codersize.c

IBE是一种非对称密码技术

/* Copyright 2003-2006, Voltage Security, all rights reserved.
 */
#include "vibe.h"
#include "environment.h"
#include "base.h"
#include "libctx.h"
#include "securemail.h"
#include "base64.h"
#include "errorctx.h"

int VoltCopyGetEncodeDecodeSize (
   VtAlgorithmObject coder,
   VtRandomObject random,
   unsigned int flagEncodeDecode,
   VoltEncodeDecodeSizeInfo *encodeDecodeSizeInfo
   )
{
  VOLT_DECLARE_FNCT_LINE (fnctLine)

  encodeDecodeSizeInfo->processedDataLen =
    encodeDecodeSizeInfo->dataToProcessLen;

  VOLT_SET_FNCT_LINE (fnctLine)
  VOLT_LOG_ERROR_INFO (
    0, coder, VT_ERROR_BUFFER_TOO_SMALL, 0, VT_ERROR_TYPE_PRIMARY,
    (char *)0, "VoltCopyGetEncodeDecodeSize", fnctLine, (char *)0)

  return (VT_ERROR_BUFFER_TOO_SMALL);
}

int VoltBase64GetEncodeDecodeSize (
   VtAlgorithmObject coder,
   VtRandomObject random,
   unsigned int flagEncodeDecode,
   VoltEncodeDecodeSizeInfo *encodeDecodeSizeInfo
   )
{
  int status;
#if VT_64_BIT_LENGTH == 64
  VtUInt64 totalLen, blockCount, extra, padLen;
#else
  unsigned int totalLen, blockCount, extra, padLen;
#endif
  VoltAlgorithmObject *obj = (VoltAlgorithmObject *)coder;
  VoltEncodeClassCtx *encodeCtx = (VoltEncodeClassCtx *)(obj->classCtx);
  VoltBase64Ctx *base64Ctx = (VoltBase64Ctx *)(encodeCtx->localEncodeCtx);
  VOLT_DECLARE_FNCT_LINE (fnctLine)

  VOLT_SET_FNCT_LINE (fnctLine)
  status = VT_ERROR_BUFFER_TOO_SMALL;
  switch (flagEncodeDecode)
  {
    default:
      VOLT_SET_FNCT_LINE (fnctLine)
      status = VT_ERROR_INVALID_CALL_ORDER;
      break;

    case VOLT_CALLER_ENCODE_UPDATE:
      /* For every binary block of input, there will be one base64
       * block.
       */
#if VT_64_BIT_LENGTH == 64
      totalLen =
        encodeDecodeSizeInfo->dataToProcessLen +
        (VtUInt64)(encodeCtx->unprocessedDataLen);
      blockCount = totalLen / (VtUInt64)(encodeCtx->plainBlockSize);
      encodeDecodeSizeInfo->processedDataLen =
        blockCount * (VtUInt64)(encodeCtx->codedBlockSize);
#else
      totalLen =
        encodeDecodeSizeInfo->dataToProcessLen +
        encodeCtx->unprocessedDataLen;
      blockCount = totalLen / encodeCtx->plainBlockSize;
      encodeDecodeSizeInfo->processedDataLen =
        blockCount * encodeCtx->codedBlockSize;
#endif
      break;

    case VOLT_CALLER_ENCODE_FINAL:
      /* For every binary block of input, there will be one base64
       * block.
       */
#if VT_64_BIT_LENGTH == 64
      totalLen =
        encodeDecodeSizeInfo->dataToProcessLen +
        (VtUInt64)(encodeCtx->unprocessedDataLen);
      blockCount = totalLen / (VtUInt64)(encodeCtx->plainBlockSize);
      encodeDecodeSizeInfo->processedDataLen =
        blockCount * (VtUInt64)(encodeCtx->codedBlockSize);
#else
      totalLen =
        encodeDecodeSizeInfo->dataToProcessLen +
        encodeCtx->unprocessedDataLen;
      blockCount = totalLen / encodeCtx->plainBlockSize;
      encodeDecodeSizeInfo->processedDataLen =
        blockCount * encodeCtx->codedBlockSize;
#endif

      /* For any extra left over, we'll "pad" to a multiple of three
       * and the final output will be 4 bytes for every three.
       * Then we'll add the required number of "=" characters.
       * We'll also need the line feed at the end.
       */
#if VT_64_BIT_LENGTH == 64
      extra = totalLen - (blockCount * (VtUInt64)(encodeCtx->plainBlockSize));
#else
      extra = totalLen - (blockCount * encodeCtx->plainBlockSize);
#endif
      if (extra == 0)
        break;

      padLen = extra % 3;
      if (padLen != 0)
        padLen = 3 - padLen;
      extra += padLen;
      extra = (extra / 3) * 4;
#if VT_64_BIT_LENGTH == 64
      encodeDecodeSizeInfo->processedDataLen +=
        (extra + (VtUInt64)(base64Ctx->newLineLen));
#else
      encodeDecodeSizeInfo->processedDataLen +=
        (extra + base64Ctx->newLineLen);
#endif
      break;

    case VOLT_CALLER_DECODE_UPDATE:
      /* For every 4 bytes of input, there are 3 bytes of output.
       * Actually, there are new line characters that should not be
       * considered part of the total length, however, we're not going
       * to search for them, so we'll use 3/4 * dataToProcessLen. This
       * will produce a number that may be too large.
       */
#if VT_64_BIT_LENGTH == 64
      totalLen =
        encodeDecodeSizeInfo->dataToProcessLen +
        (VtUInt64)(base64Ctx->converterLen);
#else
      totalLen =
        encodeDecodeSizeInfo->dataToProcessLen + base64Ctx->converterLen;
#endif
      encodeDecodeSizeInfo->processedDataLen = (totalLen / 4) * 3;
      break;

    case VOLT_CALLER_DECODE_FINAL:
      /* For every 4 bytes of input, there are 3 bytes of output.
       * Actually, there are new line characters that should not be
       * considered part of the total length, however, we're not going
       * to search for them, so we'll use 3/4 * dataToProcessLen. This
       * will produce a number that may be too large.
       * For Final, the total length of valid characters must be a
       * multiple of 4. If not, there will be an error (if checking).
       * But we don't know yet how many of the characters are invalid,
       * so we'll use the same formula.
       * If there are any leftovers, we may want to deal with them, so
       * find a "padded" length (the + 3).
       */
#if VT_64_BIT_LENGTH == 64
      totalLen =
        encodeDecodeSizeInfo->dataToProcessLen +
        (VtUInt64)(base64Ctx->converterLen);
#else
      totalLen =
        encodeDecodeSizeInfo->dataToProcessLen + base64Ctx->converterLen;
#endif
      encodeDecodeSizeInfo->processedDataLen = ((totalLen + 3) / 4) * 3;
  }

  VOLT_LOG_ERROR_INFO (
    0, coder, status, 0, VT_ERROR_TYPE_PRIMARY,
    (char *)0, "VoltBase64GetEncodeDecodeSize", fnctLine, (char *)0)

  return (status);
}