Mercurial > dropbear
view ecc.c @ 1156:a8f4dade70e5
avoid getpass when not used
some systems (like android's bionic) do not provide getpass. you can
disable ENABLE_CLI_PASSWORD_AUTH & ENABLE_CLI_INTERACT_AUTH to avoid
its use (and rely on pubkey auth), but the link still fails because
the support file calls getpass. do not define this func if both of
those auth methods are not used.
author | Mike Frysinger <vapier@gentoo.org> |
---|---|
date | Wed, 21 Oct 2015 22:39:55 +0800 |
parents | 063c38ea622b |
children | 750ec4ec4cbe |
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#include "includes.h" #include "options.h" #include "ecc.h" #include "dbutil.h" #include "bignum.h" #ifdef DROPBEAR_ECC /* .dp members are filled out by dropbear_ecc_fill_dp() at startup */ #ifdef DROPBEAR_ECC_256 struct dropbear_ecc_curve ecc_curve_nistp256 = { 32, /* .ltc_size */ NULL, /* .dp */ &sha256_desc, /* .hash_desc */ "nistp256" /* .name */ }; #endif #ifdef DROPBEAR_ECC_384 struct dropbear_ecc_curve ecc_curve_nistp384 = { 48, /* .ltc_size */ NULL, /* .dp */ &sha384_desc, /* .hash_desc */ "nistp384" /* .name */ }; #endif #ifdef DROPBEAR_ECC_521 struct dropbear_ecc_curve ecc_curve_nistp521 = { 66, /* .ltc_size */ NULL, /* .dp */ &sha512_desc, /* .hash_desc */ "nistp521" /* .name */ }; #endif struct dropbear_ecc_curve *dropbear_ecc_curves[] = { #ifdef DROPBEAR_ECC_256 &ecc_curve_nistp256, #endif #ifdef DROPBEAR_ECC_384 &ecc_curve_nistp384, #endif #ifdef DROPBEAR_ECC_521 &ecc_curve_nistp521, #endif NULL }; void dropbear_ecc_fill_dp() { struct dropbear_ecc_curve **curve; /* libtomcrypt guarantees they're ordered by size */ const ltc_ecc_set_type *dp = ltc_ecc_sets; for (curve = dropbear_ecc_curves; *curve; curve++) { for (;dp->size > 0; dp++) { if (dp->size == (*curve)->ltc_size) { (*curve)->dp = dp; break; } } if (!(*curve)->dp) { dropbear_exit("Missing ECC params %s", (*curve)->name); } } } struct dropbear_ecc_curve* curve_for_dp(const ltc_ecc_set_type *dp) { struct dropbear_ecc_curve **curve = NULL; for (curve = dropbear_ecc_curves; *curve; curve++) { if ((*curve)->dp == dp) { break; } } assert(*curve); return *curve; } ecc_key * new_ecc_key(void) { ecc_key *key = m_malloc(sizeof(*key)); m_mp_alloc_init_multi((mp_int**)&key->pubkey.x, (mp_int**)&key->pubkey.y, (mp_int**)&key->pubkey.z, (mp_int**)&key->k, NULL); return key; } /* Copied from libtomcrypt ecc_import.c (version there is static), modified for different mp_int pointer without LTC_SOURCE */ static int ecc_is_point(ecc_key *key) { mp_int *prime, *b, *t1, *t2; int err; m_mp_alloc_init_multi(&prime, &b, &t1, &t2, NULL); /* load prime and b */ if ((err = mp_read_radix(prime, key->dp->prime, 16)) != CRYPT_OK) { goto error; } if ((err = mp_read_radix(b, key->dp->B, 16)) != CRYPT_OK) { goto error; } /* compute y^2 */ if ((err = mp_sqr(key->pubkey.y, t1)) != CRYPT_OK) { goto error; } /* compute x^3 */ if ((err = mp_sqr(key->pubkey.x, t2)) != CRYPT_OK) { goto error; } if ((err = mp_mod(t2, prime, t2)) != CRYPT_OK) { goto error; } if ((err = mp_mul(key->pubkey.x, t2, t2)) != CRYPT_OK) { goto error; } /* compute y^2 - x^3 */ if ((err = mp_sub(t1, t2, t1)) != CRYPT_OK) { goto error; } /* compute y^2 - x^3 + 3x */ if ((err = mp_add(t1, key->pubkey.x, t1)) != CRYPT_OK) { goto error; } if ((err = mp_add(t1, key->pubkey.x, t1)) != CRYPT_OK) { goto error; } if ((err = mp_add(t1, key->pubkey.x, t1)) != CRYPT_OK) { goto error; } if ((err = mp_mod(t1, prime, t1)) != CRYPT_OK) { goto error; } while (mp_cmp_d(t1, 0) == LTC_MP_LT) { if ((err = mp_add(t1, prime, t1)) != CRYPT_OK) { goto error; } } while (mp_cmp(t1, prime) != LTC_MP_LT) { if ((err = mp_sub(t1, prime, t1)) != CRYPT_OK) { goto error; } } /* compare to b */ if (mp_cmp(t1, b) != LTC_MP_EQ) { err = CRYPT_INVALID_PACKET; } else { err = CRYPT_OK; } error: mp_clear_multi(prime, b, t1, t2, NULL); m_free(prime); m_free(b); m_free(t1); m_free(t2); return err; } /* For the "ephemeral public key octet string" in ECDH (rfc5656 section 4) */ void buf_put_ecc_raw_pubkey_string(buffer *buf, ecc_key *key) { unsigned long len = key->dp->size*2 + 1; int err; buf_putint(buf, len); err = ecc_ansi_x963_export(key, buf_getwriteptr(buf, len), &len); if (err != CRYPT_OK) { dropbear_exit("ECC error"); } buf_incrwritepos(buf, len); } /* For the "ephemeral public key octet string" in ECDH (rfc5656 section 4) */ ecc_key * buf_get_ecc_raw_pubkey(buffer *buf, const struct dropbear_ecc_curve *curve) { ecc_key *key = NULL; int ret = DROPBEAR_FAILURE; const unsigned int size = curve->dp->size; unsigned char first; TRACE(("enter buf_get_ecc_raw_pubkey")) buf_setpos(buf, 0); first = buf_getbyte(buf); if (first == 2 || first == 3) { dropbear_log(LOG_WARNING, "Dropbear doesn't support ECC point compression"); return NULL; } if (first != 4 || buf->len != 1+2*size) { TRACE(("leave, wrong size")) return NULL; } key = new_ecc_key(); key->dp = curve->dp; if (mp_read_unsigned_bin(key->pubkey.x, buf_getptr(buf, size), size) != MP_OKAY) { TRACE(("failed to read x")) goto out; } buf_incrpos(buf, size); if (mp_read_unsigned_bin(key->pubkey.y, buf_getptr(buf, size), size) != MP_OKAY) { TRACE(("failed to read y")) goto out; } buf_incrpos(buf, size); mp_set(key->pubkey.z, 1); if (ecc_is_point(key) != CRYPT_OK) { TRACE(("failed, not a point")) goto out; } /* SEC1 3.2.3.1 Check that Q != 0 */ if (mp_cmp_d(key->pubkey.x, 0) == LTC_MP_EQ) { TRACE(("failed, x == 0")) goto out; } if (mp_cmp_d(key->pubkey.y, 0) == LTC_MP_EQ) { TRACE(("failed, y == 0")) goto out; } ret = DROPBEAR_SUCCESS; out: if (ret == DROPBEAR_FAILURE) { if (key) { ecc_free(key); m_free(key); key = NULL; } } return key; } /* a modified version of libtomcrypt's "ecc_shared_secret" to output a mp_int instead. */ mp_int * dropbear_ecc_shared_secret(ecc_key *public_key, ecc_key *private_key) { ecc_point *result = NULL; mp_int *prime = NULL, *shared_secret = NULL; int err = DROPBEAR_FAILURE; /* type valid? */ if (private_key->type != PK_PRIVATE) { goto done; } if (private_key->dp != public_key->dp) { goto done; } /* make new point */ result = ltc_ecc_new_point(); if (result == NULL) { goto done; } prime = m_malloc(sizeof(*prime)); m_mp_init(prime); if (mp_read_radix(prime, (char *)private_key->dp->prime, 16) != CRYPT_OK) { goto done; } if (ltc_mp.ecc_ptmul(private_key->k, &public_key->pubkey, result, prime, 1) != CRYPT_OK) { goto done; } err = DROPBEAR_SUCCESS; done: if (err == DROPBEAR_SUCCESS) { shared_secret = m_malloc(sizeof(*shared_secret)); m_mp_init(shared_secret); mp_copy(result->x, shared_secret); } if (prime) { mp_clear(prime); m_free(prime); } if (result) { ltc_ecc_del_point(result); } if (err == DROPBEAR_FAILURE) { dropbear_exit("ECC error"); } return shared_secret; } #endif