diff --git a/include/mbedtls/sha1.h b/include/mbedtls/sha1.h
index bcaeab5..bb6ecf0 100644
--- a/include/mbedtls/sha1.h
+++ b/include/mbedtls/sha1.h
@@ -42,6 +42,7 @@
 
 /* MBEDTLS_ERR_SHA1_HW_ACCEL_FAILED is deprecated and should not be used. */
 #define MBEDTLS_ERR_SHA1_HW_ACCEL_FAILED                  -0x0035  /**< SHA-1 hardware accelerator failed */
+#define MBEDTLS_ERR_SHA1_BAD_INPUT_DATA                   -0x0073  /**< SHA-1 input data was malformed. */
 
 #ifdef __cplusplus
 extern "C" {
@@ -79,6 +80,7 @@
  *                 stronger message digests instead.
  *
  * \param ctx      The SHA-1 context to initialize.
+ *                 This must not be \c NULL.
  *
  */
 void mbedtls_sha1_init( mbedtls_sha1_context *ctx );
@@ -90,7 +92,10 @@
  *                 constitutes a security risk. We recommend considering
  *                 stronger message digests instead.
  *
- * \param ctx      The SHA-1 context to clear.
+ * \param ctx      The SHA-1 context to clear. This may be \c NULL,
+ *                 in which case this function does nothing. If it is
+ *                 not \c NULL, it must point to an initialized
+ *                 SHA-1 context.
  *
  */
 void mbedtls_sha1_free( mbedtls_sha1_context *ctx );
@@ -102,8 +107,8 @@
  *                 constitutes a security risk. We recommend considering
  *                 stronger message digests instead.
  *
- * \param dst      The SHA-1 context to clone to.
- * \param src      The SHA-1 context to clone from.
+ * \param dst      The SHA-1 context to clone to. This must be initialized.
+ * \param src      The SHA-1 context to clone from. This must be initialized.
  *
  */
 void mbedtls_sha1_clone( mbedtls_sha1_context *dst,
@@ -116,9 +121,10 @@
  *                 constitutes a security risk. We recommend considering
  *                 stronger message digests instead.
  *
- * \param ctx      The SHA-1 context to initialize.
+ * \param ctx      The SHA-1 context to initialize. This must be initialized.
  *
  * \return         \c 0 on success.
+ * \return         A negative error code on failure.
  *
  */
 int mbedtls_sha1_starts_ret( mbedtls_sha1_context *ctx );
@@ -131,11 +137,14 @@
  *                 constitutes a security risk. We recommend considering
  *                 stronger message digests instead.
  *
- * \param ctx      The SHA-1 context.
+ * \param ctx      The SHA-1 context. This must be initialized
+ *                 and have a hash operation started.
  * \param input    The buffer holding the input data.
- * \param ilen     The length of the input data.
+ *                 This must be a readable buffer of length \p ilen Bytes.
+ * \param ilen     The length of the input data \p input in Bytes.
  *
  * \return         \c 0 on success.
+ * \return         A negative error code on failure.
  */
 int mbedtls_sha1_update_ret( mbedtls_sha1_context *ctx,
                              const unsigned char *input,
@@ -149,10 +158,13 @@
  *                 constitutes a security risk. We recommend considering
  *                 stronger message digests instead.
  *
- * \param ctx      The SHA-1 context.
- * \param output   The SHA-1 checksum result.
+ * \param ctx      The SHA-1 context to use. This must be initialized and
+ *                 have a hash operation started.
+ * \param output   The SHA-1 checksum result. This must be a writable
+ *                 buffer of length \c 20 Bytes.
  *
  * \return         \c 0 on success.
+ * \return         A negative error code on failure.
  */
 int mbedtls_sha1_finish_ret( mbedtls_sha1_context *ctx,
                              unsigned char output[20] );
@@ -164,10 +176,12 @@
  *                 constitutes a security risk. We recommend considering
  *                 stronger message digests instead.
  *
- * \param ctx      The SHA-1 context.
- * \param data     The data block being processed.
+ * \param ctx      The SHA-1 context to use. This must be initialized.
+ * \param data     The data block being processed. This must be a
+ *                 readable buffer of length \c 64 Bytes.
  *
  * \return         \c 0 on success.
+ * \return         A negative error code on failure.
  *
  */
 int mbedtls_internal_sha1_process( mbedtls_sha1_context *ctx,
@@ -188,7 +202,7 @@
  *
  * \deprecated     Superseded by mbedtls_sha1_starts_ret() in 2.7.0.
  *
- * \param ctx      The SHA-1 context to initialize.
+ * \param ctx      The SHA-1 context to initialize. This must be initialized.
  *
  */
 MBEDTLS_DEPRECATED void mbedtls_sha1_starts( mbedtls_sha1_context *ctx );
@@ -203,9 +217,11 @@
  *
  * \deprecated     Superseded by mbedtls_sha1_update_ret() in 2.7.0.
  *
- * \param ctx      The SHA-1 context.
+ * \param ctx      The SHA-1 context. This must be initialized and
+ *                 have a hash operation started.
  * \param input    The buffer holding the input data.
- * \param ilen     The length of the input data.
+ *                 This must be a readable buffer of length \p ilen Bytes.
+ * \param ilen     The length of the input data \p input in Bytes.
  *
  */
 MBEDTLS_DEPRECATED void mbedtls_sha1_update( mbedtls_sha1_context *ctx,
@@ -222,9 +238,10 @@
  *
  * \deprecated     Superseded by mbedtls_sha1_finish_ret() in 2.7.0.
  *
- * \param ctx      The SHA-1 context.
+ * \param ctx      The SHA-1 context. This must be initialized and
+ *                 have a hash operation started.
  * \param output   The SHA-1 checksum result.
- *
+ *                 This must be a writable buffer of length \c 20 Bytes.
  */
 MBEDTLS_DEPRECATED void mbedtls_sha1_finish( mbedtls_sha1_context *ctx,
                                              unsigned char output[20] );
@@ -238,8 +255,9 @@
  *
  * \deprecated     Superseded by mbedtls_internal_sha1_process() in 2.7.0.
  *
- * \param ctx      The SHA-1 context.
+ * \param ctx      The SHA-1 context. This must be initialized.
  * \param data     The data block being processed.
+ *                 This must be a readable buffer of length \c 64 bytes.
  *
  */
 MBEDTLS_DEPRECATED void mbedtls_sha1_process( mbedtls_sha1_context *ctx,
@@ -262,10 +280,13 @@
  *                 stronger message digests instead.
  *
  * \param input    The buffer holding the input data.
- * \param ilen     The length of the input data.
+ *                 This must be a readable buffer of length \p ilen Bytes.
+ * \param ilen     The length of the input data \p input in Bytes.
  * \param output   The SHA-1 checksum result.
+ *                 This must be a writable buffer of length \c 20 Bytes.
  *
  * \return         \c 0 on success.
+ * \return         A negative error code on failure.
  *
  */
 int mbedtls_sha1_ret( const unsigned char *input,
@@ -294,8 +315,10 @@
  * \deprecated     Superseded by mbedtls_sha1_ret() in 2.7.0
  *
  * \param input    The buffer holding the input data.
- * \param ilen     The length of the input data.
- * \param output   The SHA-1 checksum result.
+ *                 This must be a readable buffer of length \p ilen Bytes.
+ * \param ilen     The length of the input data \p input in Bytes.
+ * \param output   The SHA-1 checksum result. This must be a writable
+ *                 buffer of size \c 20 Bytes.
  *
  */
 MBEDTLS_DEPRECATED void mbedtls_sha1( const unsigned char *input,
@@ -305,6 +328,8 @@
 #undef MBEDTLS_DEPRECATED
 #endif /* !MBEDTLS_DEPRECATED_REMOVED */
 
+#if defined(MBEDTLS_SELF_TEST)
+
 /**
  * \brief          The SHA-1 checkup routine.
  *
@@ -318,6 +343,8 @@
  */
 int mbedtls_sha1_self_test( int verbose );
 
+#endif /* MBEDTLS_SELF_TEST */
+
 #ifdef __cplusplus
 }
 #endif