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Diffstat (limited to 'stubdom/vtpmmgr/tpmrsa.c')
| -rw-r--r-- | stubdom/vtpmmgr/tpmrsa.c | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/stubdom/vtpmmgr/tpmrsa.c b/stubdom/vtpmmgr/tpmrsa.c new file mode 100644 index 0000000000..56094e735f --- /dev/null +++ b/stubdom/vtpmmgr/tpmrsa.c @@ -0,0 +1,175 @@ +/* + * The RSA public-key cryptosystem + * + * Copyright (C) 2006-2011, Brainspark B.V. + * + * This file is part of PolarSSL (http://www.polarssl.org) + * Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org> + * + * All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ +/* + * RSA was designed by Ron Rivest, Adi Shamir and Len Adleman. + * + * http://theory.lcs.mit.edu/~rivest/rsapaper.pdf + * http://www.cacr.math.uwaterloo.ca/hac/about/chap8.pdf + */ + +#include "tcg.h" +#include "polarssl/sha1.h" + +#include <stdlib.h> +#include <stdio.h> + +#include "tpmrsa.h" + +#define HASH_LEN 20 + +void tpmrsa_set_pubkey(tpmrsa_context* ctx, + const unsigned char* key, + int keylen, + const unsigned char* exponent, + int explen) { + + tpmrsa_free(ctx); + + if(explen == 0) { //Default e= 2^16+1 + mpi_lset(&ctx->E, 65537); + } else { + mpi_read_binary(&ctx->E, exponent, explen); + } + mpi_read_binary(&ctx->N, key, keylen); + + ctx->len = ( mpi_msb(&ctx->N) + 7) >> 3; +} + +static TPM_RESULT tpmrsa_public( tpmrsa_context *ctx, + const unsigned char *input, + unsigned char *output ) +{ + int ret; + size_t olen; + mpi T; + + mpi_init( &T ); + + MPI_CHK( mpi_read_binary( &T, input, ctx->len ) ); + + if( mpi_cmp_mpi( &T, &ctx->N ) >= 0 ) + { + mpi_free( &T ); + return TPM_ENCRYPT_ERROR; + } + + olen = ctx->len; + MPI_CHK( mpi_exp_mod( &T, &T, &ctx->E, &ctx->N, &ctx->RN ) ); + MPI_CHK( mpi_write_binary( &T, output, olen ) ); + +cleanup: + + mpi_free( &T ); + + if( ret != 0 ) + return TPM_ENCRYPT_ERROR; + + return TPM_SUCCESS; +} + +static void mgf_mask( unsigned char *dst, int dlen, unsigned char *src, int slen) +{ + unsigned char mask[HASH_LEN]; + unsigned char counter[4] = {0, 0, 0, 0}; + int i; + sha1_context mctx; + + //We always hash the src with the counter, so save the partial hash + sha1_starts(&mctx); + sha1_update(&mctx, src, slen); + + // Generate and apply dbMask + while(dlen > 0) { + //Copy the sha1 context + sha1_context ctx = mctx; + + //compute hash for input || counter + sha1_update(&ctx, counter, sizeof(counter)); + sha1_finish(&ctx, mask); + + //Apply the mask + for(i = 0; i < (dlen < HASH_LEN ? dlen : HASH_LEN); ++i) { + *(dst++) ^= mask[i]; + } + + //Increment counter + ++counter[3]; + + dlen -= HASH_LEN; + } +} + +/* + * Add the message padding, then do an RSA operation + */ +TPM_RESULT tpmrsa_pub_encrypt_oaep( tpmrsa_context *ctx, + int (*f_rng)(void *, unsigned char *, size_t), + void *p_rng, + size_t ilen, + const unsigned char *input, + unsigned char *output ) +{ + int ret; + int olen; + unsigned char* seed = output + 1; + unsigned char* db = output + HASH_LEN +1; + + olen = ctx->len-1; + + if( f_rng == NULL ) + return TPM_ENCRYPT_ERROR; + + if( ilen > olen - 2 * HASH_LEN - 1) + return TPM_ENCRYPT_ERROR; + + output[0] = 0; + + //Encoding parameter p + sha1((unsigned char*)"TCPA", 4, db); + + //PS + memset(db + HASH_LEN, 0, + olen - ilen - 2 * HASH_LEN - 1); + + //constant 1 byte + db[olen - ilen - HASH_LEN -1] = 0x01; + + //input string + memcpy(db + olen - ilen - HASH_LEN, + input, ilen); + + //Generate random seed + if( ( ret = f_rng( p_rng, seed, HASH_LEN ) ) != 0 ) + return TPM_ENCRYPT_ERROR; + + // maskedDB: Apply dbMask to DB + mgf_mask( db, olen - HASH_LEN, seed, HASH_LEN); + + // maskedSeed: Apply seedMask to seed + mgf_mask( seed, HASH_LEN, db, olen - HASH_LEN); + + // Do the crypto op + return tpmrsa_public(ctx, output, output); +} |