fix: land program addresses off-curve

web3.js/module.flow.js

@@ -15,6 +15,7 @@ import * as BufferLayout from 'buffer-layout';
 
 declare module '@solana/web3.js' {
   // === src/publickey.js ===
+  declare export type PublicKeyNonce = [PublicKey, number];
   declare export class PublicKey {
     constructor(
       value: number | string | Buffer | Uint8Array | Array<number>,
@@ -28,6 +29,10 @@ declare module '@solana/web3.js' {
       seeds: Array<Buffer | Uint8Array>,
       programId: PublicKey,
     ): Promise<PublicKey>;
+    static findProgramAddress(
+      seeds: Array<Buffer | Uint8Array>,
+      programId: PublicKey,
+    ): Promise<PublicKeyNonce>;
     equals(publickey: PublicKey): boolean;
     toBase58(): string;
     toBuffer(): Buffer;

web3.js/src/publickey.js

@@ -2,8 +2,14 @@
 
 import BN from 'bn.js';
 import bs58 from 'bs58';
+import nacl from 'tweetnacl';
 import {sha256} from 'crypto-hash';
 
+//$FlowFixMe
+let naclLowLevel = nacl.lowlevel;
+
+type PublicKeyNonce = [PublicKey, number]; // This type exists to workaround an esdoc parse error
+
 /**
  * A public key
  */
@@ -104,7 +110,110 @@ export class PublicKey {
       Buffer.from('ProgramDerivedAddress'),
     ]);
     let hash = await sha256(new Uint8Array(buffer));
-    hash = await sha256(new Uint8Array(new BN(hash, 16).toBuffer()));
-    return new PublicKey('0x' + hash);
+    let publicKeyBytes = new BN(hash, 16).toBuffer();
+    if (is_on_curve(publicKeyBytes)) {
+      throw new Error(`Invalid seeds, address must fall off the curve`);
+    }
+    return new PublicKey(publicKeyBytes);
   }
+
+  /**
+   * Find a valid program address
+   *
+   * Valid program addresses must fall off the ed25519 curve.  This function
+   * iterates a nonce until it finds one that when combined with the seeds
+   * results in a valid program address.
+   */
+  static async findProgramAddress(
+    seeds: Array<Buffer | Uint8Array>,
+    programId: PublicKey,
+  ): Promise<PublicKeyNonce> {
+    let nonce = 255;
+    let address;
+    while (nonce != 0) {
+      try {
+        const seedsWithNonce = seeds.concat(Buffer.from([nonce]));
+        address = await this.createProgramAddress(seedsWithNonce, programId);
+      } catch (err) {
+        nonce--;
+        continue;
+      }
+      return [address, nonce];
+    }
+    throw new Error(`Unable to find a viable program address nonce`);
+  }
+}
+
+// Check that a pubkey is on the curve.
+// This function and its dependents were sourced from:
+// https://github.com/dchest/tweetnacl-js/blob/f1ec050ceae0861f34280e62498b1d3ed9c350c6/nacl.js#L792
+function is_on_curve(p) {
+  var r = [
+    naclLowLevel.gf(),
+    naclLowLevel.gf(),
+    naclLowLevel.gf(),
+    naclLowLevel.gf(),
+  ];
+
+  var t = naclLowLevel.gf(),
+    chk = naclLowLevel.gf(),
+    num = naclLowLevel.gf(),
+    den = naclLowLevel.gf(),
+    den2 = naclLowLevel.gf(),
+    den4 = naclLowLevel.gf(),
+    den6 = naclLowLevel.gf();
+
+  naclLowLevel.set25519(r[2], gf1);
+  naclLowLevel.unpack25519(r[1], p);
+  naclLowLevel.S(num, r[1]);
+  naclLowLevel.M(den, num, naclLowLevel.D);
+  naclLowLevel.Z(num, num, r[2]);
+  naclLowLevel.A(den, r[2], den);
+
+  naclLowLevel.S(den2, den);
+  naclLowLevel.S(den4, den2);
+  naclLowLevel.M(den6, den4, den2);
+  naclLowLevel.M(t, den6, num);
+  naclLowLevel.M(t, t, den);
+
+  naclLowLevel.pow2523(t, t);
+  naclLowLevel.M(t, t, num);
+  naclLowLevel.M(t, t, den);
+  naclLowLevel.M(t, t, den);
+  naclLowLevel.M(r[0], t, den);
+
+  naclLowLevel.S(chk, r[0]);
+  naclLowLevel.M(chk, chk, den);
+  if (neq25519(chk, num)) naclLowLevel.M(r[0], r[0], I);
+
+  naclLowLevel.S(chk, r[0]);
+  naclLowLevel.M(chk, chk, den);
+  if (neq25519(chk, num)) return 0;
+  return 1;
+}
+let gf1 = naclLowLevel.gf([1]);
+let I = naclLowLevel.gf([
+  0xa0b0,
+  0x4a0e,
+  0x1b27,
+  0xc4ee,
+  0xe478,
+  0xad2f,
+  0x1806,
+  0x2f43,
+  0xd7a7,
+  0x3dfb,
+  0x0099,
+  0x2b4d,
+  0xdf0b,
+  0x4fc1,
+  0x2480,
+  0x2b83,
+]);
+function neq25519(a, b) {
+  var c = new Uint8Array(32),
+    d = new Uint8Array(32);
+  naclLowLevel.pack25519(c, a);
+  naclLowLevel.pack25519(d, b);
+  return naclLowLevel.crypto_verify_32(c, 0, d, 0);
 }

web3.js/test/publickey.test.js

@@ -240,12 +240,12 @@ test('createProgramAddress', async () => {
   );
 
   let programAddress = await PublicKey.createProgramAddress(
-    [Buffer.from('', 'utf8')],
+    [Buffer.from('', 'utf8'), Buffer.from([1])],
     programId,
   );
   expect(
     programAddress.equals(
-      new PublicKey('CsdSsqp6Upkh2qajhZMBM8xT4GAyDNSmcV37g4pN8rsc'),
+      new PublicKey('3gF2KMe9KiC6FNVBmfg9i267aMPvK37FewCip4eGBFcT'),
     ),
   ).toBe(true);
 
@@ -255,7 +255,7 @@ test('createProgramAddress', async () => {
   );
   expect(
     programAddress.equals(
-      new PublicKey('A8mYnN8Pfx7Nn6f8RoQgsPNtAGAWmmKSBCDfyDvE6sXF'),
+      new PublicKey('7ytmC1nT1xY4RfxCV2ZgyA7UakC93do5ZdyhdF3EtPj7'),
     ),
   ).toBe(true);
 
@@ -265,7 +265,7 @@ test('createProgramAddress', async () => {
   );
   expect(
     programAddress.equals(
-      new PublicKey('CawYq8Rmj4JRR992wVnGEFUjMEkmtmcFgEL4iS1qPczu'),
+      new PublicKey('HwRVBufQ4haG5XSgpspwKtNd3PC9GM9m1196uJW36vds'),
     ),
   ).toBe(true);
 
@@ -275,7 +275,7 @@ test('createProgramAddress', async () => {
   );
   expect(
     programAddress.equals(
-      new PublicKey('4ak7qJacCKMAGP8xJtDkg2VYZh5QKExa71ijMDjZGQyb'),
+      new PublicKey('GUs5qLUfsEHkcMB9T38vjr18ypEhRuNWiePW2LoK4E3K'),
     ),
   ).toBe(true);
 
@@ -285,3 +285,21 @@ test('createProgramAddress', async () => {
   );
   expect(programAddress.equals(programAddress2)).toBe(false);
 });
+
+test('findProgramAddress', async () => {
+  const programId = new PublicKey(
+    'BPFLoader1111111111111111111111111111111111',
+  );
+  let [programAddress, nonce] = await PublicKey.findProgramAddress(
+    [Buffer.from('', 'utf8')],
+    programId,
+  );
+  expect(
+    programAddress.equals(
+      await PublicKey.createProgramAddress(
+        [Buffer.from('', 'utf8'), Buffer.from([nonce])],
+        programId,
+      ),
+    ),
+  ).toBe(true);
+});