Factor out the common part of the PBKDF2 algorithm into its own

function. The three copies now just call that function with different
PRF instances.

src/entry-export_all.ts

@@ -22,6 +22,7 @@ export { Sha512 } from './hash/sha512/sha512';
 export { HmacSha1 } from './hmac/hmac-sha1';
 export { HmacSha256 } from './hmac/hmac-sha256';
 export { HmacSha512 } from './hmac/hmac-sha512';
+export { Pbkdf2 } from './pbkdf2/pbkdf2';
 export { Pbkdf2HmacSha1 } from './pbkdf2/pbkdf2-hmac-sha1';
 export { Pbkdf2HmacSha256 } from './pbkdf2/pbkdf2-hmac-sha256';
 export { Pbkdf2HmacSha512 } from './pbkdf2/pbkdf2-hmac-sha512';

src/pbkdf2/pbkdf2-hmac-sha1.ts

@@ -1,21 +1,6 @@
+import { Pbkdf2 } from './pbkdf2';
 import { HmacSha1 } from '../hmac/hmac-sha1';
 
 export function Pbkdf2HmacSha1(password: Uint8Array, salt: Uint8Array, count: number, length: number): Uint8Array {
-  const hmac = new HmacSha1(password);
-
-  const result = new Uint8Array(length);
-
-  const blocks = Math.ceil(length / hmac.HMAC_SIZE);
-
-  for (let i = 1; i <= blocks; ++i) {
-    const j = (i - 1) * hmac.HMAC_SIZE;
-    const l = (i < blocks ? 0 : length % hmac.HMAC_SIZE) || hmac.HMAC_SIZE;
-
-    hmac.reset().process(salt);
-    hmac.hash.asm.pbkdf2_generate_block(hmac.hash.pos, hmac.hash.len, i, count, 0);
-
-    result.set(hmac.hash.heap.subarray(0, l), j);
-  }
-
-  return result;
+  return Pbkdf2(new HmacSha1(password), salt, count, length);
 }

src/pbkdf2/pbkdf2-hmac-sha256.ts

@@ -1,21 +1,6 @@
+import { Pbkdf2 } from './pbkdf2';
 import { HmacSha256 } from '../hmac/hmac-sha256';
 
 export function Pbkdf2HmacSha256(password: Uint8Array, salt: Uint8Array, count: number, length: number): Uint8Array {
-  const hmac = new HmacSha256(password);
-
-  const result = new Uint8Array(length);
-
-  const blocks = Math.ceil(length / hmac.HMAC_SIZE);
-
-  for (let i = 1; i <= blocks; ++i) {
-    const j = (i - 1) * hmac.HMAC_SIZE;
-    const l = (i < blocks ? 0 : length % hmac.HMAC_SIZE) || hmac.HMAC_SIZE;
-
-    hmac.reset().process(salt);
-    hmac.hash.asm.pbkdf2_generate_block(hmac.hash.pos, hmac.hash.len, i, count, 0);
-
-    result.set(hmac.hash.heap.subarray(0, l), j);
-  }
-
-  return result;
+  return Pbkdf2(new HmacSha256(password), salt, count, length);
 }

src/pbkdf2/pbkdf2-hmac-sha512.ts

@@ -1,21 +1,7 @@
+import { Pbkdf2 } from './pbkdf2';
 import { HmacSha512 } from '../hmac/hmac-sha512';
 
 export function Pbkdf2HmacSha512(password: Uint8Array, salt: Uint8Array, count: number, length: number): Uint8Array {
-  const hmac = new HmacSha512(password);
-
-  const result = new Uint8Array(length);
-
-  const blocks = Math.ceil(length / hmac.HMAC_SIZE);
-
-  for (let i = 1; i <= blocks; ++i) {
-    const j = (i - 1) * hmac.HMAC_SIZE;
-    const l = (i < blocks ? 0 : length % hmac.HMAC_SIZE) || hmac.HMAC_SIZE;
-
-    hmac.reset().process(salt);
-    hmac.hash.asm.pbkdf2_generate_block(hmac.hash.pos, hmac.hash.len, i, count, 0);
-
-    result.set(hmac.hash.heap.subarray(0, l), j);
-  }
-
-  return result;
+  return Pbkdf2(new HmacSha512(password), salt, count, length)
 }
+

src/pbkdf2/pbkdf2.ts

@@ -0,0 +1,21 @@
+import { Hmac } from './hmac';
+
+export function Pbkdf2(keyedPRF: Hmac, salt: Uint8Array, count: number, length: number): Uint8Array {
+  const hmac = keyedPRF;
+
+  const result = new Uint8Array(length);
+
+  const blocks = Math.ceil(length / hmac.HMAC_SIZE);
+
+  for (let i = 1; i <= blocks; ++i) {
+    const j = (i - 1) * hmac.HMAC_SIZE;
+    const l = (i < blocks ? 0 : length % hmac.HMAC_SIZE) || hmac.HMAC_SIZE;
+
+    hmac.reset().process(salt);
+    hmac.hash.asm.pbkdf2_generate_block(hmac.hash.pos, hmac.hash.len, i, count, 0);
+
+    result.set(hmac.hash.heap.subarray(0, l), j);
+  }
+
+  return result;
+}