diff --git a/hs20/client/est.c b/hs20/client/est.c
index db65334b2..97f913210 100644
--- a/hs20/client/est.c
+++ b/hs20/client/est.c
@@ -158,7 +158,7 @@ int est_load_cacerts(struct hs20_osu_client *ctx, const char *url)
 		return -1;
 	}
 
-	pkcs7 = base64_decode((unsigned char *) resp, resp_len, &pkcs7_len);
+	pkcs7 = base64_decode(resp, resp_len, &pkcs7_len);
 	if (pkcs7 && pkcs7_len < resp_len / 2) {
 		wpa_printf(MSG_INFO, "Too short base64 decode (%u bytes; downloaded %u bytes) - assume this was binary",
 			   (unsigned int) pkcs7_len, (unsigned int) resp_len);
@@ -639,8 +639,7 @@ int est_build_csr(struct hs20_osu_client *ctx, const char *url)
 			return -1;
 		}
 
-		attrs = base64_decode((unsigned char *) resp, resp_len,
-				      &attrs_len);
+		attrs = base64_decode(resp, resp_len, &attrs_len);
 		os_free(resp);
 
 		if (attrs == NULL) {
@@ -734,7 +733,7 @@ int est_simple_enroll(struct hs20_osu_client *ctx, const char *url,
 	}
 	wpa_printf(MSG_DEBUG, "EST simpleenroll response: %s", resp);
 
-	pkcs7 = base64_decode((unsigned char *) resp, resp_len, &pkcs7_len);
+	pkcs7 = base64_decode(resp, resp_len, &pkcs7_len);
 	if (pkcs7 == NULL) {
 		wpa_printf(MSG_INFO, "EST workaround - Could not decode base64, assume this is DER encoded PKCS7");
 		pkcs7 = os_malloc(resp_len);
diff --git a/hs20/client/osu_client.c b/hs20/client/osu_client.c
index fd99600da..a94f40c51 100644
--- a/hs20/client/osu_client.c
+++ b/hs20/client/osu_client.c
@@ -310,7 +310,7 @@ static int download_cert(struct hs20_osu_client *ctx, xml_node_t *params,
 	size_t len;
 	u8 digest1[SHA256_MAC_LEN], digest2[SHA256_MAC_LEN];
 	int res;
-	unsigned char *b64;
+	char *b64;
 	FILE *f;
 
 	url_node = get_node(ctx->xml, params, "CertURL");
@@ -364,7 +364,7 @@ static int download_cert(struct hs20_osu_client *ctx, xml_node_t *params,
 		return -1;
 	}
 
-	b64 = base64_encode((unsigned char *) cert, len, NULL);
+	b64 = base64_encode(cert, len, NULL);
 	os_free(cert);
 	if (b64 == NULL)
 		return -1;
diff --git a/hs20/server/spp_server.c b/hs20/server/spp_server.c
index 4bef0ffb2..a50e9074f 100644
--- a/hs20/server/spp_server.c
+++ b/hs20/server/spp_server.c
@@ -633,7 +633,7 @@ static xml_node_t * build_username_password(struct hs20_svc *ctx,
 
 	add_text_node(ctx, node, "Username", user);
 
-	b64 = (char *) base64_encode((unsigned char *) pw, strlen(pw), NULL);
+	b64 = base64_encode(pw, strlen(pw), NULL);
 	if (b64 == NULL)
 		return NULL;
 	len = os_strlen(b64);
@@ -1602,8 +1602,7 @@ static xml_node_t * spp_exec_get_certificate(struct hs20_svc *ctx,
 
 	xml_node_create_text(ctx->xml, enroll, ns, "estUserID", user);
 
-	b64 = (char *) base64_encode((unsigned char *) password,
-				     strlen(password), NULL);
+	b64 = base64_encode(password, strlen(password), NULL);
 	if (b64 == NULL) {
 		xml_node_free(ctx->xml, spp_node);
 		return NULL;
diff --git a/src/common/dpp.c b/src/common/dpp.c
index 1dfc34672..704f55c7a 100644
--- a/src/common/dpp.c
+++ b/src/common/dpp.c
@@ -1007,8 +1007,7 @@ static int dpp_parse_uri_pk(struct dpp_bootstrap_info *bi, const char *info)
 	if (!end)
 		return -1;
 
-	data = base64_decode((const unsigned char *) info, end - info,
-			     &data_len);
+	data = base64_decode(info, end - info, &data_len);
 	if (!data) {
 		wpa_printf(MSG_DEBUG,
 			   "DPP: Invalid base64 encoding on URI public-key");
@@ -1482,7 +1481,7 @@ int dpp_bootstrap_key_hash(struct dpp_bootstrap_info *bi)
 char * dpp_keygen(struct dpp_bootstrap_info *bi, const char *curve,
 		  const u8 *privkey, size_t privkey_len)
 {
-	unsigned char *base64 = NULL;
+	char *base64 = NULL;
 	char *pos, *end;
 	size_t len;
 	struct wpabuf *der = NULL;
@@ -1528,7 +1527,7 @@ char * dpp_keygen(struct dpp_bootstrap_info *bi, const char *curve,
 	der = NULL;
 	if (!base64)
 		goto fail;
-	pos = (char *) base64;
+	pos = base64;
 	end = pos + len;
 	for (;;) {
 		pos = os_strchr(pos, '\n');
@@ -1536,7 +1535,7 @@ char * dpp_keygen(struct dpp_bootstrap_info *bi, const char *curve,
 			break;
 		os_memmove(pos, pos + 1, end - pos);
 	}
-	return (char *) base64;
+	return base64;
 fail:
 	os_free(base64);
 	wpabuf_free(der);
diff --git a/src/eap_peer/tncc.c b/src/eap_peer/tncc.c
index a9bafe288..c46098099 100644
--- a/src/eap_peer/tncc.c
+++ b/src/eap_peer/tncc.c
@@ -144,7 +144,7 @@ static TNC_Result TNC_TNCC_SendMessage(
 	TNC_MessageType messageType)
 {
 	struct tnc_if_imc *imc;
-	unsigned char *b64;
+	char *b64;
 	size_t b64len;
 
 	wpa_printf(MSG_DEBUG, "TNC: TNC_TNCC_SendMessage(imcID=%lu "
@@ -629,8 +629,7 @@ static unsigned char * tncc_get_base64(char *start, size_t *decoded_len)
 		return NULL;
 	*pos2 = '\0';
 
-	decoded = base64_decode((unsigned char *) pos, os_strlen(pos),
-				decoded_len);
+	decoded = base64_decode(pos, os_strlen(pos), decoded_len);
 	*pos2 = '<';
 	if (decoded == NULL) {
 		wpa_printf(MSG_DEBUG, "TNC: Failed to decode Base64 data");
diff --git a/src/eap_server/tncs.c b/src/eap_server/tncs.c
index 942a19576..4a30486f7 100644
--- a/src/eap_server/tncs.c
+++ b/src/eap_server/tncs.c
@@ -179,7 +179,7 @@ static TNC_Result TNC_TNCS_SendMessage(
 	TNC_MessageType messageType)
 {
 	struct tncs_data *tncs;
-	unsigned char *b64;
+	char *b64;
 	size_t b64len;
 
 	wpa_printf(MSG_DEBUG, "TNC: TNC_TNCS_SendMessage(imvID=%lu "
@@ -678,8 +678,7 @@ static unsigned char * tncs_get_base64(char *start, size_t *decoded_len)
 		return NULL;
 	*pos2 = '\0';
 
-	decoded = base64_decode((unsigned char *) pos, os_strlen(pos),
-				decoded_len);
+	decoded = base64_decode(pos, os_strlen(pos), decoded_len);
 	*pos2 = '<';
 	if (decoded == NULL) {
 		wpa_printf(MSG_DEBUG, "TNC: Failed to decode Base64 data");
diff --git a/src/tls/tlsv1_cred.c b/src/tls/tlsv1_cred.c
index 842e5dd72..01b2f8342 100644
--- a/src/tls/tlsv1_cred.c
+++ b/src/tls/tlsv1_cred.c
@@ -130,7 +130,7 @@ static int tlsv1_add_cert(struct x509_certificate **chain,
 			return -1;
 		}
 
-		der = base64_decode(pos, end - pos, &der_len);
+		der = base64_decode((const char *) pos, end - pos, &der_len);
 		if (der == NULL) {
 			wpa_printf(MSG_INFO, "TLSv1: Could not decode PEM "
 				   "certificate");
@@ -293,7 +293,7 @@ static struct crypto_private_key * tlsv1_set_key_pem(const u8 *key, size_t len)
 		}
 	}
 
-	der = base64_decode(pos, end - pos, &der_len);
+	der = base64_decode((const char *) pos, end - pos, &der_len);
 	if (!der)
 		return NULL;
 	pkey = crypto_private_key_import(der, der_len, NULL);
@@ -321,7 +321,7 @@ static struct crypto_private_key * tlsv1_set_key_enc_pem(const u8 *key,
 	if (!end)
 		return NULL;
 
-	der = base64_decode(pos, end - pos, &der_len);
+	der = base64_decode((const char *) pos, end - pos, &der_len);
 	if (!der)
 		return NULL;
 	pkey = crypto_private_key_import(der, der_len, passwd);
@@ -1225,7 +1225,7 @@ static int tlsv1_set_dhparams_blob(struct tlsv1_credentials *cred,
 		return -1;
 	}
 
-	der = base64_decode(pos, end - pos, &der_len);
+	der = base64_decode((const char *) pos, end - pos, &der_len);
 	if (der == NULL) {
 		wpa_printf(MSG_INFO, "TLSv1: Could not decode PEM dhparams");
 		return -1;
diff --git a/src/utils/base64.c b/src/utils/base64.c
index 0518cf083..a17d2d36d 100644
--- a/src/utils/base64.c
+++ b/src/utils/base64.c
@@ -12,18 +12,16 @@
 #include "os.h"
 #include "base64.h"
 
-static const unsigned char base64_table[65] =
+static const char base64_table[65] =
 	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
-static const unsigned char base64_url_table[65] =
+static const char base64_url_table[65] =
 	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
 
 
-static unsigned char * base64_gen_encode(const unsigned char *src, size_t len,
-					 size_t *out_len,
-					 const unsigned char *table,
-					 int add_pad)
+static char * base64_gen_encode(const unsigned char *src, size_t len,
+				size_t *out_len, const char *table, int add_pad)
 {
-	unsigned char *out, *pos;
+	char *out, *pos;
 	const unsigned char *end, *in;
 	size_t olen;
 	int line_len;
@@ -83,9 +81,8 @@ static unsigned char * base64_gen_encode(const unsigned char *src, size_t len,
 }
 
 
-static unsigned char * base64_gen_decode(const unsigned char *src, size_t len,
-					 size_t *out_len,
-					 const unsigned char *table)
+static unsigned char * base64_gen_decode(const char *src, size_t len,
+					 size_t *out_len, const char *table)
 {
 	unsigned char dtable[256], *out, *pos, block[4], tmp;
 	size_t i, count, olen;
@@ -94,12 +91,12 @@ static unsigned char * base64_gen_decode(const unsigned char *src, size_t len,
 
 	os_memset(dtable, 0x80, 256);
 	for (i = 0; i < sizeof(base64_table) - 1; i++)
-		dtable[table[i]] = (unsigned char) i;
+		dtable[(unsigned char) table[i]] = (unsigned char) i;
 	dtable['='] = 0;
 
 	count = 0;
 	for (i = 0; i < len; i++) {
-		if (dtable[src[i]] != 0x80)
+		if (dtable[(unsigned char) src[i]] != 0x80)
 			count++;
 	}
 
@@ -165,8 +162,7 @@ static unsigned char * base64_gen_decode(const unsigned char *src, size_t len,
  * nul terminated to make it easier to use as a C string. The nul terminator is
  * not included in out_len.
  */
-unsigned char * base64_encode(const unsigned char *src, size_t len,
-			      size_t *out_len)
+char * base64_encode(const void *src, size_t len, size_t *out_len)
 {
 	return base64_gen_encode(src, len, out_len, base64_table, 1);
 }
@@ -174,8 +170,7 @@ unsigned char * base64_encode(const unsigned char *src, size_t len,
 
 char * base64_url_encode(const void *src, size_t len, size_t *out_len)
 {
-	return (char *) base64_gen_encode(src, len, out_len, base64_url_table,
-					  0);
+	return base64_gen_encode(src, len, out_len, base64_url_table, 0);
 }
 
 
@@ -189,8 +184,7 @@ char * base64_url_encode(const void *src, size_t len, size_t *out_len)
  *
  * Caller is responsible for freeing the returned buffer.
  */
-unsigned char * base64_decode(const unsigned char *src, size_t len,
-			      size_t *out_len)
+unsigned char * base64_decode(const char *src, size_t len, size_t *out_len)
 {
 	return base64_gen_decode(src, len, out_len, base64_table);
 }
@@ -198,6 +192,5 @@ unsigned char * base64_decode(const unsigned char *src, size_t len,
 
 unsigned char * base64_url_decode(const char *src, size_t len, size_t *out_len)
 {
-	return base64_gen_decode((const unsigned char *) src, len, out_len,
-				 base64_url_table);
+	return base64_gen_decode(src, len, out_len, base64_url_table);
 }
diff --git a/src/utils/base64.h b/src/utils/base64.h
index 1e9f0532c..6216f44e5 100644
--- a/src/utils/base64.h
+++ b/src/utils/base64.h
@@ -9,10 +9,8 @@
 #ifndef BASE64_H
 #define BASE64_H
 
-unsigned char * base64_encode(const unsigned char *src, size_t len,
-			      size_t *out_len);
-unsigned char * base64_decode(const unsigned char *src, size_t len,
-			      size_t *out_len);
+char * base64_encode(const void *src, size_t len, size_t *out_len);
+unsigned char * base64_decode(const char *src, size_t len, size_t *out_len);
 char * base64_url_encode(const void *src, size_t len, size_t *out_len);
 unsigned char * base64_url_decode(const char *src, size_t len, size_t *out_len);
 
diff --git a/src/utils/utils_module_tests.c b/src/utils/utils_module_tests.c
index 3af4fcde1..b09225de0 100644
--- a/src/utils/utils_module_tests.c
+++ b/src/utils/utils_module_tests.c
@@ -296,52 +296,53 @@ static int base64_tests(void)
 {
 	int errors = 0;
 	unsigned char *res;
+	char *res2;
 	size_t res_len;
 
 	wpa_printf(MSG_INFO, "base64 tests");
 
-	res = base64_encode((const unsigned char *) "", ~0, &res_len);
+	res2 = base64_encode("", ~0, &res_len);
+	if (res2) {
+		errors++;
+		os_free(res2);
+	}
+
+	res2 = base64_encode("=", 1, &res_len);
+	if (!res2 || res_len != 5 || res2[0] != 'P' || res2[1] != 'Q' ||
+	    res2[2] != '=' || res2[3] != '=' || res2[4] != '\n')
+		errors++;
+	os_free(res2);
+
+	res2 = base64_encode("=", 1, NULL);
+	if (!res2 || res2[0] != 'P' || res2[1] != 'Q' ||
+	    res2[2] != '=' || res2[3] != '=' || res2[4] != '\n')
+		errors++;
+	os_free(res2);
+
+	res = base64_decode("", 0, &res_len);
 	if (res) {
 		errors++;
 		os_free(res);
 	}
 
-	res = base64_encode((const unsigned char *) "=", 1, &res_len);
-	if (!res || res_len != 5 || res[0] != 'P' || res[1] != 'Q' ||
-	    res[2] != '=' || res[3] != '=' || res[4] != '\n')
-		errors++;
-	os_free(res);
-
-	res = base64_encode((const unsigned char *) "=", 1, NULL);
-	if (!res || res[0] != 'P' || res[1] != 'Q' ||
-	    res[2] != '=' || res[3] != '=' || res[4] != '\n')
-		errors++;
-	os_free(res);
-
-	res = base64_decode((const unsigned char *) "", 0, &res_len);
+	res = base64_decode("a", 1, &res_len);
 	if (res) {
 		errors++;
 		os_free(res);
 	}
 
-	res = base64_decode((const unsigned char *) "a", 1, &res_len);
+	res = base64_decode("====", 4, &res_len);
 	if (res) {
 		errors++;
 		os_free(res);
 	}
 
-	res = base64_decode((const unsigned char *) "====", 4, &res_len);
-	if (res) {
-		errors++;
-		os_free(res);
-	}
-
-	res = base64_decode((const unsigned char *) "PQ==", 4, &res_len);
+	res = base64_decode("PQ==", 4, &res_len);
 	if (!res || res_len != 1 || res[0] != '=')
 		errors++;
 	os_free(res);
 
-	res = base64_decode((const unsigned char *) "P.Q-=!=*", 8, &res_len);
+	res = base64_decode("P.Q-=!=*", 8, &res_len);
 	if (!res || res_len != 1 || res[0] != '=')
 		errors++;
 	os_free(res);
diff --git a/src/utils/xml_libxml2.c b/src/utils/xml_libxml2.c
index 7b6d2764b..d73654eb5 100644
--- a/src/utils/xml_libxml2.c
+++ b/src/utils/xml_libxml2.c
@@ -409,7 +409,7 @@ char * xml_node_get_base64_text(struct xml_node_ctx *ctx, xml_node_t *node,
 	if (txt == NULL)
 		return NULL;
 
-	ret = base64_decode((unsigned char *) txt, strlen(txt), &len);
+	ret = base64_decode(txt, strlen(txt), &len);
 	if (ret_len)
 		*ret_len = len;
 	xml_node_get_text_free(ctx, txt);
diff --git a/src/wps/upnp_xml.c b/src/wps/upnp_xml.c
index a9958eeda..ca0925cb5 100644
--- a/src/wps/upnp_xml.c
+++ b/src/wps/upnp_xml.c
@@ -235,7 +235,7 @@ struct wpabuf * xml_get_base64_item(const char *data, const char *name,
 		return NULL;
 	}
 
-	decoded = base64_decode((unsigned char *) msg, os_strlen(msg), &len);
+	decoded = base64_decode(msg, os_strlen(msg), &len);
 	os_free(msg);
 	if (decoded == NULL) {
 		*ret = UPNP_OUT_OF_MEMORY;
diff --git a/src/wps/wps_er.c b/src/wps/wps_er.c
index 06a8fdaf3..6bded1432 100644
--- a/src/wps/wps_er.c
+++ b/src/wps/wps_er.c
@@ -897,7 +897,7 @@ static struct wpabuf * wps_er_soap_hdr(const struct wpabuf *msg,
 				       const struct sockaddr_in *dst,
 				       char **len_ptr, char **body_ptr)
 {
-	unsigned char *encoded;
+	char *encoded;
 	size_t encoded_len;
 	struct wpabuf *buf;
 
@@ -939,7 +939,7 @@ static struct wpabuf * wps_er_soap_hdr(const struct wpabuf *msg,
 	wpabuf_put_str(buf, "\">\n");
 	if (encoded) {
 		wpabuf_printf(buf, "<%s>%s</%s>\n",
-			      arg_name, (char *) encoded, arg_name);
+			      arg_name, encoded, arg_name);
 		os_free(encoded);
 	}
 
diff --git a/src/wps/wps_registrar.c b/src/wps/wps_registrar.c
index 0ac5b2831..671f5fed7 100644
--- a/src/wps/wps_registrar.c
+++ b/src/wps/wps_registrar.c
@@ -1745,7 +1745,8 @@ int wps_build_cred(struct wps_data *wps, struct wpabuf *msg)
 			return -1;
 		}
 		os_free(wps->new_psk);
-		wps->new_psk = base64_encode(r, sizeof(r), &wps->new_psk_len);
+		wps->new_psk = (u8 *) base64_encode(r, sizeof(r),
+						    &wps->new_psk_len);
 		if (wps->new_psk == NULL)
 			return -1;
 		wps->new_psk_len--; /* remove newline */
diff --git a/src/wps/wps_upnp.c b/src/wps/wps_upnp.c
index ca893a43c..61d21597c 100644
--- a/src/wps/wps_upnp.c
+++ b/src/wps/wps_upnp.c
@@ -647,7 +647,7 @@ static int subscription_first_event(struct subscription *s)
 			   "initial WLANEvent");
 		msg = build_fake_wsc_ack();
 		if (msg) {
-			s->sm->wlanevent = (char *)
+			s->sm->wlanevent =
 				base64_encode(wpabuf_head(msg),
 					      wpabuf_len(msg), NULL);
 			wpabuf_free(msg);
@@ -822,7 +822,7 @@ int upnp_wps_device_send_wlan_event(struct upnp_wps_device_sm *sm,
 	}
 	raw_len = pos;
 
-	val = (char *) base64_encode(raw, raw_len, &val_len);
+	val = base64_encode(raw, raw_len, &val_len);
 	if (val == NULL)
 		goto fail;
 
diff --git a/src/wps/wps_upnp_web.c b/src/wps/wps_upnp_web.c
index 7548e8432..3c5a97c78 100644
--- a/src/wps/wps_upnp_web.c
+++ b/src/wps/wps_upnp_web.c
@@ -765,8 +765,8 @@ static void web_connection_send_reply(struct http_request *req,
 
 	if (reply) {
 		size_t len;
-		replydata = (char *) base64_encode(wpabuf_head(reply),
-						   wpabuf_len(reply), &len);
+		replydata = base64_encode(wpabuf_head(reply), wpabuf_len(reply),
+					  &len);
 	} else
 		replydata = NULL;
 
diff --git a/wpa_supplicant/config_file.c b/wpa_supplicant/config_file.c
index cf4b7bc6e..55971fcc6 100644
--- a/wpa_supplicant/config_file.c
+++ b/wpa_supplicant/config_file.c
@@ -296,7 +296,7 @@ static struct wpa_config_blob * wpa_config_read_blob(FILE *f, int *line,
 {
 	struct wpa_config_blob *blob;
 	char buf[256], *pos;
-	unsigned char *encoded = NULL, *nencoded;
+	char *encoded = NULL, *nencoded;
 	int end = 0;
 	size_t encoded_len = 0, len;
 
@@ -1098,7 +1098,7 @@ static void wpa_config_write_cred(FILE *f, struct wpa_cred *cred)
 #ifndef CONFIG_NO_CONFIG_BLOBS
 static int wpa_config_write_blob(FILE *f, struct wpa_config_blob *blob)
 {
-	unsigned char *encoded;
+	char *encoded;
 
 	encoded = base64_encode(blob->data, blob->len, NULL);
 	if (encoded == NULL)
diff --git a/wpa_supplicant/eapol_test.c b/wpa_supplicant/eapol_test.c
index 524724f19..53d75853b 100644
--- a/wpa_supplicant/eapol_test.c
+++ b/wpa_supplicant/eapol_test.c
@@ -439,7 +439,7 @@ static void eapol_sm_cb(struct eapol_sm *eapol, enum eapol_supp_result result,
 static void eapol_test_write_cert(FILE *f, const char *subject,
 				  const struct wpabuf *cert)
 {
-	unsigned char *encoded;
+	char *encoded;
 
 	encoded = base64_encode(wpabuf_head(cert), wpabuf_len(cert), NULL);
 	if (encoded == NULL)
diff --git a/wpa_supplicant/hs20_supplicant.c b/wpa_supplicant/hs20_supplicant.c
index cb236df18..47a1d0175 100644
--- a/wpa_supplicant/hs20_supplicant.c
+++ b/wpa_supplicant/hs20_supplicant.c
@@ -340,7 +340,7 @@ int hs20_get_icon(struct wpa_supplicant *wpa_s, const u8 *bssid,
 {
 	struct icon_entry *icon;
 	size_t out_size;
-	unsigned char *b64;
+	char *b64;
 	size_t b64_size;
 	int reply_size;