ssl/tls_srp.c:255: error: BUFFER_OVERRUN_L3
  Offset added: [8, +oo] Size: [0, 67108856] by call to `SRP_Calc_server_key`.
Showing all 34 steps of the trace


ssl/tls_srp.c:245:1: Parameter `s->srp_ctx.N->top`
243.   }
244.   
245. > int srp_generate_server_master_secret(SSL *s)
246.   {
247.       BIGNUM *K = NULL, *u = NULL;

ssl/tls_srp.c:251:10: Call
249.       unsigned char *tmp = NULL;
250.   
251.       if (!SRP_Verify_A_mod_N(s->srp_ctx.A, s->srp_ctx.N))
                ^
252.           goto err;
253.       if ((u = SRP_Calc_u(s->srp_ctx.A, s->srp_ctx.B, s->srp_ctx.N)) == NULL)

crypto/srp/srp_lib.c:233:1: Parameter `N->top`
  231.   }
  232.   
  233. > int SRP_Verify_A_mod_N(const BIGNUM *A, const BIGNUM *N)
  234.   {
  235.       /* Checks if A % N == 0 */

crypto/srp/srp_lib.c:236:12: Call
  234.   {
  235.       /* Checks if A % N == 0 */
  236.       return SRP_Verify_B_mod_N(A, N);
                    ^
  237.   }
  238.   

crypto/srp/srp_lib.c:212:1: Parameter `N->top`
    210.   }
    211.   
    212. > int SRP_Verify_B_mod_N(const BIGNUM *B, const BIGNUM *N)
    213.   {
    214.       BIGNUM *r;

ssl/tls_srp.c:253:14: Call
251.       if (!SRP_Verify_A_mod_N(s->srp_ctx.A, s->srp_ctx.N))
252.           goto err;
253.       if ((u = SRP_Calc_u(s->srp_ctx.A, s->srp_ctx.B, s->srp_ctx.N)) == NULL)
                    ^
254.           goto err;
255.       if ((K = SRP_Calc_server_key(s->srp_ctx.A, s->srp_ctx.v, u, s->srp_ctx.b,

crypto/srp/srp_lib.c:47:1: Parameter `N->top`
  45.   }
  46.   
  47. > BIGNUM *SRP_Calc_u(const BIGNUM *A, const BIGNUM *B, const BIGNUM *N)
  48.   {
  49.       /* k = SHA1(PAD(A) || PAD(B) ) -- tls-srp draft 8 */

crypto/srp/srp_lib.c:50:12: Call
  48.   {
  49.       /* k = SHA1(PAD(A) || PAD(B) ) -- tls-srp draft 8 */
  50.       return srp_Calc_xy(A, B, N);
                   ^
  51.   }
  52.   

crypto/srp/srp_lib.c:19:1: Parameter `N->top`
    17.   /* calculate = SHA1(PAD(x) || PAD(y)) */
    18.   
    19. > static BIGNUM *srp_Calc_xy(const BIGNUM *x, const BIGNUM *y, const BIGNUM *N)
    20.   {
    21.       unsigned char digest[SHA_DIGEST_LENGTH];

crypto/srp/srp_lib.c:23:16: Call
    21.       unsigned char digest[SHA_DIGEST_LENGTH];
    22.       unsigned char *tmp = NULL;
    23.       int numN = BN_num_bytes(N);
                         ^
    24.       BIGNUM *res = NULL;
    25.       if (x != N && BN_ucmp(x, N) >= 0)

crypto/bn/bn_lib.c:166:9: Call
      164.       bn_check_top(a);
      165.   
      166.       if (BN_is_zero(a))
                     ^
      167.           return 0;
      168.       return ((i * BN_BITS2) + BN_num_bits_word(a->d[i]));

crypto/bn/bn_lib.c:841:1: Parameter `a->top`
        839.   }
        840.   
        841. > int BN_is_zero(const BIGNUM *a)
        842.   {
        843.       return a->top == 0;

ssl/tls_srp.c:255:14: Call
253.       if ((u = SRP_Calc_u(s->srp_ctx.A, s->srp_ctx.B, s->srp_ctx.N)) == NULL)
254.           goto err;
255.       if ((K = SRP_Calc_server_key(s->srp_ctx.A, s->srp_ctx.v, u, s->srp_ctx.b,
                    ^
256.                                    s->srp_ctx.N)) == NULL)
257.           goto err;

crypto/srp/srp_lib.c:53:1: Parameter `N->top`
  51.   }
  52.   
  53. > BIGNUM *SRP_Calc_server_key(const BIGNUM *A, const BIGNUM *v, const BIGNUM *u,
  54.                               const BIGNUM *b, const BIGNUM *N)
  55.   {

crypto/srp/srp_lib.c:67:10: Call
  65.       /* S = (A*v**u) ** b */
  66.   
  67.       if (!BN_mod_exp(tmp, v, u, N, bn_ctx))
                 ^
  68.           goto err;
  69.       if (!BN_mod_mul(tmp, A, tmp, N, bn_ctx))

crypto/bn/bn_exp.c:89:1: Parameter `m->top`
    87.   }
    88.   
    89. > int BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
    90.                  BN_CTX *ctx)
    91.   {

crypto/bn/bn_exp.c:134:9: Call
    132.   
    133.   #ifdef MONT_MUL_MOD
    134.       if (BN_is_odd(m)) {
                   ^
    135.   # ifdef MONT_EXP_WORD
    136.           if (a->top == 1 && !a->neg

crypto/bn/bn_lib.c:856:1: Parameter `a->top`
      854.   }
      855.   
      856. > int BN_is_odd(const BIGNUM *a)
      857.   {
      858.       return (a->top > 0) && (a->d[0] & 1);

crypto/bn/bn_exp.c:141:19: Call
    139.               && (BN_get_flags(m, BN_FLG_CONSTTIME) == 0)) {
    140.               BN_ULONG A = a->d[0];
    141.               ret = BN_mod_exp_mont_word(r, A, p, m, ctx, NULL);
                             ^
    142.           } else
    143.   # endif

crypto/bn/bn_exp.c:1097:1: Parameter `m->top`
      1095.   }
      1096.   
      1097. > int BN_mod_exp_mont_word(BIGNUM *rr, BN_ULONG a, const BIGNUM *p,
      1098.                            const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
      1099.   {

crypto/bn/bn_exp.c:1133:10: Call
      1131.       bn_check_top(m);
      1132.   
      1133.       if (!BN_is_odd(m)) {
                       ^
      1134.           BNerr(BN_F_BN_MOD_EXP_MONT_WORD, BN_R_CALLED_WITH_EVEN_MODULUS);
      1135.           return 0;

crypto/bn/bn_lib.c:856:1: Parameter `a->top`
        854.   }
        855.   
        856. > int BN_is_odd(const BIGNUM *a)
        857.   {
        858.       return (a->top > 0) && (a->d[0] & 1);

crypto/bn/bn_exp.c:1168:14: Call
      1166.           if ((mont = BN_MONT_CTX_new()) == NULL)
      1167.               goto err;
      1168.           if (!BN_MONT_CTX_set(mont, m, ctx))
                           ^
      1169.               goto err;
      1170.       }

crypto/bn/bn_mont.c:247:1: Parameter `mod->top`
        245.   }
        246.   
        247. > int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)
        248.   {
        249.       int ret = 0;

crypto/bn/bn_mont.c:252:9: Call
        250.       BIGNUM *Ri, *R;
        251.   
        252.       if (BN_is_zero(mod))
                       ^
        253.           return 0;
        254.   

crypto/bn/bn_lib.c:841:1: Parameter `a->top`
          839.   }
          840.   
          841. > int BN_is_zero(const BIGNUM *a)
          842.   {
          843.       return a->top == 0;

crypto/bn/bn_mont.c:259:10: Call
        257.           goto err;
        258.       R = &(mont->RR);            /* grab RR as a temp */
        259.       if (!BN_copy(&(mont->N), mod))
                        ^
        260.           goto err;               /* Set N */
        261.       if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)

crypto/bn/bn_lib.c:312:1: <Offset trace>
310.   }
311.   
312. > BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
313.   {
314.       bn_check_top(b);

crypto/bn/bn_lib.c:312:1: Parameter `b->top`
          310.   }
          311.   
          312. > BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
          313.   {
          314.       bn_check_top(b);

crypto/bn/bn_lib.c:312:1: <Length trace>
310.   }
311.   
312. > BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
313.   {
314.       bn_check_top(b);

crypto/bn/bn_lib.c:312:1: Parameter `*a->d`
          310.   }
          311.   
          312. > BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
          313.   {
          314.       bn_check_top(b);

crypto/bn/bn_lib.c:318:9: Call
          316.       if (a == b)
          317.           return a;
          318.       if (bn_wexpand(a, b->top) == NULL)
                         ^
          319.           return NULL;
          320.   

crypto/bn/bn_lib.c:937:1: Parameter `*a->d`
            935.   }
            936.   
            937. > BIGNUM *bn_wexpand(BIGNUM *a, int words)
            938.   {
            939.       return (words <= a->dmax) ? a : bn_expand2(a, words);

crypto/bn/bn_lib.c:322:9: Array access: Offset added: [8, +oo] Size: [0, 67108856] by call to `SRP_Calc_server_key` 
          320.   
          321.       if (b->top > 0)
          322.           memcpy(a->d, b->d, sizeof(b->d[0]) * b->top);
                         ^
          323.   
          324.       a->top = b->top;

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->top = b->top;
    a->neg = b->neg;
    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_mont_word(BIGNUM *rr, BN_ULONG a, const BIGNUM *p,\n                         const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)\n{\n    BN_MONT_CTX *mont = NULL;\n    int b, bits, ret = 0;\n    int r_is_one;\n    BN_ULONG w, next_w;\n    BIGNUM *r, *t;\n    BIGNUM *swap_tmp;\n#define BN_MOD_MUL_WORD(r, w, m) \\\n                (BN_mul_word(r, (w)) && \\\n                (   \\\n                        (BN_mod(t, r, m, ctx) && (swap_tmp = r, r = t, t = swap_tmp, 1))))\n#define BN_TO_MONTGOMERY_WORD(r, w, mont) \\\n                (BN_set_word(r, (w)) && BN_to_montgomery(r, r, (mont), ctx))\n    if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0\n            || BN_get_flags(m, BN_FLG_CONSTTIME) != 0) {\n        BNerr(BN_F_BN_MOD_EXP_MONT_WORD, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);\n        return 0;\n    }\n    bn_check_top(p);\n    bn_check_top(m);\n    if (!BN_is_odd(m)) {\n        BNerr(BN_F_BN_MOD_EXP_MONT_WORD, BN_R_CALLED_WITH_EVEN_MODULUS);\n        return 0;\n    }\n    if (m->top == 1)\n        a %= m->d[0];\n    bits = BN_num_bits(p);\n    if (bits == 0) {\n        if (BN_is_one(m)) {\n            ret = 1;\n            BN_zero(rr);\n        } else {\n            ret = BN_one(rr);\n        }\n        return ret;\n    }\n    if (a == 0) {\n        BN_zero(rr);\n        ret = 1;\n        return ret;\n    }\n    BN_CTX_start(ctx);\n    r = BN_CTX_get(ctx);\n    t = BN_CTX_get(ctx);\n    if (t == NULL)\n        goto err;\n    if (in_mont != NULL)\n        mont = in_mont;\n    else {\n        if ((mont = BN_MONT_CTX_new()) == NULL)\n            goto err;\n        if (!BN_MONT_CTX_set(mont, m, ctx))\n            goto err;\n    }\n    r_is_one = 1;\n    w = a;\n    for (b = bits - 2; b >= 0; b--) {\n        next_w = w * w;\n        if ((next_w / w) != w) {\n            if (r_is_one) {\n                if (!BN_TO_MONTGOMERY_WORD(r, w, mont))\n                    goto err;\n                r_is_one = 0;\n            } else {\n                if (!BN_MOD_MUL_WORD(r, w, m))\n                    goto err;\n            }\n            next_w = 1;\n        }\n        w = next_w;\n        if (!r_is_one) {\n            if (!BN_mod_mul_montgomery(r, r, r, mont, ctx))\n                goto err;\n        }\n        if (BN_is_bit_set(p, b)) {\n            next_w = w * a;\n            if ((next_w / a) != w) {\n                if (r_is_one) {\n                    if (!BN_TO_MONTGOMERY_WORD(r, w, mont))\n                        goto err;\n                    r_is_one = 0;\n                } else {\n                    if (!BN_MOD_MUL_WORD(r, w, m))\n                        goto err;\n                }\n                next_w = a;\n            }\n            w = next_w;\n        }\n    }\n    if (w != 1) {\n        if (r_is_one) {\n            if (!BN_TO_MONTGOMERY_WORD(r, w, mont))\n                goto err;\n            r_is_one = 0;\n        } else {\n            if (!BN_MOD_MUL_WORD(r, w, m))\n                goto err;\n        }\n    }\n    if (r_is_one) {\n        if (!BN_one(rr))\n            goto err;\n    } else {\n        if (!BN_from_montgomery(rr, r, mont, ctx))\n            goto err;\n    }\n    ret = 1;\n err:\n    if (in_mont == NULL)\n        BN_MONT_CTX_free(mont);\n    BN_CTX_end(ctx);\n    bn_check_top(rr);\n    return ret;\n}', 'int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)\n{\n    int ret = 0;\n    BIGNUM *Ri, *R;\n    if (BN_is_zero(mod))\n        return 0;\n    BN_CTX_start(ctx);\n    if ((Ri = BN_CTX_get(ctx)) == NULL)\n        goto err;\n    R = &(mont->RR);\n    if (!BN_copy(&(mont->N), mod))\n        goto err;\n    if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)\n        BN_set_flags(&(mont->N), BN_FLG_CONSTTIME);\n    mont->N.neg = 0;\n#ifdef MONT_WORD\n    {\n        BIGNUM tmod;\n        BN_ULONG buf[2];\n        bn_init(&tmod);\n        tmod.d = buf;\n        tmod.dmax = 2;\n        tmod.neg = 0;\n        if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)\n            BN_set_flags(&tmod, BN_FLG_CONSTTIME);\n        mont->ri = (BN_num_bits(mod) + (BN_BITS2 - 1)) / BN_BITS2 * BN_BITS2;\n# if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32)\n        BN_zero(R);\n        if (!(BN_set_bit(R, 2 * BN_BITS2)))\n            goto err;\n        tmod.top = 0;\n        if ((buf[0] = mod->d[0]))\n            tmod.top = 1;\n        if ((buf[1] = mod->top > 1 ? mod->d[1] : 0))\n            tmod.top = 2;\n        if ((BN_mod_inverse(Ri, R, &tmod, ctx)) == NULL)\n            goto err;\n        if (!BN_lshift(Ri, Ri, 2 * BN_BITS2))\n            goto err;\n        if (!BN_is_zero(Ri)) {\n            if (!BN_sub_word(Ri, 1))\n                goto err;\n        } else {\n            if (bn_expand(Ri, (int)sizeof(BN_ULONG) * 2) == NULL)\n                goto err;\n            Ri->neg = 0;\n            Ri->d[0] = BN_MASK2;\n            Ri->d[1] = BN_MASK2;\n            Ri->top = 2;\n        }\n        if (!BN_div(Ri, NULL, Ri, &tmod, ctx))\n            goto err;\n        mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0;\n        mont->n0[1] = (Ri->top > 1) ? Ri->d[1] : 0;\n# else\n        BN_zero(R);\n        if (!(BN_set_bit(R, BN_BITS2)))\n            goto err;\n        buf[0] = mod->d[0];\n        buf[1] = 0;\n        tmod.top = buf[0] != 0 ? 1 : 0;\n        if ((BN_mod_inverse(Ri, R, &tmod, ctx)) == NULL)\n            goto err;\n        if (!BN_lshift(Ri, Ri, BN_BITS2))\n            goto err;\n        if (!BN_is_zero(Ri)) {\n            if (!BN_sub_word(Ri, 1))\n                goto err;\n        } else {\n            if (!BN_set_word(Ri, BN_MASK2))\n                goto err;\n        }\n        if (!BN_div(Ri, NULL, Ri, &tmod, ctx))\n            goto err;\n        mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0;\n        mont->n0[1] = 0;\n# endif\n    }\n#else\n    {\n        mont->ri = BN_num_bits(&mont->N);\n        BN_zero(R);\n        if (!BN_set_bit(R, mont->ri))\n            goto err;\n        if ((BN_mod_inverse(Ri, R, &mont->N, ctx)) == NULL)\n            goto err;\n        if (!BN_lshift(Ri, Ri, mont->ri))\n            goto err;\n        if (!BN_sub_word(Ri, 1))\n            goto err;\n        if (!BN_div(&(mont->Ni), NULL, Ri, &mont->N, ctx))\n            goto err;\n    }\n#endif\n    BN_zero(&(mont->RR));\n    if (!BN_set_bit(&(mont->RR), mont->ri * 2))\n        goto err;\n    if (!BN_mod(&(mont->RR), &(mont->RR), &(mont->N), ctx))\n        goto err;\n    ret = 1;\n err:\n    BN_CTX_end(ctx);\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->top = b->top;\n    a->neg = b->neg;\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}']