/********************************************************************************/
/*										*/
/*			   RSA_Decrypt						*/
/*			     Written by Ken Goldman				*/
/*		       IBM Thomas J. Watson Research Center			*/
/*	      $Id: rsadecrypt.c 987 2017-04-17 18:27:09Z kgoldman $		*/
/*										*/
/* (c) Copyright IBM Corporation 2015.						*/
/*										*/
/* All rights reserved.								*/
/* 										*/
/* Redistribution and use in source and binary forms, with or without		*/
/* modification, are permitted provided that the following conditions are	*/
/* met:										*/
/* 										*/
/* Redistributions of source code must retain the above copyright notice,	*/
/* this list of conditions and the following disclaimer.			*/
/* 										*/
/* Redistributions in binary form must reproduce the above copyright		*/
/* notice, this list of conditions and the following disclaimer in the		*/
/* documentation and/or other materials provided with the distribution.		*/
/* 										*/
/* Neither the names of the IBM Corporation nor the names of its		*/
/* contributors may be used to endorse or promote products derived from		*/
/* this software without specific prior written permission.			*/
/* 										*/
/* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS		*/
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/********************************************************************************/

/* 

*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>

#include <tss2/tss.h>
#include <tss2/tssutils.h>
#include <tss2/tssresponsecode.h>
#include <tss2/tssmarshal.h>
#include <tss2/tsscryptoh.h>

static void printRsaDecrypt(RSA_Decrypt_Out *out);
static TPM_RC padData(uint8_t 		**buffer,
		      size_t		*padLength,
		      TPMI_ALG_HASH 	halg,
		      TPMI_RSA_KEY_BITS	keyBits);
static void printUsage(void);

int verbose = FALSE;

int main(int argc, char *argv[])
{
    TPM_RC			rc = 0;
    int				i;    /* argc iterator */
    TSS_CONTEXT			*tssContext = NULL;
    RSA_Decrypt_In 		in;
    RSA_Decrypt_Out 		out;
    TPMI_DH_OBJECT		keyHandle = 0;
    const char			*encryptFilename = NULL;
    const char			*decryptFilename = NULL;
    const char			*keyPassword = NULL;
    TPMI_ALG_HASH 		halg = TPM_ALG_NULL;
    TPMI_SH_AUTH_SESSION    	sessionHandle0 = TPM_RS_PW;
    unsigned int		sessionAttributes0 = 0;
    TPMI_SH_AUTH_SESSION    	sessionHandle1 = TPM_RH_NULL;
    unsigned int		sessionAttributes1 = 0;
    TPMI_SH_AUTH_SESSION    	sessionHandle2 = TPM_RH_NULL;
    unsigned int		sessionAttributes2 = 0;
 
    uint16_t			written;
    size_t			length;			/* input data */
    uint8_t			*buffer = NULL;		/* for the free */
    uint8_t			*buffer1 = NULL;	/* for marshaling */

    setvbuf(stdout, 0, _IONBF, 0);      /* output may be going through pipe to log file */
    TSS_SetProperty(NULL, TPM_TRACE_LEVEL, "1");

    /* command line argument defaults */
    for (i=1 ; (i<argc) && (rc == 0) ; i++) {
	if (strcmp(argv[i],"-hk") == 0) {
	    i++;
	    if (i < argc) {
		sscanf(argv[i],"%x",&keyHandle);
	    }
	    else {
		printf("Missing parameter for -hk\n");
		printUsage();
	    }
	}
	else if (strcmp(argv[i],"-pwdk") == 0) {
	    i++;
	    if (i < argc) {
		keyPassword = argv[i];
	    }
	    else {
		printf("-pwdk option needs a value\n");
		printUsage();
	    }
	}
	else if (strcmp(argv[i],"-oid") == 0) {
	    i++;
	    if (i < argc) {
		if (strcmp(argv[i],"sha1") == 0) {
		    halg = TPM_ALG_SHA1;
		}
		else if (strcmp(argv[i],"sha256") == 0) {
		    halg = TPM_ALG_SHA256;
		}
		else if (strcmp(argv[i],"sha384") == 0) {
		    halg = TPM_ALG_SHA384;
		}
		else {
		    printf("Bad parameter for -oid\n");
		    printUsage();
		}
	    }
	    else {
		printf("-oid option needs a value\n");
		printUsage();
	    }
	}
	else if (strcmp(argv[i],"-ie") == 0) {
	    i++;
	    if (i < argc) {
		encryptFilename = argv[i];
	    }
	    else {
		printf("-ie option needs a value\n");
		printUsage();
	    }
	}
	else if (strcmp(argv[i],"-od") == 0) {
	    i++;
	    if (i < argc) {
		decryptFilename = argv[i];
	    }
	    else {
		printf("-od option needs a value\n");
		printUsage();
	    }
	}
	else if (strcmp(argv[i],"-se0") == 0) {
	    i++;
	    if (i < argc) {
		sscanf(argv[i],"%x", &sessionHandle0);
	    }
	    else {
		printf("Missing parameter for -se0\n");
		printUsage();
	    }
	    i++;
	    if (i < argc) {
		sscanf(argv[i],"%x", &sessionAttributes0);
		if (sessionAttributes0 > 0xff) {
		    printf("Out of range session attributes for -se0\n");
		    printUsage();
		}
	    }
	    else {
		printf("Missing parameter for -se0\n");
		printUsage();
	    }
	}
	else if (strcmp(argv[i],"-se1") == 0) {
	    i++;
	    if (i < argc) {
		sscanf(argv[i],"%x", &sessionHandle1);
	    }
	    else {
		printf("Missing parameter for -se1\n");
		printUsage();
	    }
	    i++;
	    if (i < argc) {
		sscanf(argv[i],"%x", &sessionAttributes1);
		if (sessionAttributes1 > 0xff) {
		    printf("Out of range session attributes for -se1\n");
		    printUsage();
		}
	    }
	    else {
		printf("Missing parameter for -se1\n");
		printUsage();
	    }
	}
	else if (strcmp(argv[i],"-se2") == 0) {
	    i++;
	    if (i < argc) {
		sscanf(argv[i],"%x", &sessionHandle2);
	    }
	    else {
		printf("Missing parameter for -se2\n");
		printUsage();
	    }
	    i++;
	    if (i < argc) {
		sscanf(argv[i],"%x", &sessionAttributes2);
		if (sessionAttributes2 > 0xff) {
		    printf("Out of range session attributes for -se2\n");
		    printUsage();
		}
	    }
	    else {
		printf("Missing parameter for -se2\n");
		printUsage();
	    }
	}
 	else if (strcmp(argv[i],"-h") == 0) {
	    printUsage();
	}
	else if (strcmp(argv[i],"-v") == 0) {
	    verbose = TRUE;
	    TSS_SetProperty(NULL, TPM_TRACE_LEVEL, "2");
	}
	else {
	    printf("\n%s is not a valid option\n", argv[i]);
	    printUsage();
	}
    }
    if (keyHandle == 0) {
	printf("Missing handle parameter -hk\n");
	printUsage();
    }
    if (encryptFilename == NULL) {
	printf("Missing encrypted message -ie\n");
	printUsage();
    }
    if (rc == 0) {
	rc = TSS_File_ReadBinaryFile(&buffer,     /* must be freed by caller */
				     &length,
				     encryptFilename);
    }
    /* if an OID was requested, treat the encryptFilename as a hash to be signed */
    if ((rc == 0) && (halg != TPM_ALG_NULL)) {
	rc = padData(&buffer,		/* realloced to fit */
		     &length,		/* resized for OID and pad */
		     halg,
		     2048);		/* hard coded RSA-2048 */
	/* FIXME use readpublic and get bit size or maybe byte size */
    }
    if (rc == 0) {
	/* Handle of key that will perform rsa decrypt */
	in.keyHandle = keyHandle;

	/* Table 158 - Definition of {RSA} TPM2B_PUBLIC_KEY_RSA Structure */
	{
	    in.cipherText.t.size = length;
	    memcpy(in.cipherText.t.buffer, buffer, length);
	}
	/* padding scheme */
	{
	    /* Table 157 - Definition of {RSA} TPMT_RSA_DECRYPT Structure */
	    in.inScheme.scheme = TPM_ALG_NULL;
	}
	/* label */
	{
	    /* Table 73 - Definition of TPM2B_DATA Structure */
	    in.label.t.size = 0;
	}
    }
    free (buffer);
    buffer = NULL;

    /* Start a TSS context */
    if (rc == 0) {
	rc = TSS_Create(&tssContext);
    }
    /* call TSS to execute the command */
    if (rc == 0) {
	rc = TSS_Execute(tssContext,
			 (RESPONSE_PARAMETERS *)&out,
			 (COMMAND_PARAMETERS *)&in,
			 NULL,
			 TPM_CC_RSA_Decrypt,
			 sessionHandle0, keyPassword, sessionAttributes0,
			 sessionHandle1, NULL, sessionAttributes1,
			 sessionHandle2, NULL, sessionAttributes2,
			 TPM_RH_NULL, NULL, 0);
    }
    {
	TPM_RC rc1 = TSS_Delete(tssContext);
	if (rc == 0) {
	    rc = rc1;
	}
    }
    if ((rc == 0) && (decryptFilename != NULL)) {
	written = 0;
	rc = TSS_TPM2B_PUBLIC_KEY_RSA_Marshal(&out.message, &written, NULL, NULL);
    }    
    if ((rc == 0) && (decryptFilename != NULL)) {
	buffer = realloc(buffer, written);
	buffer1 = buffer;
	written = 0;
	rc = TSS_TPM2B_PUBLIC_KEY_RSA_Marshal(&out.message, &written, &buffer1, NULL);
    }    
    if ((rc == 0) && (decryptFilename != NULL)) {
	rc = TSS_File_WriteBinaryFile(buffer + sizeof(uint16_t),
				      written - sizeof(uint16_t),
				      decryptFilename); 
    }    
    free(buffer);
    if (rc == 0) {
	if (verbose) printRsaDecrypt(&out);
	if (verbose) printf("rsadecrypt: success\n");
    }
    else {
	const char *msg;
	const char *submsg;
	const char *num;
	printf("rsadecrypt: failed, rc %08x\n", rc);
	TSS_ResponseCode_toString(&msg, &submsg, &num, rc);
	printf("%s%s%s\n", msg, submsg, num);
	rc = EXIT_FAILURE;
    }
    return rc;
}

static TPM_RC padData(uint8_t 			**buffer,
		      size_t			*padLength,
		      TPMI_ALG_HASH 		halg,
		      TPMI_RSA_KEY_BITS		keyBits)
{
    TPM_RC		rc = 0;
    uint16_t 		digestSize;
    const uint8_t	*oid;
    uint16_t		oidSize;
    const uint8_t	sha1Oid[] = {SHA1_DER};
    const uint8_t	sha256Oid[] = {SHA256_DER};
    const uint8_t	sha384Oid[] = {SHA384_DER};
    
    /* check that the original buffer length matches the hash algorithm */
    if (rc == 0) {
	digestSize = TSS_GetDigestSize(halg);
	if (digestSize == 0) {
	    printf("padData: Unsupported hash algorithm %04x\n", halg);
	    rc = TPM_RC_HASH;
	}
    }
    if (rc == 0) {
	if (digestSize != *padLength) {
	    unsigned long pl = *padLength;
	    printf("paddata: hash algorithm length %u not equal data length %lu\n",
		   digestSize, pl);
	    rc = TPM_RC_VALUE;
	}
    }
    /* realloc the buffer to the key size in bytes */
    if (rc == 0) {
	*padLength = keyBits / 8;
	rc = TSS_Realloc(buffer, *padLength);
    }
    /* determine the OID */
    if (rc == 0) {
	switch (halg) {
	  case TPM_ALG_SHA1:
	    oid = sha1Oid;
	    oidSize = SHA1_DER_SIZE;
	    break;
	  case TPM_ALG_SHA256:
	    oid = sha256Oid;
	    oidSize = SHA256_DER_SIZE;
	    break;
	  case TPM_ALG_SHA384:
	    oid = sha384Oid;
	    oidSize = SHA384_DER_SIZE;
	    break;
	  default:
	    printf("padData: Unsupported hash algorithm %04x\n", halg);
	    rc = TPM_RC_HASH;
	}
    }
    if (rc == 0) {
	/* move the hash to the end */
	memmove(*buffer + *padLength - digestSize, *buffer, digestSize);
	/* prepend the OID */
	memcpy(*buffer + *padLength - digestSize - oidSize, oid, oidSize);
	/* prepend the PKCS1 pad */
	(*buffer)[0] = 0x00;
	(*buffer)[1] = 0x01;
	memset(&(*buffer)[2], 0xff, *padLength - 3 - oidSize - digestSize);
	(*buffer)[*padLength - oidSize - digestSize - 1] = 0x00;
	if (verbose) TSS_PrintAll("padData: padded data", *buffer, *padLength);
    }
    return rc;
}

static void printRsaDecrypt(RSA_Decrypt_Out *out)
{
    TSS_PrintAll("outData", out->message.t.buffer, out->message.t.size);
}

static void printUsage(void)
{
    printf("\n");
    printf("rsadecrypt\n");
    printf("\n");
    printf("Runs TPM2_RSA_Decrypt\n");
    printf("\n");
    printf("\t-hk key handle\n");
    printf("\t-pwdk password for key (default empty)\n");
    printf("\t-ie encrypt file name\n");
    printf("\t-od decrypt file name (default do not save)\n");
    printf("\t[-oid (sha1, sha256, sha384) optionally add OID and PKCS1 padding\n");
    printf("\t\tto the encrypt data (demo of signing with arbitrary OID)\n");
    printf("\n");
    printf("\t-se[0-2] session handle / attributes (default PWAP)\n");
    printf("\t\t01 continue\n");
    exit(1);	
}