From ef9649a400ce641d41e6ba5dac2dc0dc11d0f3bb Mon Sep 17 00:00:00 2001
From: Juunini <juuni.ni.i@gmail.com>
Date: Sun, 29 Oct 2023 23:06:52 +0900
Subject: [PATCH] add generate function

---
 README.md           | 48 +++++++++++++-----------------
 generate.go         | 71 +++++++++++++++++++++++++++++++++++++++++++++
 test/verify_test.go | 42 +++++++++++++--------------
 3 files changed, 111 insertions(+), 50 deletions(-)
 create mode 100644 generate.go

diff --git a/README.md b/README.md
index 101b579..e67bd25 100644
--- a/README.md
+++ b/README.md
@@ -37,45 +37,37 @@ import (
   signature_header "github.com/cloudmatelabs/go-activitypub-signature-header"
 )
 
-const privateKeyBytes = []byte("-----BEGIN RSA PRIVATE KEY-----...")
-const message = []byte(`{
+privateKeyBytes := []byte("-----BEGIN RSA PRIVATE KEY-----...")
+message := []byte(`{
   "@context": "https://www.w3.org/ns/activitystreams",
-  "id": "https://snippet.cloudmt.co.kr/@juunini",
+  "id": "https://snippet.social/@juunini",
   "type": "Follow",
-  "actor": "https://snippet.cloudmt.co.kr/@juunini",
+  "actor": "https://snippet.social/@juunini",
   "object": "https://yodangang.express/users/9iffvxhojp"
 }`)
-const host := "yodangang.express"
-const path := "/users/9iffvxhojp/inbox"
-const keyID := "https://snippet.cloudmt.co.kr/@juunini#main-key"
-
-privateKey, err := signature_header.PrivateKeyFromBytes(privateKeyBytes)
-if err != nil {
-  // handle error
-}
-
+host := "yodangang.express"
+path := "/users/9iffvxhojp/inbox"
+keyID := "https://snippet.social/@juunini#main-key"
 algorithm := crypto.SHA256
-date := signature_header.Date()
-digest := signature_header.Digest(algorithm, message)
-signature, err := signature_header.Signature{
-  PrivateKey: privateKey,
-  Algorithm:  algorithm,
-  Date:       date,
-  Digest:     digest,
-  Host:       host,
-  Path:       path,
-  KeyID:      keyID,
-}.String()
+
+headers, err := signature_header.Generate(signature_header.GenerateInput{
+  PrivateKeyBytes: privateKeyBytes,
+  Algorithm:       algorithm,
+  Host:            host,
+  Path:            path,
+  Body:            message,
+  KeyID:           keyID,
+})
 if err != nil {
   // handle error
 }
 
 resty.New().R().
   SetBody(message).
-  SetHeader("Date", date).
-  SetHeader("Digest", digest).
-  SetHeader("Host", host).
-  SetHeader("Signature", signature).
+  SetHeader("Date", headers.Date).
+  SetHeader("Digest", headers.Digest).
+  SetHeader("Host", headers.Host).
+  SetHeader("Signature", headers.Signature).
   SetHeader("Content-Type", "application/activity+json").
   Post("https://" + host + path)
 ```
diff --git a/generate.go b/generate.go
new file mode 100644
index 0000000..f4d9c51
--- /dev/null
+++ b/generate.go
@@ -0,0 +1,71 @@
+package signature_header
+
+import "crypto"
+
+/*
+Example:
+
+	signature_header.GenerateInput{
+		PrivateKeyBytes: []byte("-----BEGIN RSA PRIVATE KEY-----..."),
+		Algorithm: crypto.SHA256,
+		Host: "example.com",
+		Path: "/inbox",
+		KeyID: "https://snippet.social/@juunini#main-key",
+	}
+*/
+type GenerateInput struct {
+	PrivateKeyBytes []byte
+	Algorithm       crypto.Hash
+	Host            string
+	Path            string
+	Body            []byte
+	KeyID           string
+}
+
+type GenerateOutput struct {
+	Date      string
+	Host      string
+	Digest    string
+	Signature string
+}
+
+/*
+Example:
+
+	headers, err := signature_header.Generate(signature_header.GenerateInput{
+		PrivateKeyBytes: []byte("-----BEGIN RSA PRIVATE KEY-----..."),
+		Algorithm: crypto.SHA256,
+		Host: "example.com",
+		Path: "/inbox",
+		KeyID: "https://snippet.social/@juunini#main-key",
+	})
+*/
+func Generate(input GenerateInput) (*GenerateOutput, error) {
+	date := Date()
+	digest := Digest(input.Algorithm, input.Body)
+
+	privateKey, err := PrivateKeyFromBytes(input.PrivateKeyBytes)
+	if err != nil {
+		return nil, err
+	}
+
+	signature, err := Signature{
+		PrivateKey: privateKey,
+		Algorithm:  input.Algorithm,
+		Date:       date,
+		Digest:     digest,
+		Host:       input.Host,
+		Path:       input.Path,
+		KeyID:      input.KeyID,
+	}.String()
+	if err != nil {
+		return nil, err
+	}
+
+	return &GenerateOutput{
+		Date:      date,
+		Host:      input.Host,
+		Digest:    digest,
+		Signature: signature,
+	}, nil
+}
diff --git a/test/verify_test.go b/test/verify_test.go
index 576db75..f89b772 100644
--- a/test/verify_test.go
+++ b/test/verify_test.go
@@ -82,30 +82,28 @@ func Test_VerifyWithBody(t *testing.T) {
 
 func createSignature() map[string]string {
 	message := []byte(requestMessage)
-	host := "snippet.social"
-	path := "/@juunini/inbox"
-	keyID := "http://localhost:8000/@juunini#main-key"
-
-	privateKey, _ := signature_header.PrivateKeyFromBytes([]byte(privateKeyStr))
-
-	algorithm := crypto.SHA256
-	date := signature_header.Date()
-	digest := signature_header.Digest(algorithm, message)
-	signature, _ := signature_header.Signature{
-		PrivateKey: privateKey,
-		Algorithm:  algorithm,
-		Date:       date,
-		Digest:     digest,
-		Host:       host,
-		Path:       path,
-		KeyID:      keyID,
-	}.String()
+	const host = "snippet.social"
+	const path = "/@juunini/inbox"
+	const keyID = "http://localhost:8000/@juunini#main-key"
+	const algorithm = crypto.SHA256
+
+	headers, err := signature_header.Generate(signature_header.GenerateInput{
+		PrivateKeyBytes: []byte(privateKeyStr),
+		Algorithm:       algorithm,
+		Host:            host,
+		Path:            path,
+		Body:            message,
+		KeyID:           keyID,
+	})
+	if err != nil {
+		panic(err)
+	}
 
 	return map[string]string{
-		"Signature":    signature,
-		"Date":         date,
-		"Host":         host,
-		"Digest":       digest,
+		"Signature":    headers.Signature,
+		"Date":         headers.Date,
+		"Host":         headers.Host,
+		"Digest":       headers.Digest,
 		"Content-Type": "application/activity+json",
 	}
 }