refactor: replace custom PBKDF2 implementation with OpenSSL's PKCS5_P…

…BKDF2_HMAC for improved security and maintainability

Signed-off-by: Dengfeng Liu <liudf0716@gmail.com>

fastpbkdf2.c

@@ -4,91 +4,29 @@
 #include <openssl/core_names.h>
 #include "fastpbkdf2.h"
 
-static void write32_be(uint32_t n, uint8_t out[4]) {
-    out[0] = (n >> 24) & 0xff;
-    out[1] = (n >> 16) & 0xff;
-    out[2] = (n >> 8) & 0xff;
-    out[3] = n & 0xff;
-}
-
-static void xor_block(uint8_t *out, const uint8_t *in) {
-    size_t i;
-    for (i = 0; i < EVP_MAX_MD_SIZE; i++) {
-        out[i] ^= in[i];
-    }
-}
-
-static void pbkdf2_impl(const EVP_MD *md,
-                       const uint8_t *pw, size_t npw,
-                       const uint8_t *salt, size_t nsalt,
-                       uint32_t iterations,
-                       uint8_t *out, size_t nout) {
-    EVP_MAC *mac = EVP_MAC_fetch(NULL, "HMAC", NULL);
-    EVP_MAC_CTX *ctx = EVP_MAC_CTX_new(mac);
-    OSSL_PARAM params[2];
-    uint32_t counter = 1;
-    unsigned int digestlen;
-    size_t remain = nout;
-
-    params[0] = OSSL_PARAM_construct_utf8_string(OSSL_MAC_PARAM_DIGEST,
-                                               (char *)EVP_MD_name(md), 0);
-    params[1] = OSSL_PARAM_construct_end();
-
-    EVP_MAC_init(ctx, pw, npw, params);
-
-    while (remain > 0) {
-        uint8_t countbuf[4];
-        uint8_t Txi[EVP_MAX_MD_SIZE];
-        uint8_t Ti[EVP_MAX_MD_SIZE];
-        size_t copy;
-        size_t outlen;
-
-        write32_be(counter, countbuf);
-
-        /* First iteration */
-        EVP_MAC_init(ctx, NULL, 0, NULL);
-        EVP_MAC_update(ctx, salt, nsalt);
-        EVP_MAC_update(ctx, countbuf, 4);
-        EVP_MAC_final(ctx, Ti, &outlen, EVP_MAX_MD_SIZE);
-        digestlen = outlen;
-        memcpy(Txi, Ti, digestlen);
-
-        /* Subsequent iterations */
-        for (uint32_t i = 1; i < iterations; i++) {
-            EVP_MAC_init(ctx, NULL, 0, NULL);
-            EVP_MAC_update(ctx, Ti, digestlen);
-            EVP_MAC_final(ctx, Ti, &outlen, EVP_MAX_MD_SIZE);
-            xor_block(Txi, Ti);
-        }
-
-        copy = (remain > digestlen) ? digestlen : remain;
-        memcpy(out, Txi, copy);
-        out += copy;
-        remain -= copy;
-        counter++;
-    }
-
-    EVP_MAC_CTX_free(ctx);
-    EVP_MAC_free(mac);
-}
-
 void fastpbkdf2_hmac_sha1(const uint8_t *pw, size_t npw,
                          const uint8_t *salt, size_t nsalt,
                          uint32_t iterations,
                          uint8_t *out, size_t nout) {
-    pbkdf2_impl(EVP_sha1(), pw, npw, salt, nsalt, iterations, out, nout);
+    PKCS5_PBKDF2_HMAC((const char *)pw, npw,
+                      salt, nsalt, iterations,
+                      EVP_sha1(), nout, out);
 }
 
 void fastpbkdf2_hmac_sha256(const uint8_t *pw, size_t npw,
                            const uint8_t *salt, size_t nsalt,
                            uint32_t iterations,
                            uint8_t *out, size_t nout) {
-    pbkdf2_impl(EVP_sha256(), pw, npw, salt, nsalt, iterations, out, nout);
+    PKCS5_PBKDF2_HMAC((const char *)pw, npw,
+                      salt, nsalt, iterations,
+                      EVP_sha256(), nout, out);
 }
 
 void fastpbkdf2_hmac_sha512(const uint8_t *pw, size_t npw,
                            const uint8_t *salt, size_t nsalt,
                            uint32_t iterations,
                            uint8_t *out, size_t nout) {
-    pbkdf2_impl(EVP_sha512(), pw, npw, salt, nsalt, iterations, out, nout);
+    PKCS5_PBKDF2_HMAC((const char *)pw, npw,
+                        salt, nsalt, iterations,
+                        EVP_sha512(), nout, out);
 }

fastpbkdf2.h

@@ -5,10 +5,6 @@
 #include <stdint.h>
 #include <openssl/evp.h>
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 /* Function declarations remain unchanged for API compatibility */
 void fastpbkdf2_hmac_sha1(const uint8_t *pw, size_t npw,
                           const uint8_t *salt, size_t nsalt,
@@ -25,8 +21,4 @@ void fastpbkdf2_hmac_sha512(const uint8_t *pw, size_t npw,
                             uint32_t iterations,
                             uint8_t *out, size_t nout);
 
-#ifdef __cplusplus
-}
-#endif
-
 #endif

test_fastpbkdf2.c

@@ -1,28 +1,30 @@
-#include <stdio.h>
+#include <openssl/evp.h>
+#include <openssl/sha.h>
 #include <string.h>
 #include <stdint.h>
-#include "fastpbkdf2.h"
+#include <stdio.h>
 
-void print_hex(const uint8_t *data, size_t len) {
-    for (size_t i = 0; i < len; i++) {
-        printf("%02x", data[i]);
-    }
-    printf("\n");
+void pbkdf2_key(const uint8_t *password, size_t password_len,
+                const uint8_t *salt, size_t salt_len,
+                uint32_t iterations, uint8_t *out, size_t out_len) {
+    PKCS5_PBKDF2_HMAC((const char *)password, password_len,
+                      salt, salt_len, iterations,
+                      EVP_sha1(), out_len, out);
 }
 
-void test_fastpbkdf2_hmac_sha1() {
-    const uint8_t password[] = "password";
-    const uint8_t salt[] = "salt";
-    uint32_t iterations = 1000;
-    uint8_t output[20]; // SHA-1 produces a 20-byte hash
+int main() {
+    const char *password = "password";
+    const uint8_t salt[] = "saltsalt";
+    uint8_t key[16]; // size of the derived key
 
-    fastpbkdf2_hmac_sha1(password, strlen((const char *)password), salt, strlen((const char *)salt), iterations, output, sizeof(output));
+    pbkdf2_key((const uint8_t *)password, strlen(password),
+               salt, sizeof(salt) - 1, 1000, key, sizeof(key));
 
-    printf("PBKDF2-HMAC-SHA1: ");
-    print_hex(output, sizeof(output));
-}
+    printf("Derived key: ");
+    for (size_t i = 0; i < sizeof(key); i++) {
+        printf("%02x", key[i]);
+    }
+    printf("\n");
 
-int main() {
-    test_fastpbkdf2_hmac_sha1();
     return 0;
 }