In order to get a signature, I used the following code:
ECKey key = ECKey.fromPrivate("morR2S8NfjiphGnGWwXuSXPoW9pRM9Du9h".getBytes());
String signature = key.signMessage(?create 225015613080074076?);
But I got the following exception. I don't know why?
java.lang.ArrayIndexOutOfBoundsException
at java.lang.System.arraycopy(Native Method)
at org.spongycastle.crypto.signers.HMacDSAKCalculator.init(HMacDSAKCalculator.java:58)
at org.spongycastle.crypto.signers.ECDSASigner.generateSignature(ECDSASigner.java:94)
at org.bitcoinj.core.ECKey.doSign(ECKey.java:629)
at org.bitcoinj.core.ECKey.sign(ECKey.java:619)
at org.bitcoinj.core.ECKey.signMessage(ECKey.java:769)
at org.bitcoinj.core.ECKey.signMessage(ECKey.java:756)
at com.am.coinspark.service.MessageCreate.getSignature(MessageCreate.java:115)
at com.am.coinspark.service.MessageCreate.main(MessageCreate.java:94)
follow this instructions: http://bitcoin.stackexchange.com/questions/42245/eckey-ecdsasignature-creation
here is the explicit method description: https://bitcoinj.github.io/javadoc/0.12/org/bitcoinj/core/ECKey.html#signMessage-java.lang.String-
hope it s clear now.