DER_Encode.h

Go to the documentation of this file.

/* Copyright (c) 2005-2007 Apple Inc. All Rights Reserved. */
 
/*
 * DER_Encode.h - DER encoding routines
 *
 * Created Dec. 2 2005 by dmitch
 */
 
#ifndef _DER_ENCODE_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_ */