| /* Copyright (c) 2020, Google Inc. |
| * |
| * Permission to use, copy, modify, and/or distribute this software for any |
| * purpose with or without fee is hereby granted, provided that the above |
| * copyright notice and this permission notice appear in all copies. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
| * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
| * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY |
| * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
| * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION |
| * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN |
| * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ |
| |
| #include <openssl/trust_token.h> |
| |
| #include <openssl/bn.h> |
| #include <openssl/bytestring.h> |
| #include <openssl/ec.h> |
| #include <openssl/err.h> |
| #include <openssl/mem.h> |
| #include <openssl/nid.h> |
| #include <openssl/rand.h> |
| #include <openssl/sha.h> |
| |
| #include "../ec_extra/internal.h" |
| #include "../fipsmodule/bn/internal.h" |
| #include "../fipsmodule/ec/internal.h" |
| |
| #include "internal.h" |
| |
| |
| typedef int (*hash_t_func_t)(const EC_GROUP *group, EC_RAW_POINT *out, |
| const uint8_t t[TRUST_TOKEN_NONCE_SIZE]); |
| typedef int (*hash_s_func_t)(const EC_GROUP *group, EC_RAW_POINT *out, |
| const EC_AFFINE *t, |
| const uint8_t s[TRUST_TOKEN_NONCE_SIZE]); |
| typedef int (*hash_c_func_t)(const EC_GROUP *group, EC_SCALAR *out, |
| uint8_t *buf, size_t len); |
| typedef int (*hash_to_scalar_func_t)(const EC_GROUP *group, EC_SCALAR *out, |
| uint8_t *buf, size_t len); |
| |
| typedef struct { |
| const EC_GROUP *group; |
| EC_PRECOMP g_precomp; |
| EC_PRECOMP h_precomp; |
| EC_RAW_POINT h; |
| // hash_t implements the H_t operation in PMBTokens. It returns one on success |
| // and zero on error. |
| hash_t_func_t hash_t; |
| // hash_s implements the H_s operation in PMBTokens. It returns one on success |
| // and zero on error. |
| hash_s_func_t hash_s; |
| // hash_c implements the H_c operation in PMBTokens. It returns one on success |
| // and zero on error. |
| hash_c_func_t hash_c; |
| // hash_to_scalar implements the HashToScalar operation for PMBTokens. It |
| // returns one on success and zero on error. |
| hash_to_scalar_func_t hash_to_scalar; |
| int prefix_point : 1; |
| } PMBTOKEN_METHOD; |
| |
| static const uint8_t kDefaultAdditionalData[32] = {0}; |
| |
| static int pmbtoken_init_method(PMBTOKEN_METHOD *method, int curve_nid, |
| const uint8_t *h_bytes, size_t h_len, |
| hash_t_func_t hash_t, hash_s_func_t hash_s, |
| hash_c_func_t hash_c, |
| hash_to_scalar_func_t hash_to_scalar, |
| int prefix_point) { |
| method->group = EC_GROUP_new_by_curve_name(curve_nid); |
| if (method->group == NULL) { |
| return 0; |
| } |
| |
| method->hash_t = hash_t; |
| method->hash_s = hash_s; |
| method->hash_c = hash_c; |
| method->hash_to_scalar = hash_to_scalar; |
| method->prefix_point = prefix_point; |
| |
| EC_AFFINE h; |
| if (!ec_point_from_uncompressed(method->group, &h, h_bytes, h_len)) { |
| return 0; |
| } |
| ec_affine_to_jacobian(method->group, &method->h, &h); |
| |
| if (!ec_init_precomp(method->group, &method->g_precomp, |
| &method->group->generator->raw) || |
| !ec_init_precomp(method->group, &method->h_precomp, &method->h)) { |
| return 0; |
| } |
| return 1; |
| } |
| |
| static int derive_scalar_from_secret(const PMBTOKEN_METHOD *method, |
| EC_SCALAR *out, const uint8_t *secret, |
| size_t secret_len, uint8_t scalar_id) { |
| static const uint8_t kKeygenLabel[] = "TrustTokenPMBTokenKeyGen"; |
| |
| int ok = 0; |
| CBB cbb; |
| CBB_zero(&cbb); |
| uint8_t *buf = NULL; |
| size_t len; |
| if (!CBB_init(&cbb, 0) || |
| !CBB_add_bytes(&cbb, kKeygenLabel, sizeof(kKeygenLabel)) || |
| !CBB_add_u8(&cbb, scalar_id) || |
| !CBB_add_bytes(&cbb, secret, secret_len) || |
| !CBB_finish(&cbb, &buf, &len) || |
| !method->hash_to_scalar(method->group, out, buf, len)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_KEYGEN_FAILURE); |
| goto err; |
| } |
| |
| ok = 1; |
| |
| err: |
| CBB_cleanup(&cbb); |
| OPENSSL_free(buf); |
| return ok; |
| } |
| |
| static int point_to_cbb(CBB *out, const EC_GROUP *group, |
| const EC_AFFINE *point) { |
| size_t len = |
| ec_point_to_bytes(group, point, POINT_CONVERSION_UNCOMPRESSED, NULL, 0); |
| if (len == 0) { |
| return 0; |
| } |
| uint8_t *p; |
| return CBB_add_space(out, &p, len) && |
| ec_point_to_bytes(group, point, POINT_CONVERSION_UNCOMPRESSED, p, |
| len) == len; |
| } |
| |
| static int cbb_add_prefixed_point(CBB *out, const EC_GROUP *group, |
| const EC_AFFINE *point, int prefix_point) { |
| if (prefix_point) { |
| CBB child; |
| if (!CBB_add_u16_length_prefixed(out, &child) || |
| !point_to_cbb(&child, group, point) || |
| !CBB_flush(out)) { |
| return 0; |
| } |
| } else { |
| if (!point_to_cbb(out, group, point) || |
| !CBB_flush(out)) { |
| return 0; |
| } |
| } |
| |
| return 1; |
| } |
| |
| static int cbs_get_prefixed_point(CBS *cbs, const EC_GROUP *group, |
| EC_AFFINE *out, int prefix_point) { |
| CBS child; |
| if (prefix_point) { |
| if (!CBS_get_u16_length_prefixed(cbs, &child)) { |
| return 0; |
| } |
| } else { |
| size_t plen = 1 + 2 * BN_num_bytes(&group->field); |
| if (!CBS_get_bytes(cbs, &child, plen)) { |
| return 0; |
| } |
| } |
| |
| if (!ec_point_from_uncompressed(group, out, CBS_data(&child), |
| CBS_len(&child))) { |
| return 0; |
| } |
| return 1; |
| } |
| |
| static int mul_public_3(const EC_GROUP *group, EC_RAW_POINT *out, |
| const EC_RAW_POINT *p0, const EC_SCALAR *scalar0, |
| const EC_RAW_POINT *p1, const EC_SCALAR *scalar1, |
| const EC_RAW_POINT *p2, const EC_SCALAR *scalar2) { |
| EC_RAW_POINT points[3] = {*p0, *p1, *p2}; |
| EC_SCALAR scalars[3] = {*scalar0, *scalar1, *scalar2}; |
| return ec_point_mul_scalar_public_batch(group, out, /*g_scalar=*/NULL, points, |
| scalars, 3); |
| } |
| |
| static int pmbtoken_compute_keys(const PMBTOKEN_METHOD *method, |
| CBB *out_private, CBB *out_public, |
| const EC_SCALAR *x0, const EC_SCALAR *y0, |
| const EC_SCALAR *x1, const EC_SCALAR *y1, |
| const EC_SCALAR *xs, const EC_SCALAR *ys) { |
| const EC_GROUP *group = method->group; |
| EC_RAW_POINT pub[3]; |
| if (!ec_point_mul_scalar_precomp(group, &pub[0], &method->g_precomp, |
| x0, &method->h_precomp, y0, NULL, NULL) || |
| !ec_point_mul_scalar_precomp(group, &pub[1], &method->g_precomp, |
| x1, &method->h_precomp, y1, NULL, NULL) || |
| !ec_point_mul_scalar_precomp(method->group, &pub[2], &method->g_precomp, |
| xs, &method->h_precomp, ys, NULL, NULL)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_KEYGEN_FAILURE); |
| return 0; |
| } |
| |
| const EC_SCALAR *scalars[] = {x0, y0, x1, y1, xs, ys}; |
| size_t scalar_len = BN_num_bytes(&group->order); |
| for (size_t i = 0; i < OPENSSL_ARRAY_SIZE(scalars); i++) { |
| uint8_t *buf; |
| if (!CBB_add_space(out_private, &buf, scalar_len)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_BUFFER_TOO_SMALL); |
| return 0; |
| } |
| ec_scalar_to_bytes(group, buf, &scalar_len, scalars[i]); |
| } |
| |
| EC_AFFINE pub_affine[3]; |
| if (!ec_jacobian_to_affine_batch(group, pub_affine, pub, 3)) { |
| return 0; |
| } |
| |
| if (!cbb_add_prefixed_point(out_public, group, &pub_affine[0], |
| method->prefix_point) || |
| !cbb_add_prefixed_point(out_public, group, &pub_affine[1], |
| method->prefix_point) || |
| !cbb_add_prefixed_point(out_public, group, &pub_affine[2], |
| method->prefix_point)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_BUFFER_TOO_SMALL); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| static int pmbtoken_generate_key(const PMBTOKEN_METHOD *method, |
| CBB *out_private, CBB *out_public) { |
| EC_SCALAR x0, y0, x1, y1, xs, ys; |
| if (!ec_random_nonzero_scalar(method->group, &x0, kDefaultAdditionalData) || |
| !ec_random_nonzero_scalar(method->group, &y0, kDefaultAdditionalData) || |
| !ec_random_nonzero_scalar(method->group, &x1, kDefaultAdditionalData) || |
| !ec_random_nonzero_scalar(method->group, &y1, kDefaultAdditionalData) || |
| !ec_random_nonzero_scalar(method->group, &xs, kDefaultAdditionalData) || |
| !ec_random_nonzero_scalar(method->group, &ys, kDefaultAdditionalData)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_KEYGEN_FAILURE); |
| return 0; |
| } |
| |
| return pmbtoken_compute_keys(method, out_private, out_public, &x0, &y0, &x1, |
| &y1, &xs, &ys); |
| } |
| |
| static int pmbtoken_derive_key_from_secret(const PMBTOKEN_METHOD *method, |
| CBB *out_private, CBB *out_public, |
| const uint8_t *secret, |
| size_t secret_len) { |
| EC_SCALAR x0, y0, x1, y1, xs, ys; |
| if (!derive_scalar_from_secret(method, &x0, secret, secret_len, 0) || |
| !derive_scalar_from_secret(method, &y0, secret, secret_len, 1) || |
| !derive_scalar_from_secret(method, &x1, secret, secret_len, 2) || |
| !derive_scalar_from_secret(method, &y1, secret, secret_len, 3) || |
| !derive_scalar_from_secret(method, &xs, secret, secret_len, 4) || |
| !derive_scalar_from_secret(method, &ys, secret, secret_len, 5)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_KEYGEN_FAILURE); |
| return 0; |
| } |
| |
| return pmbtoken_compute_keys(method, out_private, out_public, &x0, &y0, &x1, |
| &y1, &xs, &ys); |
| } |
| |
| static int pmbtoken_client_key_from_bytes(const PMBTOKEN_METHOD *method, |
| TRUST_TOKEN_CLIENT_KEY *key, |
| const uint8_t *in, size_t len) { |
| CBS cbs; |
| CBS_init(&cbs, in, len); |
| if (!cbs_get_prefixed_point(&cbs, method->group, &key->pub0, |
| method->prefix_point) || |
| !cbs_get_prefixed_point(&cbs, method->group, &key->pub1, |
| method->prefix_point) || |
| !cbs_get_prefixed_point(&cbs, method->group, &key->pubs, |
| method->prefix_point) || |
| CBS_len(&cbs) != 0) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_DECODE_FAILURE); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| static int pmbtoken_issuer_key_from_bytes(const PMBTOKEN_METHOD *method, |
| TRUST_TOKEN_ISSUER_KEY *key, |
| const uint8_t *in, size_t len) { |
| const EC_GROUP *group = method->group; |
| CBS cbs, tmp; |
| CBS_init(&cbs, in, len); |
| size_t scalar_len = BN_num_bytes(&group->order); |
| EC_SCALAR *scalars[] = {&key->x0, &key->y0, &key->x1, |
| &key->y1, &key->xs, &key->ys}; |
| for (size_t i = 0; i < OPENSSL_ARRAY_SIZE(scalars); i++) { |
| if (!CBS_get_bytes(&cbs, &tmp, scalar_len) || |
| !ec_scalar_from_bytes(group, scalars[i], CBS_data(&tmp), |
| CBS_len(&tmp))) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_DECODE_FAILURE); |
| return 0; |
| } |
| } |
| |
| // Recompute the public key. |
| EC_RAW_POINT pub[3]; |
| EC_AFFINE pub_affine[3]; |
| if (!ec_point_mul_scalar_precomp(group, &pub[0], &method->g_precomp, &key->x0, |
| &method->h_precomp, &key->y0, NULL, NULL) || |
| !ec_init_precomp(group, &key->pub0_precomp, &pub[0]) || |
| !ec_point_mul_scalar_precomp(group, &pub[1], &method->g_precomp, &key->x1, |
| &method->h_precomp, &key->y1, NULL, NULL) || |
| !ec_init_precomp(group, &key->pub1_precomp, &pub[1]) || |
| !ec_point_mul_scalar_precomp(group, &pub[2], &method->g_precomp, &key->xs, |
| &method->h_precomp, &key->ys, NULL, NULL) || |
| !ec_init_precomp(group, &key->pubs_precomp, &pub[2]) || |
| !ec_jacobian_to_affine_batch(group, pub_affine, pub, 3)) { |
| return 0; |
| } |
| |
| key->pub0 = pub_affine[0]; |
| key->pub1 = pub_affine[1]; |
| key->pubs = pub_affine[2]; |
| return 1; |
| } |
| |
| static STACK_OF(TRUST_TOKEN_PRETOKEN) * |
| pmbtoken_blind(const PMBTOKEN_METHOD *method, CBB *cbb, size_t count) { |
| const EC_GROUP *group = method->group; |
| STACK_OF(TRUST_TOKEN_PRETOKEN) *pretokens = sk_TRUST_TOKEN_PRETOKEN_new_null(); |
| if (pretokens == NULL) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| for (size_t i = 0; i < count; i++) { |
| // Insert |pretoken| into |pretokens| early to simplify error-handling. |
| TRUST_TOKEN_PRETOKEN *pretoken = OPENSSL_malloc(sizeof(TRUST_TOKEN_PRETOKEN)); |
| if (pretoken == NULL || |
| !sk_TRUST_TOKEN_PRETOKEN_push(pretokens, pretoken)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| TRUST_TOKEN_PRETOKEN_free(pretoken); |
| goto err; |
| } |
| |
| RAND_bytes(pretoken->t, sizeof(pretoken->t)); |
| |
| // We sample |pretoken->r| in Montgomery form to simplify inverting. |
| if (!ec_random_nonzero_scalar(group, &pretoken->r, |
| kDefaultAdditionalData)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| EC_SCALAR rinv; |
| ec_scalar_inv0_montgomery(group, &rinv, &pretoken->r); |
| // Convert both out of Montgomery form. |
| ec_scalar_from_montgomery(group, &pretoken->r, &pretoken->r); |
| ec_scalar_from_montgomery(group, &rinv, &rinv); |
| |
| EC_RAW_POINT T, Tp; |
| if (!method->hash_t(group, &T, pretoken->t) || |
| !ec_point_mul_scalar(group, &Tp, &T, &rinv) || |
| !ec_jacobian_to_affine(group, &pretoken->Tp, &Tp)) { |
| goto err; |
| } |
| |
| if (!cbb_add_prefixed_point(cbb, group, &pretoken->Tp, |
| method->prefix_point)) { |
| goto err; |
| } |
| } |
| |
| return pretokens; |
| |
| err: |
| sk_TRUST_TOKEN_PRETOKEN_pop_free(pretokens, TRUST_TOKEN_PRETOKEN_free); |
| return NULL; |
| } |
| |
| static int scalar_to_cbb(CBB *out, const EC_GROUP *group, |
| const EC_SCALAR *scalar) { |
| uint8_t *buf; |
| size_t scalar_len = BN_num_bytes(&group->order); |
| if (!CBB_add_space(out, &buf, scalar_len)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| return 0; |
| } |
| ec_scalar_to_bytes(group, buf, &scalar_len, scalar); |
| return 1; |
| } |
| |
| static int scalar_from_cbs(CBS *cbs, const EC_GROUP *group, EC_SCALAR *out) { |
| size_t scalar_len = BN_num_bytes(&group->order); |
| CBS tmp; |
| if (!CBS_get_bytes(cbs, &tmp, scalar_len)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_DECODE_FAILURE); |
| return 0; |
| } |
| |
| ec_scalar_from_bytes(group, out, CBS_data(&tmp), CBS_len(&tmp)); |
| return 1; |
| } |
| |
| static int hash_c_dleq(const PMBTOKEN_METHOD *method, EC_SCALAR *out, |
| const EC_AFFINE *X, const EC_AFFINE *T, |
| const EC_AFFINE *S, const EC_AFFINE *W, |
| const EC_AFFINE *K0, const EC_AFFINE *K1) { |
| static const uint8_t kDLEQ2Label[] = "DLEQ2"; |
| |
| int ok = 0; |
| CBB cbb; |
| CBB_zero(&cbb); |
| uint8_t *buf = NULL; |
| size_t len; |
| if (!CBB_init(&cbb, 0) || |
| !CBB_add_bytes(&cbb, kDLEQ2Label, sizeof(kDLEQ2Label)) || |
| !point_to_cbb(&cbb, method->group, X) || |
| !point_to_cbb(&cbb, method->group, T) || |
| !point_to_cbb(&cbb, method->group, S) || |
| !point_to_cbb(&cbb, method->group, W) || |
| !point_to_cbb(&cbb, method->group, K0) || |
| !point_to_cbb(&cbb, method->group, K1) || |
| !CBB_finish(&cbb, &buf, &len) || |
| !method->hash_c(method->group, out, buf, len)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| ok = 1; |
| |
| err: |
| CBB_cleanup(&cbb); |
| OPENSSL_free(buf); |
| return ok; |
| } |
| |
| static int hash_c_dleqor(const PMBTOKEN_METHOD *method, EC_SCALAR *out, |
| const EC_AFFINE *X0, const EC_AFFINE *X1, |
| const EC_AFFINE *T, const EC_AFFINE *S, |
| const EC_AFFINE *W, const EC_AFFINE *K00, |
| const EC_AFFINE *K01, const EC_AFFINE *K10, |
| const EC_AFFINE *K11) { |
| static const uint8_t kDLEQOR2Label[] = "DLEQOR2"; |
| |
| int ok = 0; |
| CBB cbb; |
| CBB_zero(&cbb); |
| uint8_t *buf = NULL; |
| size_t len; |
| if (!CBB_init(&cbb, 0) || |
| !CBB_add_bytes(&cbb, kDLEQOR2Label, sizeof(kDLEQOR2Label)) || |
| !point_to_cbb(&cbb, method->group, X0) || |
| !point_to_cbb(&cbb, method->group, X1) || |
| !point_to_cbb(&cbb, method->group, T) || |
| !point_to_cbb(&cbb, method->group, S) || |
| !point_to_cbb(&cbb, method->group, W) || |
| !point_to_cbb(&cbb, method->group, K00) || |
| !point_to_cbb(&cbb, method->group, K01) || |
| !point_to_cbb(&cbb, method->group, K10) || |
| !point_to_cbb(&cbb, method->group, K11) || |
| !CBB_finish(&cbb, &buf, &len) || |
| !method->hash_c(method->group, out, buf, len)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| ok = 1; |
| |
| err: |
| CBB_cleanup(&cbb); |
| OPENSSL_free(buf); |
| return ok; |
| } |
| |
| static int hash_c_batch(const PMBTOKEN_METHOD *method, EC_SCALAR *out, |
| const CBB *points, size_t index) { |
| static const uint8_t kDLEQBatchLabel[] = "DLEQ BATCH"; |
| if (index > 0xffff) { |
| // The protocol supports only two-byte batches. |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_OVERFLOW); |
| return 0; |
| } |
| |
| int ok = 0; |
| CBB cbb; |
| CBB_zero(&cbb); |
| uint8_t *buf = NULL; |
| size_t len; |
| if (!CBB_init(&cbb, 0) || |
| !CBB_add_bytes(&cbb, kDLEQBatchLabel, sizeof(kDLEQBatchLabel)) || |
| !CBB_add_bytes(&cbb, CBB_data(points), CBB_len(points)) || |
| !CBB_add_u16(&cbb, (uint16_t)index) || |
| !CBB_finish(&cbb, &buf, &len) || |
| !method->hash_c(method->group, out, buf, len)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| ok = 1; |
| |
| err: |
| CBB_cleanup(&cbb); |
| OPENSSL_free(buf); |
| return ok; |
| } |
| |
| // The DLEQ2 and DLEQOR2 constructions are described in appendix B of |
| // https://eprint.iacr.org/2020/072/20200324:214215. DLEQ2 is an instance of |
| // DLEQOR2 with only one value (n=1). |
| |
| static int dleq_generate(const PMBTOKEN_METHOD *method, CBB *cbb, |
| const TRUST_TOKEN_ISSUER_KEY *priv, |
| const EC_RAW_POINT *T, const EC_RAW_POINT *S, |
| const EC_RAW_POINT *W, const EC_RAW_POINT *Ws, |
| uint8_t private_metadata) { |
| const EC_GROUP *group = method->group; |
| |
| // We generate a DLEQ proof for the validity token and a DLEQOR2 proof for the |
| // private metadata token. To allow amortizing Jacobian-to-affine conversions, |
| // we compute Ki for both proofs first. |
| enum { |
| idx_T, |
| idx_S, |
| idx_W, |
| idx_Ws, |
| idx_Ks0, |
| idx_Ks1, |
| idx_Kb0, |
| idx_Kb1, |
| idx_Ko0, |
| idx_Ko1, |
| num_idx, |
| }; |
| EC_RAW_POINT jacobians[num_idx]; |
| |
| // Setup the DLEQ proof. |
| EC_SCALAR ks0, ks1; |
| if (// ks0, ks1 <- Zp |
| !ec_random_nonzero_scalar(group, &ks0, kDefaultAdditionalData) || |
| !ec_random_nonzero_scalar(group, &ks1, kDefaultAdditionalData) || |
| // Ks = ks0*(G;T) + ks1*(H;S) |
| !ec_point_mul_scalar_precomp(group, &jacobians[idx_Ks0], |
| &method->g_precomp, &ks0, &method->h_precomp, |
| &ks1, NULL, NULL) || |
| !ec_point_mul_scalar_batch(group, &jacobians[idx_Ks1], T, &ks0, S, &ks1, |
| NULL, NULL)) { |
| return 0; |
| } |
| |
| // Setup the DLEQOR proof. First, select values of xb, yb (keys corresponding |
| // to the private metadata value) and pubo (public key corresponding to the |
| // other value) in constant time. |
| BN_ULONG mask = ((BN_ULONG)0) - (private_metadata & 1); |
| EC_PRECOMP pubo_precomp; |
| EC_SCALAR xb, yb; |
| ec_scalar_select(group, &xb, mask, &priv->x1, &priv->x0); |
| ec_scalar_select(group, &yb, mask, &priv->y1, &priv->y0); |
| ec_precomp_select(group, &pubo_precomp, mask, &priv->pub0_precomp, |
| &priv->pub1_precomp); |
| |
| EC_SCALAR k0, k1, minus_co, uo, vo; |
| if (// k0, k1 <- Zp |
| !ec_random_nonzero_scalar(group, &k0, kDefaultAdditionalData) || |
| !ec_random_nonzero_scalar(group, &k1, kDefaultAdditionalData) || |
| // Kb = k0*(G;T) + k1*(H;S) |
| !ec_point_mul_scalar_precomp(group, &jacobians[idx_Kb0], |
| &method->g_precomp, &k0, &method->h_precomp, |
| &k1, NULL, NULL) || |
| !ec_point_mul_scalar_batch(group, &jacobians[idx_Kb1], T, &k0, S, &k1, |
| NULL, NULL) || |
| // co, uo, vo <- Zp |
| !ec_random_nonzero_scalar(group, &minus_co, kDefaultAdditionalData) || |
| !ec_random_nonzero_scalar(group, &uo, kDefaultAdditionalData) || |
| !ec_random_nonzero_scalar(group, &vo, kDefaultAdditionalData) || |
| // Ko = uo*(G;T) + vo*(H;S) - co*(pubo;W) |
| !ec_point_mul_scalar_precomp(group, &jacobians[idx_Ko0], |
| &method->g_precomp, &uo, &method->h_precomp, |
| &vo, &pubo_precomp, &minus_co) || |
| !ec_point_mul_scalar_batch(group, &jacobians[idx_Ko1], T, &uo, S, &vo, W, |
| &minus_co)) { |
| return 0; |
| } |
| |
| EC_AFFINE affines[num_idx]; |
| jacobians[idx_T] = *T; |
| jacobians[idx_S] = *S; |
| jacobians[idx_W] = *W; |
| jacobians[idx_Ws] = *Ws; |
| if (!ec_jacobian_to_affine_batch(group, affines, jacobians, num_idx)) { |
| return 0; |
| } |
| |
| // Select the K corresponding to K0 and K1 in constant-time. |
| EC_AFFINE K00, K01, K10, K11; |
| ec_affine_select(group, &K00, mask, &affines[idx_Ko0], &affines[idx_Kb0]); |
| ec_affine_select(group, &K01, mask, &affines[idx_Ko1], &affines[idx_Kb1]); |
| ec_affine_select(group, &K10, mask, &affines[idx_Kb0], &affines[idx_Ko0]); |
| ec_affine_select(group, &K11, mask, &affines[idx_Kb1], &affines[idx_Ko1]); |
| |
| // Compute c = Hc(...) for the two proofs. |
| EC_SCALAR cs, c; |
| if (!hash_c_dleq(method, &cs, &priv->pubs, &affines[idx_T], &affines[idx_S], |
| &affines[idx_Ws], &affines[idx_Ks0], &affines[idx_Ks1]) || |
| !hash_c_dleqor(method, &c, &priv->pub0, &priv->pub1, &affines[idx_T], |
| &affines[idx_S], &affines[idx_W], &K00, &K01, &K10, |
| &K11)) { |
| return 0; |
| } |
| |
| // Compute cb, ub, and ub for the two proofs. In each of these products, only |
| // one operand is in Montgomery form, so the product does not need to be |
| // converted. |
| |
| EC_SCALAR cs_mont; |
| ec_scalar_to_montgomery(group, &cs_mont, &cs); |
| |
| // us = ks0 + cs*xs |
| EC_SCALAR us, vs; |
| ec_scalar_mul_montgomery(group, &us, &priv->xs, &cs_mont); |
| ec_scalar_add(group, &us, &ks0, &us); |
| |
| // vs = ks1 + cs*ys |
| ec_scalar_mul_montgomery(group, &vs, &priv->ys, &cs_mont); |
| ec_scalar_add(group, &vs, &ks1, &vs); |
| |
| // Store DLEQ2 proof in transcript. |
| if (!scalar_to_cbb(cbb, group, &cs) || |
| !scalar_to_cbb(cbb, group, &us) || |
| !scalar_to_cbb(cbb, group, &vs)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| return 0; |
| } |
| |
| // cb = c - co |
| EC_SCALAR cb, ub, vb; |
| ec_scalar_add(group, &cb, &c, &minus_co); |
| |
| EC_SCALAR cb_mont; |
| ec_scalar_to_montgomery(group, &cb_mont, &cb); |
| |
| // ub = k0 + cb*xb |
| ec_scalar_mul_montgomery(group, &ub, &xb, &cb_mont); |
| ec_scalar_add(group, &ub, &k0, &ub); |
| |
| // vb = k1 + cb*yb |
| ec_scalar_mul_montgomery(group, &vb, &yb, &cb_mont); |
| ec_scalar_add(group, &vb, &k1, &vb); |
| |
| // Select c, u, v in constant-time. |
| EC_SCALAR co, c0, c1, u0, u1, v0, v1; |
| ec_scalar_neg(group, &co, &minus_co); |
| ec_scalar_select(group, &c0, mask, &co, &cb); |
| ec_scalar_select(group, &u0, mask, &uo, &ub); |
| ec_scalar_select(group, &v0, mask, &vo, &vb); |
| ec_scalar_select(group, &c1, mask, &cb, &co); |
| ec_scalar_select(group, &u1, mask, &ub, &uo); |
| ec_scalar_select(group, &v1, mask, &vb, &vo); |
| |
| // Store DLEQOR2 proof in transcript. |
| if (!scalar_to_cbb(cbb, group, &c0) || |
| !scalar_to_cbb(cbb, group, &c1) || |
| !scalar_to_cbb(cbb, group, &u0) || |
| !scalar_to_cbb(cbb, group, &u1) || |
| !scalar_to_cbb(cbb, group, &v0) || |
| !scalar_to_cbb(cbb, group, &v1)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| static int dleq_verify(const PMBTOKEN_METHOD *method, CBS *cbs, |
| const TRUST_TOKEN_CLIENT_KEY *pub, const EC_RAW_POINT *T, |
| const EC_RAW_POINT *S, const EC_RAW_POINT *W, |
| const EC_RAW_POINT *Ws) { |
| const EC_GROUP *group = method->group; |
| const EC_RAW_POINT *g = &group->generator->raw; |
| |
| // We verify a DLEQ proof for the validity token and a DLEQOR2 proof for the |
| // private metadata token. To allow amortizing Jacobian-to-affine conversions, |
| // we compute Ki for both proofs first. Additionally, all inputs to this |
| // function are public, so we can use the faster variable-time |
| // multiplications. |
| enum { |
| idx_T, |
| idx_S, |
| idx_W, |
| idx_Ws, |
| idx_Ks0, |
| idx_Ks1, |
| idx_K00, |
| idx_K01, |
| idx_K10, |
| idx_K11, |
| num_idx, |
| }; |
| EC_RAW_POINT jacobians[num_idx]; |
| |
| // Decode the DLEQ proof. |
| EC_SCALAR cs, us, vs; |
| if (!scalar_from_cbs(cbs, group, &cs) || |
| !scalar_from_cbs(cbs, group, &us) || |
| !scalar_from_cbs(cbs, group, &vs)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_DECODE_FAILURE); |
| return 0; |
| } |
| |
| // Ks = us*(G;T) + vs*(H;S) - cs*(pubs;Ws) |
| EC_RAW_POINT pubs; |
| ec_affine_to_jacobian(group, &pubs, &pub->pubs); |
| EC_SCALAR minus_cs; |
| ec_scalar_neg(group, &minus_cs, &cs); |
| if (!mul_public_3(group, &jacobians[idx_Ks0], g, &us, &method->h, &vs, &pubs, |
| &minus_cs) || |
| !mul_public_3(group, &jacobians[idx_Ks1], T, &us, S, &vs, Ws, |
| &minus_cs)) { |
| return 0; |
| } |
| |
| // Decode the DLEQOR proof. |
| EC_SCALAR c0, c1, u0, u1, v0, v1; |
| if (!scalar_from_cbs(cbs, group, &c0) || |
| !scalar_from_cbs(cbs, group, &c1) || |
| !scalar_from_cbs(cbs, group, &u0) || |
| !scalar_from_cbs(cbs, group, &u1) || |
| !scalar_from_cbs(cbs, group, &v0) || |
| !scalar_from_cbs(cbs, group, &v1)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_DECODE_FAILURE); |
| return 0; |
| } |
| |
| EC_RAW_POINT pub0, pub1; |
| ec_affine_to_jacobian(group, &pub0, &pub->pub0); |
| ec_affine_to_jacobian(group, &pub1, &pub->pub1); |
| EC_SCALAR minus_c0, minus_c1; |
| ec_scalar_neg(group, &minus_c0, &c0); |
| ec_scalar_neg(group, &minus_c1, &c1); |
| if (// K0 = u0*(G;T) + v0*(H;S) - c0*(pub0;W) |
| !mul_public_3(group, &jacobians[idx_K00], g, &u0, &method->h, &v0, &pub0, |
| &minus_c0) || |
| !mul_public_3(group, &jacobians[idx_K01], T, &u0, S, &v0, W, &minus_c0) || |
| // K1 = u1*(G;T) + v1*(H;S) - c1*(pub1;W) |
| !mul_public_3(group, &jacobians[idx_K10], g, &u1, &method->h, &v1, &pub1, |
| &minus_c1) || |
| !mul_public_3(group, &jacobians[idx_K11], T, &u1, S, &v1, W, &minus_c1)) { |
| return 0; |
| } |
| |
| EC_AFFINE affines[num_idx]; |
| jacobians[idx_T] = *T; |
| jacobians[idx_S] = *S; |
| jacobians[idx_W] = *W; |
| jacobians[idx_Ws] = *Ws; |
| if (!ec_jacobian_to_affine_batch(group, affines, jacobians, num_idx)) { |
| return 0; |
| } |
| |
| // Check the DLEQ proof. |
| EC_SCALAR calculated; |
| if (!hash_c_dleq(method, &calculated, &pub->pubs, &affines[idx_T], |
| &affines[idx_S], &affines[idx_Ws], &affines[idx_Ks0], |
| &affines[idx_Ks1])) { |
| return 0; |
| } |
| |
| // cs == calculated |
| if (!ec_scalar_equal_vartime(group, &cs, &calculated)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_INVALID_PROOF); |
| return 0; |
| } |
| |
| // Check the DLEQOR proof. |
| if (!hash_c_dleqor(method, &calculated, &pub->pub0, &pub->pub1, |
| &affines[idx_T], &affines[idx_S], &affines[idx_W], |
| &affines[idx_K00], &affines[idx_K01], &affines[idx_K10], |
| &affines[idx_K11])) { |
| return 0; |
| } |
| |
| // c0 + c1 == calculated |
| EC_SCALAR c; |
| ec_scalar_add(group, &c, &c0, &c1); |
| if (!ec_scalar_equal_vartime(group, &c, &calculated)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_INVALID_PROOF); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| static int pmbtoken_sign(const PMBTOKEN_METHOD *method, |
| const TRUST_TOKEN_ISSUER_KEY *key, CBB *cbb, CBS *cbs, |
| size_t num_requested, size_t num_to_issue, |
| uint8_t private_metadata) { |
| const EC_GROUP *group = method->group; |
| if (num_requested < num_to_issue) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_INTERNAL_ERROR); |
| return 0; |
| } |
| |
| if (num_to_issue > ((size_t)-1) / sizeof(EC_RAW_POINT) || |
| num_to_issue > ((size_t)-1) / sizeof(EC_SCALAR)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_OVERFLOW); |
| return 0; |
| } |
| |
| int ret = 0; |
| EC_RAW_POINT *Tps = OPENSSL_malloc(num_to_issue * sizeof(EC_RAW_POINT)); |
| EC_RAW_POINT *Sps = OPENSSL_malloc(num_to_issue * sizeof(EC_RAW_POINT)); |
| EC_RAW_POINT *Wps = OPENSSL_malloc(num_to_issue * sizeof(EC_RAW_POINT)); |
| EC_RAW_POINT *Wsps = OPENSSL_malloc(num_to_issue * sizeof(EC_RAW_POINT)); |
| EC_SCALAR *es = OPENSSL_malloc(num_to_issue * sizeof(EC_SCALAR)); |
| CBB batch_cbb; |
| CBB_zero(&batch_cbb); |
| if (!Tps || |
| !Sps || |
| !Wps || |
| !Wsps || |
| !es || |
| !CBB_init(&batch_cbb, 0) || |
| !point_to_cbb(&batch_cbb, method->group, &key->pubs) || |
| !point_to_cbb(&batch_cbb, method->group, &key->pub0) || |
| !point_to_cbb(&batch_cbb, method->group, &key->pub1)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| for (size_t i = 0; i < num_to_issue; i++) { |
| EC_AFFINE Tp_affine; |
| EC_RAW_POINT Tp; |
| if (!cbs_get_prefixed_point(cbs, group, &Tp_affine, method->prefix_point)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_DECODE_FAILURE); |
| goto err; |
| } |
| ec_affine_to_jacobian(group, &Tp, &Tp_affine); |
| |
| EC_SCALAR xb, yb; |
| BN_ULONG mask = ((BN_ULONG)0) - (private_metadata & 1); |
| ec_scalar_select(group, &xb, mask, &key->x1, &key->x0); |
| ec_scalar_select(group, &yb, mask, &key->y1, &key->y0); |
| |
| uint8_t s[TRUST_TOKEN_NONCE_SIZE]; |
| RAND_bytes(s, TRUST_TOKEN_NONCE_SIZE); |
| // The |jacobians| and |affines| contain Sp, Wp, and Wsp. |
| EC_RAW_POINT jacobians[3]; |
| EC_AFFINE affines[3]; |
| if (!method->hash_s(group, &jacobians[0], &Tp_affine, s) || |
| !ec_point_mul_scalar_batch(group, &jacobians[1], &Tp, &xb, |
| &jacobians[0], &yb, NULL, NULL) || |
| !ec_point_mul_scalar_batch(group, &jacobians[2], &Tp, &key->xs, |
| &jacobians[0], &key->ys, NULL, NULL) || |
| !ec_jacobian_to_affine_batch(group, affines, jacobians, 3) || |
| !CBB_add_bytes(cbb, s, TRUST_TOKEN_NONCE_SIZE) || |
| !cbb_add_prefixed_point(cbb, group, &affines[1], |
| method->prefix_point) || |
| !cbb_add_prefixed_point(cbb, group, &affines[2], |
| method->prefix_point)) { |
| goto err; |
| } |
| |
| if (!point_to_cbb(&batch_cbb, group, &Tp_affine) || |
| !point_to_cbb(&batch_cbb, group, &affines[0]) || |
| !point_to_cbb(&batch_cbb, group, &affines[1]) || |
| !point_to_cbb(&batch_cbb, group, &affines[2])) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| Tps[i] = Tp; |
| Sps[i] = jacobians[0]; |
| Wps[i] = jacobians[1]; |
| Wsps[i] = jacobians[2]; |
| |
| if (!CBB_flush(cbb)) { |
| goto err; |
| } |
| } |
| |
| // The DLEQ batching construction is described in appendix B of |
| // https://eprint.iacr.org/2020/072/20200324:214215. Note the additional |
| // computations all act on public inputs. |
| for (size_t i = 0; i < num_to_issue; i++) { |
| if (!hash_c_batch(method, &es[i], &batch_cbb, i)) { |
| goto err; |
| } |
| } |
| |
| EC_RAW_POINT Tp_batch, Sp_batch, Wp_batch, Wsp_batch; |
| if (!ec_point_mul_scalar_public_batch(group, &Tp_batch, |
| /*g_scalar=*/NULL, Tps, es, |
| num_to_issue) || |
| !ec_point_mul_scalar_public_batch(group, &Sp_batch, |
| /*g_scalar=*/NULL, Sps, es, |
| num_to_issue) || |
| !ec_point_mul_scalar_public_batch(group, &Wp_batch, |
| /*g_scalar=*/NULL, Wps, es, |
| num_to_issue) || |
| !ec_point_mul_scalar_public_batch(group, &Wsp_batch, |
| /*g_scalar=*/NULL, Wsps, es, |
| num_to_issue)) { |
| goto err; |
| } |
| |
| CBB proof; |
| if (!CBB_add_u16_length_prefixed(cbb, &proof) || |
| !dleq_generate(method, &proof, key, &Tp_batch, &Sp_batch, &Wp_batch, |
| &Wsp_batch, private_metadata) || |
| !CBB_flush(cbb)) { |
| goto err; |
| } |
| |
| // Skip over any unused requests. |
| size_t point_len = 1 + 2 * BN_num_bytes(&group->field); |
| size_t token_len = point_len; |
| if (method->prefix_point) { |
| token_len += 2; |
| } |
| if (!CBS_skip(cbs, token_len * (num_requested - num_to_issue))) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_DECODE_FAILURE); |
| goto err; |
| } |
| |
| ret = 1; |
| |
| err: |
| OPENSSL_free(Tps); |
| OPENSSL_free(Sps); |
| OPENSSL_free(Wps); |
| OPENSSL_free(Wsps); |
| OPENSSL_free(es); |
| CBB_cleanup(&batch_cbb); |
| return ret; |
| } |
| |
| static STACK_OF(TRUST_TOKEN) * |
| pmbtoken_unblind(const PMBTOKEN_METHOD *method, |
| const TRUST_TOKEN_CLIENT_KEY *key, |
| const STACK_OF(TRUST_TOKEN_PRETOKEN) * pretokens, CBS *cbs, |
| size_t count, uint32_t key_id) { |
| const EC_GROUP *group = method->group; |
| if (count > sk_TRUST_TOKEN_PRETOKEN_num(pretokens)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_DECODE_FAILURE); |
| return NULL; |
| } |
| |
| int ok = 0; |
| STACK_OF(TRUST_TOKEN) *ret = sk_TRUST_TOKEN_new_null(); |
| if (ret == NULL) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| return NULL; |
| } |
| |
| if (count > ((size_t)-1) / sizeof(EC_RAW_POINT) || |
| count > ((size_t)-1) / sizeof(EC_SCALAR)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_OVERFLOW); |
| return 0; |
| } |
| EC_RAW_POINT *Tps = OPENSSL_malloc(count * sizeof(EC_RAW_POINT)); |
| EC_RAW_POINT *Sps = OPENSSL_malloc(count * sizeof(EC_RAW_POINT)); |
| EC_RAW_POINT *Wps = OPENSSL_malloc(count * sizeof(EC_RAW_POINT)); |
| EC_RAW_POINT *Wsps = OPENSSL_malloc(count * sizeof(EC_RAW_POINT)); |
| EC_SCALAR *es = OPENSSL_malloc(count * sizeof(EC_SCALAR)); |
| CBB batch_cbb; |
| CBB_zero(&batch_cbb); |
| if (!Tps || |
| !Sps || |
| !Wps || |
| !Wsps || |
| !es || |
| !CBB_init(&batch_cbb, 0) || |
| !point_to_cbb(&batch_cbb, method->group, &key->pubs) || |
| !point_to_cbb(&batch_cbb, method->group, &key->pub0) || |
| !point_to_cbb(&batch_cbb, method->group, &key->pub1)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| for (size_t i = 0; i < count; i++) { |
| const TRUST_TOKEN_PRETOKEN *pretoken = |
| sk_TRUST_TOKEN_PRETOKEN_value(pretokens, i); |
| |
| uint8_t s[TRUST_TOKEN_NONCE_SIZE]; |
| EC_AFFINE Wp_affine, Wsp_affine; |
| if (!CBS_copy_bytes(cbs, s, TRUST_TOKEN_NONCE_SIZE) || |
| !cbs_get_prefixed_point(cbs, group, &Wp_affine, method->prefix_point) || |
| !cbs_get_prefixed_point(cbs, group, &Wsp_affine, |
| method->prefix_point)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_DECODE_FAILURE); |
| goto err; |
| } |
| |
| ec_affine_to_jacobian(group, &Tps[i], &pretoken->Tp); |
| ec_affine_to_jacobian(group, &Wps[i], &Wp_affine); |
| ec_affine_to_jacobian(group, &Wsps[i], &Wsp_affine); |
| if (!method->hash_s(group, &Sps[i], &pretoken->Tp, s)) { |
| goto err; |
| } |
| |
| EC_AFFINE Sp_affine; |
| if (!point_to_cbb(&batch_cbb, group, &pretoken->Tp) || |
| !ec_jacobian_to_affine(group, &Sp_affine, &Sps[i]) || |
| !point_to_cbb(&batch_cbb, group, &Sp_affine) || |
| !point_to_cbb(&batch_cbb, group, &Wp_affine) || |
| !point_to_cbb(&batch_cbb, group, &Wsp_affine)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| // Unblind the token. |
| EC_RAW_POINT jacobians[3]; |
| EC_AFFINE affines[3]; |
| if (!ec_point_mul_scalar(group, &jacobians[0], &Sps[i], &pretoken->r) || |
| !ec_point_mul_scalar(group, &jacobians[1], &Wps[i], &pretoken->r) || |
| !ec_point_mul_scalar(group, &jacobians[2], &Wsps[i], &pretoken->r) || |
| !ec_jacobian_to_affine_batch(group, affines, jacobians, 3)) { |
| goto err; |
| } |
| |
| // Serialize the token. Include |key_id| to avoid an extra copy in the layer |
| // above. |
| CBB token_cbb; |
| size_t point_len = 1 + 2 * BN_num_bytes(&group->field); |
| if (!CBB_init(&token_cbb, |
| 4 + TRUST_TOKEN_NONCE_SIZE + 3 * (2 + point_len)) || |
| !CBB_add_u32(&token_cbb, key_id) || |
| !CBB_add_bytes(&token_cbb, pretoken->t, TRUST_TOKEN_NONCE_SIZE) || |
| !cbb_add_prefixed_point(&token_cbb, group, &affines[0], |
| method->prefix_point) || |
| !cbb_add_prefixed_point(&token_cbb, group, &affines[1], |
| method->prefix_point) || |
| !cbb_add_prefixed_point(&token_cbb, group, &affines[2], |
| method->prefix_point) || |
| !CBB_flush(&token_cbb)) { |
| CBB_cleanup(&token_cbb); |
| goto err; |
| } |
| |
| TRUST_TOKEN *token = |
| TRUST_TOKEN_new(CBB_data(&token_cbb), CBB_len(&token_cbb)); |
| CBB_cleanup(&token_cbb); |
| if (token == NULL || |
| !sk_TRUST_TOKEN_push(ret, token)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| TRUST_TOKEN_free(token); |
| goto err; |
| } |
| } |
| |
| // The DLEQ batching construction is described in appendix B of |
| // https://eprint.iacr.org/2020/072/20200324:214215. Note the additional |
| // computations all act on public inputs. |
| for (size_t i = 0; i < count; i++) { |
| if (!hash_c_batch(method, &es[i], &batch_cbb, i)) { |
| goto err; |
| } |
| } |
| |
| EC_RAW_POINT Tp_batch, Sp_batch, Wp_batch, Wsp_batch; |
| if (!ec_point_mul_scalar_public_batch(group, &Tp_batch, |
| /*g_scalar=*/NULL, Tps, es, count) || |
| !ec_point_mul_scalar_public_batch(group, &Sp_batch, |
| /*g_scalar=*/NULL, Sps, es, count) || |
| !ec_point_mul_scalar_public_batch(group, &Wp_batch, |
| /*g_scalar=*/NULL, Wps, es, count) || |
| !ec_point_mul_scalar_public_batch(group, &Wsp_batch, |
| /*g_scalar=*/NULL, Wsps, es, count)) { |
| goto err; |
| } |
| |
| CBS proof; |
| if (!CBS_get_u16_length_prefixed(cbs, &proof) || |
| !dleq_verify(method, &proof, key, &Tp_batch, &Sp_batch, &Wp_batch, |
| &Wsp_batch) || |
| CBS_len(&proof) != 0) { |
| goto err; |
| } |
| |
| ok = 1; |
| |
| err: |
| OPENSSL_free(Tps); |
| OPENSSL_free(Sps); |
| OPENSSL_free(Wps); |
| OPENSSL_free(Wsps); |
| OPENSSL_free(es); |
| CBB_cleanup(&batch_cbb); |
| if (!ok) { |
| sk_TRUST_TOKEN_pop_free(ret, TRUST_TOKEN_free); |
| ret = NULL; |
| } |
| return ret; |
| } |
| |
| static int pmbtoken_read(const PMBTOKEN_METHOD *method, |
| const TRUST_TOKEN_ISSUER_KEY *key, |
| uint8_t out_nonce[TRUST_TOKEN_NONCE_SIZE], |
| uint8_t *out_private_metadata, const uint8_t *token, |
| size_t token_len) { |
| const EC_GROUP *group = method->group; |
| CBS cbs; |
| CBS_init(&cbs, token, token_len); |
| EC_AFFINE S, W, Ws; |
| if (!CBS_copy_bytes(&cbs, out_nonce, TRUST_TOKEN_NONCE_SIZE) || |
| !cbs_get_prefixed_point(&cbs, group, &S, method->prefix_point) || |
| !cbs_get_prefixed_point(&cbs, group, &W, method->prefix_point) || |
| !cbs_get_prefixed_point(&cbs, group, &Ws, method->prefix_point) || |
| CBS_len(&cbs) != 0) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_INVALID_TOKEN); |
| return 0; |
| } |
| |
| |
| EC_RAW_POINT T; |
| if (!method->hash_t(group, &T, out_nonce)) { |
| return 0; |
| } |
| |
| // We perform three multiplications with S and T. This is enough that it is |
| // worth using |ec_point_mul_scalar_precomp|. |
| EC_RAW_POINT S_jacobian; |
| EC_PRECOMP S_precomp, T_precomp; |
| ec_affine_to_jacobian(group, &S_jacobian, &S); |
| if (!ec_init_precomp(group, &S_precomp, &S_jacobian) || |
| !ec_init_precomp(group, &T_precomp, &T)) { |
| return 0; |
| } |
| |
| EC_RAW_POINT Ws_calculated; |
| // Check the validity of the token. |
| if (!ec_point_mul_scalar_precomp(group, &Ws_calculated, &T_precomp, &key->xs, |
| &S_precomp, &key->ys, NULL, NULL) || |
| !ec_affine_jacobian_equal(group, &Ws, &Ws_calculated)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_BAD_VALIDITY_CHECK); |
| return 0; |
| } |
| |
| EC_RAW_POINT W0, W1; |
| if (!ec_point_mul_scalar_precomp(group, &W0, &T_precomp, &key->x0, &S_precomp, |
| &key->y0, NULL, NULL) || |
| !ec_point_mul_scalar_precomp(group, &W1, &T_precomp, &key->x1, &S_precomp, |
| &key->y1, NULL, NULL)) { |
| return 0; |
| } |
| |
| const int is_W0 = ec_affine_jacobian_equal(group, &W, &W0); |
| const int is_W1 = ec_affine_jacobian_equal(group, &W, &W1); |
| const int is_valid = is_W0 ^ is_W1; |
| if (!is_valid) { |
| // Invalid tokens will fail the validity check above. |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_INTERNAL_ERROR); |
| return 0; |
| } |
| |
| *out_private_metadata = is_W1; |
| return 1; |
| } |
| |
| |
| // PMBTokens experiment v1. |
| |
| static int pmbtoken_exp1_hash_t(const EC_GROUP *group, EC_RAW_POINT *out, |
| const uint8_t t[TRUST_TOKEN_NONCE_SIZE]) { |
| const uint8_t kHashTLabel[] = "PMBTokens Experiment V1 HashT"; |
| return ec_hash_to_curve_p384_xmd_sha512_sswu_draft07( |
| group, out, kHashTLabel, sizeof(kHashTLabel), t, TRUST_TOKEN_NONCE_SIZE); |
| } |
| |
| static int pmbtoken_exp1_hash_s(const EC_GROUP *group, EC_RAW_POINT *out, |
| const EC_AFFINE *t, |
| const uint8_t s[TRUST_TOKEN_NONCE_SIZE]) { |
| const uint8_t kHashSLabel[] = "PMBTokens Experiment V1 HashS"; |
| int ret = 0; |
| CBB cbb; |
| uint8_t *buf = NULL; |
| size_t len; |
| if (!CBB_init(&cbb, 0) || |
| !point_to_cbb(&cbb, group, t) || |
| !CBB_add_bytes(&cbb, s, TRUST_TOKEN_NONCE_SIZE) || |
| !CBB_finish(&cbb, &buf, &len) || |
| !ec_hash_to_curve_p384_xmd_sha512_sswu_draft07( |
| group, out, kHashSLabel, sizeof(kHashSLabel), buf, len)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| ret = 1; |
| |
| err: |
| OPENSSL_free(buf); |
| CBB_cleanup(&cbb); |
| return ret; |
| } |
| |
| static int pmbtoken_exp1_hash_c(const EC_GROUP *group, EC_SCALAR *out, |
| uint8_t *buf, size_t len) { |
| const uint8_t kHashCLabel[] = "PMBTokens Experiment V1 HashC"; |
| return ec_hash_to_scalar_p384_xmd_sha512_draft07( |
| group, out, kHashCLabel, sizeof(kHashCLabel), buf, len); |
| } |
| |
| static int pmbtoken_exp1_hash_to_scalar(const EC_GROUP *group, EC_SCALAR *out, |
| uint8_t *buf, size_t len) { |
| const uint8_t kHashLabel[] = "PMBTokens Experiment V1 HashToScalar"; |
| return ec_hash_to_scalar_p384_xmd_sha512_draft07( |
| group, out, kHashLabel, sizeof(kHashLabel), buf, len); |
| } |
| |
| static int pmbtoken_exp1_ok = 0; |
| static PMBTOKEN_METHOD pmbtoken_exp1_method; |
| static CRYPTO_once_t pmbtoken_exp1_method_once = CRYPTO_ONCE_INIT; |
| |
| static void pmbtoken_exp1_init_method_impl(void) { |
| // This is the output of |ec_hash_to_scalar_p384_xmd_sha512_draft07| with DST |
| // "PMBTokens Experiment V1 HashH" and message "generator". |
| static const uint8_t kH[] = { |
| 0x04, 0x82, 0xd5, 0x68, 0xf5, 0x39, 0xf6, 0x08, 0x19, 0xa1, 0x75, |
| 0x9f, 0x98, 0xb5, 0x10, 0xf5, 0x0b, 0x9d, 0x2b, 0xe1, 0x64, 0x4d, |
| 0x02, 0x76, 0x18, 0x11, 0xf8, 0x2f, 0xd3, 0x33, 0x25, 0x1f, 0x2c, |
| 0xb8, 0xf6, 0xf1, 0x9e, 0x93, 0x85, 0x79, 0xb3, 0xb7, 0x81, 0xa3, |
| 0xe6, 0x23, 0xc3, 0x1c, 0xff, 0x03, 0xd9, 0x40, 0x6c, 0xec, 0xe0, |
| 0x4d, 0xea, 0xdf, 0x9d, 0x94, 0xd1, 0x87, 0xab, 0x27, 0xf7, 0x4f, |
| 0x53, 0xea, 0xa3, 0x18, 0x72, 0xb9, 0xd1, 0x56, 0xa0, 0x4e, 0x81, |
| 0xaa, 0xeb, 0x1c, 0x22, 0x6d, 0x39, 0x1c, 0x5e, 0xb1, 0x27, 0xfc, |
| 0x87, 0xc3, 0x95, 0xd0, 0x13, 0xb7, 0x0b, 0x5c, 0xc7, |
| }; |
| |
| pmbtoken_exp1_ok = pmbtoken_init_method( |
| &pmbtoken_exp1_method, NID_secp384r1, kH, sizeof(kH), |
| pmbtoken_exp1_hash_t, pmbtoken_exp1_hash_s, pmbtoken_exp1_hash_c, |
| pmbtoken_exp1_hash_to_scalar, 1); |
| } |
| |
| static int pmbtoken_exp1_init_method(void) { |
| CRYPTO_once(&pmbtoken_exp1_method_once, pmbtoken_exp1_init_method_impl); |
| if (!pmbtoken_exp1_ok) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_INTERNAL_ERROR); |
| return 0; |
| } |
| return 1; |
| } |
| |
| int pmbtoken_exp1_generate_key(CBB *out_private, CBB *out_public) { |
| if (!pmbtoken_exp1_init_method()) { |
| return 0; |
| } |
| |
| return pmbtoken_generate_key(&pmbtoken_exp1_method, out_private, out_public); |
| } |
| |
| int pmbtoken_exp1_derive_key_from_secret(CBB *out_private, CBB *out_public, |
| const uint8_t *secret, |
| size_t secret_len) { |
| if (!pmbtoken_exp1_init_method()) { |
| return 0; |
| } |
| |
| return pmbtoken_derive_key_from_secret(&pmbtoken_exp1_method, out_private, |
| out_public, secret, secret_len); |
| } |
| |
| int pmbtoken_exp1_client_key_from_bytes(TRUST_TOKEN_CLIENT_KEY *key, |
| const uint8_t *in, size_t len) { |
| if (!pmbtoken_exp1_init_method()) { |
| return 0; |
| } |
| return pmbtoken_client_key_from_bytes(&pmbtoken_exp1_method, key, in, len); |
| } |
| |
| int pmbtoken_exp1_issuer_key_from_bytes(TRUST_TOKEN_ISSUER_KEY *key, |
| const uint8_t *in, size_t len) { |
| if (!pmbtoken_exp1_init_method()) { |
| return 0; |
| } |
| return pmbtoken_issuer_key_from_bytes(&pmbtoken_exp1_method, key, in, len); |
| } |
| |
| STACK_OF(TRUST_TOKEN_PRETOKEN) * pmbtoken_exp1_blind(CBB *cbb, size_t count) { |
| if (!pmbtoken_exp1_init_method()) { |
| return NULL; |
| } |
| return pmbtoken_blind(&pmbtoken_exp1_method, cbb, count); |
| } |
| |
| int pmbtoken_exp1_sign(const TRUST_TOKEN_ISSUER_KEY *key, CBB *cbb, CBS *cbs, |
| size_t num_requested, size_t num_to_issue, |
| uint8_t private_metadata) { |
| if (!pmbtoken_exp1_init_method()) { |
| return 0; |
| } |
| return pmbtoken_sign(&pmbtoken_exp1_method, key, cbb, cbs, num_requested, |
| num_to_issue, private_metadata); |
| } |
| |
| STACK_OF(TRUST_TOKEN) * |
| pmbtoken_exp1_unblind(const TRUST_TOKEN_CLIENT_KEY *key, |
| const STACK_OF(TRUST_TOKEN_PRETOKEN) * pretokens, |
| CBS *cbs, size_t count, uint32_t key_id) { |
| if (!pmbtoken_exp1_init_method()) { |
| return NULL; |
| } |
| return pmbtoken_unblind(&pmbtoken_exp1_method, key, pretokens, cbs, count, |
| key_id); |
| } |
| |
| int pmbtoken_exp1_read(const TRUST_TOKEN_ISSUER_KEY *key, |
| uint8_t out_nonce[TRUST_TOKEN_NONCE_SIZE], |
| uint8_t *out_private_metadata, const uint8_t *token, |
| size_t token_len) { |
| if (!pmbtoken_exp1_init_method()) { |
| return 0; |
| } |
| return pmbtoken_read(&pmbtoken_exp1_method, key, out_nonce, |
| out_private_metadata, token, token_len); |
| } |
| |
| int pmbtoken_exp1_get_h_for_testing(uint8_t out[97]) { |
| if (!pmbtoken_exp1_init_method()) { |
| return 0; |
| } |
| EC_AFFINE h; |
| return ec_jacobian_to_affine(pmbtoken_exp1_method.group, &h, |
| &pmbtoken_exp1_method.h) && |
| ec_point_to_bytes(pmbtoken_exp1_method.group, &h, |
| POINT_CONVERSION_UNCOMPRESSED, out, 97) == 97; |
| } |
| |
| // PMBTokens experiment v2. |
| |
| static int pmbtoken_exp2_hash_t(const EC_GROUP *group, EC_RAW_POINT *out, |
| const uint8_t t[TRUST_TOKEN_NONCE_SIZE]) { |
| const uint8_t kHashTLabel[] = "PMBTokens Experiment V2 HashT"; |
| return ec_hash_to_curve_p384_xmd_sha512_sswu_draft07( |
| group, out, kHashTLabel, sizeof(kHashTLabel), t, TRUST_TOKEN_NONCE_SIZE); |
| } |
| |
| static int pmbtoken_exp2_hash_s(const EC_GROUP *group, EC_RAW_POINT *out, |
| const EC_AFFINE *t, |
| const uint8_t s[TRUST_TOKEN_NONCE_SIZE]) { |
| const uint8_t kHashSLabel[] = "PMBTokens Experiment V2 HashS"; |
| int ret = 0; |
| CBB cbb; |
| uint8_t *buf = NULL; |
| size_t len; |
| if (!CBB_init(&cbb, 0) || |
| !point_to_cbb(&cbb, group, t) || |
| !CBB_add_bytes(&cbb, s, TRUST_TOKEN_NONCE_SIZE) || |
| !CBB_finish(&cbb, &buf, &len) || |
| !ec_hash_to_curve_p384_xmd_sha512_sswu_draft07( |
| group, out, kHashSLabel, sizeof(kHashSLabel), buf, len)) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| ret = 1; |
| |
| err: |
| OPENSSL_free(buf); |
| CBB_cleanup(&cbb); |
| return ret; |
| } |
| |
| static int pmbtoken_exp2_hash_c(const EC_GROUP *group, EC_SCALAR *out, |
| uint8_t *buf, size_t len) { |
| const uint8_t kHashCLabel[] = "PMBTokens Experiment V2 HashC"; |
| return ec_hash_to_scalar_p384_xmd_sha512_draft07( |
| group, out, kHashCLabel, sizeof(kHashCLabel), buf, len); |
| } |
| |
| static int pmbtoken_exp2_hash_to_scalar(const EC_GROUP *group, EC_SCALAR *out, |
| uint8_t *buf, size_t len) { |
| const uint8_t kHashLabel[] = "PMBTokens Experiment V2 HashToScalar"; |
| return ec_hash_to_scalar_p384_xmd_sha512_draft07( |
| group, out, kHashLabel, sizeof(kHashLabel), buf, len); |
| } |
| |
| static int pmbtoken_exp2_ok = 0; |
| static PMBTOKEN_METHOD pmbtoken_exp2_method; |
| static CRYPTO_once_t pmbtoken_exp2_method_once = CRYPTO_ONCE_INIT; |
| |
| static void pmbtoken_exp2_init_method_impl(void) { |
| // This is the output of |ec_hash_to_scalar_p384_xmd_sha512_draft07| with DST |
| // "PMBTokens Experiment V2 HashH" and message "generator". |
| static const uint8_t kH[] = { |
| 0x04, 0xbc, 0x27, 0x24, 0x99, 0xfa, 0xc9, 0xa4, 0x74, 0x6f, 0xf9, |
| 0x07, 0x81, 0x55, 0xf8, 0x1f, 0x6f, 0xda, 0x09, 0xe7, 0x8c, 0x5d, |
| 0x9e, 0x4e, 0x14, 0x7c, 0x53, 0x14, 0xbc, 0x7e, 0x29, 0x57, 0x92, |
| 0x17, 0x94, 0x6e, 0xd2, 0xdf, 0xa5, 0x31, 0x1b, 0x4e, 0xb7, 0xfc, |
| 0x93, 0xe3, 0x6e, 0x14, 0x1f, 0x4f, 0x14, 0xf3, 0xe5, 0x47, 0x61, |
| 0x1c, 0x2c, 0x72, 0x25, 0xf0, 0x4a, 0x45, 0x23, 0x2d, 0x57, 0x93, |
| 0x0e, 0xb2, 0x55, 0xb8, 0x57, 0x25, 0x4c, 0x1e, 0xdb, 0xfd, 0x58, |
| 0x70, 0x17, 0x9a, 0xbb, 0x9e, 0x5e, 0x93, 0x9e, 0x92, 0xd3, 0xe8, |
| 0x25, 0x62, 0xbf, 0x59, 0xb2, 0xd2, 0x3d, 0x71, 0xff |
| }; |
| |
| pmbtoken_exp2_ok = pmbtoken_init_method( |
| &pmbtoken_exp2_method, NID_secp384r1, kH, sizeof(kH), |
| pmbtoken_exp2_hash_t, pmbtoken_exp2_hash_s, pmbtoken_exp2_hash_c, |
| pmbtoken_exp2_hash_to_scalar, 0); |
| } |
| |
| static int pmbtoken_exp2_init_method(void) { |
| CRYPTO_once(&pmbtoken_exp2_method_once, pmbtoken_exp2_init_method_impl); |
| if (!pmbtoken_exp2_ok) { |
| OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_INTERNAL_ERROR); |
| return 0; |
| } |
| return 1; |
| } |
| |
| int pmbtoken_exp2_generate_key(CBB *out_private, CBB *out_public) { |
| if (!pmbtoken_exp2_init_method()) { |
| return 0; |
| } |
| |
| return pmbtoken_generate_key(&pmbtoken_exp2_method, out_private, out_public); |
| } |
| |
| |
| int pmbtoken_exp2_derive_key_from_secret(CBB *out_private, CBB *out_public, |
| const uint8_t *secret, |
| size_t secret_len) { |
| if (!pmbtoken_exp2_init_method()) { |
| return 0; |
| } |
| |
| return pmbtoken_derive_key_from_secret(&pmbtoken_exp2_method, out_private, |
| out_public, secret, secret_len); |
| } |
| |
| int pmbtoken_exp2_client_key_from_bytes(TRUST_TOKEN_CLIENT_KEY *key, |
| const uint8_t *in, size_t len) { |
| if (!pmbtoken_exp2_init_method()) { |
| return 0; |
| } |
| return pmbtoken_client_key_from_bytes(&pmbtoken_exp2_method, key, in, len); |
| } |
| |
| int pmbtoken_exp2_issuer_key_from_bytes(TRUST_TOKEN_ISSUER_KEY *key, |
| const uint8_t *in, size_t len) { |
| if (!pmbtoken_exp2_init_method()) { |
| return 0; |
| } |
| return pmbtoken_issuer_key_from_bytes(&pmbtoken_exp2_method, key, in, len); |
| } |
| |
| STACK_OF(TRUST_TOKEN_PRETOKEN) * pmbtoken_exp2_blind(CBB *cbb, size_t count) { |
| if (!pmbtoken_exp2_init_method()) { |
| return NULL; |
| } |
| return pmbtoken_blind(&pmbtoken_exp2_method, cbb, count); |
| } |
| |
| int pmbtoken_exp2_sign(const TRUST_TOKEN_ISSUER_KEY *key, CBB *cbb, CBS *cbs, |
| size_t num_requested, size_t num_to_issue, |
| uint8_t private_metadata) { |
| if (!pmbtoken_exp2_init_method()) { |
| return 0; |
| } |
| return pmbtoken_sign(&pmbtoken_exp2_method, key, cbb, cbs, num_requested, |
| num_to_issue, private_metadata); |
| } |
| |
| STACK_OF(TRUST_TOKEN) * |
| pmbtoken_exp2_unblind(const TRUST_TOKEN_CLIENT_KEY *key, |
| const STACK_OF(TRUST_TOKEN_PRETOKEN) * pretokens, |
| CBS *cbs, size_t count, uint32_t key_id) { |
| if (!pmbtoken_exp2_init_method()) { |
| return NULL; |
| } |
| return pmbtoken_unblind(&pmbtoken_exp2_method, key, pretokens, cbs, count, |
| key_id); |
| } |
| |
| int pmbtoken_exp2_read(const TRUST_TOKEN_ISSUER_KEY *key, |
| uint8_t out_nonce[TRUST_TOKEN_NONCE_SIZE], |
| uint8_t *out_private_metadata, const uint8_t *token, |
| size_t token_len) { |
| if (!pmbtoken_exp2_init_method()) { |
| return 0; |
| } |
| return pmbtoken_read(&pmbtoken_exp2_method, key, out_nonce, |
| out_private_metadata, token, token_len); |
| } |
| |
| int pmbtoken_exp2_get_h_for_testing(uint8_t out[97]) { |
| if (!pmbtoken_exp2_init_method()) { |
| return 0; |
| } |
| EC_AFFINE h; |
| return ec_jacobian_to_affine(pmbtoken_exp2_method.group, &h, |
| &pmbtoken_exp2_method.h) && |
| ec_point_to_bytes(pmbtoken_exp2_method.group, &h, |
| POINT_CONVERSION_UNCOMPRESSED, out, 97) == 97; |
| } |