Merge pull request #2545 from SparkiDev/scrypt_iters

Add scrypt API that takes iterations rather than cost

wolfcrypt/src/pwdbased.c

@@ -691,7 +691,7 @@ static void scryptROMix(byte* x, byte* v, byte* y, int r, word32 n)
  * parallel   The number of parallel mix operations to perform.
  *            (Note: this implementation does not use threads.)
  * dkLen      The length of the derived key in bytes.
- * returns BAD_FUNC_ARG when: parallel not 1, blockSize is too large for cost.
+ * returns BAD_FUNC_ARG when: blockSize is too large for cost.
  */
 int wc_scrypt(byte* output, const byte* passwd, int passLen,
               const byte* salt, int saltLen, int cost, int blockSize,
@@ -748,6 +748,41 @@ end:
 
     return ret;
 }
+
+/* Generates an key derived from a password and salt using a memory hard
+ * algorithm.
+ * Implements RFC 7914: scrypt PBKDF.
+ *
+ * output      Derived key.
+ * passwd      Password to derive key from.
+ * passLen     Length of the password.
+ * salt        Key specific data.
+ * saltLen     Length of the salt data.
+ * iterations  Number of iterations to perform. Range: 1 << (1..(128*r/8-1))
+ * blockSize   Number of 128 byte octets in a working block.
+ * parallel    Number of parallel mix operations to perform.
+ *             (Note: this implementation does not use threads.)
+ * dkLen       Length of the derived key in bytes.
+ * returns BAD_FUNC_ARG when: iterations is not a power of 2 or blockSize is too
+ *                            large for iterations.
+ */
+int wc_scrypt_ex(byte* output, const byte* passwd, int passLen,
+                 const byte* salt, int saltLen, word32 iterations,
+                 int blockSize, int parallel, int dkLen)
+{
+    int cost;
+
+    /* Iterations must be a power of 2. */
+    if ((iterations & (iterations - 1)) != 0)
+        return BAD_FUNC_ARG;
+
+    for (cost = -1; iterations != 0; cost++) {
+        iterations >>= 1;
+    }
+
+    return wc_scrypt(output, passwd, passLen, salt, saltLen, cost, blockSize,
+                     parallel, dkLen);
+}
 #endif /* HAVE_SCRYPT */
 
 #endif /* NO_PWDBASED */

wolfcrypt/test/test.c

@@ -15900,6 +15900,13 @@ int scrypt_test(void)
 #endif
 #endif /* !BENCH_EMBEDDED && !HAVE_INTEL_QA */
 
+    ret = wc_scrypt_ex(derived, (byte*)"password", 8, (byte*)"NaCl", 4, 1<<10,
+                       8, 16, sizeof(verify2));
+    if (ret != 0)
+        return -7808;
+    if (XMEMCMP(derived, verify2, sizeof(verify2)) != 0)
+        return -7809;
+
     return 0;
 }
 #endif

wolfssl/wolfcrypt/pwdbased.h

@@ -60,6 +60,9 @@ WOLFSSL_API int wc_PKCS12_PBKDF_ex(byte* output, const byte* passwd,int passLen,
 WOLFSSL_API int wc_scrypt(byte* output, const byte* passwd, int passLen,
                           const byte* salt, int saltLen, int cost,
                           int blockSize, int parallel, int dkLen);
+WOLFSSL_API int wc_scrypt_ex(byte* output, const byte* passwd, int passLen,
+                             const byte* salt, int saltLen, word32 iterations,
+                             int blockSize, int parallel, int dkLen);
 #endif