From 36faab761dcb13c3cade1776680800a5aee15d85 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Matev=C5=BE=20Jekovec?= <matevz@oasisprotocol.org>
Date: Thu, 18 May 2023 13:24:36 +0200
Subject: [PATCH] feat(wallet): Add sr25519-adr8 and sr25519-raw support

---
 wallet/file/file.go    | 20 ++++++++++++----
 wallet/file/sr25519.go | 53 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+), 4 deletions(-)
 create mode 100644 wallet/file/sr25519.go

diff --git a/wallet/file/file.go b/wallet/file/file.go
index 4dfd1b2e..6eea1e7c 100644
--- a/wallet/file/file.go
+++ b/wallet/file/file.go
@@ -45,12 +45,12 @@ const (
 // SupportedAlgorithmsForImport returns the algorithms supported by the given import kind.
 func SupportedAlgorithmsForImport(kind *wallet.ImportKind) []string {
 	if kind == nil {
-		return []string{wallet.AlgorithmEd25519Adr8, wallet.AlgorithmEd25519Raw, wallet.AlgorithmSecp256k1Bip44, wallet.AlgorithmSecp256k1Raw, wallet.AlgorithmSr25519Raw}
+		return []string{wallet.AlgorithmEd25519Adr8, wallet.AlgorithmEd25519Raw, wallet.AlgorithmSecp256k1Bip44, wallet.AlgorithmSecp256k1Raw, wallet.AlgorithmSr25519Adr8, wallet.AlgorithmSr25519Raw}
 	}
 
 	switch *kind {
 	case wallet.ImportKindMnemonic:
-		return []string{wallet.AlgorithmEd25519Adr8, wallet.AlgorithmSecp256k1Bip44}
+		return []string{wallet.AlgorithmEd25519Adr8, wallet.AlgorithmSecp256k1Bip44, wallet.AlgorithmSr25519Adr8}
 	case wallet.ImportKindPrivateKey:
 		return []string{wallet.AlgorithmEd25519Raw, wallet.AlgorithmSecp256k1Raw, wallet.AlgorithmSr25519Raw}
 	default:
@@ -192,7 +192,7 @@ func (af *fileAccountFactory) PrettyKind(rawCfg map[string]interface{}) string {
 	// In case of ADR8 or BIP44 show the keypair number.
 	var number string
 	switch cfg.Algorithm {
-	case wallet.AlgorithmEd25519Adr8, wallet.AlgorithmSecp256k1Bip44:
+	case wallet.AlgorithmEd25519Adr8, wallet.AlgorithmSecp256k1Bip44, wallet.AlgorithmSr25519Adr8:
 		number = fmt.Sprintf(":%d", cfg.Number)
 	}
 	return fmt.Sprintf("%s (%s%s)", Kind, cfg.Algorithm, number)
@@ -429,7 +429,7 @@ func (af *fileAccountFactory) Import(name string, passphrase string, rawCfg map[
 	switch src.Kind {
 	case wallet.ImportKindMnemonic:
 		switch cfg.Algorithm {
-		case wallet.AlgorithmEd25519Adr8, wallet.AlgorithmSecp256k1Bip44:
+		case wallet.AlgorithmEd25519Adr8, wallet.AlgorithmSecp256k1Bip44, wallet.AlgorithmSr25519Adr8:
 		default:
 			return nil, fmt.Errorf("algorithm '%s' does not support import from mnemonic", cfg.Algorithm)
 		}
@@ -520,6 +520,18 @@ func newAccount(state *secretState, cfg *accountConfig) (wallet.Account, error)
 			return nil, fmt.Errorf("failed to initialize signer: %w", err)
 		}
 
+		return &fileAccount{
+			cfg:    cfg,
+			state:  state,
+			signer: signer,
+		}, nil
+	case wallet.AlgorithmSr25519Adr8:
+		// For Sr25519 use the ADR 0008 derivation scheme.
+		signer, err := Sr25519FromMnemonic(state.Data, cfg.Number)
+		if err != nil {
+			return nil, fmt.Errorf("failed to initialize signer: %w", err)
+		}
+
 		return &fileAccount{
 			cfg:    cfg,
 			state:  state,
diff --git a/wallet/file/sr25519.go b/wallet/file/sr25519.go
new file mode 100644
index 00000000..4bb27b73
--- /dev/null
+++ b/wallet/file/sr25519.go
@@ -0,0 +1,53 @@
+package file
+
+import (
+	"fmt"
+
+	"github.com/oasisprotocol/oasis-core/go/common/crypto/sakg"
+	"github.com/oasisprotocol/oasis-core/go/common/crypto/signature"
+	"github.com/oasisprotocol/oasis-core/go/common/crypto/slip10"
+	sdkSignature "github.com/oasisprotocol/oasis-sdk/client-sdk/go/crypto/signature"
+	"github.com/oasisprotocol/oasis-sdk/client-sdk/go/crypto/signature/sr25519"
+	"github.com/tyler-smith/go-bip39"
+)
+
+// Sr25519FromMnemonic derives a signer using ADR-8 from given mnemonic.
+func Sr25519FromMnemonic(mnemonic string, number uint32) (sdkSignature.Signer, error) {
+	if number > sakg.MaxAccountKeyNumber {
+		return nil, fmt.Errorf(
+			"sakg: invalid key number: %d (maximum: %d)",
+			number,
+			sakg.MaxAccountKeyNumber,
+		)
+	}
+
+	if !bip39.IsMnemonicValid(mnemonic) {
+		return nil, fmt.Errorf("sakg: invalid mnemonic")
+	}
+
+	seed := bip39.NewSeed(mnemonic, "")
+
+	signer, chainCode, err := slip10.NewMasterKey(seed)
+	if err != nil {
+		return nil, fmt.Errorf("sakg: error deriving master key: %w", err)
+	}
+
+	pathStr := fmt.Sprintf("%s/%d'", sakg.BIP32PathPrefix, number)
+	path, err := sakg.NewBIP32Path(pathStr)
+	if err != nil {
+		return nil, fmt.Errorf("sakg: error creating BIP-0032 path %s: %w", pathStr, err)
+	}
+
+	for _, index := range path {
+		signer, chainCode, err = slip10.NewChildKey(signer, chainCode, index)
+		if err != nil {
+			return nil, fmt.Errorf("sakg: error deriving child key: %w", err)
+		}
+	}
+
+	sr25519signer, err := sr25519.NewSigner(signer.(signature.UnsafeSigner).UnsafeBytes())
+	if err != nil {
+		return nil, err
+	}
+	return sr25519signer, nil
+}