/* * Copyright (C) 2015 Tobias Brunner * Copyright (C) 2008 Martin Willi * Hochschule fuer Technik Rapperswil * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the * Free Software Foundation; either version 2 of the License, or (at your * option) any later version. See . * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * for more details. */ #include "keymat_v2.h" #include #include #include typedef struct private_keymat_v2_t private_keymat_v2_t; /** * Private data of an keymat_t object. */ struct private_keymat_v2_t { /** * Public keymat_v2_t interface. */ keymat_v2_t public; /** * IKE_SA Role, initiator or responder */ bool initiator; /** * inbound AEAD */ aead_t *aead_in; /** * outbound AEAD */ aead_t *aead_out; /** * General purpose PRF */ prf_t *prf; /** * Negotiated PRF algorithm */ pseudo_random_function_t prf_alg; /** * Key to derive key material from for CHILD_SAs, rekeying */ chunk_t skd; /** * Key to build outging authentication data (SKp) */ chunk_t skp_build; /** * Key to verify incoming authentication data (SKp) */ chunk_t skp_verify; /** * Set of hash algorithms supported by peer for signature authentication */ hash_algorithm_set_t *hash_algorithms; }; METHOD(keymat_t, get_version, ike_version_t, private_keymat_v2_t *this) { return IKEV2; } METHOD(keymat_t, create_dh, diffie_hellman_t*, private_keymat_v2_t *this, diffie_hellman_group_t group) { return lib->crypto->create_dh(lib->crypto, group); } METHOD(keymat_t, create_nonce_gen, nonce_gen_t*, private_keymat_v2_t *this) { return lib->crypto->create_nonce_gen(lib->crypto); } /** * Derive IKE keys for a combined AEAD algorithm */ static bool derive_ike_aead(private_keymat_v2_t *this, uint16_t alg, uint16_t key_size, prf_plus_t *prf_plus) { aead_t *aead_i, *aead_r; chunk_t sk_ei = chunk_empty, sk_er = chunk_empty; u_int salt_size; switch (alg) { case ENCR_AES_GCM_ICV8: case ENCR_AES_GCM_ICV12: case ENCR_AES_GCM_ICV16: /* RFC 4106 */ case ENCR_CHACHA20_POLY1305: salt_size = 4; break; case ENCR_AES_CCM_ICV8: case ENCR_AES_CCM_ICV12: case ENCR_AES_CCM_ICV16: /* RFC 4309 */ case ENCR_CAMELLIA_CCM_ICV8: case ENCR_CAMELLIA_CCM_ICV12: case ENCR_CAMELLIA_CCM_ICV16: /* RFC 5529 */ salt_size = 3; break; default: DBG1(DBG_IKE, "nonce size for %N unknown!", encryption_algorithm_names, alg); return FALSE; } /* SK_ei/SK_er used for encryption */ aead_i = lib->crypto->create_aead(lib->crypto, alg, key_size / 8, salt_size); aead_r = lib->crypto->create_aead(lib->crypto, alg, key_size / 8, salt_size); if (aead_i == NULL || aead_r == NULL) { DBG1(DBG_IKE, "%N %N (key size %d) not supported!", transform_type_names, ENCRYPTION_ALGORITHM, encryption_algorithm_names, alg, key_size); goto failure; } key_size = aead_i->get_key_size(aead_i); if (key_size != aead_r->get_key_size(aead_r)) { goto failure; } if (!prf_plus->allocate_bytes(prf_plus, key_size, &sk_ei)) { goto failure; } DBG4(DBG_IKE, "Sk_ei secret %B", &sk_ei); if (!aead_i->set_key(aead_i, sk_ei)) { goto failure; } if (!prf_plus->allocate_bytes(prf_plus, key_size, &sk_er)) { goto failure; } DBG4(DBG_IKE, "Sk_er secret %B", &sk_er); if (!aead_r->set_key(aead_r, sk_er)) { goto failure; } if (this->initiator) { this->aead_in = aead_r; this->aead_out = aead_i; } else { this->aead_in = aead_i; this->aead_out = aead_r; } aead_i = aead_r = NULL; charon->bus->ike_derived_keys(charon->bus, sk_ei, sk_er, chunk_empty, chunk_empty); failure: DESTROY_IF(aead_i); DESTROY_IF(aead_r); chunk_clear(&sk_ei); chunk_clear(&sk_er); return this->aead_in && this->aead_out; } /** * Derive IKE keys for traditional encryption and MAC algorithms */ static bool derive_ike_traditional(private_keymat_v2_t *this, uint16_t enc_alg, uint16_t enc_size, uint16_t int_alg, prf_plus_t *prf_plus) { crypter_t *crypter_i = NULL, *crypter_r = NULL; signer_t *signer_i, *signer_r; iv_gen_t *ivg_i, *ivg_r; size_t key_size; chunk_t sk_ei = chunk_empty, sk_er = chunk_empty, sk_ai = chunk_empty, sk_ar = chunk_empty; signer_i = lib->crypto->create_signer(lib->crypto, int_alg); signer_r = lib->crypto->create_signer(lib->crypto, int_alg); crypter_i = lib->crypto->create_crypter(lib->crypto, enc_alg, enc_size / 8); crypter_r = lib->crypto->create_crypter(lib->crypto, enc_alg, enc_size / 8); if (signer_i == NULL || signer_r == NULL) { DBG1(DBG_IKE, "%N %N not supported!", transform_type_names, INTEGRITY_ALGORITHM, integrity_algorithm_names, int_alg); goto failure; } if (crypter_i == NULL || crypter_r == NULL) { DBG1(DBG_IKE, "%N %N (key size %d) not supported!", transform_type_names, ENCRYPTION_ALGORITHM, encryption_algorithm_names, enc_alg, enc_size); goto failure; } /* SK_ai/SK_ar used for integrity protection */ key_size = signer_i->get_key_size(signer_i); if (!prf_plus->allocate_bytes(prf_plus, key_size, &sk_ai)) { goto failure; } DBG4(DBG_IKE, "Sk_ai secret %B", &sk_ai); if (!signer_i->set_key(signer_i, sk_ai)) { goto failure; } if (!prf_plus->allocate_bytes(prf_plus, key_size, &sk_ar)) { goto failure; } DBG4(DBG_IKE, "Sk_ar secret %B", &sk_ar); if (!signer_r->set_key(signer_r, sk_ar)) { goto failure; } /* SK_ei/SK_er used for encryption */ key_size = crypter_i->get_key_size(crypter_i); if (!prf_plus->allocate_bytes(prf_plus, key_size, &sk_ei)) { goto failure; } DBG4(DBG_IKE, "Sk_ei secret %B", &sk_ei); if (!crypter_i->set_key(crypter_i, sk_ei)) { goto failure; } if (!prf_plus->allocate_bytes(prf_plus, key_size, &sk_er)) { goto failure; } DBG4(DBG_IKE, "Sk_er secret %B", &sk_er); if (!crypter_r->set_key(crypter_r, sk_er)) { goto failure; } ivg_i = iv_gen_create_for_alg(enc_alg); ivg_r = iv_gen_create_for_alg(enc_alg); if (!ivg_i || !ivg_r) { goto failure; } if (this->initiator) { this->aead_in = aead_create(crypter_r, signer_r, ivg_r); this->aead_out = aead_create(crypter_i, signer_i, ivg_i); } else { this->aead_in = aead_create(crypter_i, signer_i, ivg_i); this->aead_out = aead_create(crypter_r, signer_r, ivg_r); } signer_i = signer_r = NULL; crypter_i = crypter_r = NULL; charon->bus->ike_derived_keys(charon->bus, sk_ei, sk_er, sk_ai, sk_ar); failure: chunk_clear(&sk_ai); chunk_clear(&sk_ar); chunk_clear(&sk_ei); chunk_clear(&sk_er); DESTROY_IF(signer_i); DESTROY_IF(signer_r); DESTROY_IF(crypter_i); DESTROY_IF(crypter_r); return this->aead_in && this->aead_out; } METHOD(keymat_v2_t, derive_ike_keys, bool, private_keymat_v2_t *this, proposal_t *proposal, diffie_hellman_t *dh, chunk_t nonce_i, chunk_t nonce_r, ike_sa_id_t *id, pseudo_random_function_t rekey_function, chunk_t rekey_skd) { chunk_t skeyseed, key, secret, full_nonce, fixed_nonce, prf_plus_seed; chunk_t spi_i, spi_r; prf_plus_t *prf_plus = NULL; uint16_t alg, key_size, int_alg; prf_t *rekey_prf = NULL; spi_i = chunk_alloca(sizeof(uint64_t)); spi_r = chunk_alloca(sizeof(uint64_t)); if (!dh->get_shared_secret(dh, &secret)) { return FALSE; } /* Create SAs general purpose PRF first, we may use it here */ if (!proposal->get_algorithm(proposal, PSEUDO_RANDOM_FUNCTION, &alg, NULL)) { DBG1(DBG_IKE, "no %N selected", transform_type_names, PSEUDO_RANDOM_FUNCTION); chunk_clear(&secret); return FALSE; } this->prf_alg = alg; this->prf = lib->crypto->create_prf(lib->crypto, alg); if (this->prf == NULL) { DBG1(DBG_IKE, "%N %N not supported!", transform_type_names, PSEUDO_RANDOM_FUNCTION, pseudo_random_function_names, alg); chunk_clear(&secret); return FALSE; } DBG4(DBG_IKE, "shared Diffie Hellman secret %B", &secret); /* full nonce is used as seed for PRF+ ... */ full_nonce = chunk_cat("cc", nonce_i, nonce_r); /* but the PRF may need a fixed key which only uses the first bytes of * the nonces. */ switch (alg) { case PRF_AES128_XCBC: /* while rfc4434 defines variable keys for AES-XCBC, rfc3664 does * not and therefore fixed key semantics apply to XCBC for key * derivation. */ case PRF_CAMELLIA128_XCBC: /* draft-kanno-ipsecme-camellia-xcbc refers to rfc 4434, we * assume fixed key length. */ key_size = this->prf->get_key_size(this->prf)/2; nonce_i.len = min(nonce_i.len, key_size); nonce_r.len = min(nonce_r.len, key_size); break; default: /* all other algorithms use variable key length, full nonce */ break; } fixed_nonce = chunk_cat("cc", nonce_i, nonce_r); *((uint64_t*)spi_i.ptr) = id->get_initiator_spi(id); *((uint64_t*)spi_r.ptr) = id->get_responder_spi(id); prf_plus_seed = chunk_cat("ccc", full_nonce, spi_i, spi_r); /* KEYMAT = prf+ (SKEYSEED, Ni | Nr | SPIi | SPIr) * * if we are rekeying, SKEYSEED is built on another way */ if (rekey_function == PRF_UNDEFINED) /* not rekeying */ { /* SKEYSEED = prf(Ni | Nr, g^ir) */ if (this->prf->set_key(this->prf, fixed_nonce) && this->prf->allocate_bytes(this->prf, secret, &skeyseed) && this->prf->set_key(this->prf, skeyseed)) { prf_plus = prf_plus_create(this->prf, TRUE, prf_plus_seed); } } else { /* SKEYSEED = prf(SK_d (old), [g^ir (new)] | Ni | Nr) * use OLD SAs PRF functions for both prf_plus and prf */ rekey_prf = lib->crypto->create_prf(lib->crypto, rekey_function); if (!rekey_prf) { DBG1(DBG_IKE, "PRF of old SA %N not supported!", pseudo_random_function_names, rekey_function); chunk_clear(&secret); chunk_free(&full_nonce); chunk_free(&fixed_nonce); chunk_clear(&prf_plus_seed); return FALSE; } secret = chunk_cat("mc", secret, full_nonce); if (rekey_prf->set_key(rekey_prf, rekey_skd) && rekey_prf->allocate_bytes(rekey_prf, secret, &skeyseed) && rekey_prf->set_key(rekey_prf, skeyseed)) { prf_plus = prf_plus_create(rekey_prf, TRUE, prf_plus_seed); } } DBG4(DBG_IKE, "SKEYSEED %B", &skeyseed); chunk_clear(&skeyseed); chunk_clear(&secret); chunk_free(&full_nonce); chunk_free(&fixed_nonce); chunk_clear(&prf_plus_seed); if (!prf_plus) { goto failure; } /* KEYMAT = SK_d | SK_ai | SK_ar | SK_ei | SK_er | SK_pi | SK_pr */ /* SK_d is used for generating CHILD_SA key mat => store for later use */ key_size = this->prf->get_key_size(this->prf); if (!prf_plus->allocate_bytes(prf_plus, key_size, &this->skd)) { goto failure; } DBG4(DBG_IKE, "Sk_d secret %B", &this->skd); if (!proposal->get_algorithm(proposal, ENCRYPTION_ALGORITHM, &alg, &key_size)) { DBG1(DBG_IKE, "no %N selected", transform_type_names, ENCRYPTION_ALGORITHM); goto failure; } if (encryption_algorithm_is_aead(alg)) { if (!derive_ike_aead(this, alg, key_size, prf_plus)) { goto failure; } } else { if (!proposal->get_algorithm(proposal, INTEGRITY_ALGORITHM, &int_alg, NULL)) { DBG1(DBG_IKE, "no %N selected", transform_type_names, INTEGRITY_ALGORITHM); goto failure; } if (!derive_ike_traditional(this, alg, key_size, int_alg, prf_plus)) { goto failure; } } /* SK_pi/SK_pr used for authentication => stored for later */ key_size = this->prf->get_key_size(this->prf); if (!prf_plus->allocate_bytes(prf_plus, key_size, &key)) { goto failure; } DBG4(DBG_IKE, "Sk_pi secret %B", &key); if (this->initiator) { this->skp_build = key; } else { this->skp_verify = key; } if (!prf_plus->allocate_bytes(prf_plus, key_size, &key)) { goto failure; } DBG4(DBG_IKE, "Sk_pr secret %B", &key); if (this->initiator) { this->skp_verify = key; } else { this->skp_build = key; } /* all done, prf_plus not needed anymore */ failure: DESTROY_IF(prf_plus); DESTROY_IF(rekey_prf); return this->skp_build.len && this->skp_verify.len; } METHOD(keymat_v2_t, derive_child_keys, bool, private_keymat_v2_t *this, proposal_t *proposal, diffie_hellman_t *dh, chunk_t nonce_i, chunk_t nonce_r, chunk_t *encr_i, chunk_t *integ_i, chunk_t *encr_r, chunk_t *integ_r) { uint16_t enc_alg, int_alg, enc_size = 0, int_size = 0; chunk_t seed, secret = chunk_empty; prf_plus_t *prf_plus; if (proposal->get_algorithm(proposal, ENCRYPTION_ALGORITHM, &enc_alg, &enc_size)) { DBG2(DBG_CHD, " using %N for encryption", encryption_algorithm_names, enc_alg); if (!enc_size) { enc_size = keymat_get_keylen_encr(enc_alg); } if (enc_alg != ENCR_NULL && !enc_size) { DBG1(DBG_CHD, "no keylength defined for %N", encryption_algorithm_names, enc_alg); return FALSE; } /* to bytes */ enc_size /= 8; /* CCM/GCM/CTR/GMAC needs additional bytes */ switch (enc_alg) { case ENCR_AES_CCM_ICV8: case ENCR_AES_CCM_ICV12: case ENCR_AES_CCM_ICV16: case ENCR_CAMELLIA_CCM_ICV8: case ENCR_CAMELLIA_CCM_ICV12: case ENCR_CAMELLIA_CCM_ICV16: enc_size += 3; break; case ENCR_AES_GCM_ICV8: case ENCR_AES_GCM_ICV12: case ENCR_AES_GCM_ICV16: case ENCR_AES_CTR: case ENCR_CAMELLIA_CTR: case ENCR_NULL_AUTH_AES_GMAC: case ENCR_CHACHA20_POLY1305: enc_size += 4; break; default: break; } } if (proposal->get_algorithm(proposal, INTEGRITY_ALGORITHM, &int_alg, &int_size)) { DBG2(DBG_CHD, " using %N for integrity", integrity_algorithm_names, int_alg); if (!int_size) { int_size = keymat_get_keylen_integ(int_alg); } if (!int_size) { DBG1(DBG_CHD, "no keylength defined for %N", integrity_algorithm_names, int_alg); return FALSE; } /* to bytes */ int_size /= 8; } if (!this->prf->set_key(this->prf, this->skd)) { return FALSE; } if (dh) { if (!dh->get_shared_secret(dh, &secret)) { return FALSE; } DBG4(DBG_CHD, "DH secret %B", &secret); } seed = chunk_cata("scc", secret, nonce_i, nonce_r); DBG4(DBG_CHD, "seed %B", &seed); prf_plus = prf_plus_create(this->prf, TRUE, seed); memwipe(seed.ptr, seed.len); if (!prf_plus) { return FALSE; } *encr_i = *integ_i = *encr_r = *integ_r = chunk_empty; if (!prf_plus->allocate_bytes(prf_plus, enc_size, encr_i) || !prf_plus->allocate_bytes(prf_plus, int_size, integ_i) || !prf_plus->allocate_bytes(prf_plus, enc_size, encr_r) || !prf_plus->allocate_bytes(prf_plus, int_size, integ_r)) { chunk_free(encr_i); chunk_free(integ_i); chunk_free(encr_r); chunk_free(integ_r); prf_plus->destroy(prf_plus); return FALSE; } prf_plus->destroy(prf_plus); if (enc_size) { DBG4(DBG_CHD, "encryption initiator key %B", encr_i); DBG4(DBG_CHD, "encryption responder key %B", encr_r); } if (int_size) { DBG4(DBG_CHD, "integrity initiator key %B", integ_i); DBG4(DBG_CHD, "integrity responder key %B", integ_r); } return TRUE; } METHOD(keymat_v2_t, get_skd, pseudo_random_function_t, private_keymat_v2_t *this, chunk_t *skd) { *skd = this->skd; return this->prf_alg; } METHOD(keymat_t, get_aead, aead_t*, private_keymat_v2_t *this, bool in) { return in ? this->aead_in : this->aead_out; } METHOD(keymat_v2_t, get_auth_octets, bool, private_keymat_v2_t *this, bool verify, chunk_t ike_sa_init, chunk_t nonce, identification_t *id, char reserved[3], chunk_t *octets, array_t *schemes) { chunk_t chunk, idx; chunk_t skp; skp = verify ? this->skp_verify : this->skp_build; chunk = chunk_alloca(4); chunk.ptr[0] = id->get_type(id); memcpy(chunk.ptr + 1, reserved, 3); idx = chunk_cata("cc", chunk, id->get_encoding(id)); DBG3(DBG_IKE, "IDx' %B", &idx); DBG4(DBG_IKE, "SK_p %B", &skp); if (!this->prf->set_key(this->prf, skp) || !this->prf->allocate_bytes(this->prf, idx, &chunk)) { return FALSE; } *octets = chunk_cat("ccm", ike_sa_init, nonce, chunk); DBG3(DBG_IKE, "octets = message + nonce + prf(Sk_px, IDx') %B", octets); return TRUE; } /** * Key pad for the AUTH method SHARED_KEY_MESSAGE_INTEGRITY_CODE. */ #define IKEV2_KEY_PAD "Key Pad for IKEv2" #define IKEV2_KEY_PAD_LENGTH 17 METHOD(keymat_v2_t, get_psk_sig, bool, private_keymat_v2_t *this, bool verify, chunk_t ike_sa_init, chunk_t nonce, chunk_t secret, identification_t *id, char reserved[3], chunk_t *sig) { chunk_t key_pad, key, octets; if (!secret.len) { /* EAP uses SK_p if no MSK has been established */ secret = verify ? this->skp_verify : this->skp_build; } if (!get_auth_octets(this, verify, ike_sa_init, nonce, id, reserved, &octets, NULL)) { return FALSE; } /* AUTH = prf(prf(Shared Secret,"Key Pad for IKEv2"), ) */ key_pad = chunk_create(IKEV2_KEY_PAD, IKEV2_KEY_PAD_LENGTH); if (!this->prf->set_key(this->prf, secret) || !this->prf->allocate_bytes(this->prf, key_pad, &key)) { chunk_free(&octets); return FALSE; } if (!this->prf->set_key(this->prf, key) || !this->prf->allocate_bytes(this->prf, octets, sig)) { chunk_free(&key); chunk_free(&octets); return FALSE; } DBG4(DBG_IKE, "secret %B", &secret); DBG4(DBG_IKE, "prf(secret, keypad) %B", &key); DBG3(DBG_IKE, "AUTH = prf(prf(secret, keypad), octets) %B", sig); chunk_free(&octets); chunk_free(&key); return TRUE; } METHOD(keymat_v2_t, hash_algorithm_supported, bool, private_keymat_v2_t *this, hash_algorithm_t hash) { if (!this->hash_algorithms) { return FALSE; } return this->hash_algorithms->contains(this->hash_algorithms, hash); } METHOD(keymat_v2_t, add_hash_algorithm, void, private_keymat_v2_t *this, hash_algorithm_t hash) { if (!this->hash_algorithms) { this->hash_algorithms = hash_algorithm_set_create(); } this->hash_algorithms->add(this->hash_algorithms, hash); } METHOD(keymat_t, destroy, void, private_keymat_v2_t *this) { DESTROY_IF(this->aead_in); DESTROY_IF(this->aead_out); DESTROY_IF(this->prf); chunk_clear(&this->skd); chunk_clear(&this->skp_verify); chunk_clear(&this->skp_build); DESTROY_IF(this->hash_algorithms); free(this); } /** * See header */ keymat_v2_t *keymat_v2_create(bool initiator) { private_keymat_v2_t *this; INIT(this, .public = { .keymat = { .get_version = _get_version, .create_dh = _create_dh, .create_nonce_gen = _create_nonce_gen, .get_aead = _get_aead, .destroy = _destroy, }, .derive_ike_keys = _derive_ike_keys, .derive_child_keys = _derive_child_keys, .get_skd = _get_skd, .get_auth_octets = _get_auth_octets, .get_psk_sig = _get_psk_sig, .add_hash_algorithm = _add_hash_algorithm, .hash_algorithm_supported = _hash_algorithm_supported, }, .initiator = initiator, .prf_alg = PRF_UNDEFINED, ); return &this->public; }