diff --git a/src/gsm/kdf/sha1.h b/src/gsm/kdf/sha1.h
new file mode 100644
index 0000000..f0c1a5f
--- /dev/null
+++ b/src/gsm/kdf/sha1.h
@@ -0,0 +1,33 @@
+/*
+ * SHA1 hash implementation and interface functions
+ * Copyright (c) 2003-2009, Jouni Malinen <j@w1.fi>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Alternatively, this software may be distributed under the terms of BSD
+ * license.
+ *
+ * See README and COPYING for more details.
+ */
+
+#ifndef SHA1_H
+#define SHA1_H
+
+#define SHA1_MAC_LEN 20
+
+int hmac_sha1_vector(const u8 *key, size_t key_len, size_t num_elem,
+		     const u8 *addr[], const size_t *len, u8 *mac);
+int hmac_sha1(const u8 *key, size_t key_len, const u8 *data, size_t data_len,
+	       u8 *mac);
+int sha1_prf(const u8 *key, size_t key_len, const char *label,
+	     const u8 *data, size_t data_len, u8 *buf, size_t buf_len);
+int sha1_t_prf(const u8 *key, size_t key_len, const char *label,
+	       const u8 *seed, size_t seed_len, u8 *buf, size_t buf_len);
+int __must_check tls_prf_sha1_md5(const u8 *secret, size_t secret_len,
+				  const char *label, const u8 *seed,
+				  size_t seed_len, u8 *out, size_t outlen);
+int pbkdf2_sha1(const char *passphrase, const char *ssid, size_t ssid_len,
+		int iterations, u8 *buf, size_t buflen);
+#endif /* SHA1_H */