Add support for offline transaction signing

cmd/siac/main.go

@@ -21,6 +21,7 @@ var (
 	renterDownloadAsync    bool   // Downloads files asynchronously
 	renterListVerbose      bool   // Show additional info about uploaded files.
 	renterShowHistory      bool   // Show download history in addition to download queue.
+	walletRawTxn           bool   // Encode/decode transactions in base64-encoded binary.
 )
 
 var (
@@ -106,14 +107,16 @@ func main() {
 
 	root.AddCommand(walletCmd)
 	walletCmd.AddCommand(walletAddressCmd, walletAddressesCmd, walletChangepasswordCmd, walletInitCmd, walletInitSeedCmd,
-		walletLoadCmd, walletLockCmd, walletSeedsCmd, walletSendCmd, walletSweepCmd,
-		walletBalanceCmd, walletTransactionsCmd, walletUnlockCmd)
+		walletLoadCmd, walletLockCmd, walletSeedsCmd, walletSendCmd, walletSweepCmd, walletSignCmd,
+		walletBalanceCmd, walletBroadcastCmd, walletTransactionsCmd, walletUnlockCmd)
 	walletInitCmd.Flags().BoolVarP(&initPassword, "password", "p", false, "Prompt for a custom password")
 	walletInitCmd.Flags().BoolVarP(&initForce, "force", "", false, "destroy the existing wallet and re-encrypt")
 	walletInitSeedCmd.Flags().BoolVarP(&initForce, "force", "", false, "destroy the existing wallet")
 	walletLoadCmd.AddCommand(walletLoad033xCmd, walletLoadSeedCmd, walletLoadSiagCmd)
 	walletSendCmd.AddCommand(walletSendSiacoinsCmd, walletSendSiafundsCmd)
 	walletUnlockCmd.Flags().BoolVarP(&initPassword, "password", "p", false, "Display interactive password prompt even if SIA_WALLET_PASSWORD is set")
+	walletBroadcastCmd.Flags().BoolVarP(&walletRawTxn, "raw", "", false, "Decode transaction as base64 instead of JSON")
+	walletSignCmd.Flags().BoolVarP(&walletRawTxn, "raw", "", false, "Encode signed transaction as base64 instead of JSON")
 
 	root.AddCommand(renterCmd)
 	renterCmd.AddCommand(renterFilesDeleteCmd, renterFilesDownloadCmd,

cmd/siac/walletcmd.go

@@ -1,6 +1,8 @@
 package main
 
 import (
+	"encoding/base64"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"math"
@@ -12,7 +14,12 @@ import (
 	"github.com/spf13/cobra"
 	"golang.org/x/crypto/ssh/terminal"
 
+	"github.com/NebulousLabs/Sia/crypto"
+	"github.com/NebulousLabs/Sia/encoding"
+	"github.com/NebulousLabs/Sia/modules"
+	"github.com/NebulousLabs/Sia/modules/wallet"
 	"github.com/NebulousLabs/Sia/types"
+	"github.com/NebulousLabs/entropy-mnemonics"
 )
 
 var (
@@ -37,6 +44,13 @@ var (
 		Run:   wrap(walletbalancecmd),
 	}
 
+	walletBroadcastCmd = &cobra.Command{
+		Use:   "broadcast [txn]",
+		Short: "Broadcast a transaction",
+		Long:  "Broadcast a transaction to connected peers. The transaction must be valid.",
+		Run:   wrap(walletbroadcastcmd),
+	}
+
 	walletChangepasswordCmd = &cobra.Command{
 		Use:   "change-password",
 		Short: "Change the wallet password",
@@ -148,6 +162,15 @@ Run 'wallet send --help' to see a list of available units.`,
 		Run: wrap(walletsendsiafundscmd),
 	}
 
+	walletSignCmd = &cobra.Command{
+		Use:   "sign [txn] [tosign]",
+		Short: "Sign a transaction",
+		Long: `Sign the specified inputs of a transaction. If siad is running with an
+unlocked wallet, the /wallet/sign API call will be used. Otherwise, sign will
+prompt for the wallet seed, and the signing key(s) will be regenerated.`,
+		Run: walletsigncmd,
+	}
+
 	walletSweepCmd = &cobra.Command{
 		Use:   "sweep",
 		Short: "Sweep siacoins and siafunds from a seed.",
@@ -450,6 +473,29 @@ Estimated Fee:       %v / KB
 		fees.Maximum.Mul64(1e3).HumanString())
 }
 
+// walletbroadcastcmd broadcasts a transaction.
+func walletbroadcastcmd(txnStr string) {
+	var txn types.Transaction
+	var err error
+	if walletRawTxn {
+		var txnBytes []byte
+		txnBytes, err = base64.StdEncoding.DecodeString(txnStr)
+		if err == nil {
+			err = encoding.Unmarshal(txnBytes, &txn)
+		}
+	} else {
+		err = json.Unmarshal([]byte(txnStr), &txn)
+	}
+	if err != nil {
+		die("Could not decode transaction:", err)
+	}
+	err = httpClient.TransactionPoolRawPost(txn, nil)
+	if err != nil {
+		die("Could not broadcast transaction:", err)
+	}
+	fmt.Println("Transaction broadcast successfully")
+}
+
 // walletsweepcmd sweeps coins and funds from a seed.
 func walletsweepcmd() {
 	seed, err := passwordPrompt("Seed: ")
@@ -464,6 +510,57 @@ func walletsweepcmd() {
 	fmt.Printf("Swept %v and %v SF from seed.\n", currencyUnits(swept.Coins), swept.Funds)
 }
 
+// walletsigncmd signs a transaction.
+func walletsigncmd(cmd *cobra.Command, args []string) {
+	if len(args) < 1 || len(args) > 2 {
+		cmd.UsageFunc()(cmd)
+		os.Exit(exitCodeUsage)
+	}
+
+	var txn types.Transaction
+	err := json.Unmarshal([]byte(args[0]), &txn)
+	if err != nil {
+		die("Invalid transaction:", err)
+	}
+
+	var toSign []crypto.Hash
+	if len(args) == 2 {
+		err = json.Unmarshal([]byte(args[1]), &toSign)
+		if err != nil {
+			die("Invalid transaction:", err)
+		}
+	}
+
+	// try API first
+	wspr, err := httpClient.WalletSignPost(txn, toSign)
+	if err == nil {
+		txn = wspr.Transaction
+	} else {
+		// fallback to offline keygen
+		fmt.Println("Signing via API failed: either siad is not running, or your wallet is locked.")
+		fmt.Println("Enter your wallet seed to generate the signing key(s) now and sign without siad.")
+		seedString, err := passwordPrompt("Seed: ")
+		if err != nil {
+			die("Reading seed failed:", err)
+		}
+		seed, err := modules.StringToSeed(seedString, mnemonics.English)
+		if err != nil {
+			die("Invalid seed:", err)
+		}
+		err = wallet.SignTransaction(&txn, seed, toSign)
+		if err != nil {
+			die("Failed to sign transaction:", err)
+		}
+	}
+
+	if walletRawTxn {
+		base64.NewEncoder(base64.StdEncoding, os.Stdout).Write(encoding.Marshal(txn))
+	} else {
+		json.NewEncoder(os.Stdout).Encode(txn)
+	}
+	fmt.Println()
+}
+
 // wallettransactionscmd lists all of the transactions related to the wallet,
 // providing a net flow of siacoins and siafunds for each.
 func wallettransactionscmd() {

doc/API.md

@@ -1263,6 +1263,7 @@ Wallet
 | [/wallet/address](#walletaddress-get)                           | GET       |
 | [/wallet/addresses](#walletaddresses-get)                       | GET       |
 | [/wallet/backup](#walletbackup-get)                             | GET       |
+| [/wallet/changepassword](#walletchangepassword-post)            | POST      |
 | [/wallet/init](#walletinit-post)                                | POST      |
 | [/wallet/init/seed](#walletinitseed-post)                       | POST      |
 | [/wallet/lock](#walletlock-post)                                | POST      |
@@ -1271,13 +1272,14 @@ Wallet
 | [/wallet/siacoins](#walletsiacoins-post)                        | POST      |
 | [/wallet/siafunds](#walletsiafunds-post)                        | POST      |
 | [/wallet/siagkey](#walletsiagkey-post)                          | POST      |
+| [/wallet/sign](#walletsign-post)                                | POST      |
 | [/wallet/sweep/seed](#walletsweepseed-post)                     | POST      |
 | [/wallet/transaction/:___id___](#wallettransactionid-get)       | GET       |
 | [/wallet/transactions](#wallettransactions-get)                 | GET       |
 | [/wallet/transactions/:___addr___](#wallettransactionsaddr-get) | GET       |
 | [/wallet/unlock](#walletunlock-post)                            | POST      |
-| [/wallet/verify/address/:___addr___](#walletverifyaddressaddr-get)  | GET       |
-| [/wallet/changepassword](#walletchangepassword-post)            | POST      |
+| [/wallet/unspent](#walletunspent-get)                           | GET       |
+| [/wallet/verify/address/:___addr___](#walletverifyaddress-get)  | GET       |
 
 For examples and detailed descriptions of request and response parameters,
 refer to [Wallet.md](/doc/api/Wallet.md).
@@ -1367,6 +1369,20 @@ destination
 standard success or error response. See
 [#standard-responses](#standard-responses).
 
+#### /wallet/changepassword  [POST]
+
+changes the wallet's encryption key.
+
+###### Query String Parameters [(with comments)](/doc/api/Wallet.md#query-string-parameters-12)
+```
+encryptionpassword
+newpassword
+```
+
+###### Response
+standard success or error response. See
+[#standard-responses](#standard-responses).
+
 #### /wallet/init [POST]
 
 initializes the wallet. After the wallet has been initialized once, it does
@@ -1518,6 +1534,29 @@ keyfiles
 standard success or error response. See
 [#standard-responses](#standard-responses).
 
+#### /wallet/sign [POST]
+
+Function: Sign a transaction. The wallet will attempt to sign each input
+specified.
+
+###### Request Body
+```
+{
+  "transaction": { }, // types.Transaction
+  "tosign": [
+    "1234567890abcdef0123456789abcdef0123456789abcdef0123456789abcdef",
+    "abcdef0123456789abcdef0123456789abcd1234567890ef0123456789abcdef"
+  ]
+}
+```
+
+###### Response
+```javascript
+{
+  "transaction": { } // types.Transaction
+}
+```
+
 #### /wallet/sweep/seed [POST]
 
 Function: Scan the blockchain for outputs belonging to a seed and send them to
@@ -1650,28 +1689,38 @@ encryptionpassword
 standard success or error response. See
 [#standard-responses](#standard-responses).
 
-#### /wallet/verify/address/:addr [GET]
 
-takes the address specified by :addr and returns a JSON response indicating if the address is valid.
+#### /wallet/unspent [GET]
+
+returns a list of outputs that the wallet can spend.
 
 ###### JSON Response [(with comments)](/doc/api/Wallet.md#json-response-11)
 ```javascript
 {
-	"valid": true
+  "outputs": [
+    {
+      "id": "1234567890abcdef0123456789abcdef0123456789abcdef0123456789abcdef",
+      "fundtype": "siacoin output",
+      "confirmationheight": 50000,
+      "unlockconditions": {
+        "publickeys": [{"algorithm":"ed25519","key":"/XUGj8PxMDkqdae6Js6ubcERxfxnXN7XPjZyANBZH1I="}],
+        "signaturesrequired": 1
+      },
+      "unlockhash": "1234567890abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789ab",
+      "value": "1234" // big int
+    }
+  ]
 }
 ```
 
-#### /wallet/changepassword  [POST]
+#### /wallet/verify/address/:addr [GET]
 
-changes the wallet's encryption key.
+takes the address specified by :addr and returns a JSON response indicating if the address is valid.
 
-###### Query String Parameters [(with comments)](/doc/api/Wallet.md#query-string-parameters-12)
-```
-encryptionpassword
-newpassword
+###### JSON Response [(with comments)](/doc/api/Wallet.md#json-response-11)
+```javascript
+{
+	"valid": true
+}
 ```
 
-###### Response
-standard success or error response. See
-[#standard-responses](#standard-responses).
-

doc/api/Transactionpool.md

@@ -71,7 +71,7 @@ returns the ID for the requested transaction and its raw encoded parents and tra
 
 submits a raw transaction to the transaction pool, broadcasting it to the transaction pool's peers.
 
-###### Query String Parameters [(with comments)](/doc/api/Transactionpool.md#query-string-parameters)
+###### Query String Parameters
 
 ```
 parents     string // raw base64 encoded transaction parents