diff --git a/CMakeLists.txt b/CMakeLists.txt
index 79ecbfa..577a5f0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -51,6 +51,7 @@ target_sources(pico_hsm PUBLIC
         ${CMAKE_CURRENT_LIST_DIR}/src/fs/low_flash.c
         ${CMAKE_CURRENT_LIST_DIR}/src/rng/random.c
         ${CMAKE_CURRENT_LIST_DIR}/src/rng/neug.c
+        ${CMAKE_CURRENT_LIST_DIR}/src/hsm/hash_utils.c
         
         ${CMAKE_CURRENT_LIST_DIR}/mbedtls/library/sha256.c
         ${CMAKE_CURRENT_LIST_DIR}/mbedtls/library/aes.c
diff --git a/src/hsm/hash_utils.c b/src/hsm/hash_utils.c
new file mode 100644
index 0000000..28228f0
--- /dev/null
+++ b/src/hsm/hash_utils.c
@@ -0,0 +1,73 @@
+/* 
+ * This file is part of the Pico HSM distribution (https://github.com/polhenarejos/pico-hsm).
+ * Copyright (c) 2022 Pol Henarejos.
+ * 
+ * This program is free software: you can redistribute it and/or modify  
+ * it under the terms of the GNU General Public License as published by  
+ * the Free Software Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful, but 
+ * WITHOUT ANY WARRANTY; without even the implied warranty of 
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License 
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <pico/unique_id.h>
+#include "mbedtls/md.h"
+#include "mbedtls/sha256.h"
+#include "hash_utils.h"
+
+void double_hash_pin(const uint8_t *pin, size_t len, uint8_t output[32]) {
+    uint8_t o1[32];
+    hash_multi(pin, len, o1);
+    for (int i = 0; i < sizeof(o1); i++)
+        o1[i] ^= pin[i%len];
+    hash_multi(o1, sizeof(o1), output);
+}
+
+void hash_multi(const uint8_t *input, size_t len, uint8_t output[32]) {
+    mbedtls_sha256_context ctx;
+    mbedtls_sha256_init(&ctx);
+    int iters = 256;
+    pico_unique_board_id_t unique_id;
+    
+    pico_get_unique_board_id(&unique_id);
+    
+    mbedtls_sha256_starts (&ctx, 0);
+    mbedtls_sha256_update (&ctx, unique_id.id, sizeof(unique_id.id));
+    
+    while (iters > len)
+    {
+        mbedtls_sha256_update (&ctx, input, len);
+        iters -= len;
+    }
+    if (iters > 0) // remaining iterations
+        mbedtls_sha256_update (&ctx, input, iters);
+    mbedtls_sha256_finish (&ctx, output);
+    mbedtls_sha256_free (&ctx);
+}
+
+void hash256(const uint8_t *input, size_t len, uint8_t output[32]) {
+    mbedtls_sha256_context ctx;
+    mbedtls_sha256_init(&ctx);
+    
+    mbedtls_sha256_starts (&ctx, 0);
+    mbedtls_sha256_update (&ctx, input, len);
+
+    mbedtls_sha256_finish (&ctx, output);
+    mbedtls_sha256_free (&ctx);
+}
+
+void generic_hash(mbedtls_md_type_t md, const uint8_t *input, size_t len, uint8_t *output) {
+    mbedtls_md_context_t ctx;
+    mbedtls_md_init(&ctx);
+    const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type(md);
+    mbedtls_md_setup(&ctx, md_info, 0);
+    mbedtls_md_starts(&ctx);
+    mbedtls_md_update(&ctx, input, len);
+    mbedtls_md_finish(&ctx, output);
+    mbedtls_md_free(&ctx);   
+}
diff --git a/src/hsm/hash_utils.h b/src/hsm/hash_utils.h
new file mode 100644
index 0000000..cb0b067
--- /dev/null
+++ b/src/hsm/hash_utils.h
@@ -0,0 +1,26 @@
+/* 
+ * This file is part of the Pico HSM distribution (https://github.com/polhenarejos/pico-hsm).
+ * Copyright (c) 2022 Pol Henarejos.
+ * 
+ * This program is free software: you can redistribute it and/or modify  
+ * it under the terms of the GNU General Public License as published by  
+ * the Free Software Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful, but 
+ * WITHOUT ANY WARRANTY; without even the implied warranty of 
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License 
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _HASH_UTILS_H_
+#define _HASH_UTILS_H_
+
+extern void double_hash_pin(const uint8_t *pin, size_t len, uint8_t output[32]);
+extern void hash_multi(const uint8_t *input, size_t len, uint8_t output[32]);
+extern void hash256(const uint8_t *input, size_t len, uint8_t output[32]);
+extern void generic_hash(mbedtls_md_type_t md, const uint8_t *input, size_t len, uint8_t *output);
+
+#endif