Signing Transactions
Signing Transactions in Bitcoin-S
There are two kinds of transaction signing in Bitcoin-S, as defined in Signer.scala: Single Signing and Full Signing.
Single signing, which is implemented as a simple function in BitcoinSigner, consists of using a single ECPrivateKey (or other Sign implementation) to generate a PartialSignature of the given transaction. This consists of an ECDigitalSignature and a ECPublicKey. This is useful any time you have a single private key and wish to get a single ECDigitalSignature for that private key as is the case when using Partially Signed Bitcoin Transactions. In order to call signSingle, you must have access to the unsigned transaction, as well as a ECSignatureParams, which encapsulates all the information needed to sign with a single key. Note that if the unsigned transaction has signatures on it, they will be ignored.
Full signing, which is implemented by the subtypes of Signer, consists of using any number of ECPrivateKeys (or other Sign implementations) to generate a fully signed, TxSigComponent for a given transaction. In order to call sign on any instance of Signer, you must have access to the unsigned transaction, as well as a ScriptSignatureParams, which encapsulates all the information needed to sign with any number of keys. Note that the unsigned transaction can have signatures on it, just not on the input being signed. Specifically, a fully signed TxSigComponent has a member called input which will contain the fully signed TransactionInput as well as scriptSignature which contains the ScriptSignature that was just generated. Additionally, TxSigComponent has a member called transaction which returns a transaction which has all inputs of the input unsigned transaction except for it uses the new input that was just generated by the call to sign instead of an EmptyScriptSignature.