Sign

Usage: keychain.sign(transaction, privateKeys, sigType)
Description: Allow to sign a transaction with private keys

Parameters:

parameters	type	required	Description
object	Transaction	yes	Enter a valid encryption method (one of: ['aes'])
privateKeys	PrivateKey	yes	The private keys used to sign
sigtype	String	no	Default: crypto.Signature.SIGHASH_ALL

Returns : Signed Transaction.