ipfs-ipns公私钥签名算法

1. 生成公钥私钥对

2. 公钥生成ID 私钥签名。

   解析函数分析 ：resolver.Resolve
   namesys->resolve ==> base->resolve ==> namesys->resolveOnce
   routing->GetValue ==> dht->GetValue （寻找附件节点查询数据） ==》 dht ->PutValue(回写最优结果到其它节点)

   IPNS 私钥签名算法：
   IpnsEntry 结构体中 Signature签名字段构成
   私钥+消息内容构成签名
   例如 out := ed25519.Sign(k.sk, msg)
   验证消息用公钥验证和解密消息内容

搜索附件节点后，选择最新的记录

func (v Validator) Select(k string, vals [][]byte) (int, error) {
    var recs []*pb.IpnsEntry
    for _, v := range vals {
        e := new(pb.IpnsEntry)
        if err := proto.Unmarshal(v, e); err != nil {
            return -1, err
        }
        recs = append(recs, e)
    }

    return selectRecord(recs, vals)
}

func selectRecord(recs []*pb.IpnsEntry, vals [][]byte) (int, error) {
    switch len(recs) {
    case 0:
        return -1, errors.New("no usable records in given set")
    case 1:
        return 0, nil
    }

    var i int
    for j := 1; j < len(recs); j++ {
        cmp, err := Compare(recs[i], recs[j])
        if err != nil {
            return -1, err
        }
        if cmp == 0 {
            cmp = bytes.Compare(vals[i], vals[j])
        }
        if cmp < 0 {
            i = j
        }
    }

    return i, nil
}

// Compare compares two IPNS entries. It returns:
//
// * -1 if a is older than b
// * 0 if a and b cannot be ordered (this doesn't mean that they are equal)
// * +1 if a is newer than b
//
// It returns an error when either a or b are malformed.
//
// NOTE: It *does not* validate the records, the caller is responsible for calling
// `Validate` first.
//
// NOTE: If a and b cannot be ordered by this function, you can determine their
// order by comparing their serialized byte representations (using
// `bytes.Compare`). You must do this if you are implementing a libp2p record
// validator (or you can just use the one provided for you by this package).
func Compare(a, b *pb.IpnsEntry) (int, error) {
    as := a.GetSequence()
    bs := b.GetSequence()

    if as > bs {
        return 1, nil
    } else if as < bs {
        return -1, nil
    }

    at, err := u.ParseRFC3339(string(a.GetValidity()))
    if err != nil {
        return 0, err
    }

    bt, err := u.ParseRFC3339(string(b.GetValidity()))
    if err != nil {
        return 0, err
    }

    if at.After(bt) {
        return 1, nil
    } else if bt.After(at) {
        return -1, nil
    }

    return 0, nil
}