/* Demo of how to construct your own engine and using it.  The basis of this
   engine is RSAref, an old reference of the RSA algorithm which can still
   be found a little here and there. */

#include <stdio.h>
#include <string.h>
#include "./source/global.h"
#include "./source/rsaref.h"
#include "./source/rsa.h"
#include "./source/des.h"
#include <openssl/err.h>
#define OPENSSL_NO_MD2
#define OPENSSL_NO_MD5
#include <openssl/evp.h>
#include <openssl/bn.h>
#include <openssl/engine.h>

#define RSAREF_LIB_NAME "rsaref engine"
#include "rsaref_err.c"

/*****************************************************************************
 *** Function declarations and global variable definitions                 ***
 *****************************************************************************/

/*****************************************************************************
 * Constants used when creating the ENGINE
 **/
static const char *engine_rsaref_id = "rsaref";
static const char *engine_rsaref_name = "RSAref engine support";

/*****************************************************************************
 * Functions to handle the engine
 **/
static int rsaref_destroy(ENGINE *e);
static int rsaref_init(ENGINE *e);
static int rsaref_finish(ENGINE *e);
#if 0
static int rsaref_ctrl(ENGINE *e, int cmd, long i, void *p, void (*f)()); 
#endif

/*****************************************************************************
 * Engine commands
 **/
static const ENGINE_CMD_DEFN rsaref_cmd_defns[] = {
	{0, NULL, NULL, 0}
	};

/*****************************************************************************
 * RSA functions
 **/
static int rsaref_private_decrypt(int len, const unsigned char *from,
	unsigned char *to, RSA *rsa, int padding);
static int rsaref_private_encrypt(int len, const unsigned char *from,
	unsigned char *to, RSA *rsa, int padding);
static int rsaref_public_encrypt(int len, const unsigned char *from,
	unsigned char *to, RSA *rsa, int padding);
static int rsaref_public_decrypt(int len, const unsigned char *from,
	unsigned char *to, RSA *rsa, int padding);
static int bnref_mod_exp(BIGNUM *r,const BIGNUM *a,const BIGNUM *p,const BIGNUM *m,
			  BN_CTX *ctx, BN_MONT_CTX *m_ctx);
static int rsaref_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa);

/*****************************************************************************
 * Our RSA method
 **/
static RSA_METHOD rsaref_rsa =
{
  "RSAref PKCS#1 RSA",
  rsaref_public_encrypt,
  rsaref_public_decrypt,
  rsaref_private_encrypt,
  rsaref_private_decrypt,
  rsaref_mod_exp,
  bnref_mod_exp,
  NULL,
  NULL,
  0,
  NULL,
  NULL,
  NULL
};

/*****************************************************************************
 * Symetric cipher and digest function registrars
 **/
static int rsaref_ciphers(ENGINE *e, const EVP_CIPHER **cipher,
	const int **nids, int nid);
static int rsaref_digests(ENGINE *e, const EVP_MD **digest,
	const int **nids, int nid);

static int rsaref_cipher_nids[] =
	{ NID_des_cbc, NID_des_ede3_cbc, NID_desx_cbc, 0 };
static int rsaref_digest_nids[] =
	{ NID_md2, NID_md5, 0 };

/*****************************************************************************
 * DES functions
 **/
static int cipher_des_cbc_init(EVP_CIPHER_CTX *ctx, const unsigned char *key,
	const unsigned char *iv, int enc);
static int cipher_des_cbc_code(EVP_CIPHER_CTX *ctx, unsigned char *out,
	const unsigned char *in, unsigned int inl);
static int cipher_des_cbc_clean(EVP_CIPHER_CTX *);
static int cipher_des_ede3_cbc_init(EVP_CIPHER_CTX *ctx, const unsigned char *key,
	const unsigned char *iv, int enc);
static int cipher_des_ede3_cbc_code(EVP_CIPHER_CTX *ctx, unsigned char *out,
	const unsigned char *in, unsigned int inl);
static int cipher_des_ede3_cbc_clean(EVP_CIPHER_CTX *);
static int cipher_desx_cbc_init(EVP_CIPHER_CTX *ctx, const unsigned char *key,
	const unsigned char *iv, int enc);
static int cipher_desx_cbc_code(EVP_CIPHER_CTX *ctx, unsigned char *out,
	const unsigned char *in, unsigned int inl);
static int cipher_desx_cbc_clean(EVP_CIPHER_CTX *);

/*****************************************************************************
 * Our DES ciphers
 **/
static const EVP_CIPHER cipher_des_cbc =
	{
	NID_des_cbc,
	8, 8, 8,
	0 | EVP_CIPH_CBC_MODE,
	cipher_des_cbc_init,
	cipher_des_cbc_code,
	cipher_des_cbc_clean,
	sizeof(DES_CBC_CTX),
	NULL,
	NULL,
	NULL,
	NULL
	};

static const EVP_CIPHER cipher_des_ede3_cbc =
	{
	NID_des_ede3_cbc,
	8, 24, 8,
	0 | EVP_CIPH_CBC_MODE,
	cipher_des_ede3_cbc_init,
	cipher_des_ede3_cbc_code,
	cipher_des_ede3_cbc_clean,
	sizeof(DES3_CBC_CTX),
	NULL,
	NULL,
	NULL,
	NULL
	};

static const EVP_CIPHER cipher_desx_cbc =
	{
	NID_desx_cbc,
	8, 24, 8,
	0 | EVP_CIPH_CBC_MODE,
	cipher_desx_cbc_init,
	cipher_desx_cbc_code,
	cipher_desx_cbc_clean,
	sizeof(DESX_CBC_CTX),
	NULL,
	NULL,
	NULL,
	NULL
	};

/*****************************************************************************
 * MD functions
 **/
static int digest_md2_init(EVP_MD_CTX *ctx);
static int digest_md2_update(EVP_MD_CTX *ctx,const void *data,
	unsigned long count);
static int digest_md2_final(EVP_MD_CTX *ctx,unsigned char *md);
static int digest_md5_init(EVP_MD_CTX *ctx);
static int digest_md5_update(EVP_MD_CTX *ctx,const void *data,
	unsigned long count);
static int digest_md5_final(EVP_MD_CTX *ctx,unsigned char *md);

/*****************************************************************************
 * Our MD digests
 **/
static const EVP_MD digest_md2 =
	{
	NID_md2,
	NID_md2WithRSAEncryption,
	16,
	0,
	digest_md2_init,
	digest_md2_update,
	digest_md2_final,
	NULL,
	NULL,
	EVP_PKEY_RSA_method,
	16,
	sizeof(MD2_CTX)
	};

static const EVP_MD digest_md5 =
	{
	NID_md5,
	NID_md5WithRSAEncryption,
	16,
	0,
	digest_md5_init,
	digest_md5_update,
	digest_md5_final,
	NULL,
	NULL,
	EVP_PKEY_RSA_method,
	64,
	sizeof(MD5_CTX)
	};

/*****************************************************************************
 *** Function definitions                                                  ***
 *****************************************************************************/

/*****************************************************************************
 * Functions to handle the engine
 **/

static int bind_rsaref(ENGINE *e)
	{
	const RSA_METHOD *meth1;
	if(!ENGINE_set_id(e, engine_rsaref_id)
		|| !ENGINE_set_name(e, engine_rsaref_name)
		|| !ENGINE_set_RSA(e, &rsaref_rsa)
		|| !ENGINE_set_ciphers(e, rsaref_ciphers)
		|| !ENGINE_set_digests(e, rsaref_digests)
		|| !ENGINE_set_destroy_function(e, rsaref_destroy)
		|| !ENGINE_set_init_function(e, rsaref_init)
		|| !ENGINE_set_finish_function(e, rsaref_finish)
		/* || !ENGINE_set_ctrl_function(e, rsaref_ctrl) */
		/* || !ENGINE_set_cmd_defns(e, rsaref_cmd_defns) */)
		return 0;

	/* Ensure the rsaref error handling is set up */
	ERR_load_RSAREF_strings();
	return 1;
	}

#ifdef ENGINE_DYNAMIC_SUPPORT
static int bind_helper(ENGINE *e, const char *id)
	{
	if(id && (strcmp(id, engine_rsaref_id) != 0))
		return 0;
	if(!bind_rsaref(e))
		return 0;
	return 1;
	}       
IMPLEMENT_DYNAMIC_CHECK_FN()
IMPLEMENT_DYNAMIC_BIND_FN(bind_helper)
#else
static ENGINE *engine_rsaref(void)
	{
	ENGINE *ret = ENGINE_new();
	if(!ret)
		return NULL;
	if(!bind_rsaref(ret))
		{
		ENGINE_free(ret);
		return NULL;
		}
	return ret;
	}

void ENGINE_load_rsaref(void)
	{
	/* Copied from eng_[openssl|dyn].c */
	ENGINE *toadd = engine_rsaref();
	if(!toadd) return;
	ENGINE_add(toadd);
	ENGINE_free(toadd);
	ERR_clear_error();
	}
#endif

/* Initiator which is only present to make sure this engine looks available */
static int rsaref_init(ENGINE *e)
	{
	return 1;
	}

/* Finisher which is only present to make sure this engine looks available */
static int rsaref_finish(ENGINE *e)
	{
	return 1;
	}

/* Destructor (complements the "ENGINE_ncipher()" constructor) */
static int rsaref_destroy(ENGINE *e)
	{
	ERR_unload_RSAREF_strings();
	return 1;
	}

/*****************************************************************************
 * RSA functions
 **/

static int rsaref_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa)
	{
	RSAREFerr(RSAREF_F_RSAREF_MOD_EXP,ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
	return(0);
	}

static int bnref_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
			  const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx)
	{
	RSAREFerr(RSAREF_F_BNREF_MOD_EXP,ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
	return(0);
	}

/* unsigned char *to:  [max]    */
static int RSAref_bn2bin(BIGNUM *from, unsigned char *to, int max)
	{
	int i;

	i=BN_num_bytes(from);
	if (i > max)
		{
		RSAREFerr(RSAREF_F_RSAREF_BN2BIN,RSAREF_R_LEN);
		return(0);
		}

	memset(to,0,(unsigned int)max);
	if (!BN_bn2bin(from,&(to[max-i])))
		return(0);
	return(1);
	}

#ifdef undef
/* unsigned char *from:  [max]    */
static BIGNUM *RSAref_bin2bn(unsigned char *from, BIGNUM *to, int max)
	{
	int i;
	BIGNUM *ret;

	for (i=0; i<max; i++)
		if (from[i]) break;

	ret=BN_bin2bn(&(from[i]),max-i,to);
	return(ret);
	}

static int RSAref_Public_ref2eay(RSArefPublicKey *from, RSA *to)
	{
	to->n=RSAref_bin2bn(from->m,NULL,RSAref_MAX_LEN);
	to->e=RSAref_bin2bn(from->e,NULL,RSAref_MAX_LEN);
	if ((to->n == NULL) || (to->e == NULL)) return(0);
	return(1);
	}
#endif

static int RSAref_Public_eay2ref(RSA *from, R_RSA_PUBLIC_KEY *to)
	{
	to->bits=BN_num_bits(from->n);
	if (!RSAref_bn2bin(from->n,to->modulus,MAX_RSA_MODULUS_LEN)) return(0);
	if (!RSAref_bn2bin(from->e,to->exponent,MAX_RSA_MODULUS_LEN)) return(0);
	return(1);
	}

#ifdef undef
static int RSAref_Private_ref2eay(RSArefPrivateKey *from, RSA *to)
	{
	if ((to->n=RSAref_bin2bn(from->m,NULL,RSAref_MAX_LEN)) == NULL)
		return(0);
	if ((to->e=RSAref_bin2bn(from->e,NULL,RSAref_MAX_LEN)) == NULL)
		return(0);
	if ((to->d=RSAref_bin2bn(from->d,NULL,RSAref_MAX_LEN)) == NULL)
		return(0);
	if ((to->p=RSAref_bin2bn(from->prime[0],NULL,RSAref_MAX_PLEN)) == NULL)
		return(0);
	if ((to->q=RSAref_bin2bn(from->prime[1],NULL,RSAref_MAX_PLEN)) == NULL)
		return(0);
	if ((to->dmp1=RSAref_bin2bn(from->pexp[0],NULL,RSAref_MAX_PLEN))
		== NULL)
		return(0);
	if ((to->dmq1=RSAref_bin2bn(from->pexp[1],NULL,RSAref_MAX_PLEN))
		== NULL)
		return(0);
	if ((to->iqmp=RSAref_bin2bn(from->coef,NULL,RSAref_MAX_PLEN)) == NULL)
		return(0);
	return(1);
	}
#endif

static int RSAref_Private_eay2ref(RSA *from, R_RSA_PRIVATE_KEY *to)
	{
	to->bits=BN_num_bits(from->n);
	if (!RSAref_bn2bin(from->n,to->modulus,MAX_RSA_MODULUS_LEN)) return(0);
	if (!RSAref_bn2bin(from->e,to->publicExponent,MAX_RSA_MODULUS_LEN)) return(0);
	if (!RSAref_bn2bin(from->d,to->exponent,MAX_RSA_MODULUS_LEN)) return(0);
	if (!RSAref_bn2bin(from->p,to->prime[0],MAX_RSA_PRIME_LEN)) return(0);
	if (!RSAref_bn2bin(from->q,to->prime[1],MAX_RSA_PRIME_LEN)) return(0);
	if (!RSAref_bn2bin(from->dmp1,to->primeExponent[0],MAX_RSA_PRIME_LEN)) return(0);
	if (!RSAref_bn2bin(from->dmq1,to->primeExponent[1],MAX_RSA_PRIME_LEN)) return(0);
	if (!RSAref_bn2bin(from->iqmp,to->coefficient,MAX_RSA_PRIME_LEN)) return(0);
	return(1);
	}

static int rsaref_private_decrypt(int len, const unsigned char *from, unsigned char *to,
	     RSA *rsa, int padding)
	{
	int i,outlen= -1;
	R_RSA_PRIVATE_KEY RSAkey;

	if (!RSAref_Private_eay2ref(rsa,&RSAkey))
		goto err;
	if ((i=RSAPrivateDecrypt(to,(unsigned int *)&outlen,(unsigned char *)from,len,&RSAkey)) != 0)
		{
		RSAREFerr(RSAREF_F_RSAREF_PRIVATE_DECRYPT,i);
		outlen= -1;
		}
err:
	memset(&RSAkey,0,sizeof(RSAkey));
	return(outlen);
	}

static int rsaref_private_encrypt(int len, const unsigned char *from, unsigned char *to,
	     RSA *rsa, int padding)
	{
	int i,outlen= -1;
	R_RSA_PRIVATE_KEY RSAkey;

	if (padding != RSA_PKCS1_PADDING)
		{
		RSAREFerr(RSAREF_F_RSAREF_PRIVATE_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
		goto err;
	}
	if (!RSAref_Private_eay2ref(rsa,&RSAkey))
		goto err;
	if ((i=RSAPrivateEncrypt(to,(unsigned int *)&outlen,(unsigned char *)from,len,&RSAkey)) != 0)
		{
		RSAREFerr(RSAREF_F_RSAREF_PRIVATE_ENCRYPT,i);
		outlen= -1;
		}
err:
	memset(&RSAkey,0,sizeof(RSAkey));
	return(outlen);
	}

static int rsaref_public_decrypt(int len, const unsigned char *from, unsigned char *to,
	     RSA *rsa, int padding)
	{
	int i,outlen= -1;
	R_RSA_PUBLIC_KEY RSAkey;

	if (!RSAref_Public_eay2ref(rsa,&RSAkey))
		goto err;
	if ((i=RSAPublicDecrypt(to,(unsigned int *)&outlen,(unsigned char *)from,len,&RSAkey)) != 0)
		{
		RSAREFerr(RSAREF_F_RSAREF_PUBLIC_DECRYPT,i);
		outlen= -1;
		}
err:
	memset(&RSAkey,0,sizeof(RSAkey));
	return(outlen);
	}

static int rsaref_public_encrypt(int len, const unsigned char *from, unsigned char *to,
	     RSA *rsa, int padding)
	{
	int outlen= -1;
	int i;
	R_RSA_PUBLIC_KEY RSAkey;
	R_RANDOM_STRUCT rnd;
	unsigned char buf[16];

	if (padding != RSA_PKCS1_PADDING && padding != RSA_SSLV23_PADDING) 
		{
		RSAREFerr(RSAREF_F_RSAREF_PUBLIC_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
		goto err;
		}
	
	R_RandomInit(&rnd);
	R_GetRandomBytesNeeded((unsigned int *)&i,&rnd);
	while (i > 0)
		{
		if (RAND_bytes(buf,16) <= 0)
			goto err;
		R_RandomUpdate(&rnd,buf,(unsigned int)((i>16)?16:i));
		i-=16;
		}

	if (!RSAref_Public_eay2ref(rsa,&RSAkey))
		goto err;
	if ((i=RSAPublicEncrypt(to,(unsigned int *)&outlen,(unsigned char *)from,len,&RSAkey,&rnd)) != 0)
		{
		RSAREFerr(RSAREF_F_RSAREF_PUBLIC_ENCRYPT,i);
		outlen= -1;
		goto err;
		}
err:
	memset(&RSAkey,0,sizeof(RSAkey));
	R_RandomFinal(&rnd);
	memset(&rnd,0,sizeof(rnd));
	return(outlen);
	}

/*****************************************************************************
 * Symetric cipher and digest function registrars
 **/
static int rsaref_ciphers(ENGINE *e, const EVP_CIPHER **cipher,
	const int **nids, int nid)
	{
	int ok = 1;
	if(!cipher)
		{
		/* We are returning a list of supported nids */
		*nids = rsaref_cipher_nids;
		return (sizeof(rsaref_cipher_nids)-1)/sizeof(rsaref_cipher_nids[0]);
		}
	/* We are being asked for a specific cipher */
	switch (nid)
		{
	case NID_des_cbc:
		*cipher = &cipher_des_cbc; break;
	case NID_des_ede3_cbc:
		*cipher = &cipher_des_ede3_cbc; break;
	case NID_desx_cbc:
		*cipher = &cipher_desx_cbc; break;
	default:
		ok = 0;
		*cipher = NULL;
		break;
		}
	return ok;
	}
static int rsaref_digests(ENGINE *e, const EVP_MD **digest,
	const int **nids, int nid)
	{
	int ok = 1;
	if(!digest)
		{
		/* We are returning a list of supported nids */
		*nids = rsaref_digest_nids;
		return (sizeof(rsaref_digest_nids)-1)/sizeof(rsaref_digest_nids[0]);
		}
	/* We are being asked for a specific digest */
	switch (nid)
		{
	case NID_md2:
		*digest = &digest_md2; break;
	case NID_md5:
		*digest = &digest_md5; break;
	default:
		ok = 0;
		*digest = NULL;
		break;
		}
	return ok;
	}

/*****************************************************************************
 * DES functions
 **/
#undef data
#define data(ctx) ((DES_CBC_CTX *)(ctx)->cipher_data)
static int cipher_des_cbc_init(EVP_CIPHER_CTX *ctx, const unsigned char *key,
	const unsigned char *iv, int enc)
	{
	DES_CBCInit(data(ctx), (unsigned char *)key, (unsigned char *)iv, enc);
	return 1;
	}
static int cipher_des_cbc_code(EVP_CIPHER_CTX *ctx, unsigned char *out,
	const unsigned char *in, unsigned int inl)
	{
	int ret = DES_CBCUpdate(data(ctx), out, (unsigned char *)in, inl);
	switch (ret)
		{
	case RE_LEN:
		RSAREFerr(RSAREF_F_CIPHER_DES_CBC_CODE,RSAREF_R_LENGTH_NOT_BLOCK_ALIGNED);
		break;
	case 0:
		break;
	default:
		RSAREFerr(RSAREF_F_CIPHER_DES_CBC_CODE,RSAREF_R_UNKNOWN_FAULT);
		}
	return !ret;
	}
static int cipher_des_cbc_clean(EVP_CIPHER_CTX *ctx)
	{
	memset(data(ctx), 0, ctx->cipher->ctx_size);
	return 1;
	}

#undef data
#define data(ctx) ((DES3_CBC_CTX *)(ctx)->cipher_data)
static int cipher_des_ede3_cbc_init(EVP_CIPHER_CTX *ctx, const unsigned char *key,
	const unsigned char *iv, int enc)
	{
	DES3_CBCInit(data(ctx), (unsigned char *)key, (unsigned char *)iv,
		enc);
	return 1;
	}
static int cipher_des_ede3_cbc_code(EVP_CIPHER_CTX *ctx, unsigned char *out,
	const unsigned char *in, unsigned int inl)
	{
	int ret = DES3_CBCUpdate(data(ctx), out, (unsigned char *)in, inl);
	switch (ret)
		{
	case RE_LEN:
		RSAREFerr(RSAREF_F_CIPHER_DES_CBC_CODE,RSAREF_R_LENGTH_NOT_BLOCK_ALIGNED);
		break;
	case 0:
		break;
	default:
		RSAREFerr(RSAREF_F_CIPHER_DES_CBC_CODE,RSAREF_R_UNKNOWN_FAULT);
		}
	return !ret;
	}
static int cipher_des_ede3_cbc_clean(EVP_CIPHER_CTX *ctx)
	{
	memset(data(ctx), 0, ctx->cipher->ctx_size);
	return 1;
	}

#undef data
#define data(ctx) ((DESX_CBC_CTX *)(ctx)->cipher_data)
static int cipher_desx_cbc_init(EVP_CIPHER_CTX *ctx, const unsigned char *key,
	const unsigned char *iv, int enc)
	{
	DESX_CBCInit(data(ctx), (unsigned char *)key, (unsigned char *)iv,
		enc);
	return 1;
	}
static int cipher_desx_cbc_code(EVP_CIPHER_CTX *ctx, unsigned char *out,
	const unsigned char *in, unsigned int inl)
	{
	int ret = DESX_CBCUpdate(data(ctx), out, (unsigned char *)in, inl);
	switch (ret)
		{
	case RE_LEN:
		RSAREFerr(RSAREF_F_CIPHER_DES_CBC_CODE,RSAREF_R_LENGTH_NOT_BLOCK_ALIGNED);
		break;
	case 0:
		break;
	default:
		RSAREFerr(RSAREF_F_CIPHER_DES_CBC_CODE,RSAREF_R_UNKNOWN_FAULT);
		}
	return !ret;
	}
static int cipher_desx_cbc_clean(EVP_CIPHER_CTX *ctx)
	{
	memset(data(ctx), 0, ctx->cipher->ctx_size);
	return 1;
	}

/*****************************************************************************
 * MD functions
 **/
#undef data
#define data(ctx) ((MD2_CTX *)(ctx)->md_data)
static int digest_md2_init(EVP_MD_CTX *ctx)
	{
	MD2Init(data(ctx));
	return 1;
	}
static int digest_md2_update(EVP_MD_CTX *ctx,const void *data,
	unsigned long count)
	{
	MD2Update(data(ctx), (unsigned char *)data, (unsigned int)count);
	return 1;
	}
static int digest_md2_final(EVP_MD_CTX *ctx,unsigned char *md)
	{
	MD2Final(md, data(ctx));
	return 1;
	}

#undef data
#define data(ctx) ((MD5_CTX *)(ctx)->md_data)
static int digest_md5_init(EVP_MD_CTX *ctx)
	{
	MD5Init(data(ctx));
	return 1;
	}
static int digest_md5_update(EVP_MD_CTX *ctx,const void *data,
	unsigned long count)
	{
	MD5Update(data(ctx), (unsigned char *)data, (unsigned int)count);
	return 1;
	}
static int digest_md5_final(EVP_MD_CTX *ctx,unsigned char *md)
	{
	MD5Final(md, data(ctx));
	return 1;
	}