2. Transactions 交易
We define an electronic coin as a chain of digital signatures.我们定义一种电子货币为一系列的数字签名。
Each owner transfers the coin to the next by digitally signing a hash of the previous transaction and the public key of the next owner and adding these to the end of the coin. 每一个（电子货币）拥有者转给下一位，通过数字签署上一次交易的哈希和下一个拥有者的公钥，并把这些签名加在电子货币的末尾。
A payee can verify the signatures to verify the chain of ownership.收款人可以验证该签名从而确认这条链的所有者。
The problem of course is the payee can't verify that one of the owners did not double-spend the coin.这个过程的中的问题是收款人不能确认数字货币的拥有者有没有双重花费这枚币。
A common solution is to introduce a trusted central authority, or mint, that checks every transaction for double spending.一种常见的解决方法是引入一个可信任的中央机构，或者铸币厂，以检查每一笔交易有没有双重支付。
After each transaction, the coin must be returned to the mint to issue a new coin, and only coins issued directly from the mint are trusted not to be double-spent. 每笔交易之后，这枚电子货币必须返回铸币厂再发行一枚新的币，因为只有直接从铸币厂发行的币才被认为没有被双重支付过。
The problem with this solution is that the fate of the entire money system depends on the company running the mint, with every transaction having to go through them, just like a bank.然而这种方案的缺陷是整个货币系统的命运决定于运行铸币厂的公司，因为每笔交易都必须经过它们，就像一个银行。
We need a way for the payee to know that the previous owners did not sign any earlier transactions.所以我们需要一种方式使收款人知道此前的货币拥有者并没有对更早的交易签名。
For our purposes, the earliest transaction is the one that counts, so we don't care about later attempts to double-spend.为了我们的目的，我们只关心这笔交易之前的交易，所以不关心在此之后对于双重支付的尝试。
The only way to confirm the absence of a transaction is to be aware of all transactions.确认一笔交易是否缺失的唯一办法是知道所有的交易。
In the mint based model, the mint was aware of all transactions and decided which arrived first. 在铸币厂模型里面，铸币厂关注了所有的交易并且决定那一笔交易最先到达。
To accomplish this without a trusted party, transactions must be publicly announced [1], and we need a system for participants to agree on a single history of the order in which they were received.要实现这点而没有一个信任机构，交易必须公开广播，我们需要一个系统，这个系统可以让参与者就收到的订单的单一历史记录达成一致。
The payee needs proof that at the time of each transaction, the majority of nodes agreed it was the first received.收款人需要证据，即每一次交易的过程中，大多数的节点同意这笔交易是第一次收到的。
