variable length ecdsa signature [GV2-193] (#1306)

* Add signature length field to MsgEcdsaSignature

Co-authored-by: Jason Mobarak <jason@swift-nav.com>

Author: notoriaga

c/include/libsbp/cpp/message_traits.h

@@ -1475,6 +1475,43 @@ struct MessageTraits<sbp_msg_ecdsa_certificate_t> {
   }
 };
 
+template <>
+struct MessageTraits<sbp_msg_ecdsa_signature_dep_t> {
+  static constexpr sbp_msg_type_t id = SbpMsgEcdsaSignatureDep;
+  static constexpr const char *name = "MSG_ECDSA_SIGNATURE_DEP";
+  static const sbp_msg_ecdsa_signature_dep_t &get(const sbp_msg_t &msg) {
+    return msg.ecdsa_signature_dep;
+  }
+  static sbp_msg_ecdsa_signature_dep_t &get(sbp_msg_t &msg) {
+    return msg.ecdsa_signature_dep;
+  }
+  static void to_sbp_msg(const sbp_msg_ecdsa_signature_dep_t &msg,
+                         sbp_msg_t *sbp_msg) {
+    sbp_msg->ecdsa_signature_dep = msg;
+  }
+  static sbp_msg_t to_sbp_msg(const sbp_msg_ecdsa_signature_dep_t &msg) {
+    sbp_msg_t sbp_msg;
+    sbp_msg.ecdsa_signature_dep = msg;
+    return sbp_msg;
+  }
+  static s8 send(sbp_state_t *state, u16 sender_id,
+                 const sbp_msg_ecdsa_signature_dep_t &msg,
+                 sbp_write_fn_t write) {
+    return sbp_msg_ecdsa_signature_dep_send(state, sender_id, &msg, write);
+  }
+  static s8 encode(uint8_t *buf, uint8_t len, uint8_t *n_written,
+                   const sbp_msg_ecdsa_signature_dep_t &msg) {
+    return sbp_msg_ecdsa_signature_dep_encode(buf, len, n_written, &msg);
+  }
+  static s8 decode(const uint8_t *buf, uint8_t len, uint8_t *n_read,
+                   sbp_msg_ecdsa_signature_dep_t *msg) {
+    return sbp_msg_ecdsa_signature_dep_decode(buf, len, n_read, msg);
+  }
+  static size_t encoded_len(const sbp_msg_ecdsa_signature_dep_t &msg) {
+    return sbp_msg_ecdsa_signature_dep_encoded_len(&msg);
+  }
+};
+
 template <>
 struct MessageTraits<sbp_msg_ecdsa_signature_t> {
   static constexpr sbp_msg_type_t id = SbpMsgEcdsaSignature;

c/include/libsbp/legacy/cpp/message_traits.h

@@ -1192,11 +1192,17 @@ struct MessageTraits<msg_certificate_chain_t> {
 
 
 template<>
-struct MessageTraits<msg_ecdsa_signature_t> {
+struct MessageTraits<msg_ecdsa_signature_dep_t> {
   static constexpr u16 id = 3078;
 };
 
 
+template<>
+struct MessageTraits<msg_ecdsa_signature_t> {
+  static constexpr u16 id = 3079;
+};
+
+
 template<>
 struct MessageTraits<msg_fileio_config_req_t> {
   static constexpr u16 id = 4097;

c/include/libsbp/legacy/signing.h

@@ -81,6 +81,45 @@ typedef struct SBP_ATTR_PACKED {
                                         `http(s)://certs.swiftnav.com/chain`. */
 } msg_certificate_chain_t;
 
+/** An ECDSA signature
+ *
+ * An ECDSA-256 signature using SHA-256 as the message digest algorithm.
+ */
+
+typedef struct SBP_ATTR_PACKED {
+  u8 flags;              /**< Describes the format of the `signed\_messages`
+                              field below. */
+  u8 stream_counter;     /**< Signature message counter. Zero indexed and
+                              incremented with each signature message.  The
+                              counter will not increment if this message was
+                              in response to an on demand request.  The
+                              counter will roll over after 256 messages.
+                              Upon connection, the value of the counter may
+                              not initially be zero. */
+  u8 on_demand_counter;  /**< On demand message counter. Zero indexed and
+                              incremented with each signature message sent
+                              in response to an on demand message. The
+                              counter will roll over after 256 messages.
+                              Upon connection, the value of the counter may
+                              not initially be zero. */
+  u8 certificate_id[4];  /**< The last 4 bytes of the certificate's SHA-1
+                              fingerprint */
+  u8 n_signature_bytes;  /**< Number of bytes to use of the signature field.
+                              The DER encoded signature has a maximum size
+                              of 72 bytes but can vary between 70 and 72
+                              bytes in length. */
+  u8 signature[72];      /**< DER encoded ECDSA signature for the messages
+                              using SHA-256 as the digest algorithm. */
+  u8 signed_messages[0]; /**< CRCs of the messages covered by this
+                              signature.  For Skylark, which delivers SBP
+                              messages wrapped in Swift's proprietary RTCM
+                              message, these are the 24-bit CRCs from the
+                              RTCM message framing. For SBP only streams,
+                              this will be 16-bit CRCs from the SBP framing.
+                              See the `flags` field to determine the type of
+                              CRCs covered. */
+} msg_ecdsa_signature_t;
+
 /** An ECDSA signature
  *
  * An ECDSA-256 signature using SHA-256 as the message digest algorithm.
@@ -114,7 +153,7 @@ typedef struct SBP_ATTR_PACKED {
                               this will be 16-bit CRCs from the SBP framing.
                               See the `flags` field to determine the type of
                               CRCs covered. */
-} msg_ecdsa_signature_t;
+} msg_ecdsa_signature_dep_t;
 
 typedef struct SBP_ATTR_PACKED {
   u8 n_msg;                /**< Total number messages that make up the

c/include/libsbp/sbp_msg_type.h

@@ -93,6 +93,7 @@ typedef enum {
   SbpMsgDopsDepA = SBP_MSG_DOPS_DEP_A,
   SbpMsgDops = SBP_MSG_DOPS,
   SbpMsgEcdsaCertificate = SBP_MSG_ECDSA_CERTIFICATE,
+  SbpMsgEcdsaSignatureDep = SBP_MSG_ECDSA_SIGNATURE_DEP,
   SbpMsgEcdsaSignature = SBP_MSG_ECDSA_SIGNATURE,
   SbpMsgEd25519CertificateDep = SBP_MSG_ED25519_CERTIFICATE_DEP,
   SbpMsgEd25519SignatureDepA = SBP_MSG_ED25519_SIGNATURE_DEP_A,

c/include/libsbp/signing_macros.h

@@ -112,7 +112,7 @@
  */
 #define SBP_MSG_CERTIFICATE_CHAIN_ENCODED_LEN 135u
 
-#define SBP_MSG_ECDSA_SIGNATURE 0x0C06
+#define SBP_MSG_ECDSA_SIGNATURE 0x0C07
 #define SBP_ECDSA_SIGNATURE_CRC_TYPE_MASK (0x3u)
 #define SBP_ECDSA_SIGNATURE_CRC_TYPE_SHIFT (0u)
 #define SBP_ECDSA_SIGNATURE_CRC_TYPE_GET(flags)               \
@@ -142,15 +142,15 @@
  * msg_ecdsa_signature_t::signature (legacy API) before the maximum SBP message
  * size is exceeded
  */
-#define SBP_MSG_ECDSA_SIGNATURE_SIGNATURE_MAX 64u
+#define SBP_MSG_ECDSA_SIGNATURE_SIGNATURE_MAX 72u
 
 /**
  * The maximum number of items that can be stored in
  * sbp_msg_ecdsa_signature_t::signed_messages (V4 API) or
  * msg_ecdsa_signature_t::signed_messages (legacy API) before the maximum SBP
  * message size is exceeded
  */
-#define SBP_MSG_ECDSA_SIGNATURE_SIGNED_MESSAGES_MAX 184u
+#define SBP_MSG_ECDSA_SIGNATURE_SIGNED_MESSAGES_MAX 175u
 
 /**
  * Encoded length of sbp_msg_ecdsa_signature_t (V4 API) and
@@ -165,7 +165,62 @@
  * See the documentation for libsbp for more details regarding the message
  * structure and its variable length component(s)
  */
-#define SBP_MSG_ECDSA_SIGNATURE_ENCODED_OVERHEAD 71u
+#define SBP_MSG_ECDSA_SIGNATURE_ENCODED_OVERHEAD 80u
+
+#define SBP_MSG_ECDSA_SIGNATURE_DEP 0x0C06
+#define SBP_ECDSA_SIGNATURE_DEP_CRC_TYPE_MASK (0x3u)
+#define SBP_ECDSA_SIGNATURE_DEP_CRC_TYPE_SHIFT (0u)
+#define SBP_ECDSA_SIGNATURE_DEP_CRC_TYPE_GET(flags)               \
+  ((u8)((u8)((flags) >> SBP_ECDSA_SIGNATURE_DEP_CRC_TYPE_SHIFT) & \
+        SBP_ECDSA_SIGNATURE_DEP_CRC_TYPE_MASK))
+#define SBP_ECDSA_SIGNATURE_DEP_CRC_TYPE_SET(flags, val)                      \
+  do {                                                                        \
+    (flags) = (u8)((flags & (~(SBP_ECDSA_SIGNATURE_DEP_CRC_TYPE_MASK          \
+                               << SBP_ECDSA_SIGNATURE_DEP_CRC_TYPE_SHIFT))) | \
+                   (((val) & (SBP_ECDSA_SIGNATURE_DEP_CRC_TYPE_MASK))         \
+                    << (SBP_ECDSA_SIGNATURE_DEP_CRC_TYPE_SHIFT)));            \
+  } while (0)
+
+#define SBP_ECDSA_SIGNATURE_DEP_CRC_TYPE_24_BIT_CRCS_FROM_RTCM_FRAMING (0)
+#define SBP_ECDSA_SIGNATURE_DEP_CRC_TYPE_16_BIT_CRCS_FROM_SBP_FRAMING (1)
+/**
+ * The maximum number of items that can be stored in
+ * sbp_msg_ecdsa_signature_dep_t::certificate_id (V4 API) or
+ * msg_ecdsa_signature_dep_t::certificate_id (legacy API) before the maximum SBP
+ * message size is exceeded
+ */
+#define SBP_MSG_ECDSA_SIGNATURE_DEP_CERTIFICATE_ID_MAX 4u
+
+/**
+ * The maximum number of items that can be stored in
+ * sbp_msg_ecdsa_signature_dep_t::signature (V4 API) or
+ * msg_ecdsa_signature_dep_t::signature (legacy API) before the maximum SBP
+ * message size is exceeded
+ */
+#define SBP_MSG_ECDSA_SIGNATURE_DEP_SIGNATURE_MAX 64u
+
+/**
+ * The maximum number of items that can be stored in
+ * sbp_msg_ecdsa_signature_dep_t::signed_messages (V4 API) or
+ * msg_ecdsa_signature_dep_t::signed_messages (legacy API) before the maximum
+ * SBP message size is exceeded
+ */
+#define SBP_MSG_ECDSA_SIGNATURE_DEP_SIGNED_MESSAGES_MAX 184u
+
+/**
+ * Encoded length of sbp_msg_ecdsa_signature_dep_t (V4 API) and
+ * msg_ecdsa_signature_dep_t (legacy API)
+ *
+ * This type is not fixed size and an instance of this message may be longer
+ * than the value indicated by this symbol. Users of the V4 API should call
+ * #sbp_msg_ecdsa_signature_dep_encoded_len to determine the actual size of an
+ * instance of this message. Users of the legacy API are required to track the
+ * encoded message length when interacting with the legacy type.
+ *
+ * See the documentation for libsbp for more details regarding the message
+ * structure and its variable length component(s)
+ */
+#define SBP_MSG_ECDSA_SIGNATURE_DEP_ENCODED_OVERHEAD 71u
 
 #define SBP_MSG_ED25519_CERTIFICATE_DEP 0x0C02
 /**

c/include/libsbp/v4/sbp_msg.h

@@ -99,6 +99,7 @@ typedef union {
   sbp_msg_dops_dep_a_t dops_dep_a;
   sbp_msg_dops_t dops;
   sbp_msg_ecdsa_certificate_t ecdsa_certificate;
+  sbp_msg_ecdsa_signature_dep_t ecdsa_signature_dep;
   sbp_msg_ecdsa_signature_t ecdsa_signature;
   sbp_msg_ed25519_certificate_dep_t ed25519_certificate_dep;
   sbp_msg_ed25519_signature_dep_a_t ed25519_signature_dep_a;
@@ -419,6 +420,9 @@ static inline s8 sbp_message_encode(uint8_t *buf, uint8_t len,
     case SbpMsgEcdsaCertificate:
       return sbp_msg_ecdsa_certificate_encode(buf, len, n_written,
                                               &msg->ecdsa_certificate);
+    case SbpMsgEcdsaSignatureDep:
+      return sbp_msg_ecdsa_signature_dep_encode(buf, len, n_written,
+                                                &msg->ecdsa_signature_dep);
     case SbpMsgEcdsaSignature:
       return sbp_msg_ecdsa_signature_encode(buf, len, n_written,
                                             &msg->ecdsa_signature);
@@ -1065,6 +1069,9 @@ static inline s8 sbp_message_decode(const uint8_t *buf, uint8_t len,
     case SbpMsgEcdsaCertificate:
       return sbp_msg_ecdsa_certificate_decode(buf, len, n_read,
                                               &msg->ecdsa_certificate);
+    case SbpMsgEcdsaSignatureDep:
+      return sbp_msg_ecdsa_signature_dep_decode(buf, len, n_read,
+                                                &msg->ecdsa_signature_dep);
     case SbpMsgEcdsaSignature:
       return sbp_msg_ecdsa_signature_decode(buf, len, n_read,
                                             &msg->ecdsa_signature);
@@ -1681,6 +1688,8 @@ static inline size_t sbp_message_encoded_len(sbp_msg_type_t msg_type,
       return sbp_msg_dops_encoded_len(&msg->dops);
     case SbpMsgEcdsaCertificate:
       return sbp_msg_ecdsa_certificate_encoded_len(&msg->ecdsa_certificate);
+    case SbpMsgEcdsaSignatureDep:
+      return sbp_msg_ecdsa_signature_dep_encoded_len(&msg->ecdsa_signature_dep);
     case SbpMsgEcdsaSignature:
       return sbp_msg_ecdsa_signature_encoded_len(&msg->ecdsa_signature);
     case SbpMsgEd25519CertificateDep:
@@ -2226,6 +2235,9 @@ static inline int sbp_message_cmp(sbp_msg_type_t msg_type, const sbp_msg_t *a,
     case SbpMsgEcdsaCertificate:
       return sbp_msg_ecdsa_certificate_cmp(&a->ecdsa_certificate,
                                            &b->ecdsa_certificate);
+    case SbpMsgEcdsaSignatureDep:
+      return sbp_msg_ecdsa_signature_dep_cmp(&a->ecdsa_signature_dep,
+                                             &b->ecdsa_signature_dep);
     case SbpMsgEcdsaSignature:
       return sbp_msg_ecdsa_signature_cmp(&a->ecdsa_signature,
                                          &b->ecdsa_signature);

c/include/libsbp/v4/signing.h

@@ -20,6 +20,7 @@
 #include <libsbp/v4/signing/MSG_CERTIFICATE_CHAIN.h>
 #include <libsbp/v4/signing/MSG_ECDSA_CERTIFICATE.h>
 #include <libsbp/v4/signing/MSG_ECDSA_SIGNATURE.h>
+#include <libsbp/v4/signing/MSG_ECDSA_SIGNATURE_DEP.h>
 #include <libsbp/v4/signing/MSG_ED25519_CERTIFICATE_DEP.h>
 #include <libsbp/v4/signing/MSG_ED25519_SIGNATURE_DEP_A.h>
 #include <libsbp/v4/signing/MSG_ED25519_SIGNATURE_DEP_B.h>

c/include/libsbp/v4/signing/MSG_ECDSA_SIGNATURE.h

@@ -70,7 +70,15 @@ typedef struct {
   u8 certificate_id[SBP_MSG_ECDSA_SIGNATURE_CERTIFICATE_ID_MAX];
 
   /**
-   * ECDSA signature for the messages using SHA-256 as the digest algorithm.
+   * Number of bytes to use of the signature field.  The DER encoded signature
+   * has a maximum size of 72 bytes but can vary between 70 and 72 bytes in
+   * length.
+   */
+  u8 n_signature_bytes;
+
+  /**
+   * DER encoded ECDSA signature for the messages using SHA-256 as the digest
+   * algorithm.
    */
   u8 signature[SBP_MSG_ECDSA_SIGNATURE_SIGNATURE_MAX];