E2E example in PHP and Python
This commit is contained in:
Philipp Heckel
parent
99e6c0ff97
commit
67da1e4922
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@ -1,89 +1,25 @@
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package crypto
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import (
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"crypto/aes"
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"crypto/cipher"
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"crypto/rand"
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"encoding/base64"
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"errors"
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"io"
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"crypto/sha256"
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"golang.org/x/crypto/pbkdf2"
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"gopkg.in/square/go-jose.v2"
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)
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import "gopkg.in/square/go-jose.v2"
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const (
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versionByte = 0x31 // "1"
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gcmTagSize = 16
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gcmNonceSize = 12
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jweEncryption = jose.A256GCM
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jweAlgorithm = jose.DIRECT
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keyLenBytes = 32 // 256-bit for AES-256
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keyDerivIter = 50000
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)
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var (
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errCiphertextTooShort = errors.New("ciphertext too short")
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errCiphertextUnexpectedVersion = errors.New("unsupported ciphertext version")
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)
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func DeriveKey(password string, topicURL string) []byte {
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salt := sha256.Sum256([]byte(topicURL))
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return pbkdf2.Key([]byte(password), salt[:], keyDerivIter, keyLenBytes, sha256.New)
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}
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// Encrypt encrypts the given plaintext with the given key using AES-GCM,
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// and encodes the (version, tag, nonce, ciphertext) set as base64.
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//
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// The output format is (|| means concatenate):
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// "1" || tag (128 bits) || IV/nonce (96 bits) || ciphertext (remaining)
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//
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// This format is compatible with Pushbullet's encryption format.
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// See https://docs.pushbullet.com/#encryption for details.
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func Encrypt(plaintext string, key []byte) (string, error) {
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nonce := make([]byte, gcmNonceSize) // Never use more than 2^32 random nonces
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if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
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return "", err
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}
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return encryptWithNonce(plaintext, nonce, key)
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}
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func encryptWithNonce(plaintext string, nonce, key []byte) (string, error) {
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block, err := aes.NewCipher(key)
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if err != nil {
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return "", err
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}
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aesgcm, err := cipher.NewGCM(block)
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if err != nil {
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return "", err
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}
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ciphertextWithTag := aesgcm.Seal(nil, nonce, []byte(plaintext), nil)
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tagIndex := len(ciphertextWithTag) - gcmTagSize
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ciphertext, tag := ciphertextWithTag[:tagIndex], ciphertextWithTag[tagIndex:]
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output := appendSlices([]byte{versionByte}, tag, nonce, ciphertext)
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return base64.StdEncoding.EncodeToString(output), nil
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}
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// Decrypt decodes and decrypts a message that was encrypted with the Encrypt function.
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func Decrypt(input string, key []byte) (string, error) {
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inputBytes, err := base64.StdEncoding.DecodeString(input)
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if err != nil {
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return "", err
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}
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if len(inputBytes) < 1+gcmTagSize+gcmNonceSize {
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return "", errCiphertextTooShort
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}
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version, tag, nonce, ciphertext := inputBytes[0], inputBytes[1:gcmTagSize+1], inputBytes[1+gcmTagSize:1+gcmTagSize+gcmNonceSize], inputBytes[1+gcmTagSize+gcmNonceSize:]
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if version != versionByte {
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return "", errCiphertextUnexpectedVersion
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}
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cipherTextWithTag := append(ciphertext, tag...)
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block, err := aes.NewCipher(key)
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if err != nil {
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return "", err
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}
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aesgcm, err := cipher.NewGCM(block)
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if err != nil {
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return "", err
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}
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plaintext, err := aesgcm.Open(nil, nonce, cipherTextWithTag, nil)
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if err != nil {
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return "", err
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}
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return string(plaintext), nil
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}
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func EncryptJWE(plaintext string, key []byte) (string, error) {
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enc, err := jose.NewEncrypter(jose.A256GCM, jose.Recipient{Algorithm: jose.DIRECT, Key: key}, nil)
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enc, err := jose.NewEncrypter(jweEncryption, jose.Recipient{Algorithm: jweAlgorithm, Key: key}, nil)
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if err != nil {
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return "", err
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}
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@ -94,7 +30,7 @@ func EncryptJWE(plaintext string, key []byte) (string, error) {
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return jwe.CompactSerialize()
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}
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func DecryptJWE(input string, key []byte) (string, error) {
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func Decrypt(input string, key []byte) (string, error) {
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jwe, err := jose.ParseEncrypted(input)
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if err != nil {
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return "", err
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@ -105,11 +41,3 @@ func DecryptJWE(input string, key []byte) (string, error) {
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}
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return string(out), nil
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}
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func appendSlices(s ...[]byte) []byte {
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var output []byte
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for _, r := range s {
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output = append(output, r...)
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}
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return output
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}
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@ -1,10 +1,7 @@
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package crypto
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import (
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"encoding/base64"
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"encoding/hex"
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"github.com/stretchr/testify/require"
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"log"
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"testing"
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)
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@ -14,40 +11,21 @@ func TestEncryptDecrypt(t *testing.T) {
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require.Nil(t, err)
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plaintext, err := Decrypt(ciphertext, []byte("AES256Key-32Characters1234567890"))
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require.Nil(t, err)
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log.Println(ciphertext)
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require.Equal(t, message, plaintext)
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}
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func TestEncryptDecryptJWE(t *testing.T) {
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message := "this is a message or is it?"
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ciphertext, err := EncryptJWE(message, []byte("AES256Key-32Characters1234567890"))
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func TestEncryptDecrypt_FromPHP(t *testing.T) {
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ciphertext := "eyJhbGciOiJkaXIiLCJlbmMiOiJBMjU2R0NNIn0..vbe1Qv_-mKYbUgce.EfmOUIUi7lxXZG_o4bqXZ9pmpr1Rzs4Y5QLE2XD2_aw_SQ.y2hadrN5b2LEw7_PJHhbcA"
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key := DeriveKey("secr3t password", "https://ntfy.sh/mysecret")
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plaintext, err := Decrypt(ciphertext, key)
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require.Nil(t, err)
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plaintext, err := DecryptJWE(ciphertext, []byte("AES256Key-32Characters1234567890"))
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require.Nil(t, err)
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log.Println(ciphertext)
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require.Equal(t, message, plaintext)
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require.Equal(t, `{"message":"Secret!","priority":5}`, plaintext)
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}
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func TestEncryptExpectedOutputxxxxx(t *testing.T) {
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// These values are taken from https://docs.pushbullet.com/#encryption
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// The following expected ciphertext from the site was used as a baseline:
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// MQS2K9l3G8YoLccJooY64kDeWjbkI3fAx4WcrYNtbz4p8Q==
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// 31 04b62bd9771bc6282dc709a2863ae240 de5a36e42377c0c7859cad83 6d6f3e29f1
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// v tag nonce ciphertext
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message := "meow!"
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key, _ := base64.StdEncoding.DecodeString("1sW28zp7CWv5TtGjlQpDHHG4Cbr9v36fG5o4f74LsKg=")
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nonce, _ := hex.DecodeString("de5a36e42377c0c7859cad83")
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ciphertext, err := encryptWithNonce(message, nonce, key)
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func TestEncryptDecrypt_FromPython(t *testing.T) {
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ciphertext := "eyJhbGciOiJkaXIiLCJlbmMiOiJBMjU2R0NNIn0..gSRYZeX6eBhlj13w.LOchcxFXwALXE2GqdoSwFJEXdMyEbLfLKV9geXr17WrAN-nH7ya1VQ_Y6ebT1w.2eyLaTUfc_rpKaZr4-5I1Q"
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key := DeriveKey("secr3t password", "https://ntfy.sh/mysecret")
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plaintext, err := Decrypt(ciphertext, key)
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require.Nil(t, err)
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require.Equal(t, "MQS2K9l3G8YoLccJooY64kDeWjbkI3fAx4WcrYNtbz4p8Q==", ciphertext)
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}
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func TestEncryptExpectedOutput(t *testing.T) {
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// These values are taken from https://docs.pushbullet.com/#encryption, meaning that
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// all of this is compatible with how Pushbullet encrypts
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encryptedMessage := "MSfJxxY5YdjttlfUkCaKA57qU9SuCN8+ZhYg/xieI+lDnQ=="
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key, _ := base64.StdEncoding.DecodeString("1sW28zp7CWv5TtGjlQpDHHG4Cbr9v36fG5o4f74LsKg=")
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plaintext, err := Decrypt(encryptedMessage, key)
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require.Nil(t, err)
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require.Equal(t, "meow!", plaintext)
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require.Equal(t, `{"message":"Python says hi","tags":["secret"]}`, plaintext)
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}
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@ -0,0 +1,46 @@
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<?php
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$message = [
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"message" => "Secret!",
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"priority" => 5
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];
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$plaintext = json_encode($message);
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$key = deriveKey("secr3t password", "https://ntfy.sh/mysecret");
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$ciphertext = encrypt($plaintext, $key);
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file_get_contents('https://ntfy.sh/mysecret', false, stream_context_create([
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'http' => [
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'method' => 'POST', // PUT also works
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'header' =>
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"Content-Type: text/plain\r\n" .
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"Encryption: jwe",
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'content' => $ciphertext
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]
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]));
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function deriveKey($password, $topicUrl)
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{
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$salt = hex2bin(hash("sha256", $topicUrl));
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return openssl_pbkdf2($password, $salt, 32, 50000, "sha256");
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}
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function encrypt(string $plaintext, string $key): string
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{
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$encodedHeader = base64url_encode(json_encode(["alg" => "dir", "enc" => "A256GCM"]));
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$iv = openssl_random_pseudo_bytes(12); // GCM is used with a 96-bit IV
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$aad = $encodedHeader;
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$tag = null;
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$content = openssl_encrypt($plaintext, "aes-256-gcm", $key, OPENSSL_RAW_DATA, $iv, $tag, $aad);
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return
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$encodedHeader . "." .
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"." . // No content encryption key (CEK) in "dir" mode
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base64url_encode($iv) . "." .
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base64url_encode($content) . "." .
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base64url_encode($tag);
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}
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function base64url_encode($input)
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{
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return str_replace('=', '', strtr(base64_encode($input), '+/', '-_'));
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}
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@ -0,0 +1,42 @@
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#!/usr/bin/env python3
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import requests
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import json
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from base64 import b64encode, urlsafe_b64encode, b64decode
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from Crypto.Cipher import AES
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from Crypto.Random import get_random_bytes
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from Crypto.Protocol.KDF import PBKDF2
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from Crypto.Hash import SHA256
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from Crypto.Random import get_random_bytes
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def derive_key(password, topic_url):
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salt = SHA256.new(data=topic_url.encode('utf-8')).digest()
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return PBKDF2(password, salt, 32, count=50000, hmac_hash_module=SHA256)
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def encrypt(plaintext, key):
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encoded_header = b64urlencode('{"alg":"dir","enc":"A256GCM"}'.encode('utf-8'))
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iv = get_random_bytes(12) # GCM is used with a 96-bit IV
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aad = encoded_header
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cipher = AES.new(key, AES.MODE_GCM, nonce=iv)
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cipher.update(aad.encode('utf-8'))
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ciphertext, tag = cipher.encrypt_and_digest(plaintext.encode('utf-8'))
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return "{header}..{iv}.{ciphertext}.{tag}".format(
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header = encoded_header,
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iv = b64urlencode(iv),
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ciphertext = b64urlencode(ciphertext),
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tag = b64urlencode(tag)
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)
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def b64urlencode(b):
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return urlsafe_b64encode(b).decode('utf-8').replace("=", "")
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key = derive_key("secr3t password", "https://ntfy.sh/mysecret")
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ciphertext = encrypt('{"message":"Python says hi","tags":["secret"]}', key)
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resp = requests.post("https://ntfy.sh/mysecret",
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data=ciphertext,
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headers={
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"Encryption": "jwe"
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})
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resp.raise_for_status()
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@ -0,0 +1,2 @@
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requests
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pycryptodome
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