DER_Encode.h   [plain text]

/* Copyright (c) 2005-2007 Apple Inc. All Rights Reserved. */

/*
 * DER_Encode.h - DER encoding routines
 *
 * Created Dec. 2 2005 by dmitch
 */
 
#ifndef	_DER_ENCCODE_H_
#define _DER_ENCODE_H_

#ifdef __cplusplus
extern "C" {
#endif

#include "libDER.h"

/* 
 * Max size of an encoded item given its length. 
 * This includes a possible leading zero prepended to a signed integer
 * (see DER_ENC_SIGNED_INT below).
 */
#define DER_MAX_ENCODED_SIZE(len)					\
	( 1 +			/* tag */						\
	  5 +			/* max length */				\
	  1 +			/* possible prepended zero */	\
	  len)
	
/* calculate size of encoded length */
DERSize DERLengthOfLength(
	DERSize length);

/* encode length */
DERReturn DEREncodeLength(
	DERSize length,
	DERByte *buf,		/* encoded length goes here */
	DERSize *inOutLen);	/* IN/OUT */

/* calculate size of encoded length */
DERSize DERLengthOfItem(
	DERTag tag,
	DERSize length);

/* encode item */
DERReturn DEREncodeItem(
	DERTag tag,
	DERSize length,
    const DERByte *src,
	DERByte *derOut,	/* encoded item goes here */
	DERSize *inOutLen);	/* IN/OUT */

/* 
 * Per-item encode options.
 */
 
/* explicit default, no options */
#define DER_ENC_NO_OPTS			0x0000

/* signed integer check: if incoming m.s. bit is 1, prepend a zero */
#define DER_ENC_SIGNED_INT		0x0100

/* DERItem contains fully encoded item - copy, don't encode */
#define DER_ENC_WRITE_DER		0x0200


/*
 * High-level sequence or set encode support.
 *
 * The outgoing sequence is expressed as an array of DERItemSpecs, each
 * of which corresponds to one item in the encoded sequence. 
 *
 * Normally the tag of the encoded item comes from the associated 
 * DERItemSpec, and the content comes from the DERItem whose address is 
 * the src arg plus the offset value in the associated DERItemSpec.
 *
 * If the DER_ENC_WRITE_DER option is true for a given DERItemSpec then 
 * no per-item encoding is done; the DER - with tag, length, and content -
 * is taken en masse from the associated DERItem. 
 */
DERReturn DEREncodeSequence(
	DERTag				topTag,		/* ASN1_CONSTR_SEQUENCE, ASN1_CONSTR_SET */
	const void			*src,		/* generally a ptr to a struct full of 
									 *    DERItems */
	DERShort			numItems,	/* size of itemSpecs[] */
	const DERItemSpec	*itemSpecs,
	DERByte				*derOut,	/* encoded data written here */
	DERSize				*inOutLen);	/* IN/OUT */

/* precalculate the length of an encoded sequence. */
DERSize DERLengthOfEncodedSequence(
	DERTag				topTag,		/* ASN1_CONSTR_SEQUENCE, ASN1_CONSTR_SET */
	const void			*src,		/* generally a ptr to a struct full of 
									 *    DERItems */
	DERShort			numItems,	/* size of itemSpecs[] */
	const DERItemSpec	*itemSpecs);


#ifdef __cplusplus
}
#endif

#endif	/* _DER_DECODE_H_ */