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头文件:

#ifndef _UPKI__UPKI_PKCS1_PAD_H

#define _UPKI__UPKI_PKCS1_PAD_H#include <string.h>#include <stdlib.h>

/* suggested int types */

  typedef unsigned char uint8_t;  typedef unsigned short uint16_t;  typedef unsigned int uint32_t;

/* boolean type */

  typedef enum { False, True } Boolean;

enum UPKIErrStatus {

  /** Requested operation completed successfully */

  UPKI_SUCCESS = 0, /* not necessary to force value to zero, but just to be safe */  /** Message is too long for this function */  UPKI_ERR_MSG_TOO_LONG,

};

#define MemCpy(s1,s2,n) memcpy((s1),(s2),(n))

#define MemSet(s1,c,n) memset((s1),(c),(n))#define MemCmp(s1,s2,n) memcmp((s1),(s2),(n))

UPKIErrStatus UPKI_EMSA_PKCS1_v1_5_Encode(int modulusSize, uint8_t * data          );

uint8_t *UPKI_EMSA_PKCS1_v1_5_Decode(int modulusSize, uint8_t * data

         );

#endif /* _UPKI__UPKI_PKCS1_PAD_H */

 

c文件

#include "upki_pkcs1_pad.h"

const uint8_t SHA1DigestInfo[] = {

  /* SEQUENCE */  0x30,  /* length */  0x21,  /* Algorithm Identifier */  /* SEQUENCE */  0x30,  /* length */#ifdef PKCS1_v2_1_BUG  0x1f,#else  0x09,#endif  /* OBJECT IDENTIFIER */  0x06,  /* Length */  0x05,  /* id-SHA1 ::= { iso(1) identified-organisation(3) oiw(14) secsig(3)   * algorithms(2) 26 */  0x2b, 0x0e, 0x03, 0x02, 0x1a,  /* NULL */  0x05, 0x00,   /* NB: Oscar omits this parameter */  /* OCTET STRING */  0x04,  /* length */  0x14};

#define SHA1DigestInfoLen sizeof(SHA1DigestInfo)

#define PKCS1_5_TYPE_01 0x01#define PKCS1_5_TYPE_02 0x02

/** Encode a message using the EMSA-PKCS-v1_5-Encode method *  * @ingroup upki_provider * * @param emLen Size of the modulus being used for the padding * @param data Buffer to place padded message in * @param alg Digest algorithm being used in this padding- just use sha1 * * @pre The message to be encoded is already at *   data[emLen - messageLength - 1] */UPKIErrStatusUPKI_EMSA_PKCS1_v1_5_Encode(int emLen, uint8_t * data){   int startM;  const uint8_t *digestInfo;  int digestInfoLen;

  /* EM = 01 || PS || 00 || T, where PS = >8 0xff bytes

   */    digestInfo = SHA1DigestInfo;    /* FIXME: Magic numbers */    startM = emLen - (20 + SHA1DigestInfoLen);    digestInfoLen = SHA1DigestInfoLen;

 

  /* Check message length */  if (startM < 10) {     return UPKI_ERR_MSG_TOO_LONG;  }

  /* 01 */

  data[0] = PKCS1_5_TYPE_01;

  /* PS */

  MemSet(data + 1, 0xff, startM - 2);

  /* 00 */

  data[startM - 1] = 0;

  /* DigestInfo */

  MemCpy(data + startM, digestInfo, digestInfoLen);

  /* M is already in there */

  return UPKI_SUCCESS;}

/** Decode a message using the EME-PKCS-v1_5-Decode method

 *  * @ingroup upki_provider * * @param emLen Size of the modulus being used for the padding * @param data Buffer containing the padded message * @param alg Digest algorithm being used in this padding- just use sha1 * * @return offset of the message or NULL on error * * @pre The message to be encoded is already at *   data[emLen - digestSize - 1] */uint8_t *UPKI_EMSA_PKCS1_v1_5_Decode  (int emLen, uint8_t * data) {   const uint8_t *digestInfo;  int i;  int startM;  int digestInfoLen;

  /* EM = 01 || PS || 00 || T, where PS = >8 0xff bytes

   */    digestInfo = SHA1DigestInfo;    /* FIXME: Magic numbers */    startM = emLen - (20 + SHA1DigestInfoLen);    digestInfoLen = SHA1DigestInfoLen;

  /* Check type */

  if (data[0] != PKCS1_5_TYPE_01) {     return 0;  }

  /* Check FF */

  for (i = 1; i < startM - 1; i++) {     if (data[i] != 0xff) {       return 0;    }  }

  /* Check 0 */

  if (data[i] != 0) {     return 0;  }

  /* Check digest info */

  if (MemCmp(data + startM, digestInfo, digestInfoLen) != 0) {     return 0;  }

  /* All hunky dory, return offset */

  return data + startM + digestInfoLen;} 

 

测试代码

#include<stdio.h>

#include "upki_pkcs1_pad.h"

const uint8_t testSHA1[] =

{   0xa9, 0x99, 0x3e, 0x36, 0x47, 0x06, 0x81, 0x6a, 0xba, 0x3e,  0x25, 0x71, 0x78, 0x50, 0xc2, 0x6c, 0x9c, 0xd0, 0xd8, 0x9d};

 

/* Digest algorithm sizes */

 enum DigestAlgorithmSize  {     ALG_SHA1_DIGEST_SIZE = 20,    ALG_MD5_DIGEST_SIZE = 16,    ALG_MD2_DIGEST_SIZE = 16  };

int main(){   uint8_t buf[128];  uint8_t *data;  int errs = 0;

  printf("EMSA-PKCS1-v1_5-Encode with SHA-1/n");

  memcpy(buf + 127 - ALG_SHA1_DIGEST_SIZE, testSHA1, ALG_SHA1_DIGEST_SIZE);  if (UPKI_EMSA_PKCS1_v1_5_Encode(127, buf) != UPKI_SUCCESS)   {     printf("failed/n");  } else   {     printf("ok/n");  }

  printf("EMSA-PKCS1-v1_5-Decode with SHA-1/n");

  data = UPKI_EMSA_PKCS1_v1_5_Decode(127, buf);  if (!data || memcmp(data, testSHA1, ALG_SHA1_DIGEST_SIZE) != 0)   {     printf("failed/n");    errs++;  } else   {     printf("ok/n");  }

   while(1);  return 0;}

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