more key stuff

examples/example_keys.c

@@ -264,6 +264,29 @@ const unsigned char cose_ex_P_256_pub_der[91] = {
 };
 
 
+const unsigned char cose_ex_P_256_pair_cbor[] = {
+  0xa6, 0x01, 0x02, 0x02, 0x58, 0x24, 0x6d, 0x65,
+  0x72, 0x69, 0x61, 0x64, 0x6f, 0x63, 0x2e, 0x62,
+  0x72, 0x61, 0x6e, 0x64, 0x79, 0x62, 0x75, 0x63,
+  0x6b, 0x40, 0x62, 0x75, 0x63, 0x6b, 0x6c, 0x61,
+  0x6e, 0x64, 0x2e, 0x65, 0x78, 0x61, 0x6d, 0x70,
+  0x6c, 0x65, 0x20, 0x01, 0x21, 0x58, 0x20, 0x65,
+  0xed, 0xa5, 0xa1, 0x25, 0x77, 0xc2, 0xba, 0xe8,
+  0x29, 0x43, 0x7f, 0xe3, 0x38, 0x70, 0x1a, 0x10,
+  0xaa, 0xa3, 0x75, 0xe1, 0xbb, 0x5b, 0x5d, 0xe1,
+  0x08, 0xde, 0x43, 0x9c, 0x08, 0x55, 0x1d, 0x22,
+  0x58, 0x20, 0x1e, 0x52, 0xed, 0x75, 0x70, 0x11,
+  0x63, 0xf7, 0xf9, 0xe4, 0x0d, 0xdf, 0x9f, 0x34,
+  0x1b, 0x3d, 0xc9, 0xba, 0x86, 0x0a, 0xf7, 0xe0,
+  0xca, 0x7c, 0xa7, 0xe9, 0xee, 0xcd, 0x00, 0x84,
+  0xd1, 0x9c, 0x23, 0x58, 0x20, 0xaf, 0xf9, 0x07,
+  0xc9, 0x9f, 0x9a, 0xd3, 0xaa, 0xe6, 0xc4, 0xcd,
+  0xf2, 0x11, 0x22, 0xbc, 0xe2, 0xbd, 0x68, 0xb5,
+  0x28, 0x3e, 0x69, 0x07, 0x15, 0x4a, 0xd9, 0x11,
+  0x84, 0x0f, 0xa2, 0x08, 0xcf
+};
+
+
 const unsigned char cose_ex_P_521_priv_sec1[66] = {
     0x00, 0x08, 0x51, 0x38, 0xdd, 0xab, 0xf5, 0xca,
     0x97, 0x5f, 0x58, 0x60, 0xf9, 0x1a, 0x08, 0xe9,

examples/example_keys.h

@@ -201,6 +201,8 @@ extern const unsigned char cose_ex_P_256_priv_sec1[32];
 extern const unsigned char cose_ex_P_256_pub_sec1[65];
 extern const unsigned char cose_ex_P_256_pair_der[121];
 extern const unsigned char cose_ex_P_256_pub_der[91];
+extern const unsigned char cose_ex_P_256_pair_cbor[149];
+
 
 // KID: bilbo.baggins@hobbiton.example
 extern const unsigned char cose_ex_P_521_priv_sec1[66];

examples/init_keys_psa.c

@@ -240,7 +240,7 @@ init_fixed_test_ec_encryption_key(uint32_t           cose_ec_curve_id,
                             priv_key_bytes.ptr, priv_key_bytes.len,
                             (mbedtls_svc_key_id_t *)(&private_key->key.handle));
 
-
+#if 0
     /* Import the public key from the SEC1 representation. It is
      * the only format supported by psa_import_key(). ASN.1/DER/PEM
      * formats are not supported.
@@ -253,6 +253,14 @@ init_fixed_test_ec_encryption_key(uint32_t           cose_ec_curve_id,
     status = psa_import_key(&attributes,
                              pub_key_bytes.ptr, pub_key_bytes.len,
                              (mbedtls_svc_key_id_t *)(&public_key->key.handle));
+#else
+
+    t_cose_key_decode(Q_USEFUL_BUF_FROM_BYTE_ARRAY_LITERAL(cose_ex_P_256_pair_cbor), public_key);
+
+
+
+
+#endif
 
     /*
      * With PSA, it is also possible to import the private key as

inc/t_cose/t_cose_key.h

@@ -228,6 +228,10 @@ void
 t_cose_key_free_symmetric(struct t_cose_key key);
 
 
+enum t_cose_err_t
+t_cose_key_decode(struct q_useful_buf_c cbor_encoded,
+                  struct t_cose_key     *key);
+
 #ifdef __cplusplus
 }
 #endif

src/t_cose_key.c

@@ -10,6 +10,8 @@
  */
 #include "t_cose/t_cose_key.h"
 #include "t_cose_crypto.h"
+#include "qcbor/qcbor_spiffy_decode.h"
+#include "t_cose_crypto.h"
 
 
 /*
@@ -35,3 +37,74 @@ t_cose_key_free_symmetric(struct t_cose_key key)
     t_cose_crypto_free_symmetric_key(key);
 }
 
+
+
+enum t_cose_err_t
+t_cose_key_decode(struct q_useful_buf_c cbor_encoded,
+                  struct t_cose_key     *key)
+{
+    QCBORDecodeContext cbor_decoder;
+    int64_t  kty;
+    int64_t  curve;
+    struct q_useful_buf_c x;
+    struct q_useful_buf_c y_string;
+    bool y_bool;
+    QCBORItem y;
+    enum t_cose_err_t result;
+
+
+    QCBORDecode_Init(&cbor_decoder, cbor_encoded, 0);
+
+
+    QCBORDecode_EnterMap(&cbor_decoder, NULL);
+
+    QCBORDecode_GetInt64InMapN(&cbor_decoder, T_COSE_KEY_COMMON_KTY, &kty);
+    QCBORDecode_GetInt64InMapN(&cbor_decoder, T_COSE_KEY_PARAM_CRV, &curve);
+    QCBORDecode_GetByteStringInMapN(&cbor_decoder, T_COSE_KEY_PARAM_X_COORDINATE, &x);
+    QCBORDecode_GetItemInMapN(&cbor_decoder, T_COSE_KEY_PARAM_Y_COORDINATE, QCBOR_TYPE_ANY, &y);
+
+    QCBORDecode_ExitMap(&cbor_decoder);
+    if(QCBORDecode_GetError(&cbor_decoder)) {
+        return T_COSE_ERR_FAIL; // TODO: is this right?
+    }
+
+    // TODO: check kty
+
+    /* If y is a bool, then point compression is used and y is a boolean
+     * indicating the sign. If not then it is a byte string with the y.
+     * Anything else is an error. See RFC 9053 7.1.1.
+     */
+    switch(y.uDataType) {
+        case QCBOR_TYPE_BYTE_STRING:
+            y_string = y.val.string;
+            y_bool = true; /* Unused. Only here to avoid compiler warning */
+            break;
+
+        case QCBOR_TYPE_TRUE:
+            y_bool = true;
+            y_string = NULL_Q_USEFUL_BUF_C;
+            break;
+
+        case QCBOR_TYPE_FALSE:
+            y_bool = true;
+            y_string = NULL_Q_USEFUL_BUF_C;
+            break;
+
+        default:
+            return 77; // TODO: error code
+    }
+
+    /* Turn it into a t_cose_key that is imported into the library */
+
+    if(curve > INT32_MAX || curve < INT32_MIN) {
+        // Make sure cast is safe
+        return T_COSE_ERR_FAIL; // TODO: error
+    }
+    result = t_cose_crypto_import_ec2_pubkey((int32_t)curve,
+                                 x,
+                                 y_string,
+                                 y_bool,
+                                 key);
+
+    return result;
+}