12f97ef51f
The keying modules tries to solve two problems, the lack of key separation and the lack of AEAD being used for encryption. The currently used `secrets` doesn't provide this and is hard to adjust to provide this functionality. For encryption, the additional data is now a parameter that can be used, as the underlying primitive is an AEAD constructions. This allows for context binding to happen and can be seen as defense-in-depth; it ensures that if a value X is encrypted for context Y (e.g. ID=3, Column="private_key") it will only decrypt if that context Y is also given in the Decrypt function. This makes confused deputy attack harder to exploit.[^1] For key separation, HKDF is used to derives subkeys from some IKM, which is the value of the `[service].SECRET_KEY` config setting. The context for subkeys are hardcoded, any variable should be shuffled into the the additional data parameter when encrypting. [^1]: This is still possible, because the used AEAD construction is not key-comitting. For Forgejo's current use-case this risk is negligible, because the subkeys aren't known to a malicious user (which is required for such attack), unless they also have access to the IKM (at which point you can assume the whole system is compromised). See https://scottarc.blog/2022/10/17/lucid-multi-key-deputies-require-commitment/
96 lines
2.6 KiB
Go
96 lines
2.6 KiB
Go
// Copyright 2024 The Forgejo Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package keying_test
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import (
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"testing"
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"code.gitea.io/gitea/modules/keying"
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"github.com/stretchr/testify/assert"
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"github.com/stretchr/testify/require"
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"golang.org/x/crypto/chacha20poly1305"
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)
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func TestKeying(t *testing.T) {
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t.Run("Not initalized", func(t *testing.T) {
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assert.Panics(t, func() {
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keying.DeriveKey(keying.Context("TESTING"))
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})
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})
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t.Run("Initialization", func(t *testing.T) {
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keying.Init([]byte{0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07})
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})
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t.Run("Context seperation", func(t *testing.T) {
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key1 := keying.DeriveKey(keying.Context("TESTING"))
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key2 := keying.DeriveKey(keying.Context("TESTING2"))
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ciphertext := key1.Encrypt([]byte("This is for context TESTING"), nil)
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plaintext, err := key2.Decrypt(ciphertext, nil)
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require.Error(t, err)
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assert.Empty(t, plaintext)
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plaintext, err = key1.Decrypt(ciphertext, nil)
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require.NoError(t, err)
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assert.EqualValues(t, "This is for context TESTING", plaintext)
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})
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context := keying.Context("TESTING PURPOSES")
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plainText := []byte("Forgejo is run by [Redacted]")
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var cipherText []byte
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t.Run("Encrypt", func(t *testing.T) {
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key := keying.DeriveKey(context)
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cipherText = key.Encrypt(plainText, []byte{0x05, 0x06})
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cipherText2 := key.Encrypt(plainText, []byte{0x05, 0x06})
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// Ensure ciphertexts don't have an determistic output.
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assert.NotEqualValues(t, cipherText, cipherText2)
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})
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t.Run("Decrypt", func(t *testing.T) {
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key := keying.DeriveKey(context)
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t.Run("Succesful", func(t *testing.T) {
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convertedPlainText, err := key.Decrypt(cipherText, []byte{0x05, 0x06})
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require.NoError(t, err)
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assert.EqualValues(t, plainText, convertedPlainText)
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})
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t.Run("Not enougn additional data", func(t *testing.T) {
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plainText, err := key.Decrypt(cipherText, []byte{0x05})
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require.Error(t, err)
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assert.Empty(t, plainText)
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})
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t.Run("Too much additional data", func(t *testing.T) {
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plainText, err := key.Decrypt(cipherText, []byte{0x05, 0x06, 0x07})
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require.Error(t, err)
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assert.Empty(t, plainText)
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})
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t.Run("Incorrect nonce", func(t *testing.T) {
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// Flip the first byte of the nonce.
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cipherText[0] = ^cipherText[0]
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plainText, err := key.Decrypt(cipherText, []byte{0x05, 0x06})
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require.Error(t, err)
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assert.Empty(t, plainText)
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})
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t.Run("Incorrect ciphertext", func(t *testing.T) {
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assert.Panics(t, func() {
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key.Decrypt(nil, nil)
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})
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assert.Panics(t, func() {
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cipherText := make([]byte, chacha20poly1305.NonceSizeX)
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key.Decrypt(cipherText, nil)
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})
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})
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})
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}
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