static unsigned int BN_STACK_pop(BN_STACK *st)
{
    return st->indexes[--(st->depth)];
}
['int rsa_sp800_56b_check_keypair(const RSA *rsa, const BIGNUM *efixed,\n                                int strength, int nbits)\n{\n    int ret = 0;\n    BN_CTX *ctx = NULL;\n    BIGNUM *r = NULL;\n    if (rsa->p == NULL\n            || rsa->q == NULL\n            || rsa->e == NULL\n            || rsa->d == NULL\n            || rsa->n == NULL) {\n        RSAerr(RSA_F_RSA_SP800_56B_CHECK_KEYPAIR, RSA_R_INVALID_REQUEST);\n        return 0;\n    }\n    if (!rsa_sp800_56b_validate_strength(nbits, strength))\n        return 0;\n    if (efixed != NULL) {\n        if (BN_cmp(efixed, rsa->e) != 0) {\n            RSAerr(RSA_F_RSA_SP800_56B_CHECK_KEYPAIR, RSA_R_INVALID_REQUEST);\n            return 0;\n        }\n    }\n    if (!rsa_check_public_exponent(rsa->e)) {\n        RSAerr(RSA_F_RSA_SP800_56B_CHECK_KEYPAIR,\n               RSA_R_PUB_EXPONENT_OUT_OF_RANGE);\n        return 0;\n    }\n    if (nbits != BN_num_bits(rsa->n)) {\n        RSAerr(RSA_F_RSA_SP800_56B_CHECK_KEYPAIR, RSA_R_INVALID_KEYPAIR);\n        return 0;\n    }\n    ctx = BN_CTX_new();\n    if (ctx == NULL)\n        return 0;\n    BN_CTX_start(ctx);\n    r = BN_CTX_get(ctx);\n    if (r == NULL || !BN_mul(r, rsa->p, rsa->q, ctx))\n        goto err;\n    if (BN_cmp(rsa->n, r) != 0) {\n        RSAerr(RSA_F_RSA_SP800_56B_CHECK_KEYPAIR, RSA_R_INVALID_REQUEST);\n        goto err;\n    }\n    ret = rsa_check_prime_factor(rsa->p, rsa->e, nbits, ctx)\n          && rsa_check_prime_factor(rsa->q, rsa->e, nbits, ctx)\n          && (rsa_check_pminusq_diff(r, rsa->p, rsa->q, nbits) > 0)\n          && rsa_check_private_exponent(rsa, nbits, ctx)\n          && rsa_check_crt_components(rsa, ctx);\n    if (ret != 1)\n        RSAerr(RSA_F_RSA_SP800_56B_CHECK_KEYPAIR, RSA_R_INVALID_KEYPAIR);\nerr:\n    BN_clear(r);\n    BN_CTX_end(ctx);\n    BN_CTX_free(ctx);\n    return ret;\n}', 'void BN_CTX_start(BN_CTX *ctx)\n{\n    CTXDBG("ENTER BN_CTX_start()", ctx);\n    if (ctx->err_stack || ctx->too_many)\n        ctx->err_stack++;\n    else if (!BN_STACK_push(&ctx->stack, ctx->used)) {\n        BNerr(BN_F_BN_CTX_START, BN_R_TOO_MANY_TEMPORARY_VARIABLES);\n        ctx->err_stack++;\n    }\n    CTXDBG("LEAVE BN_CTX_start()", ctx);\n}', 'int rsa_check_crt_components(const RSA *rsa, BN_CTX *ctx)\n{\n    int ret = 0;\n    BIGNUM *r = NULL, *p1 = NULL, *q1 = NULL;\n    if (rsa->dmp1 == NULL || rsa->dmq1 == NULL || rsa->iqmp == NULL) {\n        if (rsa->dmp1 != NULL || rsa->dmq1 != NULL || rsa->iqmp != NULL)\n            return 0;\n        return 1;\n    }\n    BN_CTX_start(ctx);\n    r = BN_CTX_get(ctx);\n    p1 = BN_CTX_get(ctx);\n    q1 = BN_CTX_get(ctx);\n    ret = (q1 != NULL)\n          && (BN_copy(p1, rsa->p) != NULL)\n          && BN_sub_word(p1, 1)\n          && (BN_copy(q1, rsa->q) != NULL)\n          && BN_sub_word(q1, 1)\n          && (BN_cmp(rsa->dmp1, BN_value_one()) > 0)\n          && (BN_cmp(rsa->dmp1, p1) < 0)\n          && (BN_cmp(rsa->dmq1, BN_value_one()) > 0)\n          && (BN_cmp(rsa->dmq1, q1) < 0)\n          && (BN_cmp(rsa->iqmp, BN_value_one()) > 0)\n          && (BN_cmp(rsa->iqmp, rsa->p) < 0)\n          && BN_mod_mul(r, rsa->dmp1, rsa->e, p1, ctx)\n          && BN_is_one(r)\n          && BN_mod_mul(r, rsa->dmq1, rsa->e, q1, ctx)\n          && BN_is_one(r)\n          && BN_mod_mul(r, rsa->iqmp, rsa->q, rsa->p, ctx)\n          && BN_is_one(r);\n    BN_clear(p1);\n    BN_clear(q1);\n    BN_CTX_end(ctx);\n    return ret;\n}', 'BIGNUM *BN_CTX_get(BN_CTX *ctx)\n{\n    BIGNUM *ret;\n    CTXDBG("ENTER BN_CTX_get()", ctx);\n    if (ctx->err_stack || ctx->too_many)\n        return NULL;\n    if ((ret = BN_POOL_get(&ctx->pool, ctx->flags)) == NULL) {\n        ctx->too_many = 1;\n        BNerr(BN_F_BN_CTX_GET, BN_R_TOO_MANY_TEMPORARY_VARIABLES);\n        return NULL;\n    }\n    BN_zero(ret);\n    ret->flags &= (~BN_FLG_CONSTTIME);\n    ctx->used++;\n    CTXDBG("LEAVE BN_CTX_get()", ctx);\n    return ret;\n}', 'int BN_mod_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,\n               BN_CTX *ctx)\n{\n    BIGNUM *t;\n    int ret = 0;\n    bn_check_top(a);\n    bn_check_top(b);\n    bn_check_top(m);\n    BN_CTX_start(ctx);\n    if ((t = BN_CTX_get(ctx)) == NULL)\n        goto err;\n    if (a == b) {\n        if (!BN_sqr(t, a, ctx))\n            goto err;\n    } else {\n        if (!BN_mul(t, a, b, ctx))\n            goto err;\n    }\n    if (!BN_nnmod(r, t, m, ctx))\n        goto err;\n    bn_check_top(r);\n    ret = 1;\n err:\n    BN_CTX_end(ctx);\n    return ret;\n}', 'int BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)\n{\n    int ret = bn_sqr_fixed_top(r, a, ctx);\n    bn_correct_top(r);\n    bn_check_top(r);\n    return ret;\n}', 'int bn_sqr_fixed_top(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)\n{\n    int max, al;\n    int ret = 0;\n    BIGNUM *tmp, *rr;\n    bn_check_top(a);\n    al = a->top;\n    if (al <= 0) {\n        r->top = 0;\n        r->neg = 0;\n        return 1;\n    }\n    BN_CTX_start(ctx);\n    rr = (a != r) ? r : BN_CTX_get(ctx);\n    tmp = BN_CTX_get(ctx);\n    if (rr == NULL || tmp == NULL)\n        goto err;\n    max = 2 * al;\n    if (bn_wexpand(rr, max) == NULL)\n        goto err;\n    if (al == 4) {\n#ifndef BN_SQR_COMBA\n        BN_ULONG t[8];\n        bn_sqr_normal(rr->d, a->d, 4, t);\n#else\n        bn_sqr_comba4(rr->d, a->d);\n#endif\n    } else if (al == 8) {\n#ifndef BN_SQR_COMBA\n        BN_ULONG t[16];\n        bn_sqr_normal(rr->d, a->d, 8, t);\n#else\n        bn_sqr_comba8(rr->d, a->d);\n#endif\n    } else {\n#if defined(BN_RECURSION)\n        if (al < BN_SQR_RECURSIVE_SIZE_NORMAL) {\n            BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL * 2];\n            bn_sqr_normal(rr->d, a->d, al, t);\n        } else {\n            int j, k;\n            j = BN_num_bits_word((BN_ULONG)al);\n            j = 1 << (j - 1);\n            k = j + j;\n            if (al == j) {\n                if (bn_wexpand(tmp, k * 2) == NULL)\n                    goto err;\n                bn_sqr_recursive(rr->d, a->d, al, tmp->d);\n            } else {\n                if (bn_wexpand(tmp, max) == NULL)\n                    goto err;\n                bn_sqr_normal(rr->d, a->d, al, tmp->d);\n            }\n        }\n#else\n        if (bn_wexpand(tmp, max) == NULL)\n            goto err;\n        bn_sqr_normal(rr->d, a->d, al, tmp->d);\n#endif\n    }\n    rr->neg = 0;\n    rr->top = max;\n    rr->flags |= BN_FLG_FIXED_TOP;\n    if (r != rr && BN_copy(r, rr) == NULL)\n        goto err;\n    ret = 1;\n err:\n    bn_check_top(rr);\n    bn_check_top(tmp);\n    BN_CTX_end(ctx);\n    return ret;\n}', 'void BN_CTX_end(BN_CTX *ctx)\n{\n    CTXDBG("ENTER BN_CTX_end()", ctx);\n    if (ctx->err_stack)\n        ctx->err_stack--;\n    else {\n        unsigned int fp = BN_STACK_pop(&ctx->stack);\n        if (fp < ctx->used)\n            BN_POOL_release(&ctx->pool, ctx->used - fp);\n        ctx->used = fp;\n        ctx->too_many = 0;\n    }\n    CTXDBG("LEAVE BN_CTX_end()", ctx);\n}', 'static unsigned int BN_STACK_pop(BN_STACK *st)\n{\n    return st->indexes[--(st->depth)];\n}']