Initial JWE Support (#1)

Signed-off-by: ortyomka <[email protected]>

Author: ortyomka

.github/workflows/codeql-analysis.yml

@@ -0,0 +1,71 @@
+# For most projects, this workflow file will not need changing; you simply need
+# to commit it to your repository.
+#
+# You may wish to alter this file to override the set of languages analyzed,
+# or to provide custom queries or build logic.
+#
+# ******** NOTE ********
+# We have attempted to detect the languages in your repository. Please check
+# the `language` matrix defined below to confirm you have the correct set of
+# supported CodeQL languages.
+#
+name: "CodeQL"
+
+on:
+  push:
+    branches: [ main ]
+  # pull_request:
+    # The branches below must be a subset of the branches above
+    # branches: [ main ]
+  schedule:
+    - cron: '31 10 * * 5'
+
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      security-events: write
+
+    strategy:
+      fail-fast: false
+      matrix:
+        language: [ 'go' ]
+        # CodeQL supports [ 'cpp', 'csharp', 'go', 'java', 'javascript', 'python' ]
+        # Learn more:
+        # https://docs.github.com/en/free-pro-team@latest/github/finding-security-vulnerabilities-and-errors-in-your-code/configuring-code-scanning#changing-the-languages-that-are-analyzed
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+
+    # Initializes the CodeQL tools for scanning.
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v1
+      with:
+        languages: ${{ matrix.language }}
+        # If you wish to specify custom queries, you can do so here or in a config file.
+        # By default, queries listed here will override any specified in a config file.
+        # Prefix the list here with "+" to use these queries and those in the config file.
+        # queries: ./path/to/local/query, your-org/your-repo/queries@main
+
+    # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
+    # If this step fails, then you should remove it and run the build manually (see below)
+    - name: Autobuild
+      uses: github/codeql-action/autobuild@v1
+
+    # ℹ️ Command-line programs to run using the OS shell.
+    # 📚 https://git.io/JvXDl
+
+    # ✏️ If the Autobuild fails above, remove it and uncomment the following three lines
+    #    and modify them (or add more) to build your code if your project
+    #    uses a compiled language
+
+    #- run: |
+    #   make bootstrap
+    #   make release
+
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@v1

.gitignore

@@ -0,0 +1,4 @@
+.DS_Store
+bin
+.idea/
+

LICENSE

@@ -0,0 +1,8 @@
+Copyright (c) 2022 golang-jwt maintainers
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+

aesgcm.go

@@ -0,0 +1,92 @@
+package jwe
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"errors"
+	"io"
+)
+
+var (
+	ErrInvalidKeySize            = errors.New("invalid key size")
+	ErrInvalidTagSize            = errors.New("invalid tag size")
+	ErrInvalidNonceSize          = errors.New("invalid nonce size")
+	ErrUnsupportedEncryptionType = errors.New("unsupported encryption type")
+)
+
+const TagSizeAESGCM = 16
+
+type EncryptionType string
+
+var EncryptionTypeA256GCM = EncryptionType("A256GCM")
+
+type cipherAESGCM struct {
+	keySize int
+	getAEAD func(key []byte) (cipher.AEAD, error)
+}
+
+func (ci cipherAESGCM) encrypt(key, aad, plaintext []byte) (iv []byte, ciphertext []byte, tag []byte, err error) {
+	if len(key) != ci.keySize {
+		return nil, nil, nil, ErrInvalidKeySize
+	}
+
+	aead, err := ci.getAEAD(key)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+
+	iv = make([]byte, aead.NonceSize())
+	_, err = io.ReadFull(RandReader, iv)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+
+	res := aead.Seal(nil, iv, plaintext, aad)
+	tagIndex := len(res) - TagSizeAESGCM
+
+	return iv, res[:tagIndex], res[tagIndex:], nil
+}
+
+func (ci cipherAESGCM) decrypt(key, aad, iv []byte, ciphertext []byte, tag []byte) ([]byte, error) {
+	if len(key) != ci.keySize {
+		return nil, ErrInvalidKeySize
+	}
+
+	if len(tag) != TagSizeAESGCM {
+		return nil, ErrInvalidTagSize
+	}
+
+	aead, err := ci.getAEAD(key)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(iv) != aead.NonceSize() {
+		return nil, ErrInvalidNonceSize
+	}
+
+	return aead.Open(nil, iv, append(ciphertext, tag...), aad)
+}
+
+func newAESGCM(keySize int) *cipherAESGCM {
+	return &cipherAESGCM{
+		keySize: keySize,
+		getAEAD: func(key []byte) (cipher.AEAD, error) {
+			aesCipher, err := aes.NewCipher(key)
+			if err != nil {
+				return nil, err
+			}
+
+			return cipher.NewGCM(aesCipher)
+		},
+	}
+}
+
+func getCipher(alg EncryptionType) (*cipherAESGCM, error) {
+	switch alg {
+	case EncryptionTypeA256GCM:
+		return newAESGCM(32), nil
+	default:
+		return nil, ErrUnsupportedEncryptionType
+	}
+}

go.mod

@@ -1,3 +1,3 @@
 module github.com/golang-jwt/jwe
 
-go 1.19
+go 1.18

jwe.go

@@ -0,0 +1,90 @@
+package jwe
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"strings"
+)
+
+// NewJWE creates a new JWE token.
+// The plaintext will be encrypted with the method using a Content Encryption Key (cek).
+// The cek will be encrypted with the alg using the key.
+func NewJWE(alg KeyAlgorithm, key interface{}, method EncryptionType, plaintext []byte) (*jwe, error) {
+	jwe := &jwe{}
+
+	jwe.protected.Enc = method
+	chipher, err := getCipher(method)
+	if err != nil {
+		return nil, err
+	}
+
+	// Generate a random Content Encryption Key (CEK).
+	cek, err := generateKey(chipher.keySize)
+	if err != nil {
+		return nil, err
+	}
+
+	// Encrypt the CEK with the recipient's public key to produce the JWE Encrypted Key.
+	jwe.protected.Alg = alg
+	encrypter, err := createEncrypter(key)
+	if err != nil {
+		return nil, err
+	}
+	jwe.recipientKey, err = encrypter.Encrypt(cek, alg)
+	if err != nil {
+		return nil, err
+	}
+
+	// Serialize Authenticated Data
+	rawProtected, err := json.Marshal(jwe.protected)
+	if err != nil {
+		return nil, err
+	}
+	rawProtectedBase64 := base64.RawURLEncoding.EncodeToString(rawProtected)
+
+	// Perform authenticated encryption on the plaintext
+	jwe.iv, jwe.ciphertext, jwe.tag, err = chipher.encrypt(cek, []byte(rawProtectedBase64), plaintext)
+	if err != nil {
+		return nil, err
+	}
+
+	return jwe, nil
+}
+
+// jwe internal structure represents JWE in unmarshalling format.
+type jwe struct {
+	// protected fields: alg - algorithm to encrypt a key and enc - algorithm to encrypt text.
+	protected struct {
+		Alg KeyAlgorithm   `json:"alg,omitempty"`
+		Enc EncryptionType `json:"enc,omitempty"`
+	}
+
+	// recipientKey field is the key encrypted.
+	recipientKey []byte
+
+	// iv field is initialization vector.
+	iv []byte
+
+	// ciphertext filed is text encrypted by the enc with the key.
+	ciphertext []byte
+
+	// tag field is authentication tag.
+	tag []byte
+}
+
+// CompactSerialize serialize JWE to compact form.
+// https://datatracker.ietf.org/doc/html/rfc7516#section-3.1
+func (jwe *jwe) CompactSerialize() (string, error) {
+	rawProtected, err := json.Marshal(jwe.protected)
+	if err != nil {
+		return "", err
+	}
+
+	protected := base64.RawURLEncoding.EncodeToString(rawProtected)
+	encryptedKey := base64.RawURLEncoding.EncodeToString(jwe.recipientKey)
+	iv := base64.RawURLEncoding.EncodeToString(jwe.iv)
+	ciphertext := base64.RawURLEncoding.EncodeToString(jwe.ciphertext)
+	tag := base64.RawURLEncoding.EncodeToString(jwe.tag)
+
+	return strings.Join([]string{protected, encryptedKey, iv, ciphertext, tag}, "."), nil
+}

jwe_decrypt.go

@@ -0,0 +1,51 @@
+package jwe
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+)
+
+var (
+	ErrMissingEncHeader = errors.New("missing \"enc\" header")
+	ErrMissingAlgHeader = errors.New("missing \"alg\" header")
+)
+
+// Decrypt decrypts JWE ciphertext with the key
+func (jwe jwe) Decrypt(key interface{}) ([]byte, error) {
+
+	method := jwe.protected.Enc
+	if len(method) == 0 {
+		return nil, ErrMissingEncHeader
+	}
+	cipher, err := getCipher(method)
+	if err != nil {
+		return nil, err
+	}
+
+	alg := jwe.protected.Alg
+	if len(alg) == 0 {
+		return nil, ErrMissingAlgHeader
+	}
+	decrypter, err := createDecrypter(key)
+	if err != nil {
+		return nil, err
+	}
+	// Decrypt JWE Encrypted Key with the recipient's private key to produce CEK.
+	cek, err := decrypter.Decrypt(jwe.recipientKey, alg)
+	if err != nil {
+		return nil, err
+	}
+
+	// Serialize Authenticated Data
+	rawProtected, err := json.Marshal(jwe.protected)
+	if err != nil {
+		return nil, err
+	}
+	rawProtectedBase64 := base64.RawURLEncoding.EncodeToString(rawProtected)
+
+	// Perform authenticated decryption on the ciphertext
+	data, err := cipher.decrypt(cek, []byte(rawProtectedBase64), jwe.iv, jwe.ciphertext, jwe.tag)
+
+	return data, err
+}

jwe_parse.go

@@ -0,0 +1,61 @@
+package jwe
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"strings"
+)
+
+func ParseEncrypted(input string) (*jwe, error) {
+
+	if strings.HasPrefix(input, "{") {
+		// TODO (ortyomka): Add full version support
+		return nil, errors.New("don't support full JWE")
+	}
+
+	return parseEncryptedCompact(input)
+}
+
+func parseEncryptedCompact(input string) (*jwe, error) {
+	parts := strings.Split(input, ".")
+
+	if len(parts) != 5 {
+		return nil, errors.New("encrypted token contains an invalid number of segments")
+	}
+
+	jwe := &jwe{}
+
+	rawProtected, err := base64.RawURLEncoding.DecodeString(parts[0])
+	if err != nil {
+		return nil, err
+	}
+
+	if len(rawProtected) == 0 {
+		return nil, errors.New("protected headers are empty")
+	}
+
+	err = json.Unmarshal(rawProtected, &jwe.protected)
+	if err != nil {
+		return nil, errors.New("protected headers are not in JSON format")
+	}
+
+	jwe.recipientKey, err = base64.RawURLEncoding.DecodeString(parts[1])
+	if err != nil {
+		return nil, err
+	}
+	jwe.iv, err = base64.RawURLEncoding.DecodeString(parts[2])
+	if err != nil {
+		return nil, err
+	}
+	jwe.ciphertext, err = base64.RawURLEncoding.DecodeString(parts[3])
+	if err != nil {
+		return nil, err
+	}
+	jwe.tag, err = base64.RawURLEncoding.DecodeString(parts[4])
+	if err != nil {
+		return nil, err
+	}
+
+	return jwe, nil
+}