we do. We can verify that this matches the given public key by reading in the hex representation of the private key to an "internal" key string and then querying that for the public key. To enable us to verify the signature later, we read in the public key to an internal key string and make some checks.
We can also compute the HASH digest value of the public key, which we will see used below as part of the input to the signature. Note that this is a hash of the sequence of bytes 0x04,0x2D,0xAA, We can use the Hash. HexFromHex method here to compute this directly. To get the final transaction in hex, add? After adding some whitespace and newlines to show the fields for clarity, the final transaction can be reproduced as follows:. You can see the signature in the above da The amount of the transaction 0.
The rules to derive the bytes of the raw transaction that is actually signed from the output above are explained in wonderful detail by Ken Shirriff at Bitcoins the hard way: Using the raw Bitcoin protocol. The end result for the raw data-to-be-signed in this case is the byte sequence 01 be66e10dae7aeac1f91cdd1d6dfd7af2a24d 19 76 a9 14 dd6cce9fa8cc17bda8badf8ecbe 88 ac ffffffff 01 23ce 19 76 a9 14 2bc89ce0edb7d59eb5ce2f0fb 88 ac Note the HASH digest of the public key dd6cce We can compute the HASH digest of the input data.
Some applications display the double SHA digest value in reverse order, so we show it above for interest. However, we always use the "correct" order shown first. Hence the double hash. That's why we use the Sig. VerifyDigest method, not Sig. One of the problems with the ECDSA signature scheme is that it uses a different secret random value usually denoted as k each time. So every time you recompute the signature you will get a different result, and you can never reproduce the same value. For reference, we can compute a replicable signature over the same data using the deterministic digital signature generation procedure of [ RFC ].
This will always give the same result and can also be verified using the same public key. This procedure has been suggested as a standard for Bitcoin transactions.
Here is the quick-and-dirty source code in C to carry out all of the above zipped 2. A free trial edition is available here. For more information, or to comment on this page, please send us a message.
Reproducing a raw Bitcoin transaction. The first hex string is the ECDSA signature in ASN1-DER structure followed by "01" dabdafbffefefbaedbce35d05eabda58cd50aacc25efeffae9e 01 and the second hex string is the public key in X9. To verify the signature, we need four things: We have the signature value and the public key, and we know the signature algorithm is ecdsaWithSHA , but we need to obtain the exact sequence of bytes of the original data that was signed.
To do this we start with the final transaction in hex format.