diff --git a/src/hsm/cvc.c b/src/hsm/cvc.c
index 4d3f30e..347ca2b 100644
--- a/src/hsm/cvc.c
+++ b/src/hsm/cvc.c
@@ -48,13 +48,22 @@ size_t asn1_cvc_public_key_rsa(mbedtls_rsa_context *rsa, uint8_t *buf, size_t bu
     return tot_len;
 }
 
+const uint8_t *pointA[] = {
+    NULL,
+    (uint8_t *)"\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFE\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFC",
+    (uint8_t *)"\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFE\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFE"
+    (uint8_t *)"\xFF\xFF\xFF\xFF\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFC",
+    (uint8_t *)"\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFE\xFF\xFF\xFF\xFF\x00\x00\x00\x00\x00\x00\x00\x00\xFF\xFF\xFF\xFC",
+    (uint8_t *)"\x01\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFC",
+};
+
 size_t asn1_cvc_public_key_ecdsa(mbedtls_ecdsa_context *ecdsa, uint8_t *buf, size_t buf_len) {
     const uint8_t oid_ecdsa[] = { 0x04, 0x00, 0x7F, 0x00, 0x07, 0x02, 0x02, 0x02, 0x02, 0x03 };
     size_t p_size = mbedtls_mpi_size(&ecdsa->grp.P), a_size = mbedtls_mpi_size(&ecdsa->grp.A);
     size_t b_size = mbedtls_mpi_size(&ecdsa->grp.B), g_size = 1+mbedtls_mpi_size(&ecdsa->grp.G.X)+mbedtls_mpi_size(&ecdsa->grp.G.X);
     size_t o_size = mbedtls_mpi_size(&ecdsa->grp.N), y_size = 1+mbedtls_mpi_size(&ecdsa->Q.X)+mbedtls_mpi_size(&ecdsa->Q.X);
     size_t c_size = 1;
-    size_t ptot_size = asn1_len_tag(0x81, p_size), atot_size = asn1_len_tag(0x82, a_size);
+    size_t ptot_size = asn1_len_tag(0x81, p_size), atot_size = asn1_len_tag(0x82, a_size ? a_size : (pointA[ecdsa->grp.id] ? p_size : 0));
     size_t btot_size = asn1_len_tag(0x83, b_size), gtot_size = asn1_len_tag(0x84, g_size);
     size_t otot_size = asn1_len_tag(0x85, o_size), ytot_size = asn1_len_tag(0x86, y_size);
     size_t ctot_size = asn1_len_tag(0x87, c_size);
@@ -72,7 +81,17 @@ size_t asn1_cvc_public_key_ecdsa(mbedtls_ecdsa_context *ecdsa, uint8_t *buf, siz
     //p
     *p++ = 0x81; p += format_tlv_len(p_size, p); mbedtls_mpi_write_binary(&ecdsa->grp.P, p, p_size); p += p_size;
     //A
-    *p++ = 0x82; p += format_tlv_len(a_size, p); mbedtls_mpi_write_binary(&ecdsa->grp.A, p, a_size); p += a_size;
+    if (a_size) {
+        *p++ = 0x82; p += format_tlv_len(a_size, p); mbedtls_mpi_write_binary(&ecdsa->grp.A, p, a_size); p += a_size;
+    }
+    else { //mbedtls does not set point A for some curves
+        if (pointA[ecdsa->grp.id]) {
+            *p++ = 0x82; p += format_tlv_len(p_size, p); memcpy(p, pointA[ecdsa->grp.id], p_size); p += p_size;
+        }
+        else {
+            *p++ = 0x82; p += format_tlv_len(0, p);
+        }
+    }
     //B
     *p++ = 0x83; p += format_tlv_len(b_size, p); mbedtls_mpi_write_binary(&ecdsa->grp.B, p, b_size); p += b_size;
     //G