NAME

       OSSL_SELF_TEST_new, OSSL_SELF_TEST_free, OSSL_SELF_TEST_onbegin,
       OSSL_SELF_TEST_oncorrupt_byte, OSSL_SELF_TEST_onend - functionality to trigger a callback
       during a self test

SYNOPSIS

        #include <openssl/self_test.h>

        OSSL_SELF_TEST *OSSL_SELF_TEST_new(OSSL_CALLBACK *cb, void *cbarg);
        void OSSL_SELF_TEST_free(OSSL_SELF_TEST *st);

        void OSSL_SELF_TEST_onbegin(OSSL_SELF_TEST *st, const char *type,
                                    const char *desc);
        int OSSL_SELF_TEST_oncorrupt_byte(OSSL_SELF_TEST *st, unsigned char *bytes);
        void OSSL_SELF_TEST_onend(OSSL_SELF_TEST *st, int ret);

DESCRIPTION

       These methods are intended for use by provider implementors, to display diagnostic
       information during self testing.

       OSSL_SELF_TEST_new() allocates an opaque OSSL_SELF_TEST object that has a callback and
       callback argument associated with it.

       The callback cb may be triggered multiple times by a self test to indicate different
       phases.

       OSSL_SELF_TEST_free() frees the space allocated by OSSL_SELF_TEST_new().

       OSSL_SELF_TEST_onbegin() may be inserted at the start of a block of self test code. It can
       be used for diagnostic purposes.  If this method is called the callback cb will receive
       the following OSSL_PARAM object.

       "st-phase" (OSSL_PROV_PARAM_SELF_TEST_PHASE) <UTF8 string>
           The value is the string "Start"

       OSSL_SELF_TEST_oncorrupt_byte() may be inserted just after the known answer is calculated,
       but before the self test compares the result. The first byte in the passed in array of
       bytes will be corrupted if the callback returns 0, otherwise it leaves the array
       unaltered. It can be used for failure testing.  The type and desc can be used to identify
       an individual self test to target for failure testing.  If this method is called the
       callback cb will receive the following OSSL_PARAM object.

       "st-phase" (OSSL_PROV_PARAM_SELF_TEST_PHASE) <UTF8 string>
           The value is the string "Corrupt"

       OSSL_SELF_TEST_onend() may be inserted at the end of a block of self test code just before
       cleanup to indicate if the test passed or failed. It can be used for diagnostic purposes.
       If this method is called the callback cb will receive the following OSSL_PARAM object.

       "st-phase" (OSSL_PROV_PARAM_SELF_TEST_PHASE) <UTF8 string>
           The value of the string is "Pass" if ret is non zero, otherwise it has the value
           "Fail".

       After the callback cb has been called the values that were set by OSSL_SELF_TEST_onbegin()
       for type and desc are set to the value "None".

       If OSSL_SELF_TEST_onbegin(), OSSL_SELF_TEST_oncorrupt_byte() or OSSL_SELF_TEST_onend() is
       called the following additional OSSL_PARAM are passed to the callback.

       "st-type" (OSSL_PROV_PARAM_SELF_TEST_TYPE) <UTF8 string>
           The value is setup by the type passed to OSSL_SELF_TEST_onbegin().  This allows the
           callback to identify the type of test being run.

       "st-desc" (OSSL_PROV_PARAM_SELF_TEST_DESC) <UTF8 string>
           The value is setup by the type passed to OSSL_SELF_TEST_onbegin().  This allows the
           callback to identify the sub category of the test being run.

RETURN VALUES

       OSSL_SELF_TEST_new() returns the allocated OSSL_SELF_TEST object, or NULL if it fails.

       OSSL_SELF_TEST_oncorrupt_byte() returns 1 if corruption occurs, otherwise it returns 0.

EXAMPLES

       A single self test could be set up in the following way:

           OSSL_SELF_TEST *st = NULL;
           OSSL_CALLBACK *cb;
           void *cbarg;
           int ok = 0;
           unsigned char out[EVP_MAX_MD_SIZE];
           unsigned int out_len = 0;
           EVP_MD_CTX *ctx = EVP_MD_CTX_new();
           EVP_MD *md = EVP_MD_fetch(libctx, t->algorithm, NULL);

           /*
            * Retrieve the callback - will be NULL if not set by the application via
            * OSSL_SELF_TEST_set_callback().
            */
           OSSL_SELF_TEST_get_callback(libctx, &cb, &cbarg);

           st = OSSL_SELF_TEST_new(cb, cb_arg);

           /* Trigger the optional callback */
           OSSL_SELF_TEST_onbegin(st, OSSL_SELF_TEST_TYPE_KAT_DIGEST,
                                  OSSL_SELF_TEST_DESC_MD_SHA2);

           if (!EVP_DigestInit_ex(ctx, md, NULL)
               || !EVP_DigestUpdate(ctx, pt, pt_len)
               || !EVP_DigestFinal(ctx, out, &out_len))
               goto err;

           /* Optional corruption - If the application callback returns 0 */
           OSSL_SELF_TEST_oncorrupt_byte(st, out);

           if (out_len != t->expected_len
               || memcmp(out, t->expected, out_len) != 0)
               goto err;
           ok = 1;
         err:
           OSSL_SELF_TEST_onend(st, ok);
           EVP_MD_free(md);
           EVP_MD_CTX_free(ctx);

       Multiple self test's can be set up in a similar way by repeating the pattern of
       OSSL_SELF_TEST_onbegin(), OSSL_SELF_TEST_oncorrupt_byte(), OSSL_SELF_TEST_onend() for each
       test.

SEE ALSO

       OSSL_SELF_TEST_set_callback(3), openssl-core.h(7), OSSL_PROVIDER-FIPS(7)

HISTORY

       The functions described here were added in OpenSSL 3.0.

COPYRIGHT

       Copyright 2020 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (the "License").  You may not use this file except
       in compliance with the License.  You can obtain a copy in the file LICENSE in the source
       distribution or at <https://www.openssl.org/source/license.html>.