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Make trickler truly random instead of using random bucketized duratio…
…ns (#1368) * Make trickler truly random instead of using random bucketized durations * Remove comments now that the code has been validated
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,87 @@ | ||
| package main | ||
|
|
||
| import ( | ||
| "encoding/hex" | ||
| "fmt" | ||
| "sort" | ||
| "time" | ||
|
|
||
| "crypto/rand" | ||
|
|
||
| pb "decred.org/dcrwallet/rpc/walletrpc" | ||
| "github.com/decred/dcrd/chaincfg/chainhash" | ||
| v1 "github.com/decred/politeia/politeiawww/api/www/v1" | ||
| "github.com/decred/politeia/politeiawww/cmd/politeiavoter/uniformprng" | ||
| ) | ||
|
|
||
| func (c *ctx) calculateTrickle(token, voteBit string, ctres *pb.CommittedTicketsResponse, smr *pb.SignMessagesResponse) error { | ||
| votes := len(ctres.TicketAddresses) | ||
| duration := c.cfg.voteDuration | ||
| voteDuration := duration - time.Hour | ||
| if voteDuration < time.Hour { | ||
| return fmt.Errorf("not enough time left to trickle votes") | ||
| } | ||
| fmt.Printf("Total number of votes: %v\n", votes) | ||
| fmt.Printf("Total vote duration : %v\n", duration) | ||
| fmt.Printf("Duration calculated : %v\n", voteDuration) | ||
|
|
||
| prng, err := uniformprng.RandSource(rand.Reader) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
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||
| ts := make([]time.Duration, 0, votes) | ||
| for i := 0; i < votes; i++ { | ||
| ts = append(ts, time.Duration(prng.Int63n(int64(voteDuration)))) | ||
| } | ||
| sort.Slice(ts, func(i, j int) bool { return ts[i] < ts[j] }) | ||
| var previous, t time.Duration | ||
|
|
||
| buckets := make([]*voteInterval, votes) | ||
| for k := range ts { | ||
| // Assemble missing vote bits | ||
| h, err := chainhash.NewHash(ctres.TicketAddresses[k].Ticket) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| signature := hex.EncodeToString(smr.Replies[k].Signature) | ||
|
|
||
| buckets[k] = &voteInterval{ | ||
| Vote: v1.CastVote{ | ||
| Token: token, | ||
| Ticket: h.String(), | ||
| VoteBit: voteBit, | ||
| Signature: signature, | ||
| }, | ||
| At: ts[k] - previous, // Delta to previous timestamp | ||
| } | ||
| t += ts[k] - previous | ||
| previous = ts[k] | ||
| } | ||
|
|
||
| // Should not happen | ||
| if t > voteDuration { | ||
| return fmt.Errorf("assert t > voteDuration - %v > %v", | ||
| t, voteDuration) | ||
| } | ||
|
|
||
| // Sanity | ||
| if len(buckets) != len(ctres.TicketAddresses) { | ||
| return fmt.Errorf("unexpected time bucket count got "+ | ||
| "%v, wanted %v", len(ctres.TicketAddresses), | ||
| len(buckets)) | ||
| } | ||
|
|
||
| // Convert buckets to a list | ||
| for _, v := range buckets { | ||
| c.voteIntervalPush(v) | ||
| } | ||
|
|
||
| // Log work | ||
| err = c.jsonLog(workJournal, token, buckets) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
|
||
| return nil | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,59 @@ | ||
| package main | ||
|
|
||
| import ( | ||
| "container/list" | ||
| "testing" | ||
| "time" | ||
|
|
||
| pb "decred.org/dcrwallet/rpc/walletrpc" | ||
| ) | ||
|
|
||
| func fakeTickets(x int) (*pb.CommittedTicketsResponse, *pb.SignMessagesResponse) { | ||
| ctres := pb.CommittedTicketsResponse{ | ||
| TicketAddresses: make([]*pb.CommittedTicketsResponse_TicketAddress, x), | ||
| } | ||
| for k := range ctres.TicketAddresses { | ||
| ctres.TicketAddresses[k] = &pb.CommittedTicketsResponse_TicketAddress{ | ||
| Ticket: make([]byte, 32), | ||
| } | ||
| } | ||
| smr := pb.SignMessagesResponse{ | ||
| Replies: make([]*pb.SignMessagesResponse_SignReply, x), | ||
| } | ||
| for k := range smr.Replies { | ||
| smr.Replies[k] = &pb.SignMessagesResponse_SignReply{ | ||
| Signature: make([]byte, 64), | ||
| } | ||
| } | ||
|
|
||
| return &ctres, &smr | ||
| } | ||
|
|
||
| func fakeCtx(d time.Duration, x int) *ctx { | ||
| return &ctx{ | ||
| cfg: &config{ | ||
| voteDuration: d, | ||
| }, | ||
| voteIntervalQ: new(list.List), | ||
| } | ||
| } | ||
|
|
||
| func TestTrickleNotEnoughTime(t *testing.T) { | ||
| x := 10 | ||
| c := fakeCtx(time.Hour, x) | ||
| ctres, smr := fakeTickets(x) | ||
| err := c.calculateTrickle("", "", ctres, smr) | ||
| if err == nil { | ||
| t.Fatal("expected error") | ||
| } | ||
| } | ||
|
|
||
| func TestTrickle2(t *testing.T) { | ||
| x := 10 | ||
| c := fakeCtx(24*time.Hour, x) | ||
| ctres, smr := fakeTickets(x) | ||
| err := c.calculateTrickle("", "", ctres, smr) | ||
| if err != nil { | ||
| t.Fatal(err) | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,89 @@ | ||
| // Package uniformprng implements a uniform, cryptographically secure | ||
| // pseudo-random number generator. | ||
| package uniformprng | ||
|
|
||
| import ( | ||
| "encoding/binary" | ||
| "io" | ||
| "math/bits" | ||
|
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| "golang.org/x/crypto/chacha20" | ||
| ) | ||
|
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| // Source returns cryptographically-secure pseudorandom numbers with uniform | ||
| // distribution. | ||
| type Source struct { | ||
| buf [8]byte | ||
| cipher *chacha20.Cipher | ||
| } | ||
|
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| var nonce = make([]byte, chacha20.NonceSize) | ||
|
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| // NewSource seeds a Source from a 32-byte key. | ||
| func NewSource(seed *[32]byte) *Source { | ||
| cipher, _ := chacha20.NewUnauthenticatedCipher(seed[:], nonce) | ||
| return &Source{cipher: cipher} | ||
| } | ||
|
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| // RandSource creates a Source with seed randomness read from rand. | ||
| func RandSource(rand io.Reader) (*Source, error) { | ||
| seed := new([32]byte) | ||
| _, err := io.ReadFull(rand, seed[:]) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| return NewSource(seed), nil | ||
| } | ||
|
|
||
| // Uint32 returns a pseudo-random uint32. | ||
| func (s *Source) Uint32() uint32 { | ||
| b := s.buf[:4] | ||
| for i := range b { | ||
| b[i] = 0 | ||
| } | ||
| s.cipher.XORKeyStream(b, b) | ||
| return binary.LittleEndian.Uint32(b) | ||
| } | ||
|
|
||
| // Uint32n returns a pseudo-random uint32 in range [0,n) without modulo bias. | ||
| func (s *Source) Uint32n(n uint32) uint32 { | ||
| if n < 2 { | ||
| return 0 | ||
| } | ||
| n-- | ||
| mask := ^uint32(0) >> bits.LeadingZeros32(n) | ||
| for { | ||
| u := s.Uint32() & mask | ||
| if u <= n { | ||
| return u | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // Int63 returns a pseudo-random 63-bit positive integer as an int64 without | ||
| // modulo bias. | ||
| func (s *Source) Int63() int64 { | ||
| b := s.buf[:] | ||
| for i := range b { | ||
| b[i] = 0 | ||
| } | ||
| s.cipher.XORKeyStream(b, b) | ||
| return int64(binary.LittleEndian.Uint64(b) &^ (1 << 63)) | ||
| } | ||
|
|
||
| // Int63n returns, as an int64, a pseudo-random 63-bit positive integer in [0,n) | ||
| // without modulo bias. | ||
| // It panics if n <= 0. | ||
| func (s *Source) Int63n(n int64) int64 { | ||
| if n <= 0 { | ||
| panic("invalid argument to Int63n") | ||
| } | ||
| n-- | ||
| mask := int64(^uint64(0) >> bits.LeadingZeros64(uint64(n))) | ||
| for { | ||
| i := s.Int63() & mask | ||
| if i <= n { | ||
| return i | ||
| } | ||
| } | ||
| } |