Add require signed commit for protected branch (#9708)

* Add require signed commit for protected branch

* Fix fmt

* Make editor show if they will be signed

* bugfix

* Add basic merge check and better information for CRUD

* linting comment

* Add descriptors to merge signing

* Slight refactor

* Slight improvement to appearances

* Handle Merge API

* manage CRUD API

* Move error to error.go

* Remove fix to delete.go

* prep for merge

* need to tolerate \r\n in message

* check protected branch before trying to load it

* Apply suggestions from code review

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

* fix commit-reader

Co-authored-by: guillep2k <18600385+guillep2k@users.noreply.github.com>

29 files changed, 618 insertions, 122 deletions

diff --git a/models/branches.go b/models/branches.go
index b6398f5694..75f5c0a3a7 100644
--- a/models/branches.go
+++ b/models/branches.go
@@ -46,6 +46,7 @@ type ProtectedBranch struct {
 	RequiredApprovals         int64    `xorm:"NOT NULL DEFAULT 0"`
 	BlockOnRejectedReviews    bool     `xorm:"NOT NULL DEFAULT false"`
 	DismissStaleApprovals     bool     `xorm:"NOT NULL DEFAULT false"`
+	RequireSignedCommits      bool     `xorm:"NOT NULL DEFAULT false"`
 
 	CreatedUnix timeutil.TimeStamp `xorm:"created"`
 	UpdatedUnix timeutil.TimeStamp `xorm:"updated"`
diff --git a/models/error.go b/models/error.go
index f0d5699aad..fe9af70f3a 100644
--- a/models/error.go
+++ b/models/error.go
@@ -916,6 +916,22 @@ func (err ErrUserDoesNotHaveAccessToRepo) Error() string {
 	return fmt.Sprintf("user doesn't have acces to repo [user_id: %d, repo_name: %s]", err.UserID, err.RepoName)
 }
 
+// ErrWontSign explains the first reason why a commit would not be signed
+// There may be other reasons - this is just the first reason found
+type ErrWontSign struct {
+	Reason signingMode
+}
+
+func (e *ErrWontSign) Error() string {
+	return fmt.Sprintf("wont sign: %s", e.Reason)
+}
+
+// IsErrWontSign checks if an error is a ErrWontSign
+func IsErrWontSign(err error) bool {
+	_, ok := err.(*ErrWontSign)
+	return ok
+}
+
 // __________                             .__
 // \______   \____________    ____   ____ |  |__
 //  |    |  _/\_  __ \__  \  /    \_/ ___\|  |  \
diff --git a/models/migrations/migrations.go b/models/migrations/migrations.go
index 6bdec1dfba..edea36cf79 100644
--- a/models/migrations/migrations.go
+++ b/models/migrations/migrations.go
@@ -298,6 +298,8 @@ var migrations = []Migration{
 	NewMigration("Add owner_name on table repository", addOwnerNameOnRepository),
 	// v121 -> v122
 	NewMigration("add is_restricted column for users table", addIsRestricted),
+	// v122 -> v123
+	NewMigration("Add Require Signed Commits to ProtectedBranch", addRequireSignedCommits),
 }
 
 // Migrate database to current version
diff --git a/models/migrations/v122.go b/models/migrations/v122.go
new file mode 100644
index 0000000000..e28adc1d82
--- /dev/null
+++ b/models/migrations/v122.go
@@ -0,0 +1,18 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package migrations
+
+import (
+	"xorm.io/xorm"
+)
+
+func addRequireSignedCommits(x *xorm.Engine) error {
+
+	type ProtectedBranch struct {
+		RequireSignedCommits bool `xorm:"NOT NULL DEFAULT false"`
+	}
+
+	return x.Sync2(new(ProtectedBranch))
+}
diff --git a/models/pull.go b/models/pull.go
index 0435311e4e..1edd890035 100644
--- a/models/pull.go
+++ b/models/pull.go
@@ -152,16 +152,18 @@ func (pr *PullRequest) LoadProtectedBranch() (err error) {
 }
 
 func (pr *PullRequest) loadProtectedBranch(e Engine) (err error) {
-	if pr.BaseRepo == nil {
-		if pr.BaseRepoID == 0 {
-			return nil
-		}
-		pr.BaseRepo, err = getRepositoryByID(e, pr.BaseRepoID)
-		if err != nil {
-			return
+	if pr.ProtectedBranch == nil {
+		if pr.BaseRepo == nil {
+			if pr.BaseRepoID == 0 {
+				return nil
+			}
+			pr.BaseRepo, err = getRepositoryByID(e, pr.BaseRepoID)
+			if err != nil {
+				return
+			}
 		}
+		pr.ProtectedBranch, err = getProtectedBranchBy(e, pr.BaseRepo.ID, pr.BaseBranch)
 	}
-	pr.ProtectedBranch, err = getProtectedBranchBy(e, pr.BaseRepo.ID, pr.BaseBranch)
 	return
 }
 
diff --git a/models/pull_sign.go b/models/pull_sign.go
index 19d8907c3d..1d3474abe7 100644
--- a/models/pull_sign.go
+++ b/models/pull_sign.go
@@ -11,16 +11,16 @@ import (
 )
 
 // SignMerge determines if we should sign a PR merge commit to the base repository
-func (pr *PullRequest) SignMerge(u *User, tmpBasePath, baseCommit, headCommit string) (bool, string) {
+func (pr *PullRequest) SignMerge(u *User, tmpBasePath, baseCommit, headCommit string) (bool, string, error) {
 	if err := pr.GetBaseRepo(); err != nil {
 		log.Error("Unable to get Base Repo for pull request")
-		return false, ""
+		return false, "", err
 	}
 	repo := pr.BaseRepo
 
 	signingKey := signingKey(repo.RepoPath())
 	if signingKey == "" {
-		return false, ""
+		return false, "", &ErrWontSign{noKey}
 	}
 	rules := signingModeFromStrings(setting.Repository.Signing.Merges)
 
@@ -30,92 +30,101 @@ func (pr *PullRequest) SignMerge(u *User, tmpBasePath, baseCommit, headCommit st
 	for _, rule := range rules {
 		switch rule {
 		case never:
-			return false, ""
+			return false, "", &ErrWontSign{never}
 		case always:
 			break
 		case pubkey:
 			keys, err := ListGPGKeys(u.ID)
-			if err != nil || len(keys) == 0 {
-				return false, ""
+			if err != nil {
+				return false, "", err
+			}
+			if len(keys) == 0 {
+				return false, "", &ErrWontSign{pubkey}
 			}
 		case twofa:
-			twofa, err := GetTwoFactorByUID(u.ID)
-			if err != nil || twofa == nil {
-				return false, ""
+			twofaModel, err := GetTwoFactorByUID(u.ID)
+			if err != nil {
+				return false, "", err
+			}
+			if twofaModel == nil {
+				return false, "", &ErrWontSign{twofa}
 			}
 		case approved:
 			protectedBranch, err := GetProtectedBranchBy(repo.ID, pr.BaseBranch)
-			if err != nil || protectedBranch == nil {
-				return false, ""
+			if err != nil {
+				return false, "", err
+			}
+			if protectedBranch == nil {
+				return false, "", &ErrWontSign{approved}
 			}
 			if protectedBranch.GetGrantedApprovalsCount(pr) < 1 {
-				return false, ""
+				return false, "", &ErrWontSign{approved}
 			}
 		case baseSigned:
 			if gitRepo == nil {
 				gitRepo, err = git.OpenRepository(tmpBasePath)
 				if err != nil {
-					return false, ""
+					return false, "", err
 				}
 				defer gitRepo.Close()
 			}
 			commit, err := gitRepo.GetCommit(baseCommit)
 			if err != nil {
-				return false, ""
+				return false, "", err
 			}
 			verification := ParseCommitWithSignature(commit)
 			if !verification.Verified {
-				return false, ""
+				return false, "", &ErrWontSign{baseSigned}
 			}
 		case headSigned:
 			if gitRepo == nil {
 				gitRepo, err = git.OpenRepository(tmpBasePath)
 				if err != nil {
-					return false, ""
+					return false, "", err
 				}
 				defer gitRepo.Close()
 			}
 			commit, err := gitRepo.GetCommit(headCommit)
 			if err != nil {
-				return false, ""
+				return false, "", err
 			}
 			verification := ParseCommitWithSignature(commit)
 			if !verification.Verified {
-				return false, ""
+				return false, "", &ErrWontSign{headSigned}
 			}
 		case commitsSigned:
 			if gitRepo == nil {
 				gitRepo, err = git.OpenRepository(tmpBasePath)
 				if err != nil {
-					return false, ""
+					return false, "", err
 				}
 				defer gitRepo.Close()
 			}
 			commit, err := gitRepo.GetCommit(headCommit)
 			if err != nil {
-				return false, ""
+				return false, "", err
 			}
 			verification := ParseCommitWithSignature(commit)
 			if !verification.Verified {
-				return false, ""
+				return false, "", &ErrWontSign{commitsSigned}
 			}
 			// need to work out merge-base
 			mergeBaseCommit, _, err := gitRepo.GetMergeBase("", baseCommit, headCommit)
 			if err != nil {
-				return false, ""
+				return false, "", err
 			}
 			commitList, err := commit.CommitsBeforeUntil(mergeBaseCommit)
 			if err != nil {
-				return false, ""
+				return false, "", err
 			}
 			for e := commitList.Front(); e != nil; e = e.Next() {
 				commit = e.Value.(*git.Commit)
 				verification := ParseCommitWithSignature(commit)
 				if !verification.Verified {
-					return false, ""
+					return false, "", &ErrWontSign{commitsSigned}
 				}
 			}
 		}
 	}
-	return true, signingKey
+	return true, signingKey, nil
 }
diff --git a/models/repo_sign.go b/models/repo_sign.go
index a684efb55f..64f70ac7bd 100644
--- a/models/repo_sign.go
+++ b/models/repo_sign.go
@@ -25,6 +25,7 @@ const (
 	headSigned    signingMode = "headsigned"
 	commitsSigned signingMode = "commitssigned"
 	approved      signingMode = "approved"
+	noKey         signingMode = "nokey"
 )
 
 func signingModeFromStrings(modeStrings []string) []signingMode {
@@ -95,122 +96,140 @@ func PublicSigningKey(repoPath string) (string, error) {
 }
 
 // SignInitialCommit determines if we should sign the initial commit to this repository
-func SignInitialCommit(repoPath string, u *User) (bool, string) {
+func SignInitialCommit(repoPath string, u *User) (bool, string, error) {
 	rules := signingModeFromStrings(setting.Repository.Signing.InitialCommit)
 	signingKey := signingKey(repoPath)
 	if signingKey == "" {
-		return false, ""
+		return false, "", &ErrWontSign{noKey}
 	}
 
 	for _, rule := range rules {
 		switch rule {
 		case never:
-			return false, ""
+			return false, "", &ErrWontSign{never}
 		case always:
 			break
 		case pubkey:
 			keys, err := ListGPGKeys(u.ID)
-			if err != nil || len(keys) == 0 {
-				return false, ""
+			if err != nil {
+				return false, "", err
+			}
+			if len(keys) == 0 {
+				return false, "", &ErrWontSign{pubkey}
 			}
 		case twofa:
-			twofa, err := GetTwoFactorByUID(u.ID)
-			if err != nil || twofa == nil {
-				return false, ""
+			twofaModel, err := GetTwoFactorByUID(u.ID)
+			if err != nil {
+				return false, "", err
+			}
+			if twofaModel == nil {
+				return false, "", &ErrWontSign{twofa}
 			}
 		}
 	}
-	return true, signingKey
+	return true, signingKey, nil
 }
 
 // SignWikiCommit determines if we should sign the commits to this repository wiki
-func (repo *Repository) SignWikiCommit(u *User) (bool, string) {
+func (repo *Repository) SignWikiCommit(u *User) (bool, string, error) {
 	rules := signingModeFromStrings(setting.Repository.Signing.Wiki)
 	signingKey := signingKey(repo.WikiPath())
 	if signingKey == "" {
-		return false, ""
+		return false, "", &ErrWontSign{noKey}
 	}
 
 	for _, rule := range rules {
 		switch rule {
 		case never:
-			return false, ""
+			return false, "", &ErrWontSign{never}
 		case always:
 			break
 		case pubkey:
 			keys, err := ListGPGKeys(u.ID)
-			if err != nil || len(keys) == 0 {
-				return false, ""
+			if err != nil {
+				return false, "", err
+			}
+			if len(keys) == 0 {
+				return false, "", &ErrWontSign{pubkey}
 			}
 		case twofa:
-			twofa, err := GetTwoFactorByUID(u.ID)
-			if err != nil || twofa == nil {
-				return false, ""
+			twofaModel, err := GetTwoFactorByUID(u.ID)
+			if err != nil {
+				return false, "", err
+			}
+			if twofaModel == nil {
+				return false, "", &ErrWontSign{twofa}
 			}
 		case parentSigned:
 			gitRepo, err := git.OpenRepository(repo.WikiPath())
 			if err != nil {
-				return false, ""
+				return false, "", err
 			}
 			defer gitRepo.Close()
 			commit, err := gitRepo.GetCommit("HEAD")
 			if err != nil {
-				return false, ""
+				return false, "", err
 			}
 			if commit.Signature == nil {
-				return false, ""
+				return false, "", &ErrWontSign{parentSigned}
 			}
 			verification := ParseCommitWithSignature(commit)
 			if !verification.Verified {
-				return false, ""
+				return false, "", &ErrWontSign{parentSigned}
 			}
 		}
 	}
-	return true, signingKey
+	return true, signingKey, nil
 }
 
 // SignCRUDAction determines if we should sign a CRUD commit to this repository
-func (repo *Repository) SignCRUDAction(u *User, tmpBasePath, parentCommit string) (bool, string) {
+func (repo *Repository) SignCRUDAction(u *User, tmpBasePath, parentCommit string) (bool, string, error) {
 	rules := signingModeFromStrings(setting.Repository.Signing.CRUDActions)
 	signingKey := signingKey(repo.RepoPath())
 	if signingKey == "" {
-		return false, ""
+		return false, "", &ErrWontSign{noKey}
 	}
 
 	for _, rule := range rules {
 		switch rule {
 		case never:
-			return false, ""
+			return false, "", &ErrWontSign{never}
 		case always:
 			break
 		case pubkey:
 			keys, err := ListGPGKeys(u.ID)
-			if err != nil || len(keys) == 0 {
-				return false, ""
+			if err != nil {
+				return false, "", err
+			}
+			if len(keys) == 0 {
+				return false, "", &ErrWontSign{pubkey}
 			}
 		case twofa:
-			twofa, err := GetTwoFactorByUID(u.ID)
-			if err != nil || twofa == nil {
-				return false, ""
+			twofaModel, err := GetTwoFactorByUID(u.ID)
+			if err != nil {
+				return false, "", err
+			}
+			if twofaModel == nil {
+				return false, "", &ErrWontSign{twofa}
 			}
 		case parentSigned:
 			gitRepo, err := git.OpenRepository(tmpBasePath)
 			if err != nil {
-				return false, ""
+				return false, "", err
 			}
 			defer gitRepo.Close()
 			commit, err := gitRepo.GetCommit(parentCommit)
 			if err != nil {
-				return false, ""
+				return false, "", err
 			}
 			if commit.Signature == nil {
-				return false, ""
+				return false, "", &ErrWontSign{parentSigned}
 			}
 			verification := ParseCommitWithSignature(commit)
 			if !verification.Verified {
-				return false, ""
+				return false, "", &ErrWontSign{parentSigned}
 			}
 		}
 	}
-	return true, signingKey
+	return true, signingKey, nil
 }
diff --git a/modules/auth/repo_form.go b/modules/auth/repo_form.go
index 0086419b65..a5071de47e 100644
--- a/modules/auth/repo_form.go
+++ b/modules/auth/repo_form.go
@@ -173,6 +173,7 @@ type ProtectBranchForm struct {
 	ApprovalsWhitelistTeams  string
 	BlockOnRejectedReviews   bool
 	DismissStaleApprovals    bool
+	RequireSignedCommits     bool
 }
 
 // Validate validates the fields
diff --git a/modules/context/repo.go b/modules/context/repo.go
index 86c7df2b05..66700a6937 100644
--- a/modules/context/repo.go
+++ b/modules/context/repo.go
@@ -74,14 +74,57 @@ func RepoMustNotBeArchived() macaron.Handler {
 	}
 }
 
+// CanCommitToBranchResults represents the results of CanCommitToBranch
+type CanCommitToBranchResults struct {
+	CanCommitToBranch bool
+	EditorEnabled     bool
+	UserCanPush       bool
+	RequireSigned     bool
+	WillSign          bool
+	SigningKey        string
+	WontSignReason    string
+}
+
 // CanCommitToBranch returns true if repository is editable and user has proper access level
 //   and branch is not protected for push
-func (r *Repository) CanCommitToBranch(doer *models.User) (bool, error) {
-	protectedBranch, err := r.Repository.IsProtectedBranchForPush(r.BranchName, doer)
+func (r *Repository) CanCommitToBranch(doer *models.User) (CanCommitToBranchResults, error) {
+	protectedBranch, err := models.GetProtectedBranchBy(r.Repository.ID, r.BranchName)
+
 	if err != nil {
-		return false, err
+		return CanCommitToBranchResults{}, err
 	}
-	return r.CanEnableEditor() && !protectedBranch, nil
+	userCanPush := true
+	requireSigned := false
+	if protectedBranch != nil {
+		userCanPush = protectedBranch.CanUserPush(doer.ID)
+		requireSigned = protectedBranch.RequireSignedCommits
+	}
+
+	sign, keyID, err := r.Repository.SignCRUDAction(doer, r.Repository.RepoPath(), git.BranchPrefix+r.BranchName)
+
+	canCommit := r.CanEnableEditor() && userCanPush
+	if requireSigned {
+		canCommit = canCommit && sign
+	}
+	wontSignReason := ""
+	if err != nil {
+		if models.IsErrWontSign(err) {
+			wontSignReason = string(err.(*models.ErrWontSign).Reason)
+			err = nil
+		} else {
+			wontSignReason = "error"
+		}
+	}
+
+	return CanCommitToBranchResults{
+		CanCommitToBranch: canCommit,
+		EditorEnabled:     r.CanEnableEditor(),
+		UserCanPush:       userCanPush,
+		RequireSigned:     requireSigned,
+		WillSign:          sign,
+		SigningKey:        keyID,
+		WontSignReason:    wontSignReason,
+	}, err
 }
 
 // CanUseTimetracker returns whether or not a user can use the timetracker.
diff --git a/modules/git/command.go b/modules/git/command.go
index 33143dbd75..3cb676c8da 100644
--- a/modules/git/command.go
+++ b/modules/git/command.go
@@ -97,7 +97,7 @@ func (c *Command) RunInDirTimeoutEnvFullPipeline(env []string, timeout time.Dura
 
 // RunInDirTimeoutEnvFullPipelineFunc executes the command in given directory with given timeout,
 // it pipes stdout and stderr to given io.Writer and passes in an io.Reader as stdin. Between cmd.Start and cmd.Wait the passed in function is run.
-func (c *Command) RunInDirTimeoutEnvFullPipelineFunc(env []string, timeout time.Duration, dir string, stdout, stderr io.Writer, stdin io.Reader, fn func(context.Context, context.CancelFunc)) error {
+func (c *Command) RunInDirTimeoutEnvFullPipelineFunc(env []string, timeout time.Duration, dir string, stdout, stderr io.Writer, stdin io.Reader, fn func(context.Context, context.CancelFunc) error) error {
 
 	if timeout == -1 {
 		timeout = DefaultCommandExecutionTimeout
@@ -135,7 +135,11 @@ func (c *Command) RunInDirTimeoutEnvFullPipelineFunc(env []string, timeout time.
 	defer process.GetManager().Remove(pid)
 
 	if fn != nil {
-		fn(ctx, cancel)
+		err := fn(ctx, cancel)
+		if err != nil {
+			cancel()
+			return err
+		}
 	}
 
 	if err := cmd.Wait(); err != nil && ctx.Err() != context.DeadlineExceeded {
diff --git a/modules/git/commit.go b/modules/git/commit.go
index dfb7adcd1a..9646d56063 100644
--- a/modules/git/commit.go
+++ b/modules/git/commit.go
@@ -33,7 +33,7 @@ type Commit struct {
 	CommitMessage string
 	Signature     *CommitGPGSignature
 
-	parents        []SHA1 // SHA1 strings
+	Parents        []SHA1 // SHA1 strings
 	submoduleCache *ObjectCache
 }
 
@@ -94,7 +94,7 @@ func convertCommit(c *object.Commit) *Commit {
 		Committer:     &c.Committer,
 		Author:        &c.Author,
 		Signature:     convertPGPSignature(c),
-		parents:       c.ParentHashes,
+		Parents:       c.ParentHashes,
 	}
 }
 
@@ -111,10 +111,10 @@ func (c *Commit) Summary() string {
 // ParentID returns oid of n-th parent (0-based index).
 // It returns nil if no such parent exists.
 func (c *Commit) ParentID(n int) (SHA1, error) {
-	if n >= len(c.parents) {
+	if n >= len(c.Parents) {
 		return SHA1{}, ErrNotExist{"", ""}
 	}
-	return c.parents[n], nil
+	return c.Parents[n], nil
 }
 
 // Parent returns n-th parent (0-based index) of the commit.
@@ -133,7 +133,7 @@ func (c *Commit) Parent(n int) (*Commit, error) {
 // ParentCount returns number of parents of the commit.
 // 0 if this is the root commit,  otherwise 1,2, etc.
 func (c *Commit) ParentCount() int {
-	return len(c.parents)
+	return len(c.Parents)
 }
 
 func isImageFile(data []byte) (string, bool) {
diff --git a/modules/git/commit_reader.go b/modules/git/commit_reader.go
new file mode 100644
index 0000000000..06d8f426d7
--- /dev/null
+++ b/modules/git/commit_reader.go
@@ -0,0 +1,108 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package git
+
+import (
+	"bufio"
+	"bytes"
+	"io"
+	"strings"
+
+	"gopkg.in/src-d/go-git.v4/plumbing"
+)
+
+// CommitFromReader will generate a Commit from a provided reader
+// We will need this to interpret commits from cat-file
+func CommitFromReader(gitRepo *Repository, sha plumbing.Hash, reader io.Reader) (*Commit, error) {
+	commit := &Commit{
+		ID: sha,
+	}
+
+	payloadSB := new(strings.Builder)
+	signatureSB := new(strings.Builder)
+	messageSB := new(strings.Builder)
+	message := false
+	pgpsig := false
+
+	scanner := bufio.NewScanner(reader)
+	// Split by '\n' but include the '\n'
+	scanner.Split(func(data []byte, atEOF bool) (advance int, token []byte, err error) {
+		if atEOF && len(data) == 0 {
+			return 0, nil, nil
+		}
+		if i := bytes.IndexByte(data, '\n'); i >= 0 {
+			// We have a full newline-terminated line.
+			return i + 1, data[0 : i+1], nil
+		}
+		// If we're at EOF, we have a final, non-terminated line. Return it.
+		if atEOF {
+			return len(data), data, nil
+		}
+		// Request more data.
+		return 0, nil, nil
+	})
+
+	for scanner.Scan() {
+		line := scanner.Bytes()
+		if pgpsig {
+			if len(line) > 0 && line[0] == ' ' {
+				_, _ = signatureSB.Write(line[1:])
+				continue
+			} else {
+				pgpsig = false
+			}
+		}
+
+		if !message {
+			// This is probably not correct but is copied from go-gits interpretation...
+			trimmed := bytes.TrimSpace(line)
+			if len(trimmed) == 0 {
+				message = true
+				_, _ = payloadSB.Write(line)
+				continue
+			}
+
+			split := bytes.SplitN(trimmed, []byte{' '}, 2)
+			var data []byte
+			if len(split) > 1 {
+				data = split[1]
+			}
+
+			switch string(split[0]) {
+			case "tree":
+				commit.Tree = *NewTree(gitRepo, plumbing.NewHash(string(data)))
+				_, _ = payloadSB.Write(line)
+			case "parent":
+				commit.Parents = append(commit.Parents, plumbing.NewHash(string(data)))
+				_, _ = payloadSB.Write(line)
+			case "author":
+				commit.Author = &Signature{}
+				commit.Author.Decode(data)
+				_, _ = payloadSB.Write(line)
+			case "committer":
+				commit.Committer = &Signature{}
+				commit.Committer.Decode(data)
+				_, _ = payloadSB.Write(line)
+			case "gpgsig":
+				_, _ = signatureSB.Write(data)
+				_ = signatureSB.WriteByte('\n')
+				pgpsig = true
+			}
+		} else {
+			_, _ = messageSB.Write(line)
+		}
+	}
+	commit.CommitMessage = messageSB.String()
+	_, _ = payloadSB.WriteString(commit.CommitMessage)
+	commit.Signature = &CommitGPGSignature{
+		Signature: signatureSB.String(),
+		Payload:   payloadSB.String(),
+	}
+	if len(commit.Signature.Signature) == 0 {
+		commit.Signature = nil
+	}
+
+	return commit, scanner.Err()
+}
diff --git a/modules/repofiles/delete.go b/modules/repofiles/delete.go
index c91f597f9a..c1689b0be0 100644
--- a/modules/repofiles/delete.go
+++ b/modules/repofiles/delete.go
@@ -55,9 +55,26 @@ func DeleteRepoFile(repo *models.Repository, doer *models.User, opts *DeleteRepo
 				BranchName: opts.NewBranch,
 			}
 		}
-	} else if protected, _ := repo.IsProtectedBranchForPush(opts.OldBranch, doer); protected {
-		return nil, models.ErrUserCannotCommit{
-			UserName: doer.LowerName,
+	} else {
+		protectedBranch, err := repo.GetBranchProtection(opts.OldBranch)
+		if err != nil {
+			return nil, err
+		}
+		if protectedBranch != nil && !protectedBranch.CanUserPush(doer.ID) {
+			return nil, models.ErrUserCannotCommit{
+				UserName: doer.LowerName,
+			}
+		}
+		if protectedBranch != nil && protectedBranch.RequireSignedCommits {
+			_, _, err := repo.SignCRUDAction(doer, repo.RepoPath(), opts.OldBranch)
+			if err != nil {
+				if !models.IsErrWontSign(err) {
+					return nil, err
+				}
+				return nil, models.ErrUserCannotCommit{
+					UserName: doer.LowerName,
+				}
+			}
 		}
 	}
 
diff --git a/modules/repofiles/temp_repo.go b/modules/repofiles/temp_repo.go
index f9ea4ba155..a1cc37e8c6 100644
--- a/modules/repofiles/temp_repo.go
+++ b/modules/repofiles/temp_repo.go
@@ -219,7 +219,7 @@ func (t *TemporaryUploadRepository) CommitTreeWithDate(author, committer *models
 
 	// Determine if we should sign
 	if version.Compare(binVersion, "1.7.9", ">=") {
-		sign, keyID := t.repo.SignCRUDAction(author, t.basePath, "HEAD")
+		sign, keyID, _ := t.repo.SignCRUDAction(author, t.basePath, "HEAD")
 		if sign {
 			args = append(args, "-S"+keyID)
 		} else if version.Compare(binVersion, "2.0.0", ">=") {
@@ -268,7 +268,7 @@ func (t *TemporaryUploadRepository) DiffIndex() (*gitdiff.Diff, error) {
 	var finalErr error
 
 	if err := git.NewCommand("diff-index", "--cached", "-p", "HEAD").
-		RunInDirTimeoutEnvFullPipelineFunc(nil, 30*time.Second, t.basePath, stdoutWriter, stderr, nil, func(ctx context.Context, cancel context.CancelFunc) {
+		RunInDirTimeoutEnvFullPipelineFunc(nil, 30*time.Second, t.basePath, stdoutWriter, stderr, nil, func(ctx context.Context, cancel context.CancelFunc) error {
 			_ = stdoutWriter.Close()
 			diff, finalErr = gitdiff.ParsePatch(setting.Git.MaxGitDiffLines, setting.Git.MaxGitDiffLineCharacters, setting.Git.MaxGitDiffFiles, stdoutReader)
 			if finalErr != nil {
@@ -276,6 +276,7 @@ func (t *TemporaryUploadRepository) DiffIndex() (*gitdiff.Diff, error) {
 				cancel()
 			}
 			_ = stdoutReader.Close()
+			return finalErr
 		}); err != nil {
 		if finalErr != nil {
 			log.Error("Unable to ParsePatch in temporary repo %s (%s). Error: %v", t.repo.FullName(), t.basePath, finalErr)
diff --git a/modules/repofiles/update.go b/modules/repofiles/update.go
index e22a2062a0..430a83093d 100644
--- a/modules/repofiles/update.go
+++ b/modules/repofiles/update.go
@@ -151,8 +151,27 @@ func CreateOrUpdateRepoFile(repo *models.Repository, doer *models.User, opts *Up
 		if err != nil && !git.IsErrBranchNotExist(err) {
 			return nil, err
 		}
-	} else if protected, _ := repo.IsProtectedBranchForPush(opts.OldBranch, doer); protected {
-		return nil, models.ErrUserCannotCommit{UserName: doer.LowerName}
+	} else {
+		protectedBranch, err := repo.GetBranchProtection(opts.OldBranch)
+		if err != nil {
+			return nil, err
+		}
+		if protectedBranch != nil && !protectedBranch.CanUserPush(doer.ID) {
+			return nil, models.ErrUserCannotCommit{
+				UserName: doer.LowerName,
+			}
+		}
+		if protectedBranch != nil && protectedBranch.RequireSignedCommits {
+			_, _, err := repo.SignCRUDAction(doer, repo.RepoPath(), opts.OldBranch)
+			if err != nil {
+				if !models.IsErrWontSign(err) {
+					return nil, err
+				}
+				return nil, models.ErrUserCannotCommit{
+					UserName: doer.LowerName,
+				}
+			}
+		}
 	}
 
 	// If FromTreePath is not set, set it to the opts.TreePath
diff --git a/modules/repository/init.go b/modules/repository/init.go
index a65b335174..9d0beb1138 100644
--- a/modules/repository/init.go
+++ b/modules/repository/init.go
@@ -130,7 +130,7 @@ func initRepoCommit(tmpPath string, repo *models.Repository, u *models.User) (er
 	}
 
 	if version.Compare(binVersion, "1.7.9", ">=") {
-		sign, keyID := models.SignInitialCommit(tmpPath, u)
+		sign, keyID, _ := models.SignInitialCommit(tmpPath, u)
 		if sign {
 			args = append(args, "-S"+keyID)
 		} else if version.Compare(binVersion, "2.0.0", ">=") {
diff --git a/options/locale/locale_en-US.ini b/options/locale/locale_en-US.ini
index 38db43a57c..140c1bd2e3 100644
--- a/options/locale/locale_en-US.ini
+++ b/options/locale/locale_en-US.ini
@@ -748,6 +748,7 @@ editor.name_your_file = Name your file…
 editor.filename_help = Add a directory by typing its name followed by a slash ('/'). Remove a directory by typing backspace at the beginning of the input field.
 editor.or = or
 editor.cancel_lower = Cancel
+editor.commit_signed_changes = Commit Signed Changes
 editor.commit_changes = Commit Changes
 editor.add_tmpl = Add '<filename>'
 editor.add = Add '%s'
@@ -780,6 +781,9 @@ editor.unable_to_upload_files = Failed to upload files to '%s' with error: %v
 editor.upload_file_is_locked = File '%s' is locked by %s.
 editor.upload_files_to_dir = Upload files to '%s'
 editor.cannot_commit_to_protected_branch = Cannot commit to protected branch '%s'.
+editor.no_commit_to_branch = Unable to commit directly to branch because:
+editor.user_no_push_to_branch = User cannot push to branch
+editor.require_signed_commit = Branch requires a signed commit
 
 commits.desc = Browse source code change history.
 commits.commits = Commits
@@ -1068,6 +1072,7 @@ pulls.merge_pull_request = Merge Pull Request
 pulls.rebase_merge_pull_request = Rebase and Merge
 pulls.rebase_merge_commit_pull_request = Rebase and Merge (--no-ff)
 pulls.squash_merge_pull_request = Squash and Merge
+pulls.require_signed_wont_sign = The branch requires signed commits but this merge will not be signed
 pulls.invalid_merge_option = You cannot use this merge option for this pull request.
 pulls.merge_conflict = Merge Failed: There was a conflict whilst merging: %[1]s<br>%[2]s<br>Hint: Try a different strategy
 pulls.rebase_conflict = Merge Failed: There was a conflict whilst rebasing commit: %[1]s<br>%[2]s<br>%[3]s<br>Hint:Try a different strategy
@@ -1109,6 +1114,19 @@ milestones.filter_sort.most_complete = Most complete
 milestones.filter_sort.most_issues = Most issues
 milestones.filter_sort.least_issues = Least issues
 
+signing.will_sign = This commit will be signed with key '%s'
+signing.wont_sign.error = There was an error whilst checking if the commit could be signed
+signing.wont_sign.nokey = There is no key available to sign this commit
+signing.wont_sign.never = Commits are never signed
+signing.wont_sign.always = Commits are always signed
+signing.wont_sign.pubkey = The commit will not be signed because you do not have a public key associated with your account
+signing.wont_sign.twofa = You must have two factor authentication enabled to have commits signed
+signing.wont_sign.parentsigned = The commit will not be signed as the parent commit is not signed
+signing.wont_sign.basesigned = The merge will not be signed as the base commit is not signed
+signing.wont_sign.headsigned = The merge will not be signed as the head commit is not signed
+signing.wont_sign.commitssigned = The merge will not be signed as all the associated commits are not signed
+signing.wont_sign.approved = The merge will not be signed as the PR is not approved
+
 ext_wiki = Ext. Wiki
 ext_wiki.desc = Link to an external wiki.
 
@@ -1416,6 +1434,8 @@ settings.protect_approvals_whitelist_users = Whitelisted reviewers:
 settings.protect_approvals_whitelist_teams = Whitelisted teams for reviews:
 settings.dismiss_stale_approvals = Dismiss stale approvals
 settings.dismiss_stale_approvals_desc = When new commits that change the content of the pull request are pushed to the branch, old approvals will be dismissed.
+settings.require_signed_commits = Require Signed Commits
+settings.require_signed_commits_desc = Reject pushes to this branch if they are unsigned or unverifiable
 settings.add_protected_branch = Enable protection
 settings.delete_protected_branch = Disable protection
 settings.update_protect_branch_success = Branch protection for branch '%s' has been updated.
diff --git a/routers/api/v1/repo/pull.go b/routers/api/v1/repo/pull.go
index 6b643371e5..bca756aea1 100644
--- a/routers/api/v1/repo/pull.go
+++ b/routers/api/v1/repo/pull.go
@@ -639,6 +639,15 @@ func MergePullRequest(ctx *context.APIContext, form auth.MergePullRequestForm) {
 		}
 	}
 
+	if _, err := pull_service.IsSignedIfRequired(pr, ctx.User); err != nil {
+		if !models.IsErrWontSign(err) {
+			ctx.Error(http.StatusInternalServerError, "IsSignedIfRequired", err)
+			return
+		}
+		ctx.Error(http.StatusMethodNotAllowed, fmt.Sprintf("Protected branch %s requires signed commits but this merge would not be signed", pr.BaseBranch), err)
+		return
+	}
+
 	if len(form.Do) == 0 {
 		form.Do = string(models.MergeStyleMerge)
 	}
diff --git a/routers/private/hook.go b/routers/private/hook.go
index b4626fddf4..6a07de15ff 100644
--- a/routers/private/hook.go
+++ b/routers/private/hook.go
@@ -6,7 +6,10 @@
 package private
 
 import (
+	"bufio"
+	"context"
 	"fmt"
+	"io"
 	"net/http"
 	"os"
 	"strings"
@@ -18,10 +21,101 @@ import (
 	"code.gitea.io/gitea/modules/repofiles"
 	"code.gitea.io/gitea/modules/util"
 	pull_service "code.gitea.io/gitea/services/pull"
+	"gopkg.in/src-d/go-git.v4/plumbing"
 
 	"gitea.com/macaron/macaron"
 )
 
+func verifyCommits(oldCommitID, newCommitID string, repo *git.Repository, env []string) error {
+	stdoutReader, stdoutWriter, err := os.Pipe()
+	if err != nil {
+		log.Error("Unable to create os.Pipe for %s", repo.Path)
+		return err
+	}
+	defer func() {
+		_ = stdoutReader.Close()
+		_ = stdoutWriter.Close()
+	}()
+
+	err = git.NewCommand("rev-list", oldCommitID+"..."+newCommitID).
+		RunInDirTimeoutEnvFullPipelineFunc(env, -1, repo.Path,
+			stdoutWriter, nil, nil,
+			func(ctx context.Context, cancel context.CancelFunc) error {
+				_ = stdoutWriter.Close()
+				err := readAndVerifyCommitsFromShaReader(stdoutReader, repo, env)
+				if err != nil {
+					log.Error("%v", err)
+					cancel()
+				}
+				_ = stdoutReader.Close()
+				return err
+			})
+	if err != nil && !isErrUnverifiedCommit(err) {
+		log.Error("Unable to check commits from %s to %s in %s: %v", oldCommitID, newCommitID, repo.Path, err)
+	}
+	return err
+}
+
+func readAndVerifyCommitsFromShaReader(input io.ReadCloser, repo *git.Repository, env []string) error {
+	scanner := bufio.NewScanner(input)
+	for scanner.Scan() {
+		line := scanner.Text()
+		err := readAndVerifyCommit(line, repo, env)
+		if err != nil {
+			log.Error("%v", err)
+			return err
+		}
+	}
+	return scanner.Err()
+}
+
+func readAndVerifyCommit(sha string, repo *git.Repository, env []string) error {
+	stdoutReader, stdoutWriter, err := os.Pipe()
+	if err != nil {
+		log.Error("Unable to create pipe for %s: %v", repo.Path, err)
+		return err
+	}
+	defer func() {
+		_ = stdoutReader.Close()
+		_ = stdoutWriter.Close()
+	}()
+	hash := plumbing.NewHash(sha)
+
+	return git.NewCommand("cat-file", "commit", sha).
+		RunInDirTimeoutEnvFullPipelineFunc(env, -1, repo.Path,
+			stdoutWriter, nil, nil,
+			func(ctx context.Context, cancel context.CancelFunc) error {
+				_ = stdoutWriter.Close()
+				commit, err := git.CommitFromReader(repo, hash, stdoutReader)
+				if err != nil {
+					return err
+				}
+				log.Info("have commit %s", commit.ID.String())
+				verification := models.ParseCommitWithSignature(commit)
+				if !verification.Verified {
+					log.Info("unverified commit %s", commit.ID.String())
+					cancel()
+					return &errUnverifiedCommit{
+						commit.ID.String(),
+					}
+				}
+				return nil
+			})
+}
+
+type errUnverifiedCommit struct {
+	sha string
+}
+
+func (e *errUnverifiedCommit) Error() string {
+	return fmt.Sprintf("Unverified commit: %s", e.sha)
+}
+
+func isErrUnverifiedCommit(err error) bool {
+	_, ok := err.(*errUnverifiedCommit)
+	return ok
+}
+
 // HookPreReceive checks whether a individual commit is acceptable
 func HookPreReceive(ctx *macaron.Context, opts private.HookOptions) {
 	ownerName := ctx.Params(":owner")
@@ -35,6 +129,30 @@ func HookPreReceive(ctx *macaron.Context, opts private.HookOptions) {
 		return
 	}
 	repo.OwnerName = ownerName
+	gitRepo, err := git.OpenRepository(repo.RepoPath())
+	if err != nil {
+		log.Error("Unable to get git repository for: %s/%s Error: %v", ownerName, repoName, err)
+		ctx.JSON(http.StatusInternalServerError, map[string]interface{}{
+			"err": err.Error(),
+		})
+		return
+	}
+	defer gitRepo.Close()
+
+	// Generate git environment for checking commits
+	env := os.Environ()
+	if opts.GitAlternativeObjectDirectories != "" {
+		env = append(env,
+			private.GitAlternativeObjectDirectories+"="+opts.GitAlternativeObjectDirectories)
+	}
+	if opts.GitObjectDirectory != "" {
+		env = append(env,
+			private.GitObjectDirectory+"="+opts.GitObjectDirectory)
+	}
+	if opts.GitQuarantinePath != "" {
+		env = append(env,
+			private.GitQuarantinePath+"="+opts.GitQuarantinePath)
+	}
 
 	for i := range opts.OldCommitIDs {
 		oldCommitID := opts.OldCommitIDs[i]
@@ -51,7 +169,7 @@ func HookPreReceive(ctx *macaron.Context, opts private.HookOptions) {
 			return
 		}
 		if protectBranch != nil && protectBranch.IsProtected() {
-			// check and deletion
+			// detect and prevent deletion
 			if newCommitID == git.EmptySHA {
 				log.Warn("Forbidden: Branch: %s in %-v is protected from deletion", branchName, repo)
 				ctx.JSON(http.StatusForbidden, map[string]interface{}{
@@ -62,20 +180,6 @@ func HookPreReceive(ctx *macaron.Context, opts private.HookOptions) {
 
 			// detect force push
 			if git.EmptySHA != oldCommitID {
-				env := os.Environ()
-				if opts.GitAlternativeObjectDirectories != "" {
-					env = append(env,
-						private.GitAlternativeObjectDirectories+"="+opts.GitAlternativeObjectDirectories)
-				}
-				if opts.GitObjectDirectory != "" {
-					env = append(env,
-						private.GitObjectDirectory+"="+opts.GitObjectDirectory)
-				}
-				if opts.GitQuarantinePath != "" {
-					env = append(env,
-						private.GitQuarantinePath+"="+opts.GitQuarantinePath)
-				}
-
 				output, err := git.NewCommand("rev-list", "--max-count=1", oldCommitID, "^"+newCommitID).RunInDirWithEnv(repo.RepoPath(), env)
 				if err != nil {
 					log.Error("Unable to detect force push between: %s and %s in %-v Error: %v", oldCommitID, newCommitID, repo, err)
@@ -92,6 +196,27 @@ func HookPreReceive(ctx *macaron.Context, opts private.HookOptions) {
 
 				}
 			}
+
+			// Require signed commits
+			if protectBranch.RequireSignedCommits {
+				err := verifyCommits(oldCommitID, newCommitID, gitRepo, env)
+				if err != nil {
+					if !isErrUnverifiedCommit(err) {
+						log.Error("Unable to check commits from %s to %s in %-v: %v", oldCommitID, newCommitID, repo, err)
+						ctx.JSON(http.StatusInternalServerError, map[string]interface{}{
+							"err": fmt.Sprintf("Unable to check commits from %s to %s: %v", oldCommitID, newCommitID, err),
+						})
+						return
+					}
+					unverifiedCommit := err.(*errUnverifiedCommit).sha
+					log.Warn("Forbidden: Branch: %s in %-v is protected from unverified commit %s", branchName, repo, unverifiedCommit)
+					ctx.JSON(http.StatusForbidden, map[string]interface{}{
+						"err": fmt.Sprintf("branch %s is protected from unverified commit %s", branchName, unverifiedCommit),
+					})
+					return
+				}
+			}
+
 			canPush := false
 			if opts.IsDeployKey {
 				canPush = protectBranch.CanPush && (!protectBranch.EnableWhitelist || protectBranch.WhitelistDeployKeys)
diff --git a/routers/repo/editor.go b/routers/repo/editor.go
index 82c74ba75f..8d4f1f8827 100644
--- a/routers/repo/editor.go
+++ b/routers/repo/editor.go
@@ -36,12 +36,13 @@ const (
 )
 
 func renderCommitRights(ctx *context.Context) bool {
-	canCommit, err := ctx.Repo.CanCommitToBranch(ctx.User)
+	canCommitToBranch, err := ctx.Repo.CanCommitToBranch(ctx.User)
 	if err != nil {
 		log.Error("CanCommitToBranch: %v", err)
 	}
-	ctx.Data["CanCommitToBranch"] = canCommit
-	return canCommit
+	ctx.Data["CanCommitToBranch"] = canCommitToBranch
+
+	return canCommitToBranch.CanCommitToBranch
 }
 
 // getParentTreeFields returns list of parent tree names and corresponding tree paths
diff --git a/routers/repo/issue.go b/routers/repo/issue.go
index ce3eb5bd2c..afc115c6e2 100644
--- a/routers/repo/issue.go
+++ b/routers/repo/issue.go
@@ -971,6 +971,21 @@ func ViewIssue(ctx *context.Context) {
 			ctx.Data["IsBlockedByApprovals"] = !pull.ProtectedBranch.HasEnoughApprovals(pull)
 			ctx.Data["IsBlockedByRejection"] = pull.ProtectedBranch.MergeBlockedByRejectedReview(pull)
 			ctx.Data["GrantedApprovals"] = cnt
+			ctx.Data["RequireSigned"] = pull.ProtectedBranch.RequireSignedCommits
+		}
+		ctx.Data["WillSign"] = false
+		if ctx.User != nil {
+			sign, key, err := pull.SignMerge(ctx.User, pull.BaseRepo.RepoPath(), pull.BaseBranch, pull.GetGitRefName())
+			ctx.Data["WillSign"] = sign
+			ctx.Data["SigningKey"] = key
+			if err != nil {
+				if models.IsErrWontSign(err) {
+					ctx.Data["WontSignReason"] = err.(*models.ErrWontSign).Reason
+				} else {
+					ctx.Data["WontSignReason"] = "error"
+					log.Error("Error whilst checking if could sign pr %d in repo %s. Error: %v", pull.ID, pull.BaseRepo.FullName(), err)
+				}
+			}
 		}
 		ctx.Data["IsPullBranchDeletable"] = canDelete &&
 			pull.HeadRepo != nil &&
diff --git a/routers/repo/setting_protected_branch.go b/routers/repo/setting_protected_branch.go
index da28ac50be..e8902ed8ac 100644
--- a/routers/repo/setting_protected_branch.go
+++ b/routers/repo/setting_protected_branch.go
@@ -246,6 +246,7 @@ func SettingsProtectedBranchPost(ctx *context.Context, f auth.ProtectBranchForm)
 		}
 		protectBranch.BlockOnRejectedReviews = f.BlockOnRejectedReviews
 		protectBranch.DismissStaleApprovals = f.DismissStaleApprovals
+		protectBranch.RequireSignedCommits = f.RequireSignedCommits
 
 		err = models.UpdateProtectBranch(ctx.Repo.Repository, protectBranch, models.WhitelistOptions{
 			UserIDs:          whitelistUsers,
diff --git a/services/pull/merge.go b/services/pull/merge.go
index e825c3fdd1..f6f0abe836 100644
--- a/services/pull/merge.go
+++ b/services/pull/merge.go
@@ -158,7 +158,7 @@ func Merge(pr *models.PullRequest, doer *models.User, baseGitRepo *git.Repositor
 	// Determine if we should sign
 	signArg := ""
 	if version.Compare(binVersion, "1.7.9", ">=") {
-		sign, keyID := pr.SignMerge(doer, tmpBasePath, "HEAD", trackingBranch)
+		sign, keyID, _ := pr.SignMerge(doer, tmpBasePath, "HEAD", trackingBranch)
 		if sign {
 			signArg = "-S" + keyID
 		} else if version.Compare(binVersion, "2.0.0", ">=") {
@@ -470,6 +470,21 @@ func getDiffTree(repoPath, baseBranch, headBranch string) (string, error) {
 	return out.String(), nil
 }
 
+// IsSignedIfRequired check if merge will be signed if required
+func IsSignedIfRequired(pr *models.PullRequest, doer *models.User) (bool, error) {
+	if err := pr.LoadProtectedBranch(); err != nil {
+		return false, err
+	}
+
+	if pr.ProtectedBranch == nil || !pr.ProtectedBranch.RequireSignedCommits {
+		return true, nil
+	}
+
+	sign, _, err := pr.SignMerge(doer, pr.BaseRepo.RepoPath(), pr.BaseBranch, pr.GetGitRefName())
+
+	return sign, err
+}
+
 // IsUserAllowedToMerge check if user is allowed to merge PR with given permissions and branch protections
 func IsUserAllowedToMerge(pr *models.PullRequest, p models.Permission, user *models.User) (bool, error) {
 	if p.IsAdmin() {
diff --git a/services/pull/patch.go b/services/pull/patch.go
index 1dbeb81c01..815263e898 100644
--- a/services/pull/patch.go
+++ b/services/pull/patch.go
@@ -162,7 +162,7 @@ func TestPatch(pr *models.PullRequest) error {
 		RunInDirTimeoutEnvFullPipelineFunc(
 			nil, -1, tmpBasePath,
 			nil, stderrWriter, nil,
-			func(ctx context.Context, cancel context.CancelFunc) {
+			func(ctx context.Context, cancel context.CancelFunc) error {
 				_ = stderrWriter.Close()
 				const prefix = "error: patch failed:"
 				const errorPrefix = "error: "
@@ -199,6 +199,7 @@ func TestPatch(pr *models.PullRequest) error {
 					}
 				}
 				_ = stderrReader.Close()
+				return nil
 			})
 
 	if err != nil {
diff --git a/services/wiki/wiki.go b/services/wiki/wiki.go
index 58af203cfd..e2b04ade77 100644
--- a/services/wiki/wiki.go
+++ b/services/wiki/wiki.go
@@ -184,7 +184,7 @@ func updateWikiPage(doer *models.User, repo *models.Repository, oldWikiName, new
 		Message: message,
 	}
 
-	sign, signingKey := repo.SignWikiCommit(doer)
+	sign, signingKey, _ := repo.SignWikiCommit(doer)
 	if sign {
 		commitTreeOpts.KeyID = signingKey
 	} else {
@@ -298,7 +298,7 @@ func DeleteWikiPage(doer *models.User, repo *models.Repository, wikiName string)
 		Parents: []string{"HEAD"},
 	}
 
-	sign, signingKey := repo.SignWikiCommit(doer)
+	sign, signingKey, _ := repo.SignWikiCommit(doer)
 	if sign {
 		commitTreeOpts.KeyID = signingKey
 	} else {
diff --git a/templates/repo/editor/commit_form.tmpl b/templates/repo/editor/commit_form.tmpl
index 2ff08e3931..1915e9be21 100644
--- a/templates/repo/editor/commit_form.tmpl
+++ b/templates/repo/editor/commit_form.tmpl
@@ -1,7 +1,11 @@
 <div class="commit-form-wrapper">
 	<img width="48" height="48" class="ui image commit-avatar" src="{{.SignedUser.RelAvatarLink}}">
 	<div class="commit-form">
-		<h3>{{.i18n.Tr "repo.editor.commit_changes"}}</h3>
+		<h3>{{- if .CanCommitToBranch.WillSign}}
+		<i title="{{.i18n.Tr "repo.signing.will_sign" .CanCommitToBranch.SigningKey}}" class="lock green icon"></i>{{.i18n.Tr "repo.editor.commit_signed_changes"}}
+		{{- else}}
+		<i title="{{.i18n.Tr (printf "repo.signing.wont_sign.%s" .CanCommitToBranch.WontSignReason)}}" class="unlock grey icon"></i>{{.i18n.Tr "repo.editor.commit_changes"}}
+		{{- end}}</h3>
 		<div class="field">
 			<input name="commit_summary" placeholder="{{if .PageIsDelete}}{{.i18n.Tr "repo.editor.delete" .TreePath}}{{else if .PageIsUpload}}{{.i18n.Tr "repo.editor.upload_files_to_dir" .TreePath}}{{else if .IsNewFile}}{{.i18n.Tr "repo.editor.add_tmpl"}}{{else}}{{.i18n.Tr "repo.editor.update" .TreePath}}{{end}}" value="{{.commit_summary}}" autofocus>
 		</div>
@@ -10,11 +14,20 @@
 		</div>
 		<div class="quick-pull-choice js-quick-pull-choice">
 			<div class="field">
-		 		<div class="ui radio checkbox {{if not .CanCommitToBranch}}disabled{{end}}">
+				<div class="ui radio checkbox {{if not .CanCommitToBranch.CanCommitToBranch}}disabled{{end}}">
 					<input type="radio" class="js-quick-pull-choice-option" name="commit_choice" value="direct" button_text="{{.i18n.Tr "repo.editor.commit_changes"}}" {{if eq .commit_choice "direct"}}checked{{end}}>
 					<label>
 						<i class="octicon octicon-git-commit" height="16" width="14"></i>
 						{{.i18n.Tr "repo.editor.commit_directly_to_this_branch" (.BranchName|Escape) | Safe}}
+						{{if not .CanCommitToBranch.CanCommitToBranch}}
+						<div class="ui visible small warning message">
+							{{.i18n.Tr "repo.editor.no_commit_to_branch"}}
+							<ul>
+								{{if not .CanCommitToBranch.UserCanPush}}<li>{{.i18n.Tr "repo.editor.user_no_push_to_branch"}}</li>{{end}}
+								{{if and .CanCommitToBranch.RequireSigned (not .CanCommitToBranch.WillSign)}}<li>{{.i18n.Tr "repo.editor.require_signed_commit"}}</li>{{end}}
+							</ul>
+						</div>
+						{{end}}
 					</label>
 				</div>
 			</div>
diff --git a/templates/repo/issue/view_content/pull.tmpl b/templates/repo/issue/view_content/pull.tmpl
index 7073312b1f..1bf0fa7864 100644
--- a/templates/repo/issue/view_content/pull.tmpl
+++ b/templates/repo/issue/view_content/pull.tmpl
@@ -48,6 +48,7 @@
 	{{else if .IsBlockedByApprovals}}red
 	{{else if .IsBlockedByRejection}}red
 	{{else if and .EnableStatusCheck (not .IsRequiredStatusCheckSuccess)}}red
+	{{else if and .RequireSigned (not .WillSign)}}}red
 	{{else if .Issue.PullRequest.IsChecking}}yellow
 	{{else if .Issue.PullRequest.CanAutoMerge}}green
 	{{else}}red{{end}}"><span class="mega-octicon octicon-git-merge"></span></a>
@@ -93,49 +94,69 @@
 				</div>
 			{{else if .IsPullRequestBroken}}
 				<div class="item text red">
-					<span class="octicon octicon-x"></span>
+					<i class="icon icon-octicon"><span class="octicon octicon-x"></span></i>
 					{{$.i18n.Tr "repo.pulls.data_broken"}}
 				</div>
 			{{else if .IsPullWorkInProgress}}
 				<div class="item text grey">
-					<span class="octicon octicon-x"></span>
+					<i class="icon icon-octicon"><span class="octicon octicon-x"></span></i>
 					{{$.i18n.Tr "repo.pulls.cannot_merge_work_in_progress" .WorkInProgressPrefix | Str2html}}
 				</div>
 			{{else if .Issue.PullRequest.IsChecking}}
 				<div class="item text yellow">
-					<span class="octicon octicon-sync"></span>
+					<i class="icon icon-octicon"><span class="octicon octicon-sync"></span></i>
 					{{$.i18n.Tr "repo.pulls.is_checking"}}
 				</div>
 			{{else if .Issue.PullRequest.CanAutoMerge}}
 				{{if .IsBlockedByApprovals}}
 					<div class="item text red">
-						<span class="octicon octicon-x"></span>
+						<i class="icon icon-octicon"><span class="octicon octicon-x"></span></i>
 					{{$.i18n.Tr "repo.pulls.blocked_by_approvals" .GrantedApprovals .Issue.PullRequest.ProtectedBranch.RequiredApprovals}}
 					</div>
 				{{else if .IsBlockedByRejection}}
 					<div class="item text red">
-						<span class="octicon octicon-x"></span>
+						<i class="icon icon-octicon"><span class="octicon octicon-x"></span></i>
 					{{$.i18n.Tr "repo.pulls.blocked_by_rejection"}}
 					</div>
 				{{else if and .EnableStatusCheck (not .IsRequiredStatusCheckSuccess)}}
 					<div class="item text red">
-						<span class="octicon octicon-x"></span>
+						<i class="icon icon-octicon"><span class="octicon octicon-x"></span></i>
 						{{$.i18n.Tr "repo.pulls.required_status_check_failed"}}
 					</div>
+				{{else if and .RequireSigned (not .WillSign)}}
+					<div class="item text red">
+						<i class="icon icon-octicon"><span class="octicon octicon-x"></span></i>
+						{{$.i18n.Tr "repo.pulls.require_signed_wont_sign"}}
+					</div>
+					<div class="item text yellow">
+						<i class="icon unlock grey"></i>
+						{{$.i18n.Tr (printf "repo.signing.wont_sign.%s" .WontSignReason) }}
+					</div>
 				{{end}}
-				{{$notAllOk := or .IsBlockedByApprovals .IsBlockedByRejection (and .EnableStatusCheck (not .IsRequiredStatusCheckSuccess))}}	
-				{{if or $.IsRepoAdmin (not $notAllOk)}}
+				{{$notAllOk := or .IsBlockedByApprovals .IsBlockedByRejection (and .RequireSigned (not .WillSign)) (and .EnableStatusCheck (not .IsRequiredStatusCheckSuccess))}}
+				{{if and (or $.IsRepoAdmin (not $notAllOk)) (or (not .RequireSigned) .WillSign)}}
 					{{if $notAllOk}}
 						<div class="item text yellow">
-							<span class="octicon octicon-primitive-dot"></span>
+							<i class="icon icon-octicon"><span class="octicon octicon-primitive-dot"></span></i>
 							{{$.i18n.Tr "repo.pulls.required_status_check_administrator"}}
 						</div>
 					{{else}}
 						<div class="item text green">
-							<span class="octicon octicon-check"></span>
+							<i class="icon icon-octicon"><span class="octicon octicon-check"></span></i>
 							{{$.i18n.Tr "repo.pulls.can_auto_merge_desc"}}
 						</div>
 					{{end}}
+					{{if .WillSign}}
+						<div class="item text green">
+							<i class="icon lock green"></i>
+							{{$.i18n.Tr "repo.signing.will_sign" .SigningKey}}
+						</div>
+					{{else}}
+						<div class="item text yellow">
+							<i class="icon unlock grey"></i>
+							{{$.i18n.Tr (printf "repo.signing.wont_sign.%s" .WontSignReason) }}
+						</div>
+					{{end}}
 					{{if .AllowMerge}}
 						{{$prUnit := .Repository.MustGetUnit $.UnitTypePullRequests}}
 						{{$approvers := .Issue.PullRequest.GetApprovers}}
@@ -282,6 +303,11 @@
 						<span class="octicon octicon-x"></span>
 						{{$.i18n.Tr "repo.pulls.required_status_check_failed"}}
 					</div>
+				{{else if and .RequireSigned (not .WillSign)}}
+					<div class="item text red">
+						<span class="octicon octicon-x"></span>
+						{{$.i18n.Tr "repo.pulls.require_signed_wont_sign"}}
+					</div>
 				{{else}}
 					<div class="item text red">
 						<span class="octicon octicon-x"></span>
diff --git a/templates/repo/settings/protected_branch.tmpl b/templates/repo/settings/protected_branch.tmpl
index c6701ce8a9..b4c65f7830 100644
--- a/templates/repo/settings/protected_branch.tmpl
+++ b/templates/repo/settings/protected_branch.tmpl
@@ -210,7 +210,7 @@
 							<label for="block_on_rejected_reviews">{{.i18n.Tr "repo.settings.block_rejected_reviews"}}</label>
 							<p class="help">{{.i18n.Tr "repo.settings.block_rejected_reviews_desc"}}</p>
 						</div>
-					</div>					
+					</div>
 					<div class="field">
 						<div class="ui checkbox">
 							<input name="dismiss_stale_approvals" type="checkbox" {{if .Branch.DismissStaleApprovals}}checked{{end}}>
@@ -218,6 +218,13 @@
 							<p class="help">{{.i18n.Tr "repo.settings.dismiss_stale_approvals_desc"}}</p>
 						</div>
 					</div>
+					<div class="field">
+						<div class="ui checkbox">
+							<input name="require_signed_commits" type="checkbox" {{if .Branch.RequireSignedCommits}}checked{{end}}>
+							<label for="require_signed_commits">{{.i18n.Tr "repo.settings.require_signed_commits"}}</label>
+							<p class="help">{{.i18n.Tr "repo.settings.require_signed_commits_desc"}}</p>
+						</div>
+					</div>
 
 				</div>
 
diff --git a/web_src/less/_repository.less b/web_src/less/_repository.less
index cd35b88f3b..27a0698f7b 100644
--- a/web_src/less/_repository.less
+++ b/web_src/less/_repository.less
@@ -652,6 +652,9 @@
                     margin-left: 10px;
                     margin-top: 10px;
                 }
+                .icon-octicon {
+                    padding-left: 2px;
+                }
             }
 
             .review-item {