diff --git a/src/secret.c b/src/secret.c
index e7a119c..cb3264e 100644
--- a/src/secret.c
+++ b/src/secret.c
@@ -203,40 +203,7 @@ static void mbedtls_sha3_finish(mbedtls_sha3_context *ctx,
   
 }
 
-// secretbase - internal auxiliary functions -----------------------------------
-
-static int validate_bitlength(const SEXP bits) {
-  
-  const int size = Rf_asInteger(bits);
-  if (size < 8 || size > (1 << 24))
-    Rf_error("'bits' must be between 8 and 2^24");
-  return size;
-  
-}
-
-static mbedtls_sha3_id id_from_size(size_t size) {
-  
-  mbedtls_sha3_id id;
-  switch (size) {
-  case 224:
-    id = MBEDTLS_SHA3_224;
-    break;
-  case 256:
-    id = MBEDTLS_SHA3_256;
-    break;
-  case 384:
-    id = MBEDTLS_SHA3_384;
-    break;
-  case 512:
-    id = MBEDTLS_SHA3_512;
-    break;
-  default:
-    id = MBEDTLS_SHA3_SHAKE256;
-  break;
-  }
-  return id;
-  
-}
+// secretbase - internals ------------------------------------------------------
 
 static void hash_bytes(R_outpstream_t stream, void *src, int len) {
   
@@ -266,105 +233,121 @@ static SEXP hash_to_char(unsigned char *buf, const size_t sz) {
   
 }
 
-static SEXP create_object(const int type, unsigned char *buf, const size_t sz) {
-  
-  SEXP out;
-  switch (type) {
-  case 0:
-    out = Rf_allocVector(RAWSXP, sz);
-    memcpy(STDVEC_DATAPTR(out), buf, sz);
-    break;
-  case 1:
-    out = hash_to_char(buf, sz);
-    break;
-  default:
-    out = Rf_allocVector(INTSXP, sz / sizeof(int));
-    memcpy(STDVEC_DATAPTR(out), buf, sz);
-    break;
-  }
-  return out;
-  
-}
-
-// secretbase - exported functions ---------------------------------------------
-
-SEXP secretbase_sha3(SEXP x, SEXP bits, SEXP convert) {
+static SEXP secretbase_sha3_impl(const SEXP x, const SEXP bits,
+                                 const SEXP convert, const int file) {
   
   const int conv = LOGICAL(convert)[0];
-  const int size = validate_bitlength(bits);
+  const int size = Rf_asInteger(bits);
+  if (size < 8 || size > (1 << 24))
+    Rf_error("'bits' must be between 8 and 2^24");
   const size_t outlen = (size_t) (size / 8);
   unsigned char output[outlen];
+  SEXP out;
   
-  mbedtls_sha3_id id = id_from_size(size);
   mbedtls_sha3_context ctx;
+  mbedtls_sha3_id id;
+  switch (size) {
+  case 224:
+    id = MBEDTLS_SHA3_224;
+    break;
+  case 256:
+    id = MBEDTLS_SHA3_256;
+    break;
+  case 384:
+    id = MBEDTLS_SHA3_384;
+    break;
+  case 512:
+    id = MBEDTLS_SHA3_512;
+    break;
+  default:
+    id = MBEDTLS_SHA3_SHAKE256;
+  break;
+  }
   mbedtls_sha3_init(&ctx);
   mbedtls_sha3_starts(&ctx, id);
   
-  switch (TYPEOF(x)) {
-  case STRSXP:
-    if (XLENGTH(x) == 1 && ATTRIB(x) == R_NilValue) {
-      const char *s = CHAR(STRING_ELT(x, 0));
-      mbedtls_sha3_update(&ctx, (const uint8_t *) s, strlen(s));
-      goto finish;
+  if (file) {
+    
+    const char *filepath = R_ExpandFileName(CHAR(STRING_ELT(x, 0)));
+    unsigned char buf[SB_BUF_SIZE];
+    size_t cur;
+    
+    FILE *fp = fopen(filepath, "rb");
+    if (fp == NULL)
+      Rf_error("file not found or no read permission");
+    while ((cur = fread(buf, 1, sizeof(buf), fp))) {
+      mbedtls_sha3_update(&ctx, buf, cur);
     }
-    break;
-  case RAWSXP:
-    if (ATTRIB(x) == R_NilValue) {
-      mbedtls_sha3_update(&ctx, (const uint8_t *) STDVEC_DATAPTR(x), (size_t) XLENGTH(x));
-      goto finish;
+    fclose(fp);
+    
+  } else {
+    
+    switch (TYPEOF(x)) {
+    case STRSXP:
+      if (XLENGTH(x) == 1 && ATTRIB(x) == R_NilValue) {
+        const char *s = CHAR(STRING_ELT(x, 0));
+        mbedtls_sha3_update(&ctx, (const uint8_t *) s, strlen(s));
+        goto finish;
+      }
+      break;
+    case RAWSXP:
+      if (ATTRIB(x) == R_NilValue) {
+        mbedtls_sha3_update(&ctx, (const uint8_t *) STDVEC_DATAPTR(x), (size_t) XLENGTH(x));
+        goto finish;
+      }
+      break;
     }
-    break;
+    
+    secretbase_context sctx;
+    sctx.ctx = &ctx;
+    sctx.skip = SB_SERIAL_HEADERS;
+    
+    struct R_outpstream_st output_stream;
+    R_InitOutPStream(
+      &output_stream,
+      (R_pstream_data_t) &sctx,
+      R_pstream_xdr_format,
+      SB_R_SERIAL_VER,
+      NULL,
+      hash_bytes,
+      NULL,
+      R_NilValue
+    );
+    R_Serialize(x, &output_stream);
+    
   }
   
-  secretbase_context sctx;
-  sctx.ctx = &ctx;
-  sctx.skip = SB_SERIAL_HEADERS;
-  
-  struct R_outpstream_st output_stream;
-  R_InitOutPStream(
-    &output_stream,
-    (R_pstream_data_t) &sctx,
-    R_pstream_xdr_format,
-    SB_R_SERIAL_VER,
-    NULL,
-    hash_bytes,
-    NULL,
-    R_NilValue
-  );
-  R_Serialize(x, &output_stream);
-  
   finish:
   mbedtls_sha3_finish(&ctx, output, outlen);
   
-  return create_object(conv, output, outlen);
+  switch (conv) {
+  case 0:
+    out = Rf_allocVector(RAWSXP, outlen);
+    memcpy(STDVEC_DATAPTR(out), output, outlen);
+    break;
+  case 1:
+    out = hash_to_char(output, outlen);
+    break;
+  default:
+    out = Rf_allocVector(INTSXP, outlen / sizeof(int));
+    memcpy(STDVEC_DATAPTR(out), output, outlen);
+    break;
+  }
+  
+  return out;
   
 }
 
-SEXP secretbase_sha3_file(SEXP x, SEXP bits, SEXP convert) {
-  
-  const char *file = R_ExpandFileName(CHAR(STRING_ELT(x, 0)));
-  const int conv = LOGICAL(convert)[0];
-  const int size = validate_bitlength(bits);
-  const size_t outlen = (size_t) (size / 8);
-  unsigned char output[outlen];
-  unsigned char buf[SB_BUF_SIZE];
-  size_t cur;
+// secretbase - exported functions ---------------------------------------------
+
+SEXP secretbase_sha3(SEXP x, SEXP bits, SEXP convert) {
   
-  mbedtls_sha3_id id = id_from_size(size);
-  mbedtls_sha3_context ctx;
-  mbedtls_sha3_init(&ctx);
-  mbedtls_sha3_starts(&ctx, id);
+  return secretbase_sha3_impl(x, bits, convert, 0);
   
-  FILE *fp = fopen(file, "rb");
-  if (fp == NULL)
-    Rf_error("file not found or accessible");
-  while ((cur = fread(buf, 1, sizeof(buf), fp))) {
-    mbedtls_sha3_update(&ctx, buf, cur);
-  }
-  fclose(fp);
-    
-  mbedtls_sha3_finish(&ctx, output, outlen);
+}
+
+SEXP secretbase_sha3_file(SEXP x, SEXP bits, SEXP convert) {
   
-  return create_object(conv, output, outlen);
+  return secretbase_sha3_impl(x, bits, convert, 1);
   
 }
diff --git a/src/secret.h b/src/secret.h
index ccf0633..08a1daa 100644
--- a/src/secret.h
+++ b/src/secret.h
@@ -59,8 +59,8 @@ typedef struct mbedtls_sha3_context {
 } mbedtls_sha3_context;
 
 typedef struct secretbase_context_s {
-  mbedtls_sha3_context *ctx;
   int skip;
+  mbedtls_sha3_context *ctx;
 } secretbase_context;
 
 SEXP secretbase_sha3(SEXP, SEXP, SEXP);
diff --git a/tests/tests.R b/tests/tests.R
index f5c14c6..7d95e1a 100644
--- a/tests/tests.R
+++ b/tests/tests.R
@@ -37,4 +37,4 @@ hash_func <- function(file, string) {
   sha3file(file)
 }
 test_equal(hash_func(tempfile(), "secret base"), "a721d57570e7ce366adee2fccbe9770723c6e3622549c31c7cab9dbb4a795520")
-test_error(hash_func("", ""), "file not found or accessible")
+test_error(hash_func("", ""), "file not found or no read permission")