#include "bearssl_hash.h"
#include "bearssl_rsa.h"
-/*
- * X.509 Certificate Chain Processing
- * ----------------------------------
+/** \file bearssl_x509.h
+ *
+ * # X.509 Certificate Chain Processing
*
* An X.509 processing engine receives an X.509 chain, chunk by chunk,
* as received from a SSL/TLS client or server (the client receives the
* The engine's job is to return the public key to use for SSL/TLS.
* How exactly that key is obtained and verified is entirely up to the
* engine.
+ *
+ * **The "known key" engine** returns a public key which is already known
+ * from out-of-band information (e.g. the client _remembers_ the key from
+ * a previous connection, as in the usual SSH model). This is the simplest
+ * engine since it simply ignores the chain, thereby avoiding the need
+ * for any decoding logic.
+ *
+ * **The "minimal" engine** implements minimal X.509 decoding and chain
+ * validation:
+ *
+ * - The provided chain should validate "as is". There is no attempt
+ * at reordering, skipping or downloading extra certificates.
+ *
+ * - X.509 v1, v2 and v3 certificates are supported.
+ *
+ * - Trust anchors are a DN and a public key. Each anchor is either a
+ * "CA" anchor, or a non-CA.
+ *
+ * - If the end-entity certificate matches a non-CA anchor (subject DN
+ * is equal to the non-CA name, and public key is also identical to
+ * the anchor key), then this is a _direct trust_ case and the
+ * remaining certificates are ignored.
+ *
+ * - Unless direct trust is applied, the chain must be verifiable up to
+ * a certificate whose issuer DN matches the DN from a "CA" trust anchor,
+ * and whose signature is verifiable against that anchor's public key.
+ * Subsequent certificates in the chain are ignored.
+ *
+ * - The engine verifies subject/issuer DN matching, and enforces
+ * processing of Basic Constraints and Key Usage extensions. The
+ * Authority Key Identifier, Subject Key Identifier, Issuer Alt Name,
+ * Subject Directory Attribute, CRL Distribution Points, Freshest CRL,
+ * Authority Info Access and Subject Info Access extensions are
+ * ignored. The Subject Alt Name is decoded for the end-entity
+ * certificate under some conditions (see below). Other extensions
+ * are ignored if non-critical, or imply chain rejection if critical.
+ *
+ * - The Subject Alt Name extension is parsed for names of type `dNSName`
+ * when decoding the end-entity certificate, and only if there is a
+ * server name to match. If there is no SAN extension, then the
+ * Common Name from the subjectDN is used. That name matching is
+ * case-insensitive and honours a single starting wildcard (i.e. if
+ * the name in the certificate starts with "`*.`" then this matches
+ * any word as first element). Note: this name matching is performed
+ * also in the "direct trust" model.
+ *
+ * - DN matching is byte-to-byte equality (a future version might
+ * include some limited processing for case-insensitive matching and
+ * whitespace normalisation).
+ *
+ * - Successful validation produces a public key type but also a set
+ * of allowed usages (`BR_KEYTYPE_KEYX` and/or `BR_KEYTYPE_SIGN`).
+ * The caller is responsible for checking that the key type and
+ * usages are compatible with the expected values (e.g. with the
+ * selected cipher suite, when the client validates the server's
+ * certificate).
+ *
+ * **Important caveats:**
+ *
+ * - The "minimal" engine does not check revocation status. The relevant
+ * extensions are ignored, and CRL or OCSP responses are not gathered
+ * or checked.
+ *
+ * - The "minimal" engine does not currently support Name Constraints
+ * (some basic functionality to handle sub-domains may be added in a
+ * later version).
+ *
+ * - The decoder is not "validating" in the sense that it won't reject
+ * some certificates with invalid field values when these fields are
+ * not actually processed.
*/
/*
* X.509 error codes are in the 32..63 range.
*/
-/* Validation was successful; this is not actually an error. */
+/** \brief X.509 status: validation was successful; this is not actually
+ an error. */
#define BR_ERR_X509_OK 32
-/* Invalid value in an ASN.1 structure. */
+/** \brief X.509 status: invalid value in an ASN.1 structure. */
#define BR_ERR_X509_INVALID_VALUE 33
-/* Truncated certificate. */
+/** \brief X.509 status: truncated certificate. */
#define BR_ERR_X509_TRUNCATED 34
-/* Empty certificate chain (no certificate at all). */
+/** \brief X.509 status: empty certificate chain (no certificate at all). */
#define BR_ERR_X509_EMPTY_CHAIN 35
-/* Decoding error: inner element extends beyond outer element size. */
+/** \brief X.509 status: decoding error: inner element extends beyond
+ outer element size. */
#define BR_ERR_X509_INNER_TRUNC 36
-/* Decoding error: unsupported tag class (application or private). */
+/** \brief X.509 status: decoding error: unsupported tag class (application
+ or private). */
#define BR_ERR_X509_BAD_TAG_CLASS 37
-/* Decoding error: unsupported tag value. */
+/** \brief X.509 status: decoding error: unsupported tag value. */
#define BR_ERR_X509_BAD_TAG_VALUE 38
-/* Decoding error: indefinite length. */
+/** \brief X.509 status: decoding error: indefinite length. */
#define BR_ERR_X509_INDEFINITE_LENGTH 39
-/* Decoding error: extraneous element. */
+/** \brief X.509 status: decoding error: extraneous element. */
#define BR_ERR_X509_EXTRA_ELEMENT 40
-/* Decoding error: unexpected element. */
+/** \brief X.509 status: decoding error: unexpected element. */
#define BR_ERR_X509_UNEXPECTED 41
-/* Decoding error: expected constructed element, but is primitive. */
+/** \brief X.509 status: decoding error: expected constructed element, but
+ is primitive. */
#define BR_ERR_X509_NOT_CONSTRUCTED 42
-/* Decoding error: expected primitive element, but is constructed. */
+/** \brief X.509 status: decoding error: expected primitive element, but
+ is constructed. */
#define BR_ERR_X509_NOT_PRIMITIVE 43
-/* Decoding error: BIT STRING length is not multiple of 8. */
+/** \brief X.509 status: decoding error: BIT STRING length is not multiple
+ of 8. */
#define BR_ERR_X509_PARTIAL_BYTE 44
-/* Decoding error: BOOLEAN value has invalid length. */
+/** \brief X.509 status: decoding error: BOOLEAN value has invalid length. */
#define BR_ERR_X509_BAD_BOOLEAN 45
-/* Decoding error: value is off-limits. */
+/** \brief X.509 status: decoding error: value is off-limits. */
#define BR_ERR_X509_OVERFLOW 46
-/* Invalid distinguished name. */
+/** \brief X.509 status: invalid distinguished name. */
#define BR_ERR_X509_BAD_DN 47
-/* Invalid date/time representation. */
+/** \brief X.509 status: invalid date/time representation. */
#define BR_ERR_X509_BAD_TIME 48
-/* Certificate contains unsupported features that cannot be ignored. */
+/** \brief X.509 status: certificate contains unsupported features that
+ cannot be ignored. */
#define BR_ERR_X509_UNSUPPORTED 49
-/* Key or signature size exceeds internal limits. */
+/** \brief X.509 status: key or signature size exceeds internal limits. */
#define BR_ERR_X509_LIMIT_EXCEEDED 50
-/* Key type does not match that which was expected. */
+/** \brief X.509 status: key type does not match that which was expected. */
#define BR_ERR_X509_WRONG_KEY_TYPE 51
-/* Signature is invalid. */
+/** \brief X.509 status: signature is invalid. */
#define BR_ERR_X509_BAD_SIGNATURE 52
-/* Validation time is unknown. */
+/** \brief X.509 status: validation time is unknown. */
#define BR_ERR_X509_TIME_UNKNOWN 53
-/* Certificate is expired or not yet valid. */
+/** \brief X.509 status: certificate is expired or not yet valid. */
#define BR_ERR_X509_EXPIRED 54
-/* Issuer/Subject DN mismatch in the chain. */
+/** \brief X.509 status: issuer/subject DN mismatch in the chain. */
#define BR_ERR_X509_DN_MISMATCH 55
-/* Expected server name was not found in the chain. */
+/** \brief X.509 status: expected server name was not found in the chain. */
#define BR_ERR_X509_BAD_SERVER_NAME 56
-/* Unknown critical extension in certificate. */
+/** \brief X.509 status: unknown critical extension in certificate. */
#define BR_ERR_X509_CRITICAL_EXTENSION 57
-/* Not a CA, or path length constraint violation */
+/** \brief X.509 status: not a CA, or path length constraint violation */
#define BR_ERR_X509_NOT_CA 58
-/* Key Usage extension prohibits intended usage. */
+/** \brief X.509 status: Key Usage extension prohibits intended usage. */
#define BR_ERR_X509_FORBIDDEN_KEY_USAGE 59
-/* Public key found in certificate is too small. */
+/** \brief X.509 status: public key found in certificate is too small. */
#define BR_ERR_X509_WEAK_PUBLIC_KEY 60
-/* Chain could not be linked to a trust anchor. */
+/** \brief X.509 status: chain could not be linked to a trust anchor. */
#define BR_ERR_X509_NOT_TRUSTED 62
-/*
- * A structure to encode public keys.
+/**
+ * \brief Aggregate structure for public keys.
*/
typedef struct {
+ /** \brief Key type: `BR_KEYTYPE_RSA` or `BR_KEYTYPE_EC` */
unsigned char key_type;
+ /** \brief Actual public key. */
union {
+ /** \brief RSA public key. */
br_rsa_public_key rsa;
+ /** \brief EC public key. */
br_ec_public_key ec;
} key;
} br_x509_pkey;
-/*
- * A trust anchor consists in:
- * -- an encoded DN
- * -- a public key
- * -- flags
+/**
+ * \brief Distinguished Name (X.500) structure.
+ *
+ * The DN is DER-encoded.
*/
typedef struct {
- unsigned char *dn;
- size_t dn_len;
- /* unsigned char hashed_DN[64]; */
+ /** \brief Encoded DN data. */
+ unsigned char *data;
+ /** \brief Encoded DN length (in bytes). */
+ size_t len;
+} br_x500_name;
+
+/**
+ * \brief Trust anchor structure.
+ */
+typedef struct {
+ /** \brief Encoded DN (X.500 name). */
+ br_x500_name dn;
+ /** \brief Anchor flags (e.g. `BR_X509_TA_CA`). */
unsigned flags;
+ /** \brief Anchor public key. */
br_x509_pkey pkey;
} br_x509_trust_anchor;
-/* Trust anchor flag: trust anchor is a CA and thus acceptable for
- signing other certificates. Without this flag, the trust anchor
- is only for direct trust (name and key match EE certificate). */
+/**
+ * \brief Trust anchor flag: CA.
+ *
+ * A "CA" anchor is deemed fit to verify signatures on certificates.
+ * A "non-CA" anchor is accepted only for direct trust (server's
+ * certificate name and key match the anchor).
+ */
#define BR_X509_TA_CA 0x0001
/*
* for the key; the basic key type may be set to 0 to indicate that any
* key type compatible with the indicated purpose is acceptable.
*/
+/** \brief Key type: algorithm is RSA. */
#define BR_KEYTYPE_RSA 1
+/** \brief Key type: algorithm is EC. */
#define BR_KEYTYPE_EC 2
-#define BR_KEYTYPE_KEYX 0x10 /* key is for key exchange or encryption */
-#define BR_KEYTYPE_SIGN 0x20 /* key is for verifying signatures */
+/**
+ * \brief Key type: usage is "key exchange".
+ *
+ * This value is combined (with bitwise OR) with the algorithm
+ * (`BR_KEYTYPE_RSA` or `BR_KEYTYPE_EC`) when informing the X.509
+ * validation engine that it should find a public key of that type,
+ * fit for key exchanges (e.g. `TLS_RSA_*` and `TLS_ECDH_*` cipher
+ * suites).
+ */
+#define BR_KEYTYPE_KEYX 0x10
+
+/**
+ * \brief Key type: usage is "signature".
+ *
+ * This value is combined (with bitwise OR) with the algorithm
+ * (`BR_KEYTYPE_RSA` or `BR_KEYTYPE_EC`) when informing the X.509
+ * validation engine that it should find a public key of that type,
+ * fit for signatures (e.g. `TLS_ECDHE_*` cipher suites).
+ */
+#define BR_KEYTYPE_SIGN 0x20
/*
* start_chain Called when a new chain is started. If 'server_name'
* pointer to a public key even in some cases of validation failure,
* depending on the validation engine.
*/
+
+/**
+ * \brief Class type for an X.509 engine.
+ *
+ * A certificate chain validation uses a caller-allocated context, which
+ * contains the running state for that validation. Methods are called
+ * in due order:
+ *
+ * - `start_chain()` is called at the start of the validation.
+ * - Certificates are processed one by one, in SSL order (end-entity
+ * comes first). For each certificate, the following methods are
+ * called:
+ *
+ * - `start_cert()` at the beginning of the certificate.
+ * - `append()` is called zero, one or more times, to provide
+ * the certificate (possibly in chunks).
+ * - `end_cert()` at the end of the certificate.
+ *
+ * - `end_chain()` is called when the last certificate in the chain
+ * was processed.
+ * - `get_pkey()` is called after chain processing, if the chain
+ * validation was succesfull.
+ *
+ * A context structure may be reused; the `start_chain()` method shall
+ * ensure (re)initialisation.
+ */
typedef struct br_x509_class_ br_x509_class;
struct br_x509_class_ {
+ /**
+ * \brief X.509 context size, in bytes.
+ */
size_t context_size;
+
+ /**
+ * \brief Start a new chain.
+ *
+ * This method shall set the vtable (first field) of the context
+ * structure.
+ *
+ * The `server_name`, if not `NULL`, will be considered as a
+ * fully qualified domain name, to be matched against the `dNSName`
+ * elements of the end-entity certificate's SAN extension (if there
+ * is no SAN, then the Common Name from the subjectDN will be used).
+ * If `server_name` is `NULL` then no such matching is performed.
+ *
+ * \param ctx validation context.
+ * \param server_name server name to match (or `NULL`).
+ */
void (*start_chain)(const br_x509_class **ctx,
- unsigned expected_key_type,
const char *server_name);
+
+ /**
+ * \brief Start a new certificate.
+ *
+ * \param ctx validation context.
+ * \param length new certificate length (in bytes).
+ */
void (*start_cert)(const br_x509_class **ctx, uint32_t length);
+
+ /**
+ * \brief Receive some bytes for the current certificate.
+ *
+ * This function may be called several times in succession for
+ * a given certificate. The caller guarantees that for each
+ * call, `len` is not zero, and the sum of all chunk lengths
+ * for a certificate matches the total certificate length which
+ * was provided in the previous `start_cert()` call.
+ *
+ * If the new certificate is empty (no byte at all) then this
+ * function won't be called at all.
+ *
+ * \param ctx validation context.
+ * \param buf certificate data chunk.
+ * \param len certificate data chunk length (in bytes).
+ */
void (*append)(const br_x509_class **ctx,
const unsigned char *buf, size_t len);
+
+ /**
+ * \brief Finish the current certificate.
+ *
+ * This function is called when the end of the current certificate
+ * is reached.
+ *
+ * \param ctx validation context.
+ */
void (*end_cert)(const br_x509_class **ctx);
+
+ /**
+ * \brief Finish the chain.
+ *
+ * This function is called at the end of the chain. It shall
+ * return either 0 if the validation was successful, or a
+ * non-zero error code. The `BR_ERR_X509_*` constants are
+ * error codes, though other values may be possible.
+ *
+ * \param ctx validation context.
+ * \return 0 on success, or a non-zero error code.
+ */
unsigned (*end_chain)(const br_x509_class **ctx);
- const br_x509_pkey *(*get_pkey)(const br_x509_class *const *ctx);
+
+ /**
+ * \brief Get the resulting end-entity public key.
+ *
+ * The decoded public key is returned. The returned pointer
+ * may be valid only as long as the context structure is
+ * unmodified, i.e. it may cease to be valid if the context
+ * is released or reused.
+ *
+ * This function _may_ return `NULL` if the validation failed.
+ * However, returning a public key does not mean that the
+ * validation was wholly successful; some engines may return
+ * a decoded public key even if the chain did not end on a
+ * trusted anchor.
+ *
+ * If validation succeeded and `usage` is not `NULL`, then
+ * `*usage` is filled with a combination of `BR_KEYTYPE_SIGN`
+ * and/or `BR_KEYTYPE_KEYX` that specifies the validated key
+ * usage types. It is the caller's responsibility to check
+ * that value against the intended use of the public key.
+ *
+ * \param ctx validation context.
+ * \return the end-entity public key, or `NULL`.
+ */
+ const br_x509_pkey *(*get_pkey)(
+ const br_x509_class *const *ctx, unsigned *usages);
};
-/*
- * The "known key" X.509 engine is a trivial engine that completely
- * ignores the certificates, and instead reports an externally
- * configured public key.
+/**
+ * \brief The "known key" X.509 engine structure.
+ *
+ * The structure contents are opaque (they shall not be accessed directly),
+ * except for the first field (the vtable).
+ *
+ * The "known key" engine returns an externally configured public key,
+ * and totally ignores the certificate contents.
*/
typedef struct {
+ /** \brief Reference to the context vtable. */
const br_x509_class *vtable;
+#ifndef BR_DOXYGEN_IGNORE
br_x509_pkey pkey;
+ unsigned usages;
+#endif
} br_x509_knownkey_context;
+
+/**
+ * \brief Class instance for the "known key" X.509 engine.
+ */
extern const br_x509_class br_x509_knownkey_vtable;
-/*
- * Initialize a "known key" X.509 engine with a known RSA public key.
- * The provided pointers are linked in, not copied, so they must
- * remain valid while the public key may be in usage (i.e. at least up
- * to the end of the handshake -- and since there may be renegotiations,
- * these buffers should stay until the connection is finished).
+/**
+ * \brief Initialize a "known key" X.509 engine with a known RSA public key.
+ *
+ * The `usages` parameter indicates the allowed key usages for that key
+ * (`BR_KEYTYPE_KEYX` and/or `BR_KEYTYPE_SIGN`).
+ *
+ * The provided pointers are linked in, not copied, so they must remain
+ * valid while the public key may be in usage.
+ *
+ * \param ctx context to initialise.
+ * \param pk known public key.
+ * \param usages allowed key usages.
*/
void br_x509_knownkey_init_rsa(br_x509_knownkey_context *ctx,
- const br_rsa_public_key *pk);
+ const br_rsa_public_key *pk, unsigned usages);
-/*
- * Initialize a "known key" X.509 engine with a known EC public key.
- * The provided pointers are linked in, not copied, so they must
- * remain valid while the public key may be in usage (i.e. at least up
- * to the end of the handshake -- and since there may be renegotiations,
- * these buffers should stay until the connection is finished).
+/**
+ * \brief Initialize a "known key" X.509 engine with a known EC public key.
+ *
+ * The `usages` parameter indicates the allowed key usages for that key
+ * (`BR_KEYTYPE_KEYX` and/or `BR_KEYTYPE_SIGN`).
+ *
+ * The provided pointers are linked in, not copied, so they must remain
+ * valid while the public key may be in usage.
+ *
+ * \param ctx context to initialise.
+ * \param pk known public key.
+ * \param usages allowed key usages.
*/
void br_x509_knownkey_init_ec(br_x509_knownkey_context *ctx,
- const br_ec_public_key *pk);
+ const br_ec_public_key *pk, unsigned usages);
+#ifndef BR_DOXYGEN_IGNORE
/*
* The minimal X.509 engine has some state buffers which must be large
* enough to simultaneously accommodate:
* Though RSA public exponents can formally be as large as the modulus
* (mathematically, even larger exponents would work, but PKCS#1 forbids
* them), exponents that do not fit on 32 bits are extremely rare,
- * notably because some widespread implementation (e.g. Microsoft's
+ * notably because some widespread implementations (e.g. Microsoft's
* CryptoAPI) don't support them. Moreover, large public exponent do not
* seem to imply any tangible security benefit, and they increase the
- * cost of public key operations.
+ * cost of public key operations. The X.509 "minimal" engine will tolerate
+ * public exponents of arbitrary size as long as the modulus and the
+ * exponent can fit together in the dedicated buffer.
*
* EC public keys are shorter than RSA public keys; even with curve
* NIST P-521 (the largest curve we care to support), a public key is
*/
#define BR_X509_BUFSIZE_KEY 520
#define BR_X509_BUFSIZE_SIG 512
+#endif
-/*
- * The "minimal" X.509 engine performs basic decoding of certificates and
- * some validations:
- * -- DN matching
- * -- signatures
- * -- validity dates
- * -- Basic Constraints extension
- * -- Server name check against SAN extension
+/**
+ * \brief Type for receiving a name element.
+ *
+ * An array of such structures can be provided to the X.509 decoding
+ * engines. If the specified elements are found in the certificate
+ * subject DN or the SAN extension, then the name contents are copied
+ * as zero-terminated strings into the buffer.
+ *
+ * The decoder converts TeletexString and BMPString to UTF8String, and
+ * ensures that the resulting string is zero-terminated. If the string
+ * does not fit in the provided buffer, then the copy is aborted and an
+ * error is reported.
+ */
+typedef struct {
+ /**
+ * \brief Element OID.
+ *
+ * For X.500 name elements (to be extracted from the subject DN),
+ * this is the encoded OID for the requested name element; the
+ * first byte shall contain the length of the DER-encoded OID
+ * value, followed by the OID value (for instance, OID 2.5.4.3,
+ * for id-at-commonName, will be `03 55 04 03`). This is
+ * equivalent to full DER encoding with the length but without
+ * the tag.
+ *
+ * For SAN name elements, the first byte (`oid[0]`) has value 0,
+ * followed by another byte that matches the expected GeneralName
+ * tag. Allowed second byte values are then:
+ *
+ * - 1: `rfc822Name`
+ *
+ * - 2: `dNSName`
+ *
+ * - 6: `uniformResourceIdentifier`
+ *
+ * - 0: `otherName`
+ *
+ * If first and second byte are 0, then this is a SAN element of
+ * type `otherName`; the `oid[]` array should then contain, right
+ * after the two bytes of value 0, an encoded OID (with the same
+ * conventions as for X.500 name elements). If a match is found
+ * for that OID, then the corresponding name element will be
+ * extracted, as long as it is a supported string type.
+ */
+ const unsigned char *oid;
+
+ /**
+ * \brief Destination buffer.
+ */
+ char *buf;
+
+ /**
+ * \brief Length (in bytes) of the destination buffer.
+ *
+ * The buffer MUST NOT be smaller than 1 byte.
+ */
+ size_t len;
+
+ /**
+ * \brief Decoding status.
+ *
+ * Status is 0 if the name element was not found, 1 if it was
+ * found and decoded, or -1 on error. Error conditions include
+ * an unrecognised encoding, an invalid encoding, or a string
+ * too large for the destination buffer.
+ */
+ int status;
+
+} br_name_element;
+
+/**
+ * \brief The "minimal" X.509 engine structure.
+ *
+ * The structure contents are opaque (they shall not be accessed directly),
+ * except for the first field (the vtable).
+ *
+ * The "minimal" engine performs a rudimentary but serviceable X.509 path
+ * validation.
*/
typedef struct {
const br_x509_class *vtable;
+#ifndef BR_DOXYGEN_IGNORE
/* Structure for returning the EE public key. */
br_x509_pkey pkey;
/* Server name to match with the SAN / CN of the EE certificate. */
const char *server_name;
- /* Expected EE key type and usage. */
- unsigned char expected_key_type;
+ /* Validated key usages. */
+ unsigned char key_usages;
/* Explicitly set date and time. */
uint32_t days, seconds;
unsigned char next_dn_hash[64];
unsigned char saved_dn_hash[64];
+ /*
+ * Name elements to gather.
+ */
+ br_name_element *name_elts;
+ size_t num_name_elts;
+
/*
* Public key cryptography implementations (signature verification).
*/
br_rsa_pkcs1_vrfy irsa;
br_ecdsa_vrfy iecdsa;
const br_ec_impl *iec;
+#endif
} br_x509_minimal_context;
+
+/**
+ * \brief Class instance for the "minimal" X.509 engine.
+ */
extern const br_x509_class br_x509_minimal_vtable;
-/*
- * Initialize a "minimal" X.509 engine. Parameters are:
- * -- context to initialize
- * -- hash function to use for hashing normalized DN
- * -- list of trust anchors
+/**
+ * \brief Initialise a "minimal" X.509 engine.
*
- * After initialization, some hash function implementations for signature
- * verification MUST be added.
+ * The `dn_hash_impl` parameter shall be a hash function internally used
+ * to match X.500 names (subject/issuer DN, and anchor names). Any standard
+ * hash function may be used, but a collision-resistant hash function is
+ * advised.
+ *
+ * After initialization, some implementations for signature verification
+ * (hash functions and signature algorithms) MUST be added.
+ *
+ * \param ctx context to initialise.
+ * \param dn_hash_impl hash function for DN comparisons.
+ * \param trust_anchors trust anchors.
+ * \param trust_anchors_num number of trust anchors.
*/
void br_x509_minimal_init(br_x509_minimal_context *ctx,
const br_hash_class *dn_hash_impl,
const br_x509_trust_anchor *trust_anchors, size_t trust_anchors_num);
-/*
- * Set a hash function implementation, identified by ID, for purposes of
- * verifying signatures on certificates. This must be called after
- * br_x509_minimal_init().
+/**
+ * \brief Set a supported hash function in an X.509 "minimal" engine.
+ *
+ * Hash functions are used with signature verification algorithms.
+ * Once initialised (with `br_x509_minimal_init()`), the context must
+ * be configured with the hash functions it shall support for that
+ * purpose. The hash function identifier MUST be one of the standard
+ * hash function identifiers (1 to 6, for MD5, SHA-1, SHA-224, SHA-256,
+ * SHA-384 and SHA-512).
+ *
+ * If `impl` is `NULL`, this _removes_ support for the designated
+ * hash function.
+ *
+ * \param ctx validation context.
+ * \param id hash function identifier (from 1 to 6).
+ * \param impl hash function implementation (or `NULL`).
*/
static inline void
br_x509_minimal_set_hash(br_x509_minimal_context *ctx,
br_multihash_setimpl(&ctx->mhash, id, impl);
}
-/*
- * Set a RSA implementation, for purposes of verifying signatures on
- * certificates. This must be called after br_x509_minimal_init().
+/**
+ * \brief Set a RSA signature verification implementation in the X.509
+ * "minimal" engine.
+ *
+ * Once initialised (with `br_x509_minimal_init()`), the context must
+ * be configured with the signature verification implementations that
+ * it is supposed to support. If `irsa` is `0`, then the RSA support
+ * is disabled.
+ *
+ * \param ctx validation context.
+ * \param irsa RSA signature verification implementation (or `0`).
*/
static inline void
br_x509_minimal_set_rsa(br_x509_minimal_context *ctx,
ctx->irsa = irsa;
}
-/*
- * Set an ECDSA implementation, for purposes of verifying signatures on
- * certificates. This must be called after br_x509_minimal_init().
+/**
+ * \brief Set a ECDSA signature verification implementation in the X.509
+ * "minimal" engine.
+ *
+ * Once initialised (with `br_x509_minimal_init()`), the context must
+ * be configured with the signature verification implementations that
+ * it is supposed to support.
+ *
+ * If `iecdsa` is `0`, then this call disables ECDSA support; in that
+ * case, `iec` may be `NULL`. Otherwise, `iecdsa` MUST point to a function
+ * that verifies ECDSA signatures with format "asn1", and it will use
+ * `iec` as underlying elliptic curve support.
+ *
+ * \param ctx validation context.
+ * \param iec elliptic curve implementation (or `NULL`).
+ * \param iecdsa ECDSA implementation (or `0`).
*/
static inline void
br_x509_minimal_set_ecdsa(br_x509_minimal_context *ctx,
ctx->iec = iec;
}
-/*
- * Set the validation time, normally to the current date and time.
- * This consists in two 32-bit counts:
+/**
+ * \brief Initialise a "minimal" X.509 engine with default algorithms.
+ *
+ * This function performs the same job as `br_x509_minimal_init()`, but
+ * also sets implementations for RSA, ECDSA, and the standard hash
+ * functions.
+ *
+ * \param ctx context to initialise.
+ * \param trust_anchors trust anchors.
+ * \param trust_anchors_num number of trust anchors.
+ */
+void br_x509_minimal_init_full(br_x509_minimal_context *ctx,
+ const br_x509_trust_anchor *trust_anchors, size_t trust_anchors_num);
+
+/**
+ * \brief Set the validation time for the X.509 "minimal" engine.
+ *
+ * The validation time is set as two 32-bit integers, for days and
+ * seconds since a fixed epoch:
+ *
+ * - Days are counted in a proleptic Gregorian calendar since
+ * January 1st, 0 AD. Year "0 AD" is the one that preceded "1 AD";
+ * it is also traditionally known as "1 BC".
*
- * -- Days are counted in a proleptic Gregorian calendar since
- * January 1st, 0 AD. Year "0 AD" is the one that preceded "1 AD";
- * it is also traditionally known as "1 BC".
+ * - Seconds are counted since midnight, from 0 to 86400 (a count of
+ * 86400 is possible only if a leap second happened).
*
- * -- Seconds are counted since midnight, from 0 to 86400 (a count of
- * 86400 is possible only if a leap second happened).
+ * The validation date and time is understood in the UTC time zone.
*
* If the validation date and time are not explicitly set, but BearSSL
* was compiled with support for the system clock on the underlying
* platform, then the current time will automatically be used. Otherwise,
- * validation will fail (except in case of direct trust of the EE key).
+ * not setting the validation date and time implies a validation
+ * failure (except in case of direct trust of the EE key).
+ *
+ * \param ctx validation context.
+ * \param days days since January 1st, 0 AD (Gregorian calendar).
+ * \param seconds seconds since midnight (0 to 86400).
*/
static inline void
br_x509_minimal_set_time(br_x509_minimal_context *ctx,
ctx->seconds = seconds;
}
-/*
- * Set the minimal acceptable length for RSA keys, in bytes. Default
- * is 128 bytes, which means RSA keys of 1017 bits or more. This setting
- * applies to keys extracted from certificates (EE and intermediate CA).
- * It does _not_ apply to "CA" trust anchors.
+/**
+ * \brief Set the minimal acceptable length for RSA keys (X.509 "minimal"
+ * engine).
+ *
+ * The RSA key length is expressed in bytes. The default minimum key
+ * length is 128 bytes, corresponding to 1017 bits. RSA keys shorter
+ * than the configured length will be rejected, implying validation
+ * failure. This setting applies to keys extracted from certificates
+ * (both end-entity, and intermediate CA) but not to "CA" trust anchors.
+ *
+ * \param ctx validation context.
+ * \param byte_length minimum RSA key length, **in bytes** (not bits).
*/
static inline void
br_x509_minimal_set_minrsa(br_x509_minimal_context *ctx, int byte_length)
ctx->min_rsa_size = (int16_t)(byte_length - 128);
}
-/*
- * An X.509 decoder context. This is not for X.509 validation, but for
- * using certificates as trust anchors (e.g. self-signed certificates
- * read from files).
+/**
+ * \brief Set the name elements to gather.
+ *
+ * The provided array is linked in the context. The elements are
+ * gathered from the EE certificate. If the same element type is
+ * requested several times, then the relevant structures will be filled
+ * in the order the matching values are encountered in the certificate.
+ *
+ * \param ctx validation context.
+ * \param elts array of name element structures to fill.
+ * \param num_elts number of name element structures to fill.
+ */
+static inline void
+br_x509_minimal_set_name_elements(br_x509_minimal_context *ctx,
+ br_name_element *elts, size_t num_elts)
+{
+ ctx->name_elts = elts;
+ ctx->num_name_elts = num_elts;
+}
+
+/**
+ * \brief X.509 decoder context.
+ *
+ * This structure is _not_ for X.509 validation, but for extracting
+ * names and public keys from encoded certificates. Intended usage is
+ * to use (self-signed) certificates as trust anchors.
+ *
+ * Contents are opaque and shall not be accessed directly.
*/
typedef struct {
+#ifndef BR_DOXYGEN_IGNORE
/* Structure for returning the public key. */
br_x509_pkey pkey;
/* Type of key and hash function used in the certificate signature. */
unsigned char signer_key_type;
unsigned char signer_hash_id;
+#endif
} br_x509_decoder_context;
-/*
- * Initialise an X.509 decoder context for processing a new certificate.
+/**
+ * \brief Initialise an X.509 decoder context for processing a new
+ * certificate.
+ *
+ * The `append_dn()` callback (with opaque context `append_dn_ctx`)
+ * will be invoked to receive, chunk by chunk, the certificate's
+ * subject DN. If `append_dn` is `0` then the subject DN will be
+ * ignored.
+ *
+ * \param ctx X.509 decoder context to initialise.
+ * \param append_dn DN receiver callback (or `0`).
+ * \param append_dn_ctx context for the DN receiver callback.
*/
void br_x509_decoder_init(br_x509_decoder_context *ctx,
void (*append_dn)(void *ctx, const void *buf, size_t len),
void *append_dn_ctx);
-/*
- * Push some certificate bytes into a decoder context.
+/**
+ * \brief Push some certificate bytes into a decoder context.
+ *
+ * If `len` is non-zero, then that many bytes are pushed, from address
+ * `data`, into the provided decoder context.
+ *
+ * \param ctx X.509 decoder context.
+ * \param data certificate data chunk.
+ * \param len certificate data chunk length (in bytes).
*/
void br_x509_decoder_push(br_x509_decoder_context *ctx,
const void *data, size_t len);
-/*
- * Obtain the decoded public key. Returned value is a pointer to a
- * structure internal to the decoder context; releasing or reusing the
- * decoder context invalidates that structure.
+/**
+ * \brief Obtain the decoded public key.
+ *
+ * Returned value is a pointer to a structure internal to the decoder
+ * context; releasing or reusing the decoder context invalidates that
+ * structure.
+ *
+ * If decoding was not finished, or failed, then `NULL` is returned.
*
- * If decoding was not finished, or failed, then NULL is returned.
+ * \param ctx X.509 decoder context.
+ * \return the public key, or `NULL` on unfinished/error.
*/
static inline br_x509_pkey *
br_x509_decoder_get_pkey(br_x509_decoder_context *ctx)
}
}
-/*
- * Get decoder error. If no error was reported yet but the certificate
- * decoding is not finished, then the error code is BR_ERR_X509_TRUNCATED.
- * If decoding was successful, then 0 is returned.
+/**
+ * \brief Get decoder error status.
+ *
+ * If no error was reported yet but the certificate decoding is not
+ * finished, then the error code is `BR_ERR_X509_TRUNCATED`. If decoding
+ * was successful, then 0 is returned.
+ *
+ * \param ctx X.509 decoder context.
+ * \return 0 on successful decoding, or a non-zero error code.
*/
static inline int
br_x509_decoder_last_error(br_x509_decoder_context *ctx)
return 0;
}
-/*
- * Get the "isCA" flag from an X.509 decoder context. This flag is set
- * if the decoded certificate claims to be a CA through a Basic
- * Constraints extension.
+/**
+ * \brief Get the "isCA" flag from an X.509 decoder context.
+ *
+ * This flag is set if the decoded certificate claims to be a CA through
+ * a Basic Constraints extension. This flag should not be read before
+ * decoding completed successfully.
+ *
+ * \param ctx X.509 decoder context.
+ * \return the "isCA" flag.
*/
static inline int
br_x509_decoder_isCA(br_x509_decoder_context *ctx)
return ctx->isCA;
}
-/*
- * Get the issuing CA key type (type of key used to sign the decoded
- * certificate). This is BR_KEYTYPE_RSA or BR_KEYTYPE_EC. The value 0
- * is returned if the signature type was not recognised.
+/**
+ * \brief Get the issuing CA key type (type of algorithm used to sign the
+ * decoded certificate).
+ *
+ * This is `BR_KEYTYPE_RSA` or `BR_KEYTYPE_EC`. The value 0 is returned
+ * if the signature type was not recognised.
+ *
+ * \param ctx X.509 decoder context.
+ * \return the issuing CA key type.
*/
static inline int
br_x509_decoder_get_signer_key_type(br_x509_decoder_context *ctx)
return ctx->signer_key_type;
}
-/*
- * Get the identifier for the hash function used to sign the decoded
- * certificate. This is 0 if the hash function was not recognised.
+/**
+ * \brief Get the identifier for the hash function used to sign the decoded
+ * certificate.
+ *
+ * This is 0 if the hash function was not recognised.
+ *
+ * \param ctx X.509 decoder context.
+ * \return the signature hash function identifier.
*/
static inline int
br_x509_decoder_get_signer_hash_id(br_x509_decoder_context *ctx)
return ctx->signer_hash_id;
}
-/*
- * Type for an X.509 certificate (DER-encoded).
+/**
+ * \brief Type for an X.509 certificate (DER-encoded).
*/
typedef struct {
+ /** \brief The DER-encoded certificate data. */
unsigned char *data;
+ /** \brief The DER-encoded certificate length (in bytes). */
size_t data_len;
} br_x509_certificate;
-/*
- * Private key decoder context.
+/**
+ * \brief Private key decoder context.
+ *
+ * The private key decoder recognises RSA and EC private keys, either in
+ * their raw, DER-encoded format, or wrapped in an unencrypted PKCS#8
+ * archive (again DER-encoded).
+ *
+ * Structure contents are opaque and shall not be accessed directly.
*/
typedef struct {
-
+#ifndef BR_DOXYGEN_IGNORE
/* Structure for returning the private key. */
union {
br_rsa_private_key rsa;
to accommodate all elements for a RSA-4096 private key (roughly
five 2048-bit integers, possibly a bit more). */
unsigned char key_data[3 * BR_X509_BUFSIZE_SIG];
-
+#endif
} br_skey_decoder_context;
-/*
- * Initialise a private key decoder context.
+/**
+ * \brief Initialise a private key decoder context.
+ *
+ * \param ctx key decoder context to initialise.
*/
void br_skey_decoder_init(br_skey_decoder_context *ctx);
-/*
- * Push some data bytes into a private key decoder context.
+/**
+ * \brief Push some data bytes into a private key decoder context.
+ *
+ * If `len` is non-zero, then that many data bytes, starting at address
+ * `data`, are pushed into the decoder.
+ *
+ * \param ctx key decoder context.
+ * \param data private key data chunk.
+ * \param len private key data chunk length (in bytes).
*/
void br_skey_decoder_push(br_skey_decoder_context *ctx,
const void *data, size_t len);
-/*
- * Get the decoding status for a private key. This is either 0 on success,
- * or a non-zero error code.
+/**
+ * \brief Get the decoding status for a private key.
+ *
+ * Decoding status is 0 on success, or a non-zero error code. If the
+ * decoding is unfinished when this function is called, then the
+ * status code `BR_ERR_X509_TRUNCATED` is returned.
+ *
+ * \param ctx key decoder context.
+ * \return 0 on successful decoding, or a non-zero error code.
*/
static inline int
br_skey_decoder_last_error(const br_skey_decoder_context *ctx)
return 0;
}
-/*
- * Get the decoded private key type. This is 0 if decoding is not finished
- * or failed.
+/**
+ * \brief Get the decoded private key type.
+ *
+ * Private key type is `BR_KEYTYPE_RSA` or `BR_KEYTYPE_EC`. If decoding is
+ * not finished or failed, then 0 is returned.
+ *
+ * \param ctx key decoder context.
+ * \return decoded private key type, or 0.
*/
static inline int
br_skey_decoder_key_type(const br_skey_decoder_context *ctx)
}
}
-/*
- * Get the decoded RSA private key. This function returns NULL if the
- * decoding failed, or is not finished, or the key is not RSA. The returned
- * pointer references structures within the context that can become
- * invalid if the context is reused or released.
+/**
+ * \brief Get the decoded RSA private key.
+ *
+ * This function returns `NULL` if the decoding failed, or is not
+ * finished, or the key is not RSA. The returned pointer references
+ * structures within the context that can become invalid if the context
+ * is reused or released.
+ *
+ * \param ctx key decoder context.
+ * \return decoded RSA private key, or `NULL`.
*/
static inline const br_rsa_private_key *
br_skey_decoder_get_rsa(const br_skey_decoder_context *ctx)
}
}
-/*
- * Get the decoded EC private key. This function returns NULL if the
- * decoding failed, or is not finished, or the key is not EC. The returned
- * pointer references structures within the context that can become
- * invalid if the context is reused or released.
+/**
+ * \brief Get the decoded EC private key.
+ *
+ * This function returns `NULL` if the decoding failed, or is not
+ * finished, or the key is not EC. The returned pointer references
+ * structures within the context that can become invalid if the context
+ * is reused or released.
+ *
+ * \param ctx key decoder context.
+ * \return decoded EC private key, or `NULL`.
*/
static inline const br_ec_private_key *
br_skey_decoder_get_ec(const br_skey_decoder_context *ctx)
projects / BearSSL / blobdiff