comments added to highlight transfer syntax compatibility

FAQ

@@ -22,21 +22,6 @@
 		./x509dump -h
 
 
-3.Q: Your compiler supplies a der_encode() procedure. How do I encode BER?
-3.A:
-	The DER (and CER) are stricter subsets of a more generic BER encoding
-	method. If you encode data with DER or CER, all BER-conformant decoders
-	will easily understand that. Hence, to encode data in the BER format,
-	simply use the DER encoder, der_encode().
-
-	See also:	ISO/IEC 8825-1 / X.690:
-			"ASN.1 encoding rules: Specification of
-			 Basic Encoding Rules (BER),
-			 Canonical Encoding Rules (CER) and
-			 Distinguished Encoding Rules (DER)"
-
-
-
 -- 
 Lev Walkin
 vlm@lionet.info

skeletons/ber_decoder.h

@@ -17,7 +17,10 @@ struct asn_codec_ctx_s;		/* Forward declaration */
 /*
  * The BER decoder of any type.
  * This function may be invoked directly from the application.
- * The der_encode() function (der_encoder.h) is an opposite to ber_decode().
+ * Decodes BER, DER and CER data (DER and CER are different subsets of BER).
+ *
+ * NOTE: Use the der_encode() function (der_encoder.h) to produce encoding
+ * which is compliant with ber_decode().
  */
 asn_dec_rval_t ber_decode(struct asn_codec_ctx_s *opt_codec_ctx,
 	struct asn_TYPE_descriptor_s *type_descriptor,

skeletons/der_encoder.h

@@ -15,7 +15,10 @@ struct asn_TYPE_descriptor_s;	/* Forward declaration */
 
 /*
  * The DER encoder of any type. May be invoked by the application.
- * The ber_decode() function (ber_decoder.h) is an opposite of der_encode().
+ * Produces DER- and BER-compliant encoding. (DER is a subset of BER).
+ *
+ * NOTE: Use the ber_decode() function (ber_decoder.h) to decode data
+ * produced by der_encode().
  */
 asn_enc_rval_t der_encode(struct asn_TYPE_descriptor_s *type_descriptor,
 		void *struct_ptr,	/* Structure to be encoded */

skeletons/oer_decoder.h

@@ -18,6 +18,7 @@ struct asn_codec_ctx_s;		/* Forward declaration */
 /*
  * The Octet Encoding Rules (OER, X.696 08/2015) decoder for any given type.
  * This function may be invoked directly by the application.
+ * Parses CANONICAL-OER and BASIC-OER.
  */
 asn_dec_rval_t oer_decode(struct asn_codec_ctx_s *opt_codec_ctx,
 	struct asn_TYPE_descriptor_s *type_descriptor,

skeletons/oer_encoder.h

@@ -16,6 +16,8 @@ struct asn_TYPE_descriptor_s;	/* Forward declaration */
 /*
  * The Octet Encoding Rules (OER, X.696 08/2015) encoder for any type.
  * This function may be invoked directly by the application.
+ * Produces CANONICAL-OER output compatible with CANONICAL-OER
+ * and BASIC-OER decoders.
  */
 asn_enc_rval_t oer_encode(struct asn_TYPE_descriptor_s *type_descriptor,
                           void *struct_ptr, /* Structure to be encoded */

skeletons/xer_decoder.h

@@ -15,6 +15,7 @@ struct asn_TYPE_descriptor_s;	/* Forward declaration */
 
 /*
  * The XER decoder of any ASN.1 type. May be invoked by the application.
+ * Decodes CANONICAL-XER and BASIC-XER.
  */
 asn_dec_rval_t xer_decode(struct asn_codec_ctx_s *opt_codec_ctx,
 	struct asn_TYPE_descriptor_s *type_descriptor,

skeletons/xer_encoder.h

@@ -22,6 +22,7 @@ enum xer_encoder_flags_e {
 
 /*
  * The XER encoder of any type. May be invoked by the application.
+ * Produces CANONICAL-XER and BASIC-XER depending on the (xer_flags).
  */
 asn_enc_rval_t xer_encode(struct asn_TYPE_descriptor_s *type_descriptor,
 		void *struct_ptr,	/* Structure to be encoded */