chore: crypto/xsalsa20symmetric: remove dependency on tendermint core (#11027)

The xsalsa20symmetric package is otherwise unused in Tendermint Core.
Move the dependency to a subpackage of crypto and update the imports.

No functional changes.

CHANGELOG.md

@@ -176,6 +176,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * [\#10842](https://github.com/cosmos/cosmos-sdk/pull/10842) Fix error when `--generate-only`, `--max-msgs` fags set while executing `WithdrawAllRewards` command.
 * [\#10897](https://github.com/cosmos/cosmos-sdk/pull/10897) Fix: set a non-zero value on gas overflow.
 * [#9790](https://github.com/cosmos/cosmos-sdk/pull/10687) Fix behavior of `DecCoins.MulDecTruncate`.
+* (crypto) [#11027] Remove dependency on Tendermint core for xsalsa20symmetric.
 
 ### State Machine Breaking
 
@@ -191,7 +192,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * [#10770](https://github.com/cosmos/cosmos-sdk/pull/10770) revert tx when block gas limit exceeded
 * [\#10868](https://github.com/cosmos/cosmos-sdk/pull/10868) Bump gov to v1beta2. Both v1beta1 and v1beta2 queries and Msgs are accepted.
 
- ### Deprecated
+### Deprecated
 
 * (x/upgrade) [\#9906](https://github.com/cosmos/cosmos-sdk/pull/9906) Deprecate `UpgradeConsensusState` gRPC query since this functionality is only used for IBC, which now has its own [IBC replacement](https://github.com/cosmos/ibc-go/blob/2c880a22e9f9cc75f62b527ca94aa75ce1106001/proto/ibc/core/client/v1/query.proto#L54)
 

crypto/armor.go

@@ -8,11 +8,11 @@ import (
 
 	"github.com/tendermint/crypto/bcrypt"
 	"github.com/tendermint/tendermint/crypto"
-	"github.com/tendermint/tendermint/crypto/xsalsa20symmetric"
 	"golang.org/x/crypto/openpgp/armor" // nolint: staticcheck
 
 	"github.com/cosmos/cosmos-sdk/codec/legacy"
 	cryptotypes "github.com/cosmos/cosmos-sdk/crypto/types"
+	"github.com/cosmos/cosmos-sdk/crypto/xsalsa20symmetric"
 	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
 )
 

crypto/xsalsa20symmetric/symmetric.go

@@ -0,0 +1,63 @@
+package xsalsa20symmetric
+
+import (
+	"crypto/rand"
+	"errors"
+	"fmt"
+
+	"golang.org/x/crypto/nacl/secretbox"
+)
+
+// TODO, make this into a struct that implements crypto.Symmetric.
+
+const nonceLen = 24
+const secretLen = 32
+
+// secret must be 32 bytes long. Use something like Sha256(Bcrypt(passphrase))
+// The ciphertext is (secretbox.Overhead + 24) bytes longer than the plaintext.
+func EncryptSymmetric(plaintext []byte, secret []byte) (ciphertext []byte) {
+	if len(secret) != secretLen {
+		panic(fmt.Sprintf("Secret must be 32 bytes long, got len %v", len(secret)))
+	}
+	nonce := randBytes(nonceLen)
+	nonceArr := [nonceLen]byte{}
+	copy(nonceArr[:], nonce)
+	secretArr := [secretLen]byte{}
+	copy(secretArr[:], secret)
+	ciphertext = make([]byte, nonceLen+secretbox.Overhead+len(plaintext))
+	copy(ciphertext, nonce)
+	secretbox.Seal(ciphertext[nonceLen:nonceLen], plaintext, &nonceArr, &secretArr)
+	return ciphertext
+}
+
+// secret must be 32 bytes long. Use something like Sha256(Bcrypt(passphrase))
+// The ciphertext is (secretbox.Overhead + 24) bytes longer than the plaintext.
+func DecryptSymmetric(ciphertext []byte, secret []byte) (plaintext []byte, err error) {
+	if len(secret) != secretLen {
+		panic(fmt.Sprintf("Secret must be 32 bytes long, got len %v", len(secret)))
+	}
+	if len(ciphertext) <= secretbox.Overhead+nonceLen {
+		return nil, errors.New("ciphertext is too short")
+	}
+	nonce := ciphertext[:nonceLen]
+	nonceArr := [nonceLen]byte{}
+	copy(nonceArr[:], nonce)
+	secretArr := [secretLen]byte{}
+	copy(secretArr[:], secret)
+	plaintext = make([]byte, len(ciphertext)-nonceLen-secretbox.Overhead)
+	_, ok := secretbox.Open(plaintext[:0], ciphertext[nonceLen:], &nonceArr, &secretArr)
+	if !ok {
+		return nil, errors.New("ciphertext decryption failed")
+	}
+	return plaintext, nil
+}
+
+// This only uses the OS's randomness
+func randBytes(numBytes int) []byte {
+	b := make([]byte, numBytes)
+	_, err := rand.Read(b)
+	if err != nil {
+		panic(err)
+	}
+	return b
+}

crypto/xsalsa20symmetric/symmetric_test.go

@@ -0,0 +1,45 @@
+package xsalsa20symmetric
+
+import (
+	"crypto/sha256"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"golang.org/x/crypto/bcrypt"
+)
+
+func TestSimple(t *testing.T) {
+
+	plaintext := []byte("sometext")
+	secret := []byte("somesecretoflengththirtytwo===32")
+	ciphertext := EncryptSymmetric(plaintext, secret)
+	plaintext2, err := DecryptSymmetric(ciphertext, secret)
+
+	require.NoError(t, err, "%+v", err)
+	assert.Equal(t, plaintext, plaintext2)
+}
+
+func TestSimpleWithKDF(t *testing.T) {
+
+	plaintext := []byte("sometext")
+	secretPass := []byte("somesecret")
+	secret, err := bcrypt.GenerateFromPassword(secretPass, 12)
+	if err != nil {
+		t.Error(err)
+	}
+	secret = sha256Sum(secret)
+
+	ciphertext := EncryptSymmetric(plaintext, secret)
+	plaintext2, err := DecryptSymmetric(ciphertext, secret)
+
+	require.NoError(t, err, "%+v", err)
+	assert.Equal(t, plaintext, plaintext2)
+}
+
+func sha256Sum(bytes []byte) []byte {
+	hasher := sha256.New()
+	hasher.Write(bytes)
+	return hasher.Sum(nil)
+}