BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
{
    bn_check_top(b);
    if (a == b)
        return a;
    if (bn_wexpand(a, b->top) == NULL)
        return NULL;
    if (b->top > 0)
        memcpy(a->d, b->d, sizeof(b->d[0]) * b->top);
    a->neg = b->neg;
    a->top = b->top;
    a->flags |= b->flags & BN_FLG_FIXED_TOP;
    bn_check_top(a);
    return a;
}
['int srp_generate_server_master_secret(SSL *s)\n{\n    BIGNUM *K = NULL, *u = NULL;\n    int ret = -1, tmp_len = 0;\n    unsigned char *tmp = NULL;\n    if (!SRP_Verify_A_mod_N(s->srp_ctx.A, s->srp_ctx.N))\n        goto err;\n    if ((u = SRP_Calc_u(s->srp_ctx.A, s->srp_ctx.B, s->srp_ctx.N)) == NULL)\n        goto err;\n    if ((K = SRP_Calc_server_key(s->srp_ctx.A, s->srp_ctx.v, u, s->srp_ctx.b,\n                                 s->srp_ctx.N)) == NULL)\n        goto err;\n    tmp_len = BN_num_bytes(K);\n    if ((tmp = OPENSSL_malloc(tmp_len)) == NULL) {\n        SSLfatal(s, SSL_AD_INTERNAL_ERROR,\n                 SSL_F_SRP_GENERATE_SERVER_MASTER_SECRET, ERR_R_MALLOC_FAILURE);\n        goto err;\n    }\n    BN_bn2bin(K, tmp);\n    ret = ssl_generate_master_secret(s, tmp, tmp_len, 1);\n err:\n    BN_clear_free(K);\n    BN_clear_free(u);\n    return ret;\n}', 'int SRP_Verify_A_mod_N(const BIGNUM *A, const BIGNUM *N)\n{\n    return SRP_Verify_B_mod_N(A, N);\n}', 'int SRP_Verify_B_mod_N(const BIGNUM *B, const BIGNUM *N)\n{\n    BIGNUM *r;\n    BN_CTX *bn_ctx;\n    int ret = 0;\n    if (B == NULL || N == NULL || (bn_ctx = BN_CTX_new()) == NULL)\n        return 0;\n    if ((r = BN_new()) == NULL)\n        goto err;\n    if (!BN_nnmod(r, B, N, bn_ctx))\n        goto err;\n    ret = !BN_is_zero(r);\n err:\n    BN_CTX_free(bn_ctx);\n    BN_free(r);\n    return ret;\n}', 'BIGNUM *SRP_Calc_u(const BIGNUM *A, const BIGNUM *B, const BIGNUM *N)\n{\n    return srp_Calc_xy(A, B, N);\n}', 'static BIGNUM *srp_Calc_xy(const BIGNUM *x, const BIGNUM *y, const BIGNUM *N)\n{\n    unsigned char digest[SHA_DIGEST_LENGTH];\n    unsigned char *tmp = NULL;\n    int numN = BN_num_bytes(N);\n    BIGNUM *res = NULL;\n    if (x != N && BN_ucmp(x, N) >= 0)\n        return NULL;\n    if (y != N && BN_ucmp(y, N) >= 0)\n        return NULL;\n    if ((tmp = OPENSSL_malloc(numN * 2)) == NULL)\n        goto err;\n    if (BN_bn2binpad(x, tmp, numN) < 0\n        || BN_bn2binpad(y, tmp + numN, numN) < 0\n        || !EVP_Digest(tmp, numN * 2, digest, NULL, EVP_sha1(), NULL))\n        goto err;\n    res = BN_bin2bn(digest, sizeof(digest), NULL);\n err:\n    OPENSSL_free(tmp);\n    return res;\n}', 'int BN_num_bits(const BIGNUM *a)\n{\n    int i = a->top - 1;\n    bn_check_top(a);\n    if (BN_is_zero(a))\n        return 0;\n    return ((i * BN_BITS2) + BN_num_bits_word(a->d[i]));\n}', 'int BN_is_zero(const BIGNUM *a)\n{\n    return a->top == 0;\n}', 'BIGNUM *SRP_Calc_server_key(const BIGNUM *A, const BIGNUM *v, const BIGNUM *u,\n                            const BIGNUM *b, const BIGNUM *N)\n{\n    BIGNUM *tmp = NULL, *S = NULL;\n    BN_CTX *bn_ctx;\n    if (u == NULL || A == NULL || v == NULL || b == NULL || N == NULL)\n        return NULL;\n    if ((bn_ctx = BN_CTX_new()) == NULL || (tmp = BN_new()) == NULL)\n        goto err;\n    if (!BN_mod_exp(tmp, v, u, N, bn_ctx))\n        goto err;\n    if (!BN_mod_mul(tmp, A, tmp, N, bn_ctx))\n        goto err;\n    S = BN_new();\n    if (S != NULL && !BN_mod_exp(S, tmp, b, N, bn_ctx)) {\n        BN_free(S);\n        S = NULL;\n    }\n err:\n    BN_CTX_free(bn_ctx);\n    BN_clear_free(tmp);\n    return S;\n}', 'int BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,\n               BN_CTX *ctx)\n{\n    int ret;\n    bn_check_top(a);\n    bn_check_top(p);\n    bn_check_top(m);\n#define MONT_MUL_MOD\n#define MONT_EXP_WORD\n#define RECP_MUL_MOD\n#ifdef MONT_MUL_MOD\n    if (BN_is_odd(m)) {\n# ifdef MONT_EXP_WORD\n        if (a->top == 1 && !a->neg\n            && (BN_get_flags(p, BN_FLG_CONSTTIME) == 0)\n            && (BN_get_flags(a, BN_FLG_CONSTTIME) == 0)\n            && (BN_get_flags(m, BN_FLG_CONSTTIME) == 0)) {\n            BN_ULONG A = a->d[0];\n            ret = BN_mod_exp_mont_word(r, A, p, m, ctx, NULL);\n        } else\n# endif\n            ret = BN_mod_exp_mont(r, a, p, m, ctx, NULL);\n    } else\n#endif\n#ifdef RECP_MUL_MOD\n    {\n        ret = BN_mod_exp_recp(r, a, p, m, ctx);\n    }\n#else\n    {\n        ret = BN_mod_exp_simple(r, a, p, m, ctx);\n    }\n#endif\n    bn_check_top(r);\n    return ret;\n}', 'int BN_is_odd(const BIGNUM *a)\n{\n    return (a->top > 0) && (a->d[0] & 1);\n}', 'int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,\n                    const BIGNUM *m, BN_CTX *ctx)\n{\n    int i, j, bits, ret = 0, wstart, wend, window, wvalue;\n    int start = 1;\n    BIGNUM *aa;\n    BIGNUM *val[TABLE_SIZE];\n    BN_RECP_CTX recp;\n    if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0\n            || BN_get_flags(a, BN_FLG_CONSTTIME) != 0\n            || BN_get_flags(m, BN_FLG_CONSTTIME) != 0) {\n        BNerr(BN_F_BN_MOD_EXP_RECP, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);\n        return 0;\n    }\n    bits = BN_num_bits(p);\n    if (bits == 0) {\n        if (BN_abs_is_word(m, 1)) {\n            ret = 1;\n            BN_zero(r);\n        } else {\n            ret = BN_one(r);\n        }\n        return ret;\n    }\n    BN_CTX_start(ctx);\n    aa = BN_CTX_get(ctx);\n    val[0] = BN_CTX_get(ctx);\n    if (val[0] == NULL)\n        goto err;\n    BN_RECP_CTX_init(&recp);\n    if (m->neg) {\n        if (!BN_copy(aa, m))\n            goto err;\n        aa->neg = 0;\n        if (BN_RECP_CTX_set(&recp, aa, ctx) <= 0)\n            goto err;\n    } else {\n        if (BN_RECP_CTX_set(&recp, m, ctx) <= 0)\n            goto err;\n    }\n    if (!BN_nnmod(val[0], a, m, ctx))\n        goto err;\n    if (BN_is_zero(val[0])) {\n        BN_zero(r);\n        ret = 1;\n        goto err;\n    }\n    window = BN_window_bits_for_exponent_size(bits);\n    if (window > 1) {\n        if (!BN_mod_mul_reciprocal(aa, val[0], val[0], &recp, ctx))\n            goto err;\n        j = 1 << (window - 1);\n        for (i = 1; i < j; i++) {\n            if (((val[i] = BN_CTX_get(ctx)) == NULL) ||\n                !BN_mod_mul_reciprocal(val[i], val[i - 1], aa, &recp, ctx))\n                goto err;\n        }\n    }\n    start = 1;\n    wvalue = 0;\n    wstart = bits - 1;\n    wend = 0;\n    if (!BN_one(r))\n        goto err;\n    for (;;) {\n        if (BN_is_bit_set(p, wstart) == 0) {\n            if (!start)\n                if (!BN_mod_mul_reciprocal(r, r, r, &recp, ctx))\n                    goto err;\n            if (wstart == 0)\n                break;\n            wstart--;\n            continue;\n        }\n        j = wstart;\n        wvalue = 1;\n        wend = 0;\n        for (i = 1; i < window; i++) {\n            if (wstart - i < 0)\n                break;\n            if (BN_is_bit_set(p, wstart - i)) {\n                wvalue <<= (i - wend);\n                wvalue |= 1;\n                wend = i;\n            }\n        }\n        j = wend + 1;\n        if (!start)\n            for (i = 0; i < j; i++) {\n                if (!BN_mod_mul_reciprocal(r, r, r, &recp, ctx))\n                    goto err;\n            }\n        if (!BN_mod_mul_reciprocal(r, r, val[wvalue >> 1], &recp, ctx))\n            goto err;\n        wstart -= wend + 1;\n        wvalue = 0;\n        start = 0;\n        if (wstart < 0)\n            break;\n    }\n    ret = 1;\n err:\n    BN_CTX_end(ctx);\n    BN_RECP_CTX_free(&recp);\n    bn_check_top(r);\n    return ret;\n}', 'BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)\n{\n    bn_check_top(b);\n    if (a == b)\n        return a;\n    if (bn_wexpand(a, b->top) == NULL)\n        return NULL;\n    if (b->top > 0)\n        memcpy(a->d, b->d, sizeof(b->d[0]) * b->top);\n    a->neg = b->neg;\n    a->top = b->top;\n    a->flags |= b->flags & BN_FLG_FIXED_TOP;\n    bn_check_top(a);\n    return a;\n}', 'BIGNUM *bn_wexpand(BIGNUM *a, int words)\n{\n    return (words <= a->dmax) ? a : bn_expand2(a, words);\n}']