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Align TRUST_TOKEN_pst_v1_voprf with draft-21 of VOPRF

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This aligns the DLEQ proof portion of TRUST_TOKEN_pst_v1_voprf
with draft-irtf-cfrg-voprf-21. The blind and finalize operations
still differ. Additionally, as VOPRF doesn't include batched
issuance, the issuance process around the DLEQ proof is adapted
from draft-robert-privacypass-batched-tokens-01.

Bug: chromium:1414562
Change-Id: If1c6de0f92089a826968a57279ae598ccf89ca3e
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/58906
Commit-Queue: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
This commit is contained in:
Steven Valdez 2023-04-18 12:03:42 -04:00 committed by Boringssl LUCI CQ
parent ece1f86968
commit 4b6d950d89
4 changed files with 753 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
crypto/fipsmodule/ec/internal.h
View File

@ -91,6 +91,8 @@ extern "C" {
// be the largest fields anyone plausibly uses.
#define EC_MAX_BYTES 66
#define EC_MAX_WORDS ((EC_MAX_BYTES + BN_BYTES - 1) / BN_BYTES)
#define EC_MAX_COMPRESSED (EC_MAX_BYTES + 1)
#define EC_MAX_UNCOMPRESSED (2 * EC_MAX_BYTES + 1)
static_assert(EC_MAX_WORDS <= BN_SMALL_MAX_WORDS,
"bn_*_small functions not usable");
@ -119,8 +121,8 @@ OPENSSL_EXPORT void ec_scalar_to_bytes(const EC_GROUP *group, uint8_t *out,
// ec_scalar_from_bytes deserializes |in| and stores the resulting scalar over
// group |group| to |out|. It returns one on success and zero if |in| is
// invalid.
int ec_scalar_from_bytes(const EC_GROUP *group, EC_SCALAR *out,
const uint8_t *in, size_t len);
OPENSSL_EXPORT int ec_scalar_from_bytes(const EC_GROUP *group, EC_SCALAR *out,
const uint8_t *in, size_t len);
// ec_scalar_reduce sets |out| to |words|, reduced modulo the group order.
// |words| must be less than order^2. |num| must be at most twice the width of
@ -279,8 +281,8 @@ void ec_affine_to_jacobian(const EC_GROUP *group, EC_RAW_POINT *out,
//
// If only extracting the x-coordinate, use |ec_get_x_coordinate_*| which is
// slightly faster.
int ec_jacobian_to_affine(const EC_GROUP *group, EC_AFFINE *out,
const EC_RAW_POINT *p);
OPENSSL_EXPORT int ec_jacobian_to_affine(const EC_GROUP *group, EC_AFFINE *out,
const EC_RAW_POINT *p);
// ec_jacobian_to_affine_batch converts |num| points in |in| from Jacobian
// coordinates to affine coordinates and writes the results to |out|. It returns

4
crypto/trust_token/internal.h
View File

@ -239,6 +239,10 @@ STACK_OF(TRUST_TOKEN_PRETOKEN) *voprf_pst1_blind(CBB *cbb, size_t count,
int voprf_pst1_sign(const TRUST_TOKEN_ISSUER_KEY *key, CBB *cbb, CBS *cbs,
size_t num_requested, size_t num_to_issue,
uint8_t private_metadata);
OPENSSL_EXPORT int voprf_pst1_sign_with_proof_scalar_for_testing(
const TRUST_TOKEN_ISSUER_KEY *key, CBB *cbb, CBS *cbs, size_t num_requested,
size_t num_to_issue, uint8_t private_metadata,
const uint8_t *proof_scalar_buf, size_t proof_scalar_len);
STACK_OF(TRUST_TOKEN) *voprf_pst1_unblind(
const TRUST_TOKEN_CLIENT_KEY *key,
const STACK_OF(TRUST_TOKEN_PRETOKEN) *pretokens, CBS *cbs, size_t count,

289
crypto/trust_token/trust_token_test.cc
View File

@ -314,6 +314,295 @@ TEST(TrustTokenTest, HPST1) {
EXPECT_EQ(Bytes(h), Bytes(expected_bytes, expected_len));
}
static int ec_point_uncompressed_from_compressed(
const EC_GROUP *group, uint8_t out[EC_MAX_UNCOMPRESSED], size_t *out_len,
const uint8_t *in, size_t len) {
bssl::UniquePtr<EC_POINT> point(EC_POINT_new(group));
if (!point ||
!EC_POINT_oct2point(group, point.get(), in, len, nullptr)) {
return 0;
}
*out_len =
EC_POINT_point2oct(group, point.get(), POINT_CONVERSION_UNCOMPRESSED, out,
EC_MAX_UNCOMPRESSED, nullptr);
return 1;
}
static bool setup_voprf_test_key(const EC_GROUP *group,
TRUST_TOKEN_ISSUER_KEY *out) {
static const uint8_t kPrivateKey[] = {
0x05, 0x16, 0x46, 0xb9, 0xe6, 0xe7, 0xa7, 0x1a, 0xe2, 0x7c, 0x1e, 0x1d,
0x0b, 0x87, 0xb4, 0x38, 0x1d, 0xb6, 0xd3, 0x59, 0x5e, 0xee, 0xb1, 0xad,
0xb4, 0x15, 0x79, 0xad, 0xbf, 0x99, 0x2f, 0x42, 0x78, 0xf9, 0x01, 0x6e,
0xaf, 0xc9, 0x44, 0xed, 0xaa, 0x2b, 0x43, 0x18, 0x35, 0x81, 0x77, 0x9d
};
static const uint8_t kPublicKey[] = {
0x03, 0x1d, 0x68, 0x96, 0x86, 0xc6, 0x11, 0x99, 0x1b, 0x55,
0xf1, 0xa1, 0xd8, 0xf4, 0x30, 0x5c, 0xcd, 0x6c, 0xb7, 0x19,
0x44, 0x6f, 0x66, 0x0a, 0x30, 0xdb, 0x61, 0xb7, 0xaa, 0x87,
0xb4, 0x6a, 0xcf, 0x59, 0xb7, 0xc0, 0xd4, 0xa9, 0x07, 0x7b,
0x3d, 0xa2, 0x1c, 0x25, 0xdd, 0x48, 0x22, 0x29, 0xa0
};
if (!ec_scalar_from_bytes(group, &out->xs, kPrivateKey,
sizeof(kPrivateKey))) {
return false;
}
bssl::UniquePtr<EC_POINT> pub(EC_POINT_new(group));
return pub &&
EC_POINT_oct2point(group, pub.get(), kPublicKey, sizeof(kPublicKey),
nullptr) &&
ec_jacobian_to_affine(group, &out->pubs, &pub->raw);
}
TEST(TrustTokenTest, PSTV1VOPRFTestVector1) {
const EC_GROUP *group = EC_GROUP_new_by_curve_name(NID_secp384r1);
TRUST_TOKEN_ISSUER_KEY key;
ASSERT_TRUE(setup_voprf_test_key(group, &key));
static const uint8_t kBlindedElement[] = {
0x02, 0xd3, 0x38, 0xc0, 0x5c, 0xbe, 0xcb, 0x82, 0xde, 0x13,
0xd6, 0x70, 0x0f, 0x09, 0xcb, 0x61, 0x19, 0x05, 0x43, 0xa7,
0xb7, 0xe2, 0xc6, 0xcd, 0x4f, 0xca, 0x56, 0x88, 0x7e, 0x56,
0x4e, 0xa8, 0x26, 0x53, 0xb2, 0x7f, 0xda, 0xd3, 0x83, 0x99,
0x5e, 0xa6, 0xd0, 0x2c, 0xf2, 0x6d, 0x0e, 0x24, 0xd9
};
static const uint8_t kEvaluatedElement[] = {
0x02, 0xa7, 0xbb, 0xa5, 0x89, 0xb3, 0xe8, 0x67, 0x2a, 0xa1,
0x9e, 0x8f, 0xd2, 0x58, 0xde, 0x2e, 0x6a, 0xae, 0x20, 0x10,
0x1c, 0x8d, 0x76, 0x12, 0x46, 0xde, 0x97, 0xa6, 0xb5, 0xee,
0x9c, 0xf1, 0x05, 0xfe, 0xbc, 0xe4, 0x32, 0x7a, 0x32, 0x62,
0x55, 0xa3, 0xc6, 0x04, 0xf6, 0x3f, 0x60, 0x0e, 0xf6
};
static const uint8_t kProof[] = {
0xbf, 0xc6, 0xcf, 0x38, 0x59, 0x12, 0x7f, 0x5f, 0xe2, 0x55, 0x48, 0x85,
0x98, 0x56, 0xd6, 0xb7, 0xfa, 0x1c, 0x74, 0x59, 0xf0, 0xba, 0x57, 0x12,
0xa8, 0x06, 0xfc, 0x09, 0x1a, 0x30, 0x00, 0xc4, 0x2d, 0x8b, 0xa3, 0x4f,
0xf4, 0x5f, 0x32, 0xa5, 0x2e, 0x40, 0x53, 0x3e, 0xfd, 0x2a, 0x03, 0xbc,
0x87, 0xf3, 0xbf, 0x4f, 0x9f, 0x58, 0x02, 0x82, 0x97, 0xcc, 0xb9, 0xcc,
0xb1, 0x8a, 0xe7, 0x18, 0x2b, 0xcd, 0x1e, 0xf2, 0x39, 0xdf, 0x77, 0xe3,
0xbe, 0x65, 0xef, 0x14, 0x7f, 0x3a, 0xcf, 0x8b, 0xc9, 0xcb, 0xfc, 0x55,
0x24, 0xb7, 0x02, 0x26, 0x34, 0x14, 0xf0, 0x43, 0xe3, 0xb7, 0xca, 0x2e
};
static const uint8_t kProofScalar[] = {
0x80, 0x3d, 0x95, 0x5f, 0x0e, 0x07, 0x3a, 0x04, 0xaa, 0x5d, 0x92, 0xb3,
0xfb, 0x73, 0x9f, 0x56, 0xf9, 0xdb, 0x00, 0x12, 0x66, 0x67, 0x7f, 0x62,
0xc0, 0x95, 0x02, 0x1d, 0xb0, 0x18, 0xcd, 0x8c, 0xbb, 0x55, 0x94, 0x1d,
0x40, 0x73, 0x69, 0x8c, 0xe4, 0x5c, 0x40, 0x5d, 0x13, 0x48, 0xb7, 0xb1
};
uint8_t blinded_buf[EC_MAX_UNCOMPRESSED];
size_t blinded_len;
ASSERT_TRUE(ec_point_uncompressed_from_compressed(
group, blinded_buf, &blinded_len, kBlindedElement,
sizeof(kBlindedElement)));
CBS sign_input;
CBS_init(&sign_input, blinded_buf, blinded_len);
bssl::ScopedCBB response;
ASSERT_TRUE(CBB_init(response.get(), 0));
ASSERT_TRUE(voprf_pst1_sign_with_proof_scalar_for_testing(
&key, response.get(), &sign_input, /*num_requested=*/1,
/*num_to_issue=*/1,
/*private_metadata=*/0, kProofScalar, sizeof(kProofScalar)));
uint8_t evaluated_buf[EC_MAX_UNCOMPRESSED];
size_t evaluated_len;
ASSERT_TRUE(ec_point_uncompressed_from_compressed(
group, evaluated_buf, &evaluated_len, kEvaluatedElement,
sizeof(kEvaluatedElement)));
bssl::ScopedCBB expected_response;
ASSERT_TRUE(CBB_init(expected_response.get(), 0));
ASSERT_TRUE(
CBB_add_bytes(expected_response.get(), evaluated_buf, evaluated_len));
ASSERT_TRUE(CBB_add_u16(expected_response.get(), sizeof(kProof)));
ASSERT_TRUE(CBB_add_bytes(expected_response.get(), kProof, sizeof(kProof)));
ASSERT_TRUE(CBB_flush(expected_response.get()));
ASSERT_EQ(Bytes(CBB_data(expected_response.get()),
CBB_len(expected_response.get())),
Bytes(CBB_data(response.get()), CBB_len(response.get())));
}
TEST(TrustTokenTest, PSTV1VOPRFTestVector2) {
const EC_GROUP *group = EC_GROUP_new_by_curve_name(NID_secp384r1);
TRUST_TOKEN_ISSUER_KEY key;
ASSERT_TRUE(setup_voprf_test_key(group, &key));
static const uint8_t kBlindedElement[] = {
0x02, 0xf2, 0x74, 0x69, 0xe0, 0x59, 0x88, 0x6f, 0x22, 0x1b,
0xe5, 0xf2, 0xcc, 0xa0, 0x3d, 0x2b, 0xdc, 0x61, 0xe5, 0x52,
0x21, 0x72, 0x1c, 0x3b, 0x3e, 0x56, 0xfc, 0x01, 0x2e, 0x36,
0xd3, 0x1a, 0xe5, 0xf8, 0xdc, 0x05, 0x81, 0x09, 0x59, 0x15,
0x56, 0xa6, 0xdb, 0xd3, 0xa8, 0xc6, 0x9c, 0x43, 0x3b
};
static const uint8_t kEvaluatedElement[] = {
0x03, 0xf1, 0x6f, 0x90, 0x39, 0x47, 0x03, 0x54, 0x00, 0xe9,
0x6b, 0x7f, 0x53, 0x1a, 0x38, 0xd4, 0xa0, 0x7a, 0xc8, 0x9a,
0x80, 0xf8, 0x9d, 0x86, 0xa1, 0xbf, 0x08, 0x9c, 0x52, 0x5a,
0x92, 0xc7, 0xf4, 0x73, 0x37, 0x29, 0xca, 0x30, 0xc5, 0x6c,
0xe7, 0x8b, 0x1a, 0xb4, 0xf7, 0xd9, 0x2d, 0xb8, 0xb4
};
static const uint8_t kProof[] = {
0xd0, 0x05, 0xd6, 0xda, 0xaa, 0xd7, 0x57, 0x14, 0x14, 0xc1, 0xe0,
0xc7, 0x5f, 0x7e, 0x57, 0xf2, 0x11, 0x3c, 0xa9, 0xf4, 0x60, 0x4e,
0x84, 0xbc, 0x90, 0xf9, 0xbe, 0x52, 0xda, 0x89, 0x6f, 0xff, 0x3b,
0xee, 0x49, 0x6d, 0xcd, 0xe2, 0xa5, 0x78, 0xae, 0x9d, 0xf3, 0x15,
0x03, 0x25, 0x85, 0xf8, 0x01, 0xfb, 0x21, 0xc6, 0x08, 0x0a, 0xc0,
0x56, 0x72, 0xb2, 0x91, 0xe5, 0x75, 0xa4, 0x02, 0x95, 0xb3, 0x06,
0xd9, 0x67, 0x71, 0x7b, 0x28, 0xe0, 0x8f, 0xcc, 0x8a, 0xd1, 0xca,
0xb4, 0x78, 0x45, 0xd1, 0x6a, 0xf7, 0x3b, 0x3e, 0x64, 0x3d, 0xdc,
0xc1, 0x91, 0x20, 0x8e, 0x71, 0xc6, 0x46, 0x30
};
static const uint8_t kProofScalar[] = {
0x80, 0x3d, 0x95, 0x5f, 0x0e, 0x07, 0x3a, 0x04, 0xaa, 0x5d, 0x92, 0xb3,
0xfb, 0x73, 0x9f, 0x56, 0xf9, 0xdb, 0x00, 0x12, 0x66, 0x67, 0x7f, 0x62,
0xc0, 0x95, 0x02, 0x1d, 0xb0, 0x18, 0xcd, 0x8c, 0xbb, 0x55, 0x94, 0x1d,
0x40, 0x73, 0x69, 0x8c, 0xe4, 0x5c, 0x40, 0x5d, 0x13, 0x48, 0xb7, 0xb1
};
uint8_t blinded_buf[EC_MAX_UNCOMPRESSED];
size_t blinded_len;
ASSERT_TRUE(ec_point_uncompressed_from_compressed(
group, blinded_buf, &blinded_len, kBlindedElement,
sizeof(kBlindedElement)));
CBS sign_input;
CBS_init(&sign_input, blinded_buf, blinded_len);
bssl::ScopedCBB response;
ASSERT_TRUE(CBB_init(response.get(), 0));
ASSERT_TRUE(voprf_pst1_sign_with_proof_scalar_for_testing(
&key, response.get(), &sign_input, /*num_requested=*/1,
/*num_to_issue=*/1,
/*private_metadata=*/0, kProofScalar, sizeof(kProofScalar)));
uint8_t evaluated_buf[EC_MAX_UNCOMPRESSED];
size_t evaluated_len;
ASSERT_TRUE(ec_point_uncompressed_from_compressed(
group, evaluated_buf, &evaluated_len, kEvaluatedElement,
sizeof(kEvaluatedElement)));
bssl::ScopedCBB expected_response;
ASSERT_TRUE(CBB_init(expected_response.get(), 0));
ASSERT_TRUE(
CBB_add_bytes(expected_response.get(), evaluated_buf, evaluated_len));
ASSERT_TRUE(CBB_add_u16(expected_response.get(), sizeof(kProof)));
ASSERT_TRUE(CBB_add_bytes(expected_response.get(), kProof, sizeof(kProof)));
ASSERT_TRUE(CBB_flush(expected_response.get()));
ASSERT_EQ(Bytes(CBB_data(expected_response.get()),
CBB_len(expected_response.get())),
Bytes(CBB_data(response.get()), CBB_len(response.get())));
}
TEST(TrustTokenTest, PSTV1VOPRFTestVector3) {
const EC_GROUP *group = EC_GROUP_new_by_curve_name(NID_secp384r1);
TRUST_TOKEN_ISSUER_KEY key;
ASSERT_TRUE(setup_voprf_test_key(group, &key));
static const uint8_t kBlindedElement1[] = {
0x02, 0xd3, 0x38, 0xc0, 0x5c, 0xbe, 0xcb, 0x82, 0xde, 0x13,
0xd6, 0x70, 0x0f, 0x09, 0xcb, 0x61, 0x19, 0x05, 0x43, 0xa7,
0xb7, 0xe2, 0xc6, 0xcd, 0x4f, 0xca, 0x56, 0x88, 0x7e, 0x56,
0x4e, 0xa8, 0x26, 0x53, 0xb2, 0x7f, 0xda, 0xd3, 0x83, 0x99,
0x5e, 0xa6, 0xd0, 0x2c, 0xf2, 0x6d, 0x0e, 0x24, 0xd9
};
static const uint8_t kBlindedElement2[] = {
0x02, 0xfa, 0x02, 0x47, 0x0d, 0x7f, 0x15, 0x10, 0x18, 0xb4,
0x1e, 0x82, 0x22, 0x3c, 0x32, 0xfa, 0xd8, 0x24, 0xde, 0x6a,
0xd4, 0xb5, 0xce, 0x9f, 0x8e, 0x9f, 0x98, 0x08, 0x3c, 0x9a,
0x72, 0x6d, 0xe9, 0xa1, 0xfc, 0x39, 0xd7, 0xa0, 0xcb, 0x6f,
0x4f, 0x18, 0x8d, 0xd9, 0xce, 0xa0, 0x14, 0x74, 0xcd
};
static const uint8_t kEvaluatedElement1[] = {
0x02, 0xa7, 0xbb, 0xa5, 0x89, 0xb3, 0xe8, 0x67, 0x2a, 0xa1,
0x9e, 0x8f, 0xd2, 0x58, 0xde, 0x2e, 0x6a, 0xae, 0x20, 0x10,
0x1c, 0x8d, 0x76, 0x12, 0x46, 0xde, 0x97, 0xa6, 0xb5, 0xee,
0x9c, 0xf1, 0x05, 0xfe, 0xbc, 0xe4, 0x32, 0x7a, 0x32, 0x62,
0x55, 0xa3, 0xc6, 0x04, 0xf6, 0x3f, 0x60, 0x0e, 0xf6
};
static const uint8_t kEvaluatedElement2[] = {
0x02, 0x8e, 0x9e, 0x11, 0x56, 0x25, 0xff, 0x4c, 0x2f, 0x07,
0xbf, 0x87, 0xce, 0x3f, 0xd7, 0x3f, 0xc7, 0x79, 0x94, 0xa7,
0xa0, 0xc1, 0xdf, 0x03, 0xd2, 0xa6, 0x30, 0xa3, 0xd8, 0x45,
0x93, 0x0e, 0x2e, 0x63, 0xa1, 0x65, 0xb1, 0x14, 0xd9, 0x8f,
0xe3, 0x4e, 0x61, 0xb6, 0x8d, 0x23, 0xc0, 0xb5, 0x0a
};
static const uint8_t kProof[] = {
0x6d, 0x8d, 0xcb, 0xd2, 0xfc, 0x95, 0x55, 0x0a, 0x02, 0x21, 0x1f,
0xb7, 0x8a, 0xfd, 0x01, 0x39, 0x33, 0xf3, 0x07, 0xd2, 0x1e, 0x7d,
0x85, 0x5b, 0x0b, 0x1e, 0xd0, 0xaf, 0x78, 0x07, 0x6d, 0x81, 0x37,
0xad, 0x8b, 0x0a, 0x1b, 0xfa, 0x05, 0x67, 0x6d, 0x32, 0x52, 0x49,
0xc1, 0xdb, 0xb9, 0xa5, 0x2b, 0xd8, 0x1b, 0x1c, 0x2b, 0x7b, 0x0e,
0xfc, 0x77, 0xcf, 0x7b, 0x27, 0x8e, 0x1c, 0x94, 0x7f, 0x62, 0x83,
0xf1, 0xd4, 0xc5, 0x13, 0x05, 0x3f, 0xc0, 0xad, 0x19, 0xe0, 0x26,
0xfb, 0x0c, 0x30, 0x65, 0x4b, 0x53, 0xd9, 0xce, 0xa4, 0xb8, 0x7b,
0x03, 0x72, 0x71, 0xb5, 0xd2, 0xe2, 0xd0, 0xea
};
static const uint8_t kProofScalar[] = {
0xa0, 0x97, 0xe7, 0x22, 0xed, 0x24, 0x27, 0xde, 0x86, 0x96,
0x69, 0x10, 0xac, 0xba, 0x9f, 0x5c, 0x35, 0x0e, 0x80, 0x40,
0xf8, 0x28, 0xbf, 0x6c, 0xec, 0xa2, 0x74, 0x05, 0x42, 0x0c,
0xdf, 0x3d, 0x63, 0xcb, 0x3a, 0xef, 0x00, 0x5f, 0x40, 0xba,
0x51, 0x94, 0x3c, 0x80, 0x26, 0x87, 0x79, 0x63
};
uint8_t blinded_buf[2*EC_MAX_UNCOMPRESSED];
size_t blinded_len;
ASSERT_TRUE(ec_point_uncompressed_from_compressed(
group, blinded_buf, &blinded_len, kBlindedElement1,
sizeof(kBlindedElement1)));
size_t offset = blinded_len;
ASSERT_TRUE(ec_point_uncompressed_from_compressed(
group, blinded_buf + offset, &blinded_len, kBlindedElement2,
sizeof(kBlindedElement2)));
CBS sign_input;
CBS_init(&sign_input, blinded_buf, offset + blinded_len);
bssl::ScopedCBB response;
ASSERT_TRUE(CBB_init(response.get(), 0));
ASSERT_TRUE(voprf_pst1_sign_with_proof_scalar_for_testing(
&key, response.get(), &sign_input, /*num_requested=*/2,
/*num_to_issue=*/2,
/*private_metadata=*/0, kProofScalar, sizeof(kProofScalar)));
uint8_t evaluated_buf[2 * EC_MAX_UNCOMPRESSED];
size_t evaluated_len;
ASSERT_TRUE(ec_point_uncompressed_from_compressed(
group, evaluated_buf, &evaluated_len, kEvaluatedElement1,
sizeof(kEvaluatedElement1)));
offset = evaluated_len;
ASSERT_TRUE(ec_point_uncompressed_from_compressed(
group, evaluated_buf + offset, &evaluated_len, kEvaluatedElement2,
sizeof(kEvaluatedElement2)));
bssl::ScopedCBB expected_response;
ASSERT_TRUE(CBB_init(expected_response.get(), 0));
ASSERT_TRUE(CBB_add_bytes(expected_response.get(), evaluated_buf,
offset + evaluated_len));
ASSERT_TRUE(CBB_add_u16(expected_response.get(), sizeof(kProof)));
ASSERT_TRUE(CBB_add_bytes(expected_response.get(), kProof, sizeof(kProof)));
ASSERT_TRUE(CBB_flush(expected_response.get()));
ASSERT_EQ(Bytes(CBB_data(expected_response.get()),
CBB_len(expected_response.get())),
Bytes(CBB_data(response.get()), CBB_len(response.get())));
}
static std::vector<const TRUST_TOKEN_METHOD *> AllMethods() {
return {
TRUST_TOKEN_experiment_v1(),

472
crypto/trust_token/voprf.c
View File

@ -63,18 +63,24 @@ static int voprf_init_method(VOPRF_METHOD *method, int curve_nid,
static int cbb_add_point(CBB *out, const EC_GROUP *group,
const EC_AFFINE *point) {
size_t len = ec_point_byte_len(group, POINT_CONVERSION_UNCOMPRESSED);
if (len == 0) {
return 0;
}
uint8_t *p;
size_t len = ec_point_byte_len(group, POINT_CONVERSION_UNCOMPRESSED);
return CBB_add_space(out, &p, len) &&
ec_point_to_bytes(group, point, POINT_CONVERSION_UNCOMPRESSED, p,
len) == len &&
CBB_flush(out);
}
static int cbb_serialize_point(CBB *out, const EC_GROUP *group,
const EC_AFFINE *point) {
uint8_t *p;
size_t len = ec_point_byte_len(group, POINT_CONVERSION_COMPRESSED);
return CBB_add_u16(out, len) && CBB_add_space(out, &p, len) &&
ec_point_to_bytes(group, point, POINT_CONVERSION_COMPRESSED, p, len) ==
len &&
CBB_flush(out);
}
static int cbs_get_point(CBS *cbs, const EC_GROUP *group, EC_AFFINE *out) {
CBS child;
size_t plen = 1 + 2 * BN_num_bytes(&group->field);
@ -299,6 +305,30 @@ err:
return ok;
}
static int hash_to_scalar_challenge(const VOPRF_METHOD *method, EC_SCALAR *out,
const EC_AFFINE *Bm, const EC_AFFINE *a0,
const EC_AFFINE *a1, const EC_AFFINE *a2,
const EC_AFFINE *a3) {
static const uint8_t kChallengeLabel[] = "Challenge";
CBB cbb;
uint8_t transcript[5 * EC_MAX_COMPRESSED + 2 + sizeof(kChallengeLabel) - 1];
size_t len;
if (!CBB_init_fixed(&cbb, transcript, sizeof(transcript)) ||
!cbb_serialize_point(&cbb, method->group, Bm) ||
!cbb_serialize_point(&cbb, method->group, a0) ||
!cbb_serialize_point(&cbb, method->group, a1) ||
!cbb_serialize_point(&cbb, method->group, a2) ||
!cbb_serialize_point(&cbb, method->group, a3) ||
!CBB_add_bytes(&cbb, kChallengeLabel, sizeof(kChallengeLabel) - 1) ||
!CBB_finish(&cbb, NULL, &len) ||
!method->hash_to_scalar(method->group, out, transcript, len)) {
return 0;
}
return 1;
}
static int hash_to_scalar_batch(const VOPRF_METHOD *method, EC_SCALAR *out,
const CBB *points, size_t index) {
static const uint8_t kDLEQBatchLabel[] = "DLEQ BATCH";
@ -455,9 +485,9 @@ static int dleq_verify(const VOPRF_METHOD *method, CBS *cbs,
return 1;
}
static int voprf_sign(const VOPRF_METHOD *method,
const TRUST_TOKEN_ISSUER_KEY *key, CBB *cbb, CBS *cbs,
size_t num_requested, size_t num_to_issue) {
static int voprf_sign_tt(const VOPRF_METHOD *method,
const TRUST_TOKEN_ISSUER_KEY *key, CBB *cbb, CBS *cbs,
size_t num_requested, size_t num_to_issue) {
const EC_GROUP *group = method->group;
if (num_requested < num_to_issue) {
OPENSSL_PUT_ERROR(TRUST_TOKEN, ERR_R_INTERNAL_ERROR);
@ -553,7 +583,7 @@ err:
return ret;
}
static STACK_OF(TRUST_TOKEN) *voprf_unblind(
static STACK_OF(TRUST_TOKEN) *voprf_unblind_tt(
const VOPRF_METHOD *method, const TRUST_TOKEN_CLIENT_KEY *key,
const STACK_OF(TRUST_TOKEN_PRETOKEN) *pretokens, CBS *cbs, size_t count,
uint32_t key_id) {
@ -673,6 +703,397 @@ err:
return ret;
}
static void sha384_update_u16(SHA512_CTX *ctx, uint16_t v) {
uint8_t buf[2] = {v >> 8, v & 0xff};
SHA384_Update(ctx, buf, 2);
}
static void sha384_update_point_with_length(
SHA512_CTX *ctx, const EC_GROUP *group, const EC_AFFINE *point) {
uint8_t buf[EC_MAX_COMPRESSED];
size_t len = ec_point_to_bytes(group, point, POINT_CONVERSION_COMPRESSED,
buf, sizeof(buf));
assert(len > 0);
sha384_update_u16(ctx, (uint16_t)len);
SHA384_Update(ctx, buf, len);
}
static int compute_composite_seed(const VOPRF_METHOD *method,
uint8_t out[SHA384_DIGEST_LENGTH],
const EC_AFFINE *pub) {
const EC_GROUP *group = method->group;
static const uint8_t kSeedDST[] = "Seed-OPRFV1-\x01-P384-SHA384";
SHA512_CTX hash_ctx;
SHA384_Init(&hash_ctx);
sha384_update_point_with_length(&hash_ctx, group, pub);
sha384_update_u16(&hash_ctx, sizeof(kSeedDST) - 1);
SHA384_Update(&hash_ctx, kSeedDST, sizeof(kSeedDST) - 1);
SHA384_Final(out, &hash_ctx);
return 1;
}
static int compute_composite_element(const VOPRF_METHOD *method,
uint8_t seed[SHA384_DIGEST_LENGTH],
EC_SCALAR *di, size_t index,
const EC_AFFINE *C, const EC_AFFINE *D) {
static const uint8_t kCompositeLabel[] = "Composite";
const EC_GROUP *group = method->group;
if (index > UINT16_MAX) {
return 0;
}
CBB cbb;
uint8_t transcript[2 + SHA384_DIGEST_LENGTH + 2 + 2 * EC_MAX_COMPRESSED +
sizeof(kCompositeLabel) - 1];
size_t len;
if (!CBB_init_fixed(&cbb, transcript, sizeof(transcript)) ||
!CBB_add_u16(&cbb, SHA384_DIGEST_LENGTH) ||
!CBB_add_bytes(&cbb, seed, SHA384_DIGEST_LENGTH) ||
!CBB_add_u16(&cbb, index) ||
!cbb_serialize_point(&cbb, group, C) ||
!cbb_serialize_point(&cbb, group, D) ||
!CBB_add_bytes(&cbb, kCompositeLabel,
sizeof(kCompositeLabel) - 1) ||
!CBB_finish(&cbb, NULL, &len) ||
!method->hash_to_scalar(method->group, di, transcript, len)) {
return 0;
}
return 1;
}
static int generate_proof(const VOPRF_METHOD *method, CBB *cbb,
const TRUST_TOKEN_ISSUER_KEY *priv,
const EC_SCALAR *r, const EC_RAW_POINT *M,
const EC_RAW_POINT *Z) {
const EC_GROUP *group = method->group;
enum {
idx_M,
idx_Z,
idx_t2,
idx_t3,
num_idx,
};
EC_RAW_POINT jacobians[num_idx];
if (!ec_point_mul_scalar_base(group, &jacobians[idx_t2], r) ||
!ec_point_mul_scalar(group, &jacobians[idx_t3], M, r)) {
return 0;
}
EC_AFFINE affines[num_idx];
jacobians[idx_M] = *M;
jacobians[idx_Z] = *Z;
if (!ec_jacobian_to_affine_batch(group, affines, jacobians, num_idx)) {
return 0;
}
EC_SCALAR c;
if (!hash_to_scalar_challenge(method, &c, &priv->pubs, &affines[idx_M],
&affines[idx_Z], &affines[idx_t2],
&affines[idx_t3])) {
return 0;
}
EC_SCALAR c_mont;
ec_scalar_to_montgomery(group, &c_mont, &c);
// s = r - c*xs
EC_SCALAR s;
ec_scalar_mul_montgomery(group, &s, &priv->xs, &c_mont);
ec_scalar_sub(group, &s, r, &s);
// Store DLEQ proof in transcript.
if (!scalar_to_cbb(cbb, group, &c) ||
!scalar_to_cbb(cbb, group, &s)) {
return 0;
}
return 1;
}
static int verify_proof(const VOPRF_METHOD *method, CBS *cbs,
const TRUST_TOKEN_CLIENT_KEY *pub,
const EC_RAW_POINT *M, const EC_RAW_POINT *Z) {
const EC_GROUP *group = method->group;
enum {
idx_M,
idx_Z,
idx_t2,
idx_t3,
num_idx,
};
EC_RAW_POINT jacobians[num_idx];
EC_SCALAR c, s;
if (!scalar_from_cbs(cbs, group, &c) ||
!scalar_from_cbs(cbs, group, &s)) {
OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_DECODE_FAILURE);
return 0;
}
EC_RAW_POINT pubs;
ec_affine_to_jacobian(group, &pubs, &pub->pubs);
if (!ec_point_mul_scalar_public(group, &jacobians[idx_t2], &s, &pubs,
&c) ||
!mul_public_2(group, &jacobians[idx_t3], M, &s, Z, &c)) {
return 0;
}
EC_AFFINE affines[num_idx];
jacobians[idx_M] = *M;
jacobians[idx_Z] = *Z;
if (!ec_jacobian_to_affine_batch(group, affines, jacobians, num_idx)) {
return 0;
}
EC_SCALAR expected_c;
if (!hash_to_scalar_challenge(method, &expected_c, &pub->pubs,
&affines[idx_M], &affines[idx_Z],
&affines[idx_t2], &affines[idx_t3])) {
return 0;
}
// c == expected_c
if (!ec_scalar_equal_vartime(group, &c, &expected_c)) {
OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_INVALID_PROOF);
return 0;
}
return 1;
}
static int voprf_sign_impl(const VOPRF_METHOD *method,
const TRUST_TOKEN_ISSUER_KEY *key, CBB *cbb,
CBS *cbs, size_t num_requested, size_t num_to_issue,
const EC_SCALAR *proof_scalar) {
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 *BTs = OPENSSL_malloc(num_to_issue * sizeof(EC_RAW_POINT));
EC_RAW_POINT *Zs = OPENSSL_malloc(num_to_issue * sizeof(EC_RAW_POINT));
EC_SCALAR *dis = OPENSSL_malloc(num_to_issue * sizeof(EC_SCALAR));
if (!BTs || !Zs || !dis) {
goto err;
}
uint8_t seed[SHA384_DIGEST_LENGTH];
if (!compute_composite_seed(method, seed, &key->pubs)) {
goto err;
}
// This implements the BlindEvaluateBatch as defined in section 4 of
// draft-robert-privacypass-batched-tokens-01, based on the constructions
// in draft-irtf-cfrg-voprf-21. To optimize the computation of the proof,
// the computation of di is done during the token signing and passed into
// the proof generation.
for (size_t i = 0; i < num_to_issue; i++) {
EC_AFFINE BT_affine, Z_affine;
EC_RAW_POINT BT, Z;
if (!cbs_get_point(cbs, group, &BT_affine)) {
OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_DECODE_FAILURE);
goto err;
}
ec_affine_to_jacobian(group, &BT, &BT_affine);
if (!ec_point_mul_scalar(group, &Z, &BT, &key->xs) ||
!ec_jacobian_to_affine(group, &Z_affine, &Z) ||
!cbb_add_point(cbb, group, &Z_affine)) {
goto err;
}
BTs[i] = BT;
Zs[i] = Z;
if (!compute_composite_element(method, seed, &dis[i], i, &BT_affine,
&Z_affine)) {
goto err;
}
if (!CBB_flush(cbb)) {
goto err;
}
}
EC_RAW_POINT M, Z;
if (!ec_point_mul_scalar_public_batch(group, &M,
/*g_scalar=*/NULL, BTs, dis,
num_to_issue) ||
!ec_point_mul_scalar(group, &Z, &M, &key->xs)) {
goto err;
}
CBB proof;
if (!CBB_add_u16_length_prefixed(cbb, &proof) ||
!generate_proof(method, &proof, key, proof_scalar, &M, &Z) ||
!CBB_flush(cbb)) {
goto err;
}
// Skip over any unused requests.
size_t point_len = 1 + 2 * BN_num_bytes(&group->field);
if (!CBS_skip(cbs, point_len * (num_requested - num_to_issue))) {
OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_DECODE_FAILURE);
goto err;
}
ret = 1;
err:
OPENSSL_free(BTs);
OPENSSL_free(Zs);
OPENSSL_free(dis);
return ret;
}
static int voprf_sign(const VOPRF_METHOD *method,
const TRUST_TOKEN_ISSUER_KEY *key, CBB *cbb, CBS *cbs,
size_t num_requested, size_t num_to_issue) {
EC_SCALAR proof_scalar;
if (!ec_random_nonzero_scalar(method->group, &proof_scalar,
kDefaultAdditionalData)) {
return 0;
}
return voprf_sign_impl(method, key, cbb, cbs, num_requested, num_to_issue,
&proof_scalar);
}
static int voprf_sign_with_proof_scalar_for_testing(
const VOPRF_METHOD *method, const TRUST_TOKEN_ISSUER_KEY *key, CBB *cbb,
CBS *cbs, size_t num_requested, size_t num_to_issue,
const uint8_t *proof_scalar_buf, size_t proof_scalar_len) {
EC_SCALAR proof_scalar;
if (!ec_scalar_from_bytes(method->group, &proof_scalar, proof_scalar_buf,
proof_scalar_len)) {
return 0;
}
return voprf_sign_impl(method, key, cbb, cbs, num_requested, num_to_issue,
&proof_scalar);
}
static STACK_OF(TRUST_TOKEN) *voprf_unblind(
const VOPRF_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;
}
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 NULL;
}
int ok = 0;
STACK_OF(TRUST_TOKEN) *ret = sk_TRUST_TOKEN_new_null();
EC_RAW_POINT *BTs = OPENSSL_malloc(count * sizeof(EC_RAW_POINT));
EC_RAW_POINT *Zs = OPENSSL_malloc(count * sizeof(EC_RAW_POINT));
EC_SCALAR *dis = OPENSSL_malloc(count * sizeof(EC_SCALAR));
if (ret == NULL || !BTs || !Zs || !dis) {
goto err;
}
uint8_t seed[SHA384_DIGEST_LENGTH];
if (!compute_composite_seed(method, seed, &key->pubs)) {
goto err;
}
for (size_t i = 0; i < count; i++) {
const TRUST_TOKEN_PRETOKEN *pretoken =
sk_TRUST_TOKEN_PRETOKEN_value(pretokens, i);
EC_AFFINE Z_affine;
if (!cbs_get_point(cbs, group, &Z_affine)) {
OPENSSL_PUT_ERROR(TRUST_TOKEN, TRUST_TOKEN_R_DECODE_FAILURE);
goto err;
}
ec_affine_to_jacobian(group, &BTs[i], &pretoken->Tp);
ec_affine_to_jacobian(group, &Zs[i], &Z_affine);
if (!compute_composite_element(method, seed, &dis[i], i, &pretoken->Tp,
&Z_affine)) {
goto err;
}
// Unblind the token.
// pretoken->r is rinv.
EC_RAW_POINT N;
EC_AFFINE N_affine;
if (!ec_point_mul_scalar(group, &N, &Zs[i], &pretoken->r) ||
!ec_jacobian_to_affine(group, &N_affine, &N)) {
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 + (2 + point_len)) ||
!CBB_add_u32(&token_cbb, key_id) ||
!CBB_add_bytes(&token_cbb, pretoken->salt, TRUST_TOKEN_NONCE_SIZE) ||
!cbb_add_point(&token_cbb, group, &N_affine) ||
!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)) {
TRUST_TOKEN_free(token);
goto err;
}
}
EC_RAW_POINT M, Z;
if (!ec_point_mul_scalar_public_batch(group, &M,
/*g_scalar=*/NULL, BTs, dis,
count) ||
!ec_point_mul_scalar_public_batch(group, &Z,
/*g_scalar=*/NULL, Zs, dis,
count)) {
goto err;
}
CBS proof;
if (!CBS_get_u16_length_prefixed(cbs, &proof) ||
!verify_proof(method, &proof, key, &M, &Z) ||
CBS_len(&proof) != 0) {
goto err;
}
ok = 1;
err:
OPENSSL_free(BTs);
OPENSSL_free(Zs);
OPENSSL_free(dis);
if (!ok) {
sk_TRUST_TOKEN_pop_free(ret, TRUST_TOKEN_free);
ret = NULL;
}
return ret;
}
static int voprf_read(const VOPRF_METHOD *method,
const TRUST_TOKEN_ISSUER_KEY *key,
uint8_t out_nonce[TRUST_TOKEN_NONCE_SIZE],
@ -804,8 +1225,8 @@ int voprf_exp2_sign(const TRUST_TOKEN_ISSUER_KEY *key, CBB *cbb, CBS *cbs,
if (!voprf_exp2_init_method() || private_metadata != 0) {
return 0;
}
return voprf_sign(&voprf_exp2_method, key, cbb, cbs, num_requested,
num_to_issue);
return voprf_sign_tt(&voprf_exp2_method, key, cbb, cbs, num_requested,
num_to_issue);
}
STACK_OF(TRUST_TOKEN) *voprf_exp2_unblind(
@ -815,7 +1236,8 @@ STACK_OF(TRUST_TOKEN) *voprf_exp2_unblind(
if (!voprf_exp2_init_method()) {
return NULL;
}
return voprf_unblind(&voprf_exp2_method, key, pretokens, cbs, count, key_id);
return voprf_unblind_tt(&voprf_exp2_method, key, pretokens, cbs, count,
key_id);
}
int voprf_exp2_read(const TRUST_TOKEN_ISSUER_KEY *key,
@ -834,16 +1256,17 @@ int voprf_exp2_read(const TRUST_TOKEN_ISSUER_KEY *key,
static int voprf_pst1_hash_to_group(const EC_GROUP *group, EC_RAW_POINT *out,
const uint8_t t[TRUST_TOKEN_NONCE_SIZE]) {
const uint8_t kHashTLabel[] = "TrustToken VOPRF PST V1 HashToGroup";
return ec_hash_to_curve_p384_xmd_sha384_sswu(
group, out, kHashTLabel, sizeof(kHashTLabel), t, TRUST_TOKEN_NONCE_SIZE);
const uint8_t kHashTLabel[] = "HashToGroup-OPRFV1-\x01-P384-SHA384";
return ec_hash_to_curve_p384_xmd_sha384_sswu(group, out, kHashTLabel,
sizeof(kHashTLabel) - 1, t,
TRUST_TOKEN_NONCE_SIZE);
}
static int voprf_pst1_hash_to_scalar(const EC_GROUP *group, EC_SCALAR *out,
uint8_t *buf, size_t len) {
const uint8_t kHashCLabel[] = "TrustToken VOPRF PST V1 HashToScalar";
return ec_hash_to_scalar_p384_xmd_sha384(
group, out, kHashCLabel, sizeof(kHashCLabel), buf, len);
const uint8_t kHashCLabel[] = "HashToScalar-OPRFV1-\x01-P384-SHA384";
return ec_hash_to_scalar_p384_xmd_sha384(group, out, kHashCLabel,
sizeof(kHashCLabel) - 1, buf, len);
}
static int voprf_pst1_ok = 0;
@ -921,6 +1344,19 @@ int voprf_pst1_sign(const TRUST_TOKEN_ISSUER_KEY *key, CBB *cbb, CBS *cbs,
num_to_issue);
}
int voprf_pst1_sign_with_proof_scalar_for_testing(
const TRUST_TOKEN_ISSUER_KEY *key, CBB *cbb, CBS *cbs, size_t num_requested,
size_t num_to_issue, uint8_t private_metadata,
const uint8_t *proof_scalar_buf, size_t proof_scalar_len) {
if (!voprf_pst1_init_method() || private_metadata != 0) {
return 0;
}
return voprf_sign_with_proof_scalar_for_testing(
&voprf_pst1_method, key, cbb, cbs, num_requested, num_to_issue,
proof_scalar_buf, proof_scalar_len);
}
STACK_OF(TRUST_TOKEN) *voprf_pst1_unblind(
const TRUST_TOKEN_CLIENT_KEY *key,
const STACK_OF(TRUST_TOKEN_PRETOKEN) *pretokens, CBS *cbs, size_t count,