AES en/decryption precompiles (#274)

* add aes en/decrypt precompiles (suave gen output missing)

* run suave gen

* fix bugs

* fix aes buffer encoding, use GCM, add AES precompile tests

* add clarifying comment

* set better example in test

* remove commented code

* catch unhandled err in aes test

core/vm/contracts_suave.go

@@ -3,6 +3,8 @@ package vm
 import (
 	"bytes"
 	"context"
+	"crypto/aes"
+	"crypto/cipher"
 	"crypto/rand"
 	"fmt"
 	"io"
@@ -347,3 +349,46 @@ func (s *suaveRuntime) contextGet(key string) ([]byte, error) {
 	}
 	return val, nil
 }
+
+func (s *suaveRuntime) aesEncrypt(key []byte, message []byte) ([]byte, error) {
+	// force 32-byte key for best security
+	keyBytes := make([]byte, 32)
+	copy(keyBytes[:], key[:])
+	c, err := aes.NewCipher(keyBytes)
+	if err != nil {
+		return nil, err
+	}
+	gcm, err := cipher.NewGCM(c)
+	if err != nil {
+		return nil, err
+	}
+	nonce := make([]byte, gcm.NonceSize())
+	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
+		return nil, err
+	}
+	buf := gcm.Seal(nonce, nonce, message, nil)
+	return buf, nil
+}
+
+func (s *suaveRuntime) aesDecrypt(key []byte, ciphertext []byte) ([]byte, error) {
+	keyBytes := make([]byte, 32)
+	copy(keyBytes[:], key[:])
+	c, err := aes.NewCipher(keyBytes)
+	if err != nil {
+		return nil, err
+	}
+	gcm, err := cipher.NewGCM(c)
+	if err != nil {
+		return nil, err
+	}
+	nonceSize := gcm.NonceSize()
+	if len(ciphertext) < nonceSize {
+		return nil, fmt.Errorf("ciphertext too short")
+	}
+	nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
+	plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		return nil, err
+	}
+	return plaintext, nil
+}

core/vm/contracts_suave_runtime_adapter_test.go

@@ -103,6 +103,14 @@ func (m *mockRuntime) randomBytes(length uint8) ([]byte, error) {
 	return bytes, nil
 }
 
+func (m *mockRuntime) aesEncrypt(key []byte, message []byte) ([]byte, error) {
+	return []byte{0x1}, nil
+}
+
+func (m *mockRuntime) aesDecrypt(key []byte, ciphertext []byte) ([]byte, error) {
+	return []byte{0x1}, nil
+}
+
 func TestRuntimeAdapter(t *testing.T) {
 	adapter := &SuaveRuntimeAdapter{
 		impl: &mockRuntime{},

core/vm/contracts_suave_test.go

@@ -2,6 +2,7 @@ package vm
 
 import (
 	"context"
+	"crypto/rand"
 	"math/big"
 	"net/http"
 	"net/http/httptest"
@@ -16,6 +17,7 @@ import (
 	suave "github.com/ethereum/go-ethereum/suave/core"
 	"github.com/ethereum/go-ethereum/suave/cstore"
 	"github.com/stretchr/testify/require"
+	"golang.org/x/crypto/scrypt"
 )
 
 type mockSuaveBackend struct {
@@ -137,6 +139,28 @@ func TestSuave_DataRecordWorkflow(t *testing.T) {
 	}
 }
 
+func TestSuave_AESPrecompiles(t *testing.T) {
+	b := newTestBackend(t)
+
+	message := []byte("hello world")
+
+	// safely generate a 32-byte secret
+	salt := make([]byte, 32)
+	_, err := rand.Read(salt)
+	require.NoError(t, err)
+	pk, err := scrypt.Key([]byte("some password"), salt, 32768, 8, 1, 32)
+	require.NoError(t, err)
+
+	// note: any 32-byte value will do for pk
+	// if your secret is not 32 bytes long, it's right-padded with 0s
+	ciphertext, err := b.aesEncrypt(pk, message)
+	require.NoError(t, err)
+
+	decrypted, err := b.aesDecrypt(pk, ciphertext)
+	require.NoError(t, err)
+	require.Equal(t, message, decrypted)
+}
+
 func TestSuave_ConfStoreWorkflow(t *testing.T) {
 	b := newTestBackend(t)
 

suave/gen/suave_spec.yaml

@@ -445,3 +445,33 @@ functions:
         - name: value
           type: bytes
           description: "Randomly-generated bytes"
+  - name: aesEncrypt
+    address: "0x000000000000000000000000000000005670000e"
+    description: "Encrypts a message using given bytes as a cipher."
+    input:
+      - name: key
+        type: bytes
+        description: "Private key used to encrypt the message"
+      - name: message
+        type: bytes
+        description: "Message to encrypt"
+    output:
+      fields:
+        - name: ciphertext
+          type: bytes
+          description: "Encrypted message"
+  - name: aesDecrypt
+    address: "0x000000000000000000000000000000005670000d"
+    description: "Decrypts a message using given bytes as a cipher."
+    input:
+      - name: key
+        type: bytes
+        description: "Private key used to decrypt the ciphertext"
+      - name: ciphertext
+        type: bytes
+        description: "Message to decrypt"
+    output:
+      fields:
+        - name: message
+          type: bytes
+          description: "Decrypted message"

suave/sol/libraries/Suave.sol

@@ -108,6 +108,10 @@ library Suave {
 
     address public constant IS_CONFIDENTIAL_ADDR = 0x0000000000000000000000000000000042010000;
 
+    address public constant AES_DECRYPT = 0x000000000000000000000000000000005670000D;
+
+    address public constant AES_ENCRYPT = 0x000000000000000000000000000000005670000e;
+
     address public constant BUILD_ETH_BLOCK = 0x0000000000000000000000000000000042100001;
 
     address public constant BUILD_ETH_BLOCK_TO = 0x0000000000000000000000000000000042100006;
@@ -165,6 +169,32 @@ library Suave {
         }
     }
 
+    /// @notice Decrypts a message using given bytes as a cipher.
+    /// @param key Private key used to decrypt the ciphertext
+    /// @param ciphertext Message to decrypt
+    /// @return message Decrypted message
+    function aesDecrypt(bytes memory key, bytes memory ciphertext) internal returns (bytes memory) {
+        (bool success, bytes memory data) = AES_DECRYPT.call(abi.encode(key, ciphertext));
+        if (!success) {
+            revert PeekerReverted(AES_DECRYPT, data);
+        }
+
+        return abi.decode(data, (bytes));
+    }
+
+    /// @notice Encrypts a message using given bytes as a cipher.
+    /// @param key Private key used to encrypt the message
+    /// @param message Message to encrypt
+    /// @return ciphertext Encrypted message
+    function aesEncrypt(bytes memory key, bytes memory message) internal returns (bytes memory) {
+        (bool success, bytes memory data) = AES_ENCRYPT.call(abi.encode(key, message));
+        if (!success) {
+            revert PeekerReverted(AES_ENCRYPT, data);
+        }
+
+        return abi.decode(data, (bytes));
+    }
+
     /// @notice Constructs an Ethereum block based on the provided data records. No blobs are returned.
     /// @param blockArgs Arguments to build the block
     /// @param dataId ID of the data record with mev-share bundle data