ASN1_INTEGER_get_uint64, ASN1_INTEGER_set_uint64, ASN1_INTEGER_get_int64, ASN1_INTEGER_get,

       The ambiguous return values of ASN1_INTEGER_get() and ASN1_ENUMERATED_get() mean these functions should
       be avoided if possible. They are retained for compatibility. Normally the ambiguous return values are not
       legitimate values for the fields they represent.

       Copyright 2015-2020 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>.

3.5.0                                              2025-06-04                       ASN1_INTEGER_GET_INT64(3SSL)

       These functions convert to and from ASN1_INTEGER and ASN1_ENUMERATED structures.

       ASN1_INTEGER_get_int64() converts an ASN1_INTEGER into an int64_t type If successful it returns 1 and
       sets *pr to the value of a. If it fails (due to invalid type or the value being too big to fit into an
       int64_t type) it returns 0.

       ASN1_INTEGER_get_uint64() is similar to ASN1_INTEGER_get_int64_t() except it converts to a uint64_t type
       and an error is returned if the passed integer is negative.

       ASN1_INTEGER_get() also returns the value of a but it returns 0 if a is NULL and -1 on error (which is
       ambiguous because -1 is a legitimate value for an ASN1_INTEGER). New applications should use
       ASN1_INTEGER_get_int64() instead.

       ASN1_INTEGER_set_int64() sets the value of ASN1_INTEGERa to the int64_t value r.

       ASN1_INTEGER_set_uint64() sets the value of ASN1_INTEGERa to the uint64_t value r.

       ASN1_INTEGER_set() sets the value of ASN1_INTEGERa to the long value v.

       BN_to_ASN1_INTEGER() converts BIGNUMbn to an ASN1_INTEGER. If ai is NULL a new ASN1_INTEGER structure is
       returned. If ai is not NULL then the existing structure will be used instead.

       ASN1_INTEGER_to_BN() converts ASN1_INTEGER ai into a BIGNUM. If bn is NULL a new BIGNUM structure is
       returned. If bn is not NULL then the existing structure will be used instead.

       ASN1_ENUMERATED_get_int64(), ASN1_ENUMERATED_set_int64(), ASN1_ENUMERATED_set(), BN_to_ASN1_ENUMERATED()
       and ASN1_ENUMERATED_to_BN() behave in an identical way to their ASN1_INTEGER counterparts except they
       operate on an ASN1_ENUMERATED value.

       ASN1_ENUMERATED_get() returns the value of a in a similar way to ASN1_INTEGER_get() but it returns
       0xffffffffL if the value of a will not fit in a long type. New applications should use
       ASN1_ENUMERATED_get_int64() instead.

ASN1_INTEGER_set_int64(), ASN1_INTEGER_get_int64(), ASN1_ENUMERATED_set_int64() and
       ASN1_ENUMERATED_get_int64() were added in OpenSSL 1.1.0.

       ASN1_INTEGER_get_uint64, ASN1_INTEGER_set_uint64, ASN1_INTEGER_get_int64, ASN1_INTEGER_get,
       ASN1_INTEGER_set_int64, ASN1_INTEGER_set, BN_to_ASN1_INTEGER, ASN1_INTEGER_to_BN,
       ASN1_ENUMERATED_get_int64, ASN1_ENUMERATED_get, ASN1_ENUMERATED_set_int64, ASN1_ENUMERATED_set,
       BN_to_ASN1_ENUMERATED, ASN1_ENUMERATED_to_BN - ASN.1 INTEGER and ENUMERATED utilities

       In general an ASN1_INTEGER or ASN1_ENUMERATED type can contain an integer of almost arbitrary size and so
       cannot always be represented by a C int64_t type. However, in many cases (for example version numbers)
       they represent small integers which can be more easily manipulated if converted to an appropriate C
       integer type.

ASN1_INTEGER_set_int64(), ASN1_INTEGER_set(), ASN1_ENUMERATED_set_int64() and ASN1_ENUMERATED_set()
       return 1 for success and 0 for failure. They will only fail if a memory allocation error occurs.

       ASN1_INTEGER_get_int64() and ASN1_ENUMERATED_get_int64() return 1 for success and 0 for failure. They
       will fail if the passed type is incorrect (this will only happen if there is a programming error) or if
       the value exceeds the range of an int64_t type.

       BN_to_ASN1_INTEGER() and BN_to_ASN1_ENUMERATED() return an ASN1_INTEGER or ASN1_ENUMERATED structure
       respectively or NULL if an error occurs. They will only fail due to a memory allocation error.

       ASN1_INTEGER_to_BN() and ASN1_ENUMERATED_to_BN() return a BIGNUM structure of NULL if an error occurs.
       They can fail if the passed type is incorrect (due to programming error) or due to a memory allocation
       failure.

ERR_get_error(3)

        #include <openssl/asn1.h>

        int ASN1_INTEGER_get_int64(int64_t *pr, const ASN1_INTEGER *a);
        long ASN1_INTEGER_get(const ASN1_INTEGER *a);

        int ASN1_INTEGER_set_int64(ASN1_INTEGER *a, int64_t r);
        int ASN1_INTEGER_set(ASN1_INTEGER *a, long v);

        int ASN1_INTEGER_get_uint64(uint64_t *pr, const ASN1_INTEGER *a);
        int ASN1_INTEGER_set_uint64(ASN1_INTEGER *a, uint64_t r);

        ASN1_INTEGER *BN_to_ASN1_INTEGER(const BIGNUM *bn, ASN1_INTEGER *ai);
        BIGNUM *ASN1_INTEGER_to_BN(const ASN1_INTEGER *ai, BIGNUM *bn);

        int ASN1_ENUMERATED_get_int64(int64_t *pr, const ASN1_ENUMERATED *a);
        long ASN1_ENUMERATED_get(const ASN1_ENUMERATED *a);

        int ASN1_ENUMERATED_set_int64(ASN1_ENUMERATED *a, int64_t r);
        int ASN1_ENUMERATED_set(ASN1_ENUMERATED *a, long v);

        ASN1_ENUMERATED *BN_to_ASN1_ENUMERATED(const BIGNUM *bn, ASN1_ENUMERATED *ai);
        BIGNUM *ASN1_ENUMERATED_to_BN(const ASN1_ENUMERATED *ai, BIGNUM *bn);