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| -rw-r--r-- | src/libdnssec/key.h | 318 |
1 files changed, 318 insertions, 0 deletions
diff --git a/src/libdnssec/key.h b/src/libdnssec/key.h new file mode 100644 index 0000000..27de778 --- /dev/null +++ b/src/libdnssec/key.h @@ -0,0 +1,318 @@ +/* Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz> + + 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 3 of the License, or + (at your option) any later version. + + 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. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. +*/ +/*! + * \file + * + * \addtogroup key + * + * \brief DNSSEC public and private key manipulation. + * + * The dnssec_key_t is an abstraction for a DNSSEC key pair. If the key + * key is initialized with a public key data only, it can be used only for + * signature verification. In order to use the key for signing, private key + * has to be loaded. If only a private key is loaded into the structure, + * the public key is automatically constructed. + * + * The module interface provides various functions to retrieve information + * about the key. But the key is mostly used by other modules of the library. + * + * The following example shows construction of a key from DNSKEY RDATA: + * + * ~~~~~ {.c} + * + * dnssec_binary_t rdata = // ...; + * + * int result; + * dnssec_key_t *key = NULL; + * + * // create new DNSSEC key + * result = dnssec_key_new(&key); + * if (result != DNSSEC_EOK) { + * return result; + * } + * + * // load the DNSKEY RDATA + * result = dnssec_key_set_rdata(key, &rdata); + * if (result != DNSSEC_EOK) { + * dnssec_key_free(key); + * return result; + * } + * + * // print key tag + * printf("key %s\n", dnssec_key_get_keytag(key)); + * + * // make sure what we can do with the key + * assert(dnssec_key_can_verify(key) == true); + * assert(dnssec_key_can_sign(key) == false); + * + * // ... + * + * // cleanup + * dnssec_key_free(key); + * + * ~~~~~ + * + * @{ + */ + +#pragma once + +#include <stdbool.h> +#include <stdint.h> + +#include <libdnssec/binary.h> + +/*! + * DNSKEY algorithm numbers. + * + * \see https://www.iana.org/assignments/dns-sec-alg-numbers/dns-sec-alg-numbers.xhtml + */ +typedef enum dnssec_key_algorithm { + DNSSEC_KEY_ALGORITHM_INVALID = 0, + DNSSEC_KEY_ALGORITHM_RSA_SHA1 = 5, + DNSSEC_KEY_ALGORITHM_RSA_SHA1_NSEC3 = 7, + DNSSEC_KEY_ALGORITHM_RSA_SHA256 = 8, + DNSSEC_KEY_ALGORITHM_RSA_SHA512 = 10, + DNSSEC_KEY_ALGORITHM_ECDSA_P256_SHA256 = 13, + DNSSEC_KEY_ALGORITHM_ECDSA_P384_SHA384 = 14, + DNSSEC_KEY_ALGORITHM_ED25519 = 15, + DNSSEC_KEY_ALGORITHM_ED448 = 16, +} dnssec_key_algorithm_t; + +struct dnssec_key; + +/*! + * DNSSEC key. + */ +typedef struct dnssec_key dnssec_key_t; + +/*! + * Check whether a DNSKEY algorithm is supported. + * + * @note: less secure algorithms may go unsupported on purpose. + */ +bool dnssec_algorithm_key_support(dnssec_key_algorithm_t algo); + +/*! + * Allocate new DNSSEC key. + * + * The protocol field of the key is set to 3 (DNSSEC). + * The flags field of the key is set to 256 (zone key, no SEP). + * + * \return Error code, DNSSEC_EOK if successful. + */ +int dnssec_key_new(dnssec_key_t **key); + +/*! + * Clear the DNSSEC key. + * + * Has the same effect as calling \ref dnssec_key_free and \ref dnssec_key_new. + */ +void dnssec_key_clear(dnssec_key_t *key); + +/*! + * Free the key allocated by \ref dnssec_key_new. + */ +void dnssec_key_free(dnssec_key_t *key); + +/*! + * Create a copy of a DNSSEC key. + * + * Only a public part of the key is copied. + */ +dnssec_key_t *dnssec_key_dup(const dnssec_key_t *key); + +/*! + * Get the key tag of the DNSSEC key. + */ +uint16_t dnssec_key_get_keytag(const dnssec_key_t *key); + +/*! + * Get the domain name of the DNSSEC key. + */ +const uint8_t *dnssec_key_get_dname(const dnssec_key_t *key); + +/*! + * Set the domain name of the DNSSEC key. + */ +int dnssec_key_set_dname(dnssec_key_t *key, const uint8_t *dname); + +/*! + * Get the flags field of the DNSSEC key. + */ +uint16_t dnssec_key_get_flags(const dnssec_key_t *key); + +/*! + * Set the flags field of the DNSSEC key. + */ +int dnssec_key_set_flags(dnssec_key_t *key, uint16_t flags); + +/*! + * Get the protocol field of the DNSSEC key. + */ +uint8_t dnssec_key_get_protocol(const dnssec_key_t *key); + +/*! + * Get the protocol field of the DNSSEC key. + */ +int dnssec_key_set_protocol(dnssec_key_t *key, uint8_t protocol); + +/*! + * Get the algorithm field of the DNSSEC key. + */ +uint8_t dnssec_key_get_algorithm(const dnssec_key_t *key); + +/*! + * Set the algorithm field of the DNSSEC key. + * + * The function will fail if the algorithm is incompatible with the + * loaded key. This means, that the function can be used to set the initial + * algorithm and later, only the hashing algorithm can be changed. + */ +int dnssec_key_set_algorithm(dnssec_key_t *key, uint8_t algorithm); + +/*! + * Get the public key field of the DNSSEC key. + * + * The returned content must not be modified by the caller. A reference + * to internally allocated structure is returned. + */ +int dnssec_key_get_pubkey(const dnssec_key_t *key, dnssec_binary_t *pubkey); + +/*! + * Set the public key field of the DNSSEC key. + * + * A valid algorithm has to be set prior to calling this function. + * + * The function will fail if the key is already loaded in the structure. + */ +int dnssec_key_set_pubkey(dnssec_key_t *key, const dnssec_binary_t *pubkey); + +/*! + * Get the bit size of the cryptographic key used with the DNSSEC key. + */ +unsigned dnssec_key_get_size(const dnssec_key_t *key); + +/*! + * \brief Compute key ID from public key. + * + * \param key Key structure holding the public key. + * \param id Output: key ID in hex. + * + * \return DNSSEC_E* + */ +int dnssec_key_get_keyid(const dnssec_key_t *key, char **id); + +/*! + * Get the RDATA of the DNSSEC key. + * + * The returned content must not be modified by the caller. A reference + * to internally allocated structure is returned. + */ +int dnssec_key_get_rdata(const dnssec_key_t *key, dnssec_binary_t *rdata); + +/*! + * Set the RDATA of the DNSSEC key. + * + * Calling this function has the same effect as setting the individual + * fields of the key step-by-step. The same limitations apply. + */ +int dnssec_key_set_rdata(dnssec_key_t *key, const dnssec_binary_t *rdata); + +/*! + * Load PKCS #8 private key in the unencrypted PEM format. + * + * At least an algorithm must be set prior to calling this function. + * + * The function will create public key, unless it was already set (using + * \ref dnssec_key_set_pubkey or \ref dnssec_key_set_rdata). If the public key + * was set, the function will prevent loading of non-matching private key. + */ +int dnssec_key_load_pkcs8(dnssec_key_t *key, const dnssec_binary_t *pem); + +/*! + * Check if the key can be used for signing. + */ +bool dnssec_key_can_sign(const dnssec_key_t *key); + +/*! + * Check if the key can be used for verification. + */ +bool dnssec_key_can_verify(const dnssec_key_t *key); + +/*! + * Get private key size range for a DNSSEC algorithm. + * + * \param[in] algorithm DNSKEY algorithm. + * \param[out] min Minimal size of the private key (can be NULL). + * \param[out] max Maximal size of the private key (can be NULL). + * + * \return DNSSEC_EOK for valid parameters. + */ +int dnssec_algorithm_key_size_range(dnssec_key_algorithm_t algorithm, + unsigned *min, unsigned *max); + +/*! + * Check if the private key size matches DNSKEY constraints. + * + * \param algorithm DNSKEY algorithm. + * \param bits Private key size. + * + * \return DNSKEY algorithm matches the key size constraints. + */ +bool dnssec_algorithm_key_size_check(dnssec_key_algorithm_t algorithm, + unsigned bits); + +/*! + * Get default key size for given algorithm. + * + * The default size is balance between security and response lengths with + * respect to use in DNS. + */ +int dnssec_algorithm_key_size_default(dnssec_key_algorithm_t algorithm); + +/*! + * DS algorithm numbers. + * + * \see https://www.iana.org/assignments/ds-rr-types/ds-rr-types.xhtml + */ +typedef enum dnssec_key_digest { + DNSSEC_KEY_DIGEST_INVALID = 0, + DNSSEC_KEY_DIGEST_SHA1 = 1, + DNSSEC_KEY_DIGEST_SHA256 = 2, + DNSSEC_KEY_DIGEST_SHA384 = 4, +} dnssec_key_digest_t; + +/*! + * Check whether a DS algorithm is supported. + * + * @note: less secure algorithms may go unsupported on purpose. + */ +bool dnssec_algorithm_digest_support(dnssec_key_digest_t algo); + +/*! + * Create DS (Delgation Signer) RDATA from DNSSEC key. + * + * \param[in] key DNSSEC key. + * \param[in] digest Digest algorithm to be used. + * \param[out] rdata Allocated DS RDATA. + * + * \return Error code, DNSSEC_EOK if successful. + */ +int dnssec_key_create_ds(const dnssec_key_t *key, dnssec_key_digest_t digest, + dnssec_binary_t *rdata); + +/** @} */ |