gnunet-android

trust_token.h (17201B)

---

 // Copyright 2020 The BoringSSL Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     https://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
 #ifndef OPENSSL_HEADER_TRUST_TOKEN_H
 #define OPENSSL_HEADER_TRUST_TOKEN_H
 
 #include <openssl/base.h>   // IWYU pragma: export
 #include <openssl/stack.h>
 
 #if defined(__cplusplus)
 extern "C" {
 #endif
 
 
 // Trust Token implementation.
 //
 // Trust Token is an implementation of an experimental mechanism similar to
 // Privacy Pass which allows issuance and redemption of anonymized tokens with
 // limited private metadata.
 //
 // References:
 // https://eprint.iacr.org/2020/072.pdf
 // https://github.com/ietf-wg-privacypass/base-drafts
 // https://github.com/WICG/trust-token-api/blob/main/README.md
 //
 // WARNING: This API is unstable and subject to change.
 
 // TRUST_TOKEN_experiment_v1 is an experimental Trust Tokens protocol using
 // PMBTokens and P-384.
 OPENSSL_EXPORT const TRUST_TOKEN_METHOD *TRUST_TOKEN_experiment_v1(void);
 
 // TRUST_TOKEN_experiment_v2_voprf is an experimental Trust Tokens protocol
 // using VOPRFs and P-384 with up to 6 keys, without RR verification.
 OPENSSL_EXPORT const TRUST_TOKEN_METHOD *TRUST_TOKEN_experiment_v2_voprf(void);
 
 // TRUST_TOKEN_experiment_v2_pmb is an experimental Trust Tokens protocol using
 // PMBTokens and P-384 with up to 3 keys, without RR verification.
 OPENSSL_EXPORT const TRUST_TOKEN_METHOD *TRUST_TOKEN_experiment_v2_pmb(void);
 
 // TRUST_TOKEN_pst_v1_voprf is an experimental Trust Tokens protocol
 // using VOPRFs and P-384 with up to 6 keys, without RR verification.
 OPENSSL_EXPORT const TRUST_TOKEN_METHOD *TRUST_TOKEN_pst_v1_voprf(void);
 
 // TRUST_TOKEN_pst_v1_pmb is an experimental Trust Tokens protocol using
 // PMBTokens and P-384 with up to 3 keys, without RR verification.
 OPENSSL_EXPORT const TRUST_TOKEN_METHOD *TRUST_TOKEN_pst_v1_pmb(void);
 
 // trust_token_st represents a single-use token for the Trust Token protocol.
 // For the client, this is the token and its corresponding signature. For the
 // issuer, this is the token itself.
 struct trust_token_st {
   uint8_t *data;
   size_t len;
 };
 
 DEFINE_STACK_OF(TRUST_TOKEN)
 
 // TRUST_TOKEN_new creates a newly-allocated |TRUST_TOKEN| with value |data| or
 // NULL on allocation failure.
 OPENSSL_EXPORT TRUST_TOKEN *TRUST_TOKEN_new(const uint8_t *data, size_t len);
 
 // TRUST_TOKEN_free releases memory associated with |token|.
 OPENSSL_EXPORT void TRUST_TOKEN_free(TRUST_TOKEN *token);
 
 #define TRUST_TOKEN_MAX_PRIVATE_KEY_SIZE 512
 #define TRUST_TOKEN_MAX_PUBLIC_KEY_SIZE 512
 
 // TRUST_TOKEN_generate_key creates a new Trust Token keypair labeled with |id|
 // and serializes the private and public keys, writing the private key to
 // |out_priv_key| and setting |*out_priv_key_len| to the number of bytes
 // written, and writing the public key to |out_pub_key| and setting
 // |*out_pub_key_len| to the number of bytes written.
 //
 // At most |max_priv_key_len| and |max_pub_key_len| bytes are written. In order
 // to ensure success, these should be at least
 // |TRUST_TOKEN_MAX_PRIVATE_KEY_SIZE| and |TRUST_TOKEN_MAX_PUBLIC_KEY_SIZE|.
 //
 // This function returns one on success or zero on error.
 OPENSSL_EXPORT int TRUST_TOKEN_generate_key(
     const TRUST_TOKEN_METHOD *method, uint8_t *out_priv_key,
     size_t *out_priv_key_len, size_t max_priv_key_len, uint8_t *out_pub_key,
     size_t *out_pub_key_len, size_t max_pub_key_len, uint32_t id);
 
 // TRUST_TOKEN_derive_key_from_secret deterministically derives a new Trust
 // Token keypair labeled with |id| from an input |secret| and serializes the
 // private and public keys, writing the private key to |out_priv_key| and
 // setting |*out_priv_key_len| to the number of bytes written, and writing the
 // public key to |out_pub_key| and setting |*out_pub_key_len| to the number of
 // bytes written.
 //
 // At most |max_priv_key_len| and |max_pub_key_len| bytes are written. In order
 // to ensure success, these should be at least
 // |TRUST_TOKEN_MAX_PRIVATE_KEY_SIZE| and |TRUST_TOKEN_MAX_PUBLIC_KEY_SIZE|.
 //
 // This function returns one on success or zero on error.
 OPENSSL_EXPORT int TRUST_TOKEN_derive_key_from_secret(
     const TRUST_TOKEN_METHOD *method, uint8_t *out_priv_key,
     size_t *out_priv_key_len, size_t max_priv_key_len, uint8_t *out_pub_key,
     size_t *out_pub_key_len, size_t max_pub_key_len, uint32_t id,
     const uint8_t *secret, size_t secret_len);
 
 
 // Trust Token client implementation.
 //
 // These functions implements the client half of the Trust Token protocol. A
 // single |TRUST_TOKEN_CLIENT| can perform a single protocol operation.
 
 // TRUST_TOKEN_CLIENT_new returns a newly-allocated |TRUST_TOKEN_CLIENT|
 // configured to use a max batchsize of |max_batchsize| or NULL on error.
 // Issuance requests must be made in batches smaller than |max_batchsize|. This
 // function will return an error if |max_batchsize| is too large for Trust
 // Tokens.
 OPENSSL_EXPORT TRUST_TOKEN_CLIENT *TRUST_TOKEN_CLIENT_new(
     const TRUST_TOKEN_METHOD *method, size_t max_batchsize);
 
 // TRUST_TOKEN_CLIENT_free releases memory associated with |ctx|.
 OPENSSL_EXPORT void TRUST_TOKEN_CLIENT_free(TRUST_TOKEN_CLIENT *ctx);
 
 // TRUST_TOKEN_CLIENT_add_key configures the |ctx| to support the public key
 // |key|. It sets |*out_key_index| to the index this key has been configured to.
 // It returns one on success or zero on error if the |key| can't be parsed or
 // too many keys have been configured.
 OPENSSL_EXPORT int TRUST_TOKEN_CLIENT_add_key(TRUST_TOKEN_CLIENT *ctx,
                                               size_t *out_key_index,
                                               const uint8_t *key,
                                               size_t key_len);
 
 // TRUST_TOKEN_CLIENT_set_srr_key sets the public key used to verify the SRR. It
 // returns one on success and zero on error.
 OPENSSL_EXPORT int TRUST_TOKEN_CLIENT_set_srr_key(TRUST_TOKEN_CLIENT *ctx,
                                                   EVP_PKEY *key);
 
 // TRUST_TOKEN_CLIENT_begin_issuance produces a request for |count| trust tokens
 // and serializes the request into a newly-allocated buffer, setting |*out| to
 // that buffer and |*out_len| to its length. The caller takes ownership of the
 // buffer and must call |OPENSSL_free| when done. It returns one on success and
 // zero on error.
 OPENSSL_EXPORT int TRUST_TOKEN_CLIENT_begin_issuance(TRUST_TOKEN_CLIENT *ctx,
                                                      uint8_t **out,
                                                      size_t *out_len,
                                                      size_t count);
 
 // TRUST_TOKEN_CLIENT_begin_issuance_over_message produces a request for a trust
 // token derived from |msg| and serializes the request into a newly-allocated
 // buffer, setting |*out| to that buffer and |*out_len| to its length. The
 // caller takes ownership of the buffer and must call |OPENSSL_free| when done.
 // It returns one on success and zero on error.
 OPENSSL_EXPORT int TRUST_TOKEN_CLIENT_begin_issuance_over_message(
     TRUST_TOKEN_CLIENT *ctx, uint8_t **out, size_t *out_len, size_t count,
     const uint8_t *msg, size_t msg_len);
 
 // TRUST_TOKEN_CLIENT_finish_issuance consumes |response| from the issuer and
 // extracts the tokens, returning a list of tokens and the index of the key used
 // to sign the tokens in |*out_key_index|. The caller can use this to determine
 // what key was used in an issuance and to drop tokens if a new key commitment
 // arrives without the specified key present. The caller takes ownership of the
 // list and must call |sk_TRUST_TOKEN_pop_free| when done. The list is empty if
 // issuance fails.
 OPENSSL_EXPORT STACK_OF(TRUST_TOKEN) *
     TRUST_TOKEN_CLIENT_finish_issuance(TRUST_TOKEN_CLIENT *ctx,
                                        size_t *out_key_index,
                                        const uint8_t *response,
                                        size_t response_len);
 
 
 // TRUST_TOKEN_CLIENT_begin_redemption produces a request to redeem a token
 // |token| and receive a signature over |data| and serializes the request into
 // a newly-allocated buffer, setting |*out| to that buffer and |*out_len| to
 // its length. |time| is the number of seconds since the UNIX epoch and used to
 // verify the validity of the issuer's response in TrustTokenV1 and ignored in
 // other versions. The caller takes ownership of the buffer and must call
 // |OPENSSL_free| when done. It returns one on success or zero on error.
 OPENSSL_EXPORT int TRUST_TOKEN_CLIENT_begin_redemption(
     TRUST_TOKEN_CLIENT *ctx, uint8_t **out, size_t *out_len,
     const TRUST_TOKEN *token, const uint8_t *data, size_t data_len,
     uint64_t time);
 
 // TRUST_TOKEN_CLIENT_finish_redemption consumes |response| from the issuer. In
 // |TRUST_TOKEN_experiment_v1|, it then verifies the SRR and if valid  sets
 // |*out_rr| and |*out_rr_len| (respectively, |*out_sig| and |*out_sig_len|)
 // to a newly-allocated buffer containing the SRR (respectively, the SRR
 // signature). In other versions, it sets |*out_rr| and |*out_rr_len|
 // to a newly-allocated buffer containing |response| and leaves all validation
 // to the caller. It returns one on success or zero on failure.
 OPENSSL_EXPORT int TRUST_TOKEN_CLIENT_finish_redemption(
     TRUST_TOKEN_CLIENT *ctx, uint8_t **out_rr, size_t *out_rr_len,
     uint8_t **out_sig, size_t *out_sig_len, const uint8_t *response,
     size_t response_len);
 
 
 // Trust Token issuer implementation.
 //
 // These functions implement the issuer half of the Trust Token protocol. A
 // |TRUST_TOKEN_ISSUER| can be reused across multiple protocol operations. It
 // may be used concurrently on multiple threads by non-mutating functions,
 // provided no other thread is concurrently calling a mutating function.
 // Functions which take a |const| pointer are non-mutating and functions which
 // take a non-|const| pointer are mutating.
 
 // TRUST_TOKEN_ISSUER_new returns a newly-allocated |TRUST_TOKEN_ISSUER|
 // configured to use a max batchsize of |max_batchsize| or NULL on error.
 // Issuance requests must be made in batches smaller than |max_batchsize|. This
 // function will return an error if |max_batchsize| is too large for Trust
 // Tokens.
 OPENSSL_EXPORT TRUST_TOKEN_ISSUER *TRUST_TOKEN_ISSUER_new(
     const TRUST_TOKEN_METHOD *method, size_t max_batchsize);
 
 // TRUST_TOKEN_ISSUER_free releases memory associated with |ctx|.
 OPENSSL_EXPORT void TRUST_TOKEN_ISSUER_free(TRUST_TOKEN_ISSUER *ctx);
 
 // TRUST_TOKEN_ISSUER_add_key configures the |ctx| to support the private key
 // |key|. It must be a private key returned by |TRUST_TOKEN_generate_key|. It
 // returns one on success or zero on error. This function may fail if the |key|
 // can't be parsed or too many keys have been configured.
 OPENSSL_EXPORT int TRUST_TOKEN_ISSUER_add_key(TRUST_TOKEN_ISSUER *ctx,
                                               const uint8_t *key,
                                               size_t key_len);
 
 // TRUST_TOKEN_ISSUER_set_srr_key sets the private key used to sign the SRR. It
 // returns one on success and zero on error.
 OPENSSL_EXPORT int TRUST_TOKEN_ISSUER_set_srr_key(TRUST_TOKEN_ISSUER *ctx,
                                                   EVP_PKEY *key);
 
 // TRUST_TOKEN_ISSUER_set_metadata_key sets the key used to encrypt the private
 // metadata. The key is a randomly generated bytestring of at least 32 bytes
 // used to encode the private metadata bit in the SRR. It returns one on success
 // and zero on error.
 OPENSSL_EXPORT int TRUST_TOKEN_ISSUER_set_metadata_key(TRUST_TOKEN_ISSUER *ctx,
                                                        const uint8_t *key,
                                                        size_t len);
 
 // TRUST_TOKEN_ISSUER_issue ingests |request| for token issuance
 // and generates up to |max_issuance| valid tokens, producing a list of blinded
 // tokens and storing the response into a newly-allocated buffer and setting
 // |*out| to that buffer, |*out_len| to its length, and |*out_tokens_issued| to
 // the number of tokens issued. The tokens are issued with public metadata of
 // |public_metadata| and a private metadata value of |private_metadata|.
 // |public_metadata| must be one of the previously configured key IDs.
 // |private_metadata| must be 0 or 1. The caller takes ownership of the buffer
 // and must call |OPENSSL_free| when done. It returns one on success or zero on
 // error.
 OPENSSL_EXPORT int TRUST_TOKEN_ISSUER_issue(
     const TRUST_TOKEN_ISSUER *ctx, uint8_t **out, size_t *out_len,
     size_t *out_tokens_issued, const uint8_t *request, size_t request_len,
     uint32_t public_metadata, uint8_t private_metadata, size_t max_issuance);
 
 // TRUST_TOKEN_ISSUER_redeem ingests a |request| for token redemption and
 // verifies the token. The public metadata is stored in |*out_public|. The
 // private metadata (if any) is stored in |*out_private|. The extracted
 // |TRUST_TOKEN| is stored into a newly-allocated buffer and stored in
 // |*out_token|. The extracted client data is stored into a newly-allocated
 // buffer and stored in |*out_client_data|. The caller takes ownership of each
 // output buffer and must call |OPENSSL_free| when done. It returns one on
 // success or zero on error.
 //
 // The caller must keep track of all values of |*out_token| seen globally before
 // returning a response to the client. If the value has been reused, the caller
 // must report an error to the client. Returning a response with replayed values
 // allows an attacker to double-spend tokens.
 OPENSSL_EXPORT int TRUST_TOKEN_ISSUER_redeem(
     const TRUST_TOKEN_ISSUER *ctx, uint32_t *out_public, uint8_t *out_private,
     TRUST_TOKEN **out_token, uint8_t **out_client_data,
     size_t *out_client_data_len, const uint8_t *request, size_t request_len);
 
 // TRUST_TOKEN_ISSUER_redeem_raw is a legacy alias for
 // |TRUST_TOKEN_ISSUER_redeem|.
 #define TRUST_TOKEN_ISSUER_redeem_raw TRUST_TOKEN_ISSUER_redeem
 
 // TRUST_TOKEN_ISSUER_redeem_over_message ingests a |request| for token
 // redemption and a message and verifies the token and that it is derived from
 // the provided |msg|. The public metadata is stored in
 // |*out_public|. The private metadata (if any) is stored in |*out_private|. The
 // extracted |TRUST_TOKEN| is stored into a newly-allocated buffer and stored in
 // |*out_token|. The extracted client data is stored into a newly-allocated
 // buffer and stored in |*out_client_data|. The caller takes ownership of each
 // output buffer and must call |OPENSSL_free| when done. It returns one on
 // success or zero on error.
 //
 // The caller must keep track of all values of |*out_token| seen globally before
 // returning a response to the client. If the value has been reused, the caller
 // must report an error to the client. Returning a response with replayed values
 // allows an attacker to double-spend tokens.
 OPENSSL_EXPORT int TRUST_TOKEN_ISSUER_redeem_over_message(
     const TRUST_TOKEN_ISSUER *ctx, uint32_t *out_public, uint8_t *out_private,
     TRUST_TOKEN **out_token, uint8_t **out_client_data,
     size_t *out_client_data_len, const uint8_t *request, size_t request_len,
     const uint8_t *msg, size_t msg_len);
 
 // TRUST_TOKEN_decode_private_metadata decodes |encrypted_bit| using the
 // private metadata key specified by a |key| buffer of length |key_len| and the
 // nonce by a |nonce| buffer of length |nonce_len|. The nonce in
 // |TRUST_TOKEN_experiment_v1| is the token-hash field of the SRR. |*out_value|
 // is set to the decrypted value, either zero or one. It returns one on success
 // and zero on error.
 OPENSSL_EXPORT int TRUST_TOKEN_decode_private_metadata(
     const TRUST_TOKEN_METHOD *method, uint8_t *out_value, const uint8_t *key,
     size_t key_len, const uint8_t *nonce, size_t nonce_len,
     uint8_t encrypted_bit);
 
 
 #if defined(__cplusplus)
 }  // extern C
 
 extern "C++" {
 
 BSSL_NAMESPACE_BEGIN
 
 BORINGSSL_MAKE_DELETER(TRUST_TOKEN, TRUST_TOKEN_free)
 BORINGSSL_MAKE_DELETER(TRUST_TOKEN_CLIENT, TRUST_TOKEN_CLIENT_free)
 BORINGSSL_MAKE_DELETER(TRUST_TOKEN_ISSUER, TRUST_TOKEN_ISSUER_free)
 
 BSSL_NAMESPACE_END
 
 }  // extern C++
 #endif
 
 #define TRUST_TOKEN_R_KEYGEN_FAILURE 100
 #define TRUST_TOKEN_R_BUFFER_TOO_SMALL 101
 #define TRUST_TOKEN_R_OVER_BATCHSIZE 102
 #define TRUST_TOKEN_R_DECODE_ERROR 103
 #define TRUST_TOKEN_R_SRR_SIGNATURE_ERROR 104
 #define TRUST_TOKEN_R_DECODE_FAILURE 105
 #define TRUST_TOKEN_R_INVALID_METADATA 106
 #define TRUST_TOKEN_R_TOO_MANY_KEYS 107
 #define TRUST_TOKEN_R_NO_KEYS_CONFIGURED 108
 #define TRUST_TOKEN_R_INVALID_KEY_ID 109
 #define TRUST_TOKEN_R_INVALID_TOKEN 110
 #define TRUST_TOKEN_R_BAD_VALIDITY_CHECK 111
 #define TRUST_TOKEN_R_NO_SRR_KEY_CONFIGURED 112
 #define TRUST_TOKEN_R_INVALID_METADATA_KEY 113
 #define TRUST_TOKEN_R_INVALID_PROOF 114
 
 #endif  // OPENSSL_HEADER_TRUST_TOKEN_H