Add NewAccountFromEntropy common utility

go.mod

@@ -4,6 +4,7 @@ go 1.26.0
 
 require (
 	filippo.io/edwards25519 v1.1.0
+	github.com/anyproto/go-slip10 v1.0.1
 	github.com/aws/aws-sdk-go-v2 v1.41.9
 	github.com/aws/aws-sdk-go-v2/feature/rds/auth v1.6.25
 	github.com/aws/aws-sdk-go-v2/service/s3 v1.102.2
@@ -30,6 +31,7 @@ require (
 	github.com/spaolacci/murmur3 v1.1.0
 	github.com/spf13/viper v1.7.0
 	github.com/stretchr/testify v1.8.4
+	github.com/tyler-smith/go-bip39 v1.1.0
 	github.com/ybbus/jsonrpc v2.1.2+incompatible
 	go.uber.org/zap v1.27.1
 	golang.org/x/image v0.36.0

go.sum

@@ -54,6 +54,8 @@ github.com/Nvveen/Gotty v0.0.0-20120604004816-cd527374f1e5/go.mod h1:lmUJ/7eu/Q8
 github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAElWljhcU=
 github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
 github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
+github.com/anyproto/go-slip10 v1.0.1 h1:Pa/OpYoOE668fip4ygAd4T07chLBx4XoBa5fwnGq0/M=
+github.com/anyproto/go-slip10 v1.0.1/go.mod h1:BCmIlM1KB8wX6K4/8pOvxPl9oVKfEvZ5vsmO5rkK6vg=
 github.com/armon/circbuf v0.0.0-20150827004946-bbbad097214e/go.mod h1:3U/XgcO3hCbHZ8TKRvWD2dDTCfh9M9ya+I9JpbB7O8o=
 github.com/armon/go-metrics v0.0.0-20180917152333-f0300d1749da/go.mod h1:Q73ZrmVTwzkszR9V5SSuryQ31EELlFMUz1kKyl939pY=
 github.com/armon/go-radix v0.0.0-20180808171621-7fddfc383310/go.mod h1:ufUuZ+zHj4x4TnLV4JWEpy2hxWSpsRywHrMgIH9cCH8=
@@ -468,6 +470,8 @@ github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXl
 github.com/subosito/gotenv v1.2.0 h1:Slr1R9HxAlEKefgq5jn9U+DnETlIUa6HfgEzj0g5d7s=
 github.com/subosito/gotenv v1.2.0/go.mod h1:N0PQaV/YGNqwC0u51sEeR/aUtSLEXKX9iv69rRypqCw=
 github.com/tmc/grpc-websocket-proxy v0.0.0-20190109142713-0ad062ec5ee5/go.mod h1:ncp9v5uamzpCO7NfCPTXjqaC+bZgJeR0sMTm6dMHP7U=
+github.com/tyler-smith/go-bip39 v1.1.0 h1:5eUemwrMargf3BSLRRCalXT93Ns6pQJIjYQN2nyfOP8=
+github.com/tyler-smith/go-bip39 v1.1.0/go.mod h1:gUYDtqQw1JS3ZJ8UWVcGTGqqr6YIN3CWg+kkNaLt55U=
 github.com/xeipuuv/gojsonpointer v0.0.0-20180127040702-4e3ac2762d5f h1:J9EGpcZtP0E/raorCMxlFGSTBrsSlaDGf3jU/qvAE2c=
 github.com/xeipuuv/gojsonpointer v0.0.0-20180127040702-4e3ac2762d5f/go.mod h1:N2zxlSyiKSe5eX1tZViRH5QA0qijqEDrYZiPEAiq3wU=
 github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415 h1:EzJWgHovont7NscjpAxXsDA8S8BMYve8Y5+7cuRE7R0=

ocp/common/account.go

@@ -7,7 +7,9 @@ import (
 	"fmt"
 
 	"filippo.io/edwards25519"
+	slip10 "github.com/anyproto/go-slip10"
 	"github.com/pkg/errors"
+	bip39 "github.com/tyler-smith/go-bip39"
 
 	commonpb "github.com/code-payments/ocp-protobuf-api/generated/go/common/v1"
 
@@ -21,6 +23,10 @@ import (
 	"github.com/code-payments/ocp-server/solana/vm"
 )
 
+// solanaDerivationPath is the standard BIP-44 derivation path for Solana
+// accounts. All components are hardened per SLIP-0010 for ed25519.
+const solanaDerivationPath = "m/44'/501'/0'/0'"
+
 type Account struct {
 	publicKey  *Key
 	privateKey *Key // Optional
@@ -139,6 +145,41 @@ func NewAccountFromPrivateKeyString(privateKey string) (*Account, error) {
 	return NewAccountFromPrivateKey(key)
 }
 
+// NewAccountFromEntropy deterministically derives an account from a 16-byte
+// BIP-39 entropy value following the standard Solana key derivation used by Code
+// and other wallets:
+//
+//	entropy -> BIP-39 mnemonic -> BIP-39 seed (PBKDF2) -> SLIP-0010 ed25519 key
+//	at m/44'/501'/0'/0'
+//
+// The same entropy always produces the same account, while different entropy
+// values produce unrelated accounts.
+func NewAccountFromEntropy(entropy []byte) (*Account, error) {
+	if len(entropy) != 16 {
+		return nil, errors.New("entropy must be 16 bytes")
+	}
+
+	mnemonic, err := bip39.NewMnemonic(entropy)
+	if err != nil {
+		return nil, errors.Wrap(err, "error deriving mnemonic from entropy")
+	}
+
+	seed := bip39.NewSeed(mnemonic, "")
+
+	node, err := slip10.DeriveForPath(solanaDerivationPath, seed)
+	if err != nil {
+		return nil, errors.Wrap(err, "error deriving key from seed")
+	}
+	_, privateKey := node.Keypair()
+
+	derivedKey, err := NewKeyFromBytes(privateKey)
+	if err != nil {
+		return nil, errors.Wrap(err, "error creating private key from entropy")
+	}
+
+	return NewAccountFromPrivateKey(derivedKey)
+}
+
 func NewAccountFromProto(proto *commonpb.SolanaAccountId) (*Account, error) {
 	publicKey, err := NewKeyFromBytes(proto.Value)
 	if err != nil {

ocp/common/account_test.go

@@ -3,11 +3,14 @@ package common
 import (
 	"context"
 	"crypto/ed25519"
+	"encoding/hex"
 	"testing"
 
+	slip10 "github.com/anyproto/go-slip10"
 	"github.com/mr-tron/base58/base58"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	bip39 "github.com/tyler-smith/go-bip39"
 
 	commonpb "github.com/code-payments/ocp-protobuf-api/generated/go/common/v1"
 
@@ -79,6 +82,58 @@ func TestAccountWithPrivateKey(t *testing.T) {
 	}
 }
 
+func TestNewAccountFromEntropy(t *testing.T) {
+	// All-zeros BIP-39 entropy maps to the canonical "abandon ... about"
+	// mnemonic, whose Solana account at m/44'/501'/0'/0' (empty passphrase) is a
+	// well-known address shared with standard wallets (Phantom, Solana CLI).
+	entropy := make([]byte, 16)
+
+	account, err := NewAccountFromEntropy(entropy)
+	require.NoError(t, err)
+	require.NotNil(t, account.PrivateKey())
+	assert.Equal(t, "HAgk14JpMQLgt6rVgv7cBQFJWFto5Dqxi472uT3DKpqk", account.PublicKey().ToBase58())
+
+	// The same entropy is deterministic; different entropy is unrelated.
+	again, err := NewAccountFromEntropy(entropy)
+	require.NoError(t, err)
+	assert.Equal(t, account.PublicKey().ToBase58(), again.PublicKey().ToBase58())
+	assert.Equal(t, account.PrivateKey().ToBase58(), again.PrivateKey().ToBase58())
+
+	otherEntropy := make([]byte, 16)
+	otherEntropy[15] = 1
+	other, err := NewAccountFromEntropy(otherEntropy)
+	require.NoError(t, err)
+	assert.NotEqual(t, account.PublicKey().ToBase58(), other.PublicKey().ToBase58())
+
+	// Only 16-byte entropy is accepted.
+	for _, badLen := range []int{0, 15, 17, 32} {
+		_, err := NewAccountFromEntropy(make([]byte, badLen))
+		assert.Error(t, err)
+	}
+}
+
+// TestNewAccountFromEntropy_SpecVectors anchors each stage of the derivation
+// pipeline to its canonical specification test vector, guarding against a
+// dependency behaving non-standardly.
+func TestNewAccountFromEntropy_SpecVectors(t *testing.T) {
+	// BIP-39: zero entropy -> mnemonic -> seed.
+	mnemonic, err := bip39.NewMnemonic(make([]byte, 16))
+	require.NoError(t, err)
+	assert.Equal(t, "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about", mnemonic)
+	assert.Equal(t,
+		"5eb00bbddcf069084889a8ab9155568165f5c453ccb85e70811aaed6f6da5fc19a5ac40b389cd370d086206dec8aa6c43daea6690f20ad3d8d48b2d2ce9e38e4",
+		hex.EncodeToString(bip39.NewSeed(mnemonic, "")),
+	)
+
+	// SLIP-0010 ed25519 test vector 1 (seed 000102...0f), deepest path.
+	seed, err := hex.DecodeString("000102030405060708090a0b0c0d0e0f")
+	require.NoError(t, err)
+	node, err := slip10.DeriveForPath("m/0'/1'/2'/2'/1000000000'", seed)
+	require.NoError(t, err)
+	_, privateKey := node.Keypair()
+	assert.Equal(t, "8f94d394a8e8fd6b1bc2f3f49f5c47e385281d5c17e65324b0f62483e37e8793", hex.EncodeToString(privateKey.Seed()))
+}
+
 func TestInvalidAccount(t *testing.T) {
 	stringValue := "invalid-account"
 	bytesValue := []byte(stringValue)