| /* Copyright (c) 2019, 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. */ |
| |
| #ifndef OPENSSL_HEADER_TRUST_TOKEN_INTERNAL_H |
| #define OPENSSL_HEADER_TRUST_TOKEN_INTERNAL_H |
| |
| #include <openssl/base.h> |
| #include <openssl/ec.h> |
| #include <openssl/ec_key.h> |
| #include <openssl/nid.h> |
| |
| #include "../fipsmodule/ec/internal.h" |
| |
| #include <openssl/trust_token.h> |
| |
| |
| #if defined(__cplusplus) |
| extern "C" { |
| #endif |
| |
| |
| // PMBTokens. |
| // |
| // PMBTokens is described in https://eprint.iacr.org/2020/072/20200324:214215 |
| // and provides anonymous tokens with private metadata. We implement the |
| // construction with validity verification, described in appendix H, |
| // construction 6. |
| |
| // PMBTOKEN_NONCE_SIZE is the size of nonces used as part of the PMBToken |
| // protocol. |
| #define PMBTOKEN_NONCE_SIZE 64 |
| |
| typedef struct { |
| // TODO(https://crbug.com/boringssl/334): These should store |EC_PRECOMP| so |
| // that |TRUST_TOKEN_finish_issuance| can use |ec_point_mul_scalar_precomp|. |
| EC_AFFINE pub0; |
| EC_AFFINE pub1; |
| EC_AFFINE pubs; |
| } PMBTOKEN_CLIENT_KEY; |
| |
| typedef struct { |
| EC_SCALAR x0; |
| EC_SCALAR y0; |
| EC_SCALAR x1; |
| EC_SCALAR y1; |
| EC_SCALAR xs; |
| EC_SCALAR ys; |
| EC_AFFINE pub0; |
| EC_PRECOMP pub0_precomp; |
| EC_AFFINE pub1; |
| EC_PRECOMP pub1_precomp; |
| EC_AFFINE pubs; |
| EC_PRECOMP pubs_precomp; |
| } PMBTOKEN_ISSUER_KEY; |
| |
| // PMBTOKEN_PRETOKEN represents the intermediate state a client keeps during a |
| // PMBToken issuance operation. |
| typedef struct pmb_pretoken_st { |
| uint8_t t[PMBTOKEN_NONCE_SIZE]; |
| EC_SCALAR r; |
| EC_AFFINE Tp; |
| } PMBTOKEN_PRETOKEN; |
| |
| // PMBTOKEN_PRETOKEN_free releases the memory associated with |token|. |
| OPENSSL_EXPORT void PMBTOKEN_PRETOKEN_free(PMBTOKEN_PRETOKEN *token); |
| |
| DEFINE_STACK_OF(PMBTOKEN_PRETOKEN) |
| |
| // The following functions implement the corresponding |TRUST_TOKENS_METHOD| |
| // functions for |TRUST_TOKENS_experiment_v0|'s PMBTokens construction which |
| // uses P-521. |
| int pmbtoken_exp0_generate_key(CBB *out_private, CBB *out_public); |
| int pmbtoken_exp0_client_key_from_bytes(PMBTOKEN_CLIENT_KEY *key, |
| const uint8_t *in, size_t len); |
| int pmbtoken_exp0_issuer_key_from_bytes(PMBTOKEN_ISSUER_KEY *key, |
| const uint8_t *in, size_t len); |
| STACK_OF(PMBTOKEN_PRETOKEN) * pmbtoken_exp0_blind(CBB *cbb, size_t count); |
| int pmbtoken_exp0_sign(const PMBTOKEN_ISSUER_KEY *key, CBB *cbb, CBS *cbs, |
| size_t num_requested, size_t num_to_issue, |
| uint8_t private_metadata); |
| STACK_OF(TRUST_TOKEN) * |
| pmbtoken_exp0_unblind(const PMBTOKEN_CLIENT_KEY *key, |
| const STACK_OF(PMBTOKEN_PRETOKEN) * pretokens, |
| CBS *cbs, size_t count, uint32_t key_id); |
| int pmbtoken_exp0_read(const PMBTOKEN_ISSUER_KEY *key, |
| uint8_t out_nonce[PMBTOKEN_NONCE_SIZE], |
| uint8_t *out_private_metadata, const uint8_t *token, |
| size_t token_len); |
| |
| // The following functions implement the corresponding |TRUST_TOKENS_METHOD| |
| // functions for |TRUST_TOKENS_experiment_v1|'s PMBTokens construction which |
| // uses P-384. |
| // |
| // We use P-384 instead of our usual choice of P-256. See Appendix I which |
| // describes two attacks which may affect smaller curves. In particular, p-1 for |
| // P-256 is smooth, giving a low complexity for the p-1 attack. P-384's p-1 has |
| // a 281-bit prime factor, |
| // 3055465788140352002733946906144561090641249606160407884365391979704929268480326390471. |
| // This lower-bounds the p-1 attack at O(2^140). The p+1 attack is lower-bounded |
| // by O(p^(1/3)) or O(2^128), so we do not need to check the smoothness of p+1. |
| int pmbtoken_exp1_generate_key(CBB *out_private, CBB *out_public); |
| int pmbtoken_exp1_client_key_from_bytes(PMBTOKEN_CLIENT_KEY *key, |
| const uint8_t *in, size_t len); |
| int pmbtoken_exp1_issuer_key_from_bytes(PMBTOKEN_ISSUER_KEY *key, |
| const uint8_t *in, size_t len); |
| STACK_OF(PMBTOKEN_PRETOKEN) * pmbtoken_exp1_blind(CBB *cbb, size_t count); |
| int pmbtoken_exp1_sign(const PMBTOKEN_ISSUER_KEY *key, CBB *cbb, CBS *cbs, |
| size_t num_requested, size_t num_to_issue, |
| uint8_t private_metadata); |
| STACK_OF(TRUST_TOKEN) * |
| pmbtoken_exp1_unblind(const PMBTOKEN_CLIENT_KEY *key, |
| const STACK_OF(PMBTOKEN_PRETOKEN) * pretokens, |
| CBS *cbs, size_t count, uint32_t key_id); |
| int pmbtoken_exp1_read(const PMBTOKEN_ISSUER_KEY *key, |
| uint8_t out_nonce[PMBTOKEN_NONCE_SIZE], |
| uint8_t *out_private_metadata, const uint8_t *token, |
| size_t token_len); |
| |
| // pmbtoken_exp1_get_h_for_testing returns H in uncompressed coordinates. This |
| // function is used to confirm H was computed as expected. |
| OPENSSL_EXPORT int pmbtoken_exp1_get_h_for_testing(uint8_t out[97]); |
| |
| |
| // Trust Tokens internals. |
| |
| struct trust_token_method_st { |
| // generate_key generates a fresh keypair and writes their serialized |
| // forms into |out_private| and |out_public|. It returns one on success and |
| // zero on failure. |
| int (*generate_key)(CBB *out_private, CBB *out_public); |
| |
| // client_key_from_bytes decodes a client key from |in| and sets |key| |
| // to the resulting key. It returns one on success and zero |
| // on failure. |
| int (*client_key_from_bytes)(PMBTOKEN_CLIENT_KEY *key, const uint8_t *in, |
| size_t len); |
| |
| // issuer_key_from_bytes decodes a issuer key from |in| and sets |key| |
| // to the resulting key. It returns one on success and zero |
| // on failure. |
| int (*issuer_key_from_bytes)(PMBTOKEN_ISSUER_KEY *key, const uint8_t *in, |
| size_t len); |
| |
| // blind generates a new issuance request for |count| tokens. On |
| // success, it returns a newly-allocated |STACK_OF(PMBTOKEN_PRETOKEN)| and |
| // writes a request to the issuer to |cbb|. On failure, it returns NULL. The |
| // |STACK_OF(PMBTOKEN_PRETOKEN)|s should be passed to |pmbtoken_unblind| when |
| // the server responds. |
| // |
| // This function implements the AT.Usr0 operation. |
| STACK_OF(PMBTOKEN_PRETOKEN) *(*blind)(CBB *cbb, size_t count); |
| |
| // sign parses a request for |num_requested| tokens from |cbs| and |
| // issues |num_to_issue| tokens with |key| and a private metadata value of |
| // |private_metadata|. It then writes the response to |cbb|. It returns one on |
| // success and zero on failure. |
| // |
| // This function implements the AT.Sig operation. |
| int (*sign)(const PMBTOKEN_ISSUER_KEY *key, CBB *cbb, CBS *cbs, |
| size_t num_requested, size_t num_to_issue, |
| uint8_t private_metadata); |
| |
| // unblind processes an issuance response for |count| tokens from |cbs| |
| // and unblinds the signed tokens. |pretokens| are the pre-tokens returned |
| // from the corresponding |blind| call. On success, the function returns a |
| // newly-allocated |STACK_OF(TRUST_TOKEN)| containing the resulting tokens. |
| // Each token's serialization will have |key_id| prepended. Otherwise, it |
| // returns NULL. |
| // |
| // This function implements the AT.Usr1 operation. |
| STACK_OF(TRUST_TOKEN) * |
| (*unblind)(const PMBTOKEN_CLIENT_KEY *key, |
| const STACK_OF(PMBTOKEN_PRETOKEN) * pretokens, CBS *cbs, |
| size_t count, uint32_t key_id); |
| |
| // read parses a PMBToken from |token| and verifies it using |key|. On |
| // success, it returns one and stores the nonce and private metadata bit in |
| // |out_nonce| and |*out_private_metadata|. Otherwise, it returns zero. Note |
| // that, unlike the output of |unblind|, |token| does not have a |
| // four-byte key ID prepended. |
| int (*read)(const PMBTOKEN_ISSUER_KEY *key, |
| uint8_t out_nonce[PMBTOKEN_NONCE_SIZE], |
| uint8_t *out_private_metadata, const uint8_t *token, |
| size_t token_len); |
| |
| // use_token_hash determines whether to include the token hash in the SRR and |
| // private metadata encryption. |
| int use_token_hash : 1; |
| |
| // batched_proof determines whether PMBToken uses a batched DLEQOR proof when |
| // signing tokens. |
| int batched_proof : 1; |
| }; |
| |
| // Structure representing a single Trust Token public key with the specified ID. |
| struct trust_token_client_key_st { |
| uint32_t id; |
| PMBTOKEN_CLIENT_KEY key; |
| }; |
| |
| // Structure representing a single Trust Token private key with the specified |
| // ID. |
| struct trust_token_issuer_key_st { |
| uint32_t id; |
| PMBTOKEN_ISSUER_KEY key; |
| }; |
| |
| struct trust_token_client_st { |
| const TRUST_TOKEN_METHOD *method; |
| |
| // max_batchsize is the maximum supported batchsize. |
| uint16_t max_batchsize; |
| |
| // keys is the set of public keys that are supported by the client for |
| // issuance/redemptions. |
| struct trust_token_client_key_st keys[3]; |
| |
| // num_keys is the number of keys currently configured. |
| size_t num_keys; |
| |
| // pretokens is the intermediate state during an active issuance. |
| STACK_OF(PMBTOKEN_PRETOKEN)* pretokens; |
| |
| // srr_key is the public key used to verify the signature of the SRR. |
| EVP_PKEY *srr_key; |
| }; |
| |
| |
| struct trust_token_issuer_st { |
| const TRUST_TOKEN_METHOD *method; |
| |
| // max_batchsize is the maximum supported batchsize. |
| uint16_t max_batchsize; |
| |
| // keys is the set of private keys that are supported by the issuer for |
| // issuance/redemptions. The public metadata is an index into this list of |
| // keys. |
| struct trust_token_issuer_key_st keys[3]; |
| |
| // num_keys is the number of keys currently configured. |
| size_t num_keys; |
| |
| // srr_key is the private key used to sign the SRR. |
| EVP_PKEY *srr_key; |
| |
| // metadata_key is the secret material used to encode the private metadata bit |
| // in the SRR. |
| uint8_t *metadata_key; |
| size_t metadata_key_len; |
| }; |
| |
| |
| #if defined(__cplusplus) |
| } // extern C |
| |
| extern "C++" { |
| |
| BSSL_NAMESPACE_BEGIN |
| |
| BORINGSSL_MAKE_DELETER(PMBTOKEN_PRETOKEN, PMBTOKEN_PRETOKEN_free) |
| |
| BSSL_NAMESPACE_END |
| |
| } // extern C++ |
| #endif |
| |
| #endif // OPENSSL_HEADER_TRUST_TOKEN_INTERNAL_H |