1

I have my ECKey key. In order to create an ECDSASignature object with BitcoinJ, we have to call ECDSASignature mySignature = key.sign(Sha256Hash input).

Is the Sha256Hash input my message? Or is it the result of Sha256(byte[] myArray)?

What if I don't have a message to sign? Is it acceptable to sign the key.getPrivKeyBytes() in order to create an ECDSASignature, or it is unacceptable because it reveals information including in getPrivKeyBytes() and as a result reveal my private key?

And if it is unacceptable what must be my message? Can I can sign whatever I want in order to create my ECDSASignature?

5
  • Are you trying to sign a transaction? There are better ways of doing that in bitcoinj. What are you trying to sign?
    – Nick ODell
    Jan 9 '16 at 17:28
  • Let's say that first: i am trying to sign a transaction and as a second secnario that i am going to sign a message in the form of String variable.Which are these better ways?Thanks.
    – gtopal
    Jan 9 '16 at 17:34
  • 1
  • Thanks. I will actually create a message (as a String variable) rather than a whole transaction,and finally i will sign this message to fulfill my program's functionality desires.
    – gtopal
    Jan 9 '16 at 20:32
  • 1
    @Top If you're trying to sign a transaction, you should use Wallet.signTransaction(Wallet.SendRequest.forTx(transaction)); If you're trying to sign a message, you should hash the message first with SHA256.
    – Nick ODell
    Jan 9 '16 at 21:55
1

Signing the bytes of the private key of ECKey key is unacceptable because you are vulnerable for realeasing information about your private key.

In the case of signing a message(as a String) you have to estimate the :

 byte[] result= sha256(message)

The result will be a byte[] and this array finally will insert to the :

 Sha256Hash input= new Sha256Hash(result);

Then the procedure is simple in order to produce the ECDSASignature. You have to do the following:

ECDSASignature signature= key.sign(input);

and finally in order to validate your signature you have to check the following:

key.verify(input, signature)

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.