From 78bbfa42fa1159bce12c2c1d29eeb0bb9a8a2f75 Mon Sep 17 00:00:00 2001 From: Brian Picciano Date: Fri, 25 Aug 2023 21:04:59 +0200 Subject: Remove mailinglist and proof-of-work functionality --- src/pow/pow.go | 321 --------------------------------------------------------- 1 file changed, 321 deletions(-) delete mode 100644 src/pow/pow.go (limited to 'src/pow/pow.go') diff --git a/src/pow/pow.go b/src/pow/pow.go deleted file mode 100644 index ada8439..0000000 --- a/src/pow/pow.go +++ /dev/null @@ -1,321 +0,0 @@ -// Package pow creates proof-of-work challenges and validates their solutions. -package pow - -import ( - "bytes" - "context" - "crypto/hmac" - "crypto/md5" - "crypto/rand" - "crypto/sha512" - "encoding/binary" - "errors" - "fmt" - "hash" - "strconv" - "time" - - "github.com/mediocregopher/blog.mediocregopher.com/srv/cfg" - "github.com/mediocregopher/mediocre-go-lib/v2/mctx" - "github.com/tilinna/clock" -) - -type challengeParams struct { - Target uint32 - ExpiresAt int64 - Random []byte -} - -func (c challengeParams) MarshalBinary() ([]byte, error) { - buf := new(bytes.Buffer) - - var err error - write := func(v interface{}) { - if err != nil { - return - } - err = binary.Write(buf, binary.BigEndian, v) - } - - write(c.Target) - write(c.ExpiresAt) - - if err != nil { - return nil, err - } - - if _, err := buf.Write(c.Random); err != nil { - panic(err) - } - - return buf.Bytes(), nil -} - -func (c *challengeParams) UnmarshalBinary(b []byte) error { - buf := bytes.NewBuffer(b) - - var err error - read := func(into interface{}) { - if err != nil { - return - } - err = binary.Read(buf, binary.BigEndian, into) - } - - read(&c.Target) - read(&c.ExpiresAt) - - if buf.Len() > 0 { - c.Random = buf.Bytes() // whatever is left - } - - return err -} - -// The seed takes the form: -// -// (version)+(signature of challengeParams)+(challengeParams) -// -// Version is currently always 0. -func newSeed(c challengeParams, secret []byte) ([]byte, error) { - buf := new(bytes.Buffer) - buf.WriteByte(0) // version - - cb, err := c.MarshalBinary() - if err != nil { - return nil, err - } - - h := hmac.New(md5.New, secret) - h.Write(cb) - buf.Write(h.Sum(nil)) - - buf.Write(cb) - - return buf.Bytes(), nil -} - -var errMalformedSeed = errors.New("malformed seed") - -func challengeParamsFromSeed(seed, secret []byte) (challengeParams, error) { - h := hmac.New(md5.New, secret) - hSize := h.Size() - - if len(seed) < hSize+1 || seed[0] != 0 { - return challengeParams{}, errMalformedSeed - } - seed = seed[1:] - - sig, cb := seed[:hSize], seed[hSize:] - - // check signature - h.Write(cb) - if !hmac.Equal(sig, h.Sum(nil)) { - return challengeParams{}, errMalformedSeed - } - - var c challengeParams - if err := c.UnmarshalBinary(cb); err != nil { - return challengeParams{}, fmt.Errorf("unmarshaling challenge parameters: %w", err) - } - - return c, nil -} - -// Challenge is a set of fields presented to a client, with which they must -// generate a solution. -// -// Generating a solution is done by: -// -// - Collect up to len(Seed) random bytes. These will be the potential -// solution. -// -// - Calculate the sha512 of the concatenation of Seed and PotentialSolution. -// -// - Parse the first 4 bytes of the sha512 result as a big-endian uint32. -// -// - If the resulting number is _less_ than Target, the solution has been -// found. Otherwise go back to step 1 and try again. -// -type Challenge struct { - Seed []byte - Target uint32 -} - -// Errors which may be produced by a Manager. -var ( - ErrInvalidSolution = errors.New("invalid solution") - ErrExpiredSeed = errors.New("expired seed") -) - -// Manager is used to both produce proof-of-work challenges and check their -// solutions. -type Manager interface { - NewChallenge() Challenge - - // Will produce ErrInvalidSolution if the solution is invalid, or - // ErrExpiredSeed if the seed has expired. - CheckSolution(seed, solution []byte) error -} - -// ManagerParams are used to initialize a new Manager instance. All fields are -// required unless otherwise noted. -type ManagerParams struct { - Clock clock.Clock - Store Store - - // Secret is used to sign each Challenge's Seed, it should _not_ be shared - // with clients. - Secret []byte - - // The Target which Challenges should hit. Lower is more difficult. - // - // Defaults to 0x00FFFFFF - Target uint32 - - // ChallengeTimeout indicates how long before Challenges are considered - // expired and cannot be solved. - // - // Defaults to 1 minute. - ChallengeTimeout time.Duration -} - -func (p *ManagerParams) setDefaults() { - if p.Target == 0 { - p.Target = 0x00FFFFFF - } - if p.ChallengeTimeout == 0 { - p.ChallengeTimeout = 1 * time.Minute - } -} - -// SetupCfg implement the cfg.Cfger interface. -func (p *ManagerParams) SetupCfg(cfg *cfg.Cfg) { - powTargetStr := cfg.String("pow-target", "0x0000FFFF", "Proof-of-work target, lower is more difficult") - powSecretStr := cfg.String("pow-secret", "", "Secret used to sign proof-of-work challenge seeds") - - cfg.OnInit(func(ctx context.Context) error { - p.setDefaults() - - if *powSecretStr == "" { - return errors.New("-pow-secret is required") - } - - powTargetUint, err := strconv.ParseUint(*powTargetStr, 0, 32) - if err != nil { - return fmt.Errorf("parsing -pow-target: %w", err) - } - - p.Target = uint32(powTargetUint) - p.Secret = []byte(*powSecretStr) - - return nil - }) -} - -// Annotate implements mctx.Annotator interface. -func (p *ManagerParams) Annotate(a mctx.Annotations) { - a["powTarget"] = fmt.Sprintf("%x", p.Target) -} - -type manager struct { - params ManagerParams -} - -// NewManager initializes and returns a Manager instance using the given -// parameters. -func NewManager(params ManagerParams) Manager { - params.setDefaults() - return &manager{ - params: params, - } -} - -func (m *manager) NewChallenge() Challenge { - target := m.params.Target - - c := challengeParams{ - Target: target, - ExpiresAt: m.params.Clock.Now().Add(m.params.ChallengeTimeout).Unix(), - Random: make([]byte, 8), - } - - if _, err := rand.Read(c.Random); err != nil { - panic(err) - } - - seed, err := newSeed(c, m.params.Secret) - if err != nil { - panic(err) - } - - return Challenge{ - Seed: seed, - Target: target, - } -} - -// SolutionChecker can be used to check possible Challenge solutions. It will -// cache certain values internally to save on allocations when used in a loop -// (e.g. when generating a solution). -// -// SolutionChecker is not thread-safe. -type SolutionChecker struct { - h hash.Hash // sha512 - sum []byte -} - -// Check returns true if the given bytes are a solution to the given Challenge. -func (s SolutionChecker) Check(challenge Challenge, solution []byte) bool { - if s.h == nil { - s.h = sha512.New() - } - s.h.Reset() - - s.h.Write(challenge.Seed) - s.h.Write(solution) - s.sum = s.h.Sum(s.sum[:0]) - - i := binary.BigEndian.Uint32(s.sum[:4]) - return i < challenge.Target -} - -func (m *manager) CheckSolution(seed, solution []byte) error { - c, err := challengeParamsFromSeed(seed, m.params.Secret) - if err != nil { - return fmt.Errorf("parsing challenge parameters from seed: %w", err) - - } else if now := m.params.Clock.Now().Unix(); c.ExpiresAt <= now { - return ErrExpiredSeed - } - - ok := (SolutionChecker{}).Check( - Challenge{Seed: seed, Target: c.Target}, solution, - ) - - if !ok { - return ErrInvalidSolution - } - - expiresAt := time.Unix(c.ExpiresAt, 0) - if err := m.params.Store.MarkSolved(seed, expiresAt.Add(1*time.Minute)); err != nil { - return fmt.Errorf("marking solution as solved: %w", err) - } - - return nil -} - -// Solve returns a solution for the given Challenge. This may take a while. -func Solve(challenge Challenge) []byte { - - chk := SolutionChecker{} - b := make([]byte, len(challenge.Seed)) - - for { - if _, err := rand.Read(b); err != nil { - panic(err) - } else if chk.Check(challenge, b) { - return b - } - } -} -- cgit v1.2.3