diff --git a/api/server/httputils/httputils.go b/api/server/httputils/httputils.go
index d37ee5cafe..2c2e8452f9 100644
--- a/api/server/httputils/httputils.go
+++ b/api/server/httputils/httputils.go
@@ -14,9 +14,6 @@ import (
 // APIVersionKey is the client's requested API version.
 const APIVersionKey = "api-version"
 
-// UAStringKey is used as key type for user-agent string in net/context struct
-const UAStringKey = "upstream-user-agent"
-
 // APIFunc is an adapter to allow the use of ordinary functions as Docker API endpoints.
 // Any function that has the appropriate signature can be registered as an API endpoint (e.g. getVersion).
 type APIFunc func(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error
diff --git a/api/server/server.go b/api/server/server.go
index d988b8e17f..d8b716e100 100644
--- a/api/server/server.go
+++ b/api/server/server.go
@@ -12,6 +12,7 @@ import (
 	"github.com/docker/docker/api/server/httputils"
 	"github.com/docker/docker/api/server/middleware"
 	"github.com/docker/docker/api/server/router"
+	"github.com/docker/docker/dockerversion"
 	"github.com/gorilla/mux"
 	"golang.org/x/net/context"
 )
@@ -128,7 +129,7 @@ func (s *Server) makeHTTPHandler(handler httputils.APIFunc) http.HandlerFunc {
 		// apply to all requests. Data that is specific to the
 		// immediate function being called should still be passed
 		// as 'args' on the function call.
-		ctx := context.WithValue(context.Background(), httputils.UAStringKey, r.Header.Get("User-Agent"))
+		ctx := context.WithValue(context.Background(), dockerversion.UAStringKey, r.Header.Get("User-Agent"))
 		handlerFunc := s.handlerWithGlobalMiddlewares(handler)
 
 		vars := mux.Vars(r)
diff --git a/api/types/types.go b/api/types/types.go
index 47ec86ceeb..e97df9bc9c 100644
--- a/api/types/types.go
+++ b/api/types/types.go
@@ -547,3 +547,12 @@ type SecretCreateResponse struct {
 type SecretListOptions struct {
 	Filters filters.Args
 }
+
+// PushResult contains the tag, manifest digest, and manifest size from the
+// push. It's used to signal this information to the trust code in the client
+// so it can sign the manifest if necessary.
+type PushResult struct {
+	Tag    string
+	Digest string
+	Size   int
+}
diff --git a/builder/utils_test.go b/builder/utils_test.go
index 1101ff1d1d..adc264539a 100644
--- a/builder/utils_test.go
+++ b/builder/utils_test.go
@@ -59,29 +59,3 @@ func createTestTempFile(t *testing.T, dir, filename, contents string, perm os.Fi
 
 	return filePath
 }
-
-// chdir changes current working directory to dir.
-// It returns a function which changes working directory back to the previous one.
-// This function is meant to be executed as a deferred call.
-// When an error occurs, it terminates the test.
-func chdir(t *testing.T, dir string) func() {
-	workingDirectory, err := os.Getwd()
-
-	if err != nil {
-		t.Fatalf("Error when retrieving working directory: %s", err)
-	}
-
-	err = os.Chdir(dir)
-
-	if err != nil {
-		t.Fatalf("Error when changing directory to %s: %s", dir, err)
-	}
-
-	return func() {
-		err = os.Chdir(workingDirectory)
-
-		if err != nil {
-			t.Fatalf("Error when changing back to working directory (%s): %s", workingDirectory, err)
-		}
-	}
-}
diff --git a/cli/command/image/build.go b/cli/command/image/build.go
index e3e7ff2b02..f194659e08 100644
--- a/cli/command/image/build.go
+++ b/cli/command/image/build.go
@@ -16,10 +16,10 @@ import (
 	"github.com/docker/docker/api"
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/api/types/container"
-	"github.com/docker/docker/builder"
 	"github.com/docker/docker/builder/dockerignore"
 	"github.com/docker/docker/cli"
 	"github.com/docker/docker/cli/command"
+	"github.com/docker/docker/cli/command/image/build"
 	"github.com/docker/docker/opts"
 	"github.com/docker/docker/pkg/archive"
 	"github.com/docker/docker/pkg/fileutils"
@@ -29,7 +29,7 @@ import (
 	"github.com/docker/docker/pkg/urlutil"
 	"github.com/docker/docker/reference"
 	runconfigopts "github.com/docker/docker/runconfig/opts"
-	"github.com/docker/go-units"
+	units "github.com/docker/go-units"
 	"github.com/spf13/cobra"
 )
 
@@ -156,13 +156,13 @@ func runBuild(dockerCli *command.DockerCli, options buildOptions) error {
 
 	switch {
 	case specifiedContext == "-":
-		buildCtx, relDockerfile, err = builder.GetContextFromReader(dockerCli.In(), options.dockerfileName)
+		buildCtx, relDockerfile, err = build.GetContextFromReader(dockerCli.In(), options.dockerfileName)
 	case urlutil.IsGitURL(specifiedContext):
-		tempDir, relDockerfile, err = builder.GetContextFromGitURL(specifiedContext, options.dockerfileName)
+		tempDir, relDockerfile, err = build.GetContextFromGitURL(specifiedContext, options.dockerfileName)
 	case urlutil.IsURL(specifiedContext):
-		buildCtx, relDockerfile, err = builder.GetContextFromURL(progBuff, specifiedContext, options.dockerfileName)
+		buildCtx, relDockerfile, err = build.GetContextFromURL(progBuff, specifiedContext, options.dockerfileName)
 	default:
-		contextDir, relDockerfile, err = builder.GetContextFromLocalDir(specifiedContext, options.dockerfileName)
+		contextDir, relDockerfile, err = build.GetContextFromLocalDir(specifiedContext, options.dockerfileName)
 	}
 
 	if err != nil {
@@ -198,7 +198,7 @@ func runBuild(dockerCli *command.DockerCli, options buildOptions) error {
 			}
 		}
 
-		if err := builder.ValidateContextDirectory(contextDir, excludes); err != nil {
+		if err := build.ValidateContextDirectory(contextDir, excludes); err != nil {
 			return fmt.Errorf("Error checking context: '%s'.", err)
 		}
 
diff --git a/builder/context.go b/cli/command/image/build/context.go
similarity index 98%
rename from builder/context.go
rename to cli/command/image/build/context.go
index 600f42319b..86157c359d 100644
--- a/builder/context.go
+++ b/cli/command/image/build/context.go
@@ -1,4 +1,4 @@
-package builder
+package build
 
 import (
 	"bufio"
@@ -20,6 +20,11 @@ import (
 	"github.com/docker/docker/pkg/streamformatter"
 )
 
+const (
+	// DefaultDockerfileName is the Default filename with Docker commands, read by docker build
+	DefaultDockerfileName string = "Dockerfile"
+)
+
 // ValidateContextDirectory checks if all the contents of the directory
 // can be read and returns an error if some files can't be read
 // symlinks which point to non-existing files don't trigger an error
diff --git a/builder/context_test.go b/cli/command/image/build/context_test.go
similarity index 78%
rename from builder/context_test.go
rename to cli/command/image/build/context_test.go
index 27d29d79f4..afa04a4fcd 100644
--- a/builder/context_test.go
+++ b/cli/command/image/build/context_test.go
@@ -1,10 +1,11 @@
-package builder
+package build
 
 import (
 	"archive/tar"
 	"bytes"
 	"io"
 	"io/ioutil"
+	"os"
 	"path/filepath"
 	"runtime"
 	"strings"
@@ -13,6 +14,8 @@ import (
 	"github.com/docker/docker/pkg/archive"
 )
 
+const dockerfileContents = "FROM busybox"
+
 var prepareEmpty = func(t *testing.T) (string, func()) {
 	return "", func() {}
 }
@@ -305,3 +308,76 @@ func TestValidateContextDirectoryWithOneFile(t *testing.T) {
 func TestValidateContextDirectoryWithOneFileExcludes(t *testing.T) {
 	testValidateContextDirectory(t, prepareOneFile, []string{DefaultDockerfileName})
 }
+
+// createTestTempDir creates a temporary directory for testing.
+// It returns the created path and a cleanup function which is meant to be used as deferred call.
+// When an error occurs, it terminates the test.
+func createTestTempDir(t *testing.T, dir, prefix string) (string, func()) {
+	path, err := ioutil.TempDir(dir, prefix)
+
+	if err != nil {
+		t.Fatalf("Error when creating directory %s with prefix %s: %s", dir, prefix, err)
+	}
+
+	return path, func() {
+		err = os.RemoveAll(path)
+
+		if err != nil {
+			t.Fatalf("Error when removing directory %s: %s", path, err)
+		}
+	}
+}
+
+// createTestTempSubdir creates a temporary directory for testing.
+// It returns the created path but doesn't provide a cleanup function,
+// so createTestTempSubdir should be used only for creating temporary subdirectories
+// whose parent directories are properly cleaned up.
+// When an error occurs, it terminates the test.
+func createTestTempSubdir(t *testing.T, dir, prefix string) string {
+	path, err := ioutil.TempDir(dir, prefix)
+
+	if err != nil {
+		t.Fatalf("Error when creating directory %s with prefix %s: %s", dir, prefix, err)
+	}
+
+	return path
+}
+
+// createTestTempFile creates a temporary file within dir with specific contents and permissions.
+// When an error occurs, it terminates the test
+func createTestTempFile(t *testing.T, dir, filename, contents string, perm os.FileMode) string {
+	filePath := filepath.Join(dir, filename)
+	err := ioutil.WriteFile(filePath, []byte(contents), perm)
+
+	if err != nil {
+		t.Fatalf("Error when creating %s file: %s", filename, err)
+	}
+
+	return filePath
+}
+
+// chdir changes current working directory to dir.
+// It returns a function which changes working directory back to the previous one.
+// This function is meant to be executed as a deferred call.
+// When an error occurs, it terminates the test.
+func chdir(t *testing.T, dir string) func() {
+	workingDirectory, err := os.Getwd()
+
+	if err != nil {
+		t.Fatalf("Error when retrieving working directory: %s", err)
+	}
+
+	err = os.Chdir(dir)
+
+	if err != nil {
+		t.Fatalf("Error when changing directory to %s: %s", dir, err)
+	}
+
+	return func() {
+		err = os.Chdir(workingDirectory)
+
+		if err != nil {
+			t.Fatalf("Error when changing back to working directory (%s): %s", workingDirectory, err)
+		}
+	}
+}
diff --git a/builder/context_unix.go b/cli/command/image/build/context_unix.go
similarity index 90%
rename from builder/context_unix.go
rename to cli/command/image/build/context_unix.go
index d1f72e0573..cb2634f079 100644
--- a/builder/context_unix.go
+++ b/cli/command/image/build/context_unix.go
@@ -1,6 +1,6 @@
 // +build !windows
 
-package builder
+package build
 
 import (
 	"path/filepath"
diff --git a/builder/context_windows.go b/cli/command/image/build/context_windows.go
similarity index 94%
rename from builder/context_windows.go
rename to cli/command/image/build/context_windows.go
index b8ba2ba231..c577cfa7be 100644
--- a/builder/context_windows.go
+++ b/cli/command/image/build/context_windows.go
@@ -1,6 +1,6 @@
 // +build windows
 
-package builder
+package build
 
 import (
 	"path/filepath"
diff --git a/cli/command/image/trust.go b/cli/command/image/trust.go
index f32c301959..192bc047c9 100644
--- a/cli/command/image/trust.go
+++ b/cli/command/image/trust.go
@@ -9,19 +9,17 @@ import (
 	"path"
 	"sort"
 
-	"golang.org/x/net/context"
-
 	"github.com/Sirupsen/logrus"
 	"github.com/docker/distribution/digest"
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/cli/command"
 	"github.com/docker/docker/cli/trust"
-	"github.com/docker/docker/distribution"
 	"github.com/docker/docker/pkg/jsonmessage"
 	"github.com/docker/docker/reference"
 	"github.com/docker/docker/registry"
 	"github.com/docker/notary/client"
 	"github.com/docker/notary/tuf/data"
+	"golang.org/x/net/context"
 )
 
 type target struct {
@@ -52,17 +50,19 @@ func trustedPush(ctx context.Context, cli *command.DockerCli, repoInfo *registry
 			return
 		}
 
-		var pushResult distribution.PushResult
+		var pushResult types.PushResult
 		err := json.Unmarshal(*aux, &pushResult)
-		if err == nil && pushResult.Tag != "" && pushResult.Digest.Validate() == nil {
-			h, err := hex.DecodeString(pushResult.Digest.Hex())
-			if err != nil {
-				target = nil
-				return
+		if err == nil && pushResult.Tag != "" {
+			if dgst, err := digest.ParseDigest(pushResult.Digest); err == nil {
+				h, err := hex.DecodeString(dgst.Hex())
+				if err != nil {
+					target = nil
+					return
+				}
+				target.Name = pushResult.Tag
+				target.Hashes = data.Hashes{string(dgst.Algorithm()): h}
+				target.Length = int64(pushResult.Size)
 			}
-			target.Name = pushResult.Tag
-			target.Hashes = data.Hashes{string(pushResult.Digest.Algorithm()): h}
-			target.Length = int64(pushResult.Size)
 		}
 	}
 
diff --git a/distribution/push_v2.go b/distribution/push_v2.go
index 1f8c822fec..e56f80065b 100644
--- a/distribution/push_v2.go
+++ b/distribution/push_v2.go
@@ -18,6 +18,7 @@ import (
 	"github.com/docker/distribution/manifest/schema2"
 	distreference "github.com/docker/distribution/reference"
 	"github.com/docker/distribution/registry/client"
+	apitypes "github.com/docker/docker/api/types"
 	"github.com/docker/docker/distribution/metadata"
 	"github.com/docker/docker/distribution/xfer"
 	"github.com/docker/docker/layer"
@@ -33,15 +34,6 @@ const (
 	middleLayerMaximumSize = 10 * (1 << 20)  // 10MB
 )
 
-// PushResult contains the tag, manifest digest, and manifest size from the
-// push. It's used to signal this information to the trust code in the client
-// so it can sign the manifest if necessary.
-type PushResult struct {
-	Tag    string
-	Digest digest.Digest
-	Size   int
-}
-
 type v2Pusher struct {
 	v2MetadataService metadata.V2MetadataService
 	ref               reference.Named
@@ -225,7 +217,7 @@ func (p *v2Pusher) pushV2Tag(ctx context.Context, ref reference.NamedTagged, id
 
 	// Signal digest to the trust client so it can sign the
 	// push, if appropriate.
-	progress.Aux(p.config.ProgressOutput, PushResult{Tag: ref.Tag(), Digest: manifestDigest, Size: len(canonicalManifest)})
+	progress.Aux(p.config.ProgressOutput, apitypes.PushResult{Tag: ref.Tag(), Digest: manifestDigest.String(), Size: len(canonicalManifest)})
 
 	return nil
 }
diff --git a/dockerversion/useragent.go b/dockerversion/useragent.go
index d2a891c4d6..53632cbc35 100644
--- a/dockerversion/useragent.go
+++ b/dockerversion/useragent.go
@@ -4,12 +4,14 @@ import (
 	"fmt"
 	"runtime"
 
-	"github.com/docker/docker/api/server/httputils"
 	"github.com/docker/docker/pkg/parsers/kernel"
 	"github.com/docker/docker/pkg/useragent"
 	"golang.org/x/net/context"
 )
 
+// UAStringKey is used as key type for user-agent string in net/context struct
+const UAStringKey = "upstream-user-agent"
+
 // DockerUserAgent is the User-Agent the Docker client uses to identify itself.
 // In accordance with RFC 7231 (5.5.3) is of the form:
 //    [docker client's UA] UpstreamClient([upstream client's UA])
@@ -37,9 +39,9 @@ func DockerUserAgent(ctx context.Context) string {
 func getUserAgentFromContext(ctx context.Context) string {
 	var upstreamUA string
 	if ctx != nil {
-		var ki interface{} = ctx.Value(httputils.UAStringKey)
+		var ki interface{} = ctx.Value(UAStringKey)
 		if ki != nil {
-			upstreamUA = ctx.Value(httputils.UAStringKey).(string)
+			upstreamUA = ctx.Value(UAStringKey).(string)
 		}
 	}
 	return upstreamUA
diff --git a/image/v1/imagev1.go b/image/v1/imagev1.go
index 9c167a2ce9..b52b447e82 100644
--- a/image/v1/imagev1.go
+++ b/image/v1/imagev1.go
@@ -2,9 +2,7 @@ package v1
 
 import (
 	"encoding/json"
-	"fmt"
 	"reflect"
-	"regexp"
 	"strings"
 
 	"github.com/Sirupsen/logrus"
@@ -12,10 +10,9 @@ import (
 	"github.com/docker/docker/api/types/versions"
 	"github.com/docker/docker/image"
 	"github.com/docker/docker/layer"
+	"github.com/docker/docker/pkg/stringid"
 )
 
-var validHex = regexp.MustCompile(`^([a-f0-9]{64})$`)
-
 // noFallbackMinVersion is the minimum version for which v1compatibility
 // information will not be marshaled through the Image struct to remove
 // blank fields.
@@ -149,8 +146,5 @@ func rawJSON(value interface{}) *json.RawMessage {
 
 // ValidateID checks whether an ID string is a valid image ID.
 func ValidateID(id string) error {
-	if ok := validHex.MatchString(id); !ok {
-		return fmt.Errorf("image ID %q is invalid", id)
-	}
-	return nil
+	return stringid.ValidateID(id)
 }
diff --git a/pkg/stringid/stringid.go b/pkg/stringid/stringid.go
index fa35d8bad5..82f85596c7 100644
--- a/pkg/stringid/stringid.go
+++ b/pkg/stringid/stringid.go
@@ -4,6 +4,7 @@ package stringid
 import (
 	"crypto/rand"
 	"encoding/hex"
+	"fmt"
 	"io"
 	"regexp"
 	"strconv"
@@ -14,7 +15,10 @@ import (
 
 const shortLen = 12
 
-var validShortID = regexp.MustCompile("^[a-z0-9]{12}$")
+var (
+	validShortID = regexp.MustCompile("^[a-f0-9]{12}$")
+	validHex     = regexp.MustCompile(`^[a-f0-9]{64}$`)
+)
 
 // IsShortID determines if an arbitrary string *looks like* a short ID.
 func IsShortID(id string) bool {
@@ -67,3 +71,11 @@ func GenerateRandomID() string {
 func GenerateNonCryptoID() string {
 	return generateID(false)
 }
+
+// ValidateID checks whether an ID string is a valid image ID.
+func ValidateID(id string) error {
+	if ok := validHex.MatchString(id); !ok {
+		return fmt.Errorf("image ID %q is invalid", id)
+	}
+	return nil
+}
diff --git a/reference/reference.go b/reference/reference.go
index 996fc50704..15854e5a5b 100644
--- a/reference/reference.go
+++ b/reference/reference.go
@@ -7,7 +7,7 @@ import (
 
 	"github.com/docker/distribution/digest"
 	distreference "github.com/docker/distribution/reference"
-	"github.com/docker/docker/image/v1"
+	"github.com/docker/docker/pkg/stringid"
 )
 
 const (
@@ -163,7 +163,7 @@ func IsNameOnly(ref Named) bool {
 // ParseIDOrReference parses string for an image ID or a reference. ID can be
 // without a default prefix.
 func ParseIDOrReference(idOrRef string) (digest.Digest, Named, error) {
-	if err := v1.ValidateID(idOrRef); err == nil {
+	if err := stringid.ValidateID(idOrRef); err == nil {
 		idOrRef = "sha256:" + idOrRef
 	}
 	if dgst, err := digest.ParseDigest(idOrRef); err == nil {
@@ -209,7 +209,7 @@ func normalize(name string) (string, error) {
 }
 
 func validateName(name string) error {
-	if err := v1.ValidateID(name); err == nil {
+	if err := stringid.ValidateID(name); err == nil {
 		return fmt.Errorf("Invalid repository name (%s), cannot specify 64-byte hexadecimal strings", name)
 	}
 	return nil