/* * The RSA public-key cryptosystem * * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved * SPDX-License-Identifier: Apache-2.0 * * Licensed under the Apache License, Version 2.0 (the "License"); you may * not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * * This file is part of mbed TLS (https://tls.mbed.org) */ /* * The following sources were referenced in the design of this implementation * of the RSA algorithm: * * [1] A method for obtaining digital signatures and public-key cryptosystems * R Rivest, A Shamir, and L Adleman * http://people.csail.mit.edu/rivest/pubs.html#RSA78 * * [2] Handbook of Applied Cryptography - 1997, Chapter 8 * Menezes, van Oorschot and Vanstone * * [3] Malware Guard Extension: Using SGX to Conceal Cache Attacks * Michael Schwarz, Samuel Weiser, Daniel Gruss, Clémentine Maurice and * Stefan Mangard * https://arxiv.org/abs/1702.08719v2 * */ #if !defined(MBEDTLS_CONFIG_FILE) #include "mbedtls/config.h" #else #include MBEDTLS_CONFIG_FILE #endif #if defined(MBEDTLS_RSA_C) #include "mbedtls/rsa.h" #include "mbedtls/oid.h" #include #if defined(MBEDTLS_PKCS1_V21) #include "mbedtls/md.h" #endif #if defined(MBEDTLS_PKCS1_V15) && !defined(__OpenBSD__) #include #endif #if defined(MBEDTLS_PLATFORM_C) #include "mbedtls/platform.h" #else #include #define mbedtls_printf printf #define mbedtls_calloc calloc #define mbedtls_free free #endif /* Implementation that should never be optimized out by the compiler */ static void mbedtls_zeroize( void *v, size_t n ) { volatile unsigned char *p = (unsigned char*)v; while( n-- ) *p++ = 0; } /* constant-time buffer comparison */ static inline int mbedtls_safer_memcmp( const void *a, const void *b, size_t n ) { size_t i; const unsigned char *A = (const unsigned char *) a; const unsigned char *B = (const unsigned char *) b; unsigned char diff = 0; for( i = 0; i < n; i++ ) diff |= A[i] ^ B[i]; return( diff ); } /* * Initialize an RSA context */ void mbedtls_rsa_init( mbedtls_rsa_context *ctx, int padding, int hash_id ) { memset( ctx, 0, sizeof( mbedtls_rsa_context ) ); mbedtls_rsa_set_padding( ctx, padding, hash_id ); #if defined(MBEDTLS_THREADING_C) mbedtls_mutex_init( &ctx->mutex ); #endif } /* * Set padding for an existing RSA context */ void mbedtls_rsa_set_padding( mbedtls_rsa_context *ctx, int padding, int hash_id ) { ctx->padding = padding; ctx->hash_id = hash_id; } #if defined(MBEDTLS_GENPRIME) /* * Generate an RSA keypair */ int mbedtls_rsa_gen_key( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, unsigned int nbits, int exponent ) { int ret; mbedtls_mpi P1, Q1, H, G; if( f_rng == NULL || nbits < 128 || exponent < 3 ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); if( nbits % 2 ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); mbedtls_mpi_init( &P1 ); mbedtls_mpi_init( &Q1 ); mbedtls_mpi_init( &H ); mbedtls_mpi_init( &G ); /* * find primes P and Q with Q < P so that: * GCD( E, (P-1)*(Q-1) ) == 1 */ MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &ctx->E, exponent ) ); do { MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->P, nbits >> 1, 0, f_rng, p_rng ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->Q, nbits >> 1, 0, f_rng, p_rng ) ); if( mbedtls_mpi_cmp_mpi( &ctx->P, &ctx->Q ) == 0 ) continue; MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->N, &ctx->P, &ctx->Q ) ); if( mbedtls_mpi_bitlen( &ctx->N ) != nbits ) continue; if( mbedtls_mpi_cmp_mpi( &ctx->P, &ctx->Q ) < 0 ) mbedtls_mpi_swap( &ctx->P, &ctx->Q ); MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &P1, &ctx->P, 1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &Q1, &ctx->Q, 1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &H, &P1, &Q1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &G, &ctx->E, &H ) ); } while( mbedtls_mpi_cmp_int( &G, 1 ) != 0 ); /* * D = E^-1 mod ((P-1)*(Q-1)) * DP = D mod (P - 1) * DQ = D mod (Q - 1) * QP = Q^-1 mod P */ MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->D , &ctx->E, &H ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->DP, &ctx->D, &P1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->DQ, &ctx->D, &Q1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->QP, &ctx->Q, &ctx->P ) ); ctx->len = ( mbedtls_mpi_bitlen( &ctx->N ) + 7 ) >> 3; cleanup: mbedtls_mpi_free( &P1 ); mbedtls_mpi_free( &Q1 ); mbedtls_mpi_free( &H ); mbedtls_mpi_free( &G ); if( ret != 0 ) { mbedtls_rsa_free( ctx ); return( MBEDTLS_ERR_RSA_KEY_GEN_FAILED + ret ); } return( 0 ); } #endif /* MBEDTLS_GENPRIME */ /* * Check a public RSA key */ int mbedtls_rsa_check_pubkey( const mbedtls_rsa_context *ctx ) { if( !ctx->N.p || !ctx->E.p ) return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); if( ( ctx->N.p[0] & 1 ) == 0 || ( ctx->E.p[0] & 1 ) == 0 ) return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); if( mbedtls_mpi_bitlen( &ctx->N ) < 128 || mbedtls_mpi_bitlen( &ctx->N ) > MBEDTLS_MPI_MAX_BITS ) return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); if( mbedtls_mpi_bitlen( &ctx->E ) < 2 || mbedtls_mpi_cmp_mpi( &ctx->E, &ctx->N ) >= 0 ) return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); return( 0 ); } /* * Check a private RSA key */ int mbedtls_rsa_check_privkey( const mbedtls_rsa_context *ctx ) { int ret; mbedtls_mpi PQ, DE, P1, Q1, H, I, G, G2, L1, L2, DP, DQ, QP; if( ( ret = mbedtls_rsa_check_pubkey( ctx ) ) != 0 ) return( ret ); if( !ctx->P.p || !ctx->Q.p || !ctx->D.p ) return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); mbedtls_mpi_init( &PQ ); mbedtls_mpi_init( &DE ); mbedtls_mpi_init( &P1 ); mbedtls_mpi_init( &Q1 ); mbedtls_mpi_init( &H ); mbedtls_mpi_init( &I ); mbedtls_mpi_init( &G ); mbedtls_mpi_init( &G2 ); mbedtls_mpi_init( &L1 ); mbedtls_mpi_init( &L2 ); mbedtls_mpi_init( &DP ); mbedtls_mpi_init( &DQ ); mbedtls_mpi_init( &QP ); MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &PQ, &ctx->P, &ctx->Q ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &DE, &ctx->D, &ctx->E ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &P1, &ctx->P, 1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &Q1, &ctx->Q, 1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &H, &P1, &Q1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &G, &ctx->E, &H ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &G2, &P1, &Q1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_div_mpi( &L1, &L2, &H, &G2 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &I, &DE, &L1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &DP, &ctx->D, &P1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &DQ, &ctx->D, &Q1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &QP, &ctx->Q, &ctx->P ) ); /* * Check for a valid PKCS1v2 private key */ if( mbedtls_mpi_cmp_mpi( &PQ, &ctx->N ) != 0 || mbedtls_mpi_cmp_mpi( &DP, &ctx->DP ) != 0 || mbedtls_mpi_cmp_mpi( &DQ, &ctx->DQ ) != 0 || mbedtls_mpi_cmp_mpi( &QP, &ctx->QP ) != 0 || mbedtls_mpi_cmp_int( &L2, 0 ) != 0 || mbedtls_mpi_cmp_int( &I, 1 ) != 0 || mbedtls_mpi_cmp_int( &G, 1 ) != 0 ) { ret = MBEDTLS_ERR_RSA_KEY_CHECK_FAILED; } cleanup: mbedtls_mpi_free( &PQ ); mbedtls_mpi_free( &DE ); mbedtls_mpi_free( &P1 ); mbedtls_mpi_free( &Q1 ); mbedtls_mpi_free( &H ); mbedtls_mpi_free( &I ); mbedtls_mpi_free( &G ); mbedtls_mpi_free( &G2 ); mbedtls_mpi_free( &L1 ); mbedtls_mpi_free( &L2 ); mbedtls_mpi_free( &DP ); mbedtls_mpi_free( &DQ ); mbedtls_mpi_free( &QP ); if( ret == MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ) return( ret ); if( ret != 0 ) return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED + ret ); return( 0 ); } /* * Check if contexts holding a public and private key match */ int mbedtls_rsa_check_pub_priv( const mbedtls_rsa_context *pub, const mbedtls_rsa_context *prv ) { if( mbedtls_rsa_check_pubkey( pub ) != 0 || mbedtls_rsa_check_privkey( prv ) != 0 ) { return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); } if( mbedtls_mpi_cmp_mpi( &pub->N, &prv->N ) != 0 || mbedtls_mpi_cmp_mpi( &pub->E, &prv->E ) != 0 ) { return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); } return( 0 ); } /* * Do an RSA public key operation */ int mbedtls_rsa_public( mbedtls_rsa_context *ctx, const unsigned char *input, unsigned char *output ) { int ret; size_t olen; mbedtls_mpi T; mbedtls_mpi_init( &T ); #if defined(MBEDTLS_THREADING_C) if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) return( ret ); #endif MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &T, input, ctx->len ) ); if( mbedtls_mpi_cmp_mpi( &T, &ctx->N ) >= 0 ) { ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA; goto cleanup; } olen = ctx->len; MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T, &T, &ctx->E, &ctx->N, &ctx->RN ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &T, output, olen ) ); cleanup: #if defined(MBEDTLS_THREADING_C) if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); #endif mbedtls_mpi_free( &T ); if( ret != 0 ) return( MBEDTLS_ERR_RSA_PUBLIC_FAILED + ret ); return( 0 ); } /* * Generate or update blinding values, see section 10 of: * KOCHER, Paul C. Timing attacks on implementations of Diffie-Hellman, RSA, * DSS, and other systems. In : Advances in Cryptology-CRYPTO'96. Springer * Berlin Heidelberg, 1996. p. 104-113. */ static int rsa_prepare_blinding( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) { int ret, count = 0; if( ctx->Vf.p != NULL ) { /* We already have blinding values, just update them by squaring */ MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vi, &ctx->Vi, &ctx->Vi ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vi, &ctx->Vi, &ctx->N ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vf, &ctx->Vf, &ctx->Vf ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vf, &ctx->Vf, &ctx->N ) ); goto cleanup; } /* Unblinding value: Vf = random number, invertible mod N */ do { if( count++ > 10 ) return( MBEDTLS_ERR_RSA_RNG_FAILED ); MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &ctx->Vf, ctx->len - 1, f_rng, p_rng ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &ctx->Vi, &ctx->Vf, &ctx->N ) ); } while( mbedtls_mpi_cmp_int( &ctx->Vi, 1 ) != 0 ); /* Blinding value: Vi = Vf^(-e) mod N */ MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->Vi, &ctx->Vf, &ctx->N ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->Vi, &ctx->Vi, &ctx->E, &ctx->N, &ctx->RN ) ); cleanup: return( ret ); } /* * Exponent blinding supposed to prevent side-channel attacks using multiple * traces of measurements to recover the RSA key. The more collisions are there, * the more bits of the key can be recovered. See [3]. * * Collecting n collisions with m bit long blinding value requires 2^(m-m/n) * observations on avarage. * * For example with 28 byte blinding to achieve 2 collisions the adversary has * to make 2^112 observations on avarage. * * (With the currently (as of 2017 April) known best algorithms breaking 2048 * bit RSA requires approximately as much time as trying out 2^112 random keys. * Thus in this sense with 28 byte blinding the security is not reduced by * side-channel attacks like the one in [3]) * * This countermeasure does not help if the key recovery is possible with a * single trace. */ #define RSA_EXPONENT_BLINDING 28 /* * Do an RSA private key operation */ int mbedtls_rsa_private( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, const unsigned char *input, unsigned char *output ) { int ret; size_t olen; mbedtls_mpi T, T1, T2; mbedtls_mpi P1, Q1, R; #if defined(MBEDTLS_RSA_NO_CRT) mbedtls_mpi D_blind; mbedtls_mpi *D = &ctx->D; #else mbedtls_mpi DP_blind, DQ_blind; mbedtls_mpi *DP = &ctx->DP; mbedtls_mpi *DQ = &ctx->DQ; #endif /* Make sure we have private key info, prevent possible misuse */ if( ctx->P.p == NULL || ctx->Q.p == NULL || ctx->D.p == NULL ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); mbedtls_mpi_init( &T ); mbedtls_mpi_init( &T1 ); mbedtls_mpi_init( &T2 ); mbedtls_mpi_init( &P1 ); mbedtls_mpi_init( &Q1 ); mbedtls_mpi_init( &R ); if( f_rng != NULL ) { #if defined(MBEDTLS_RSA_NO_CRT) mbedtls_mpi_init( &D_blind ); #else mbedtls_mpi_init( &DP_blind ); mbedtls_mpi_init( &DQ_blind ); #endif } #if defined(MBEDTLS_THREADING_C) if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) return( ret ); #endif MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &T, input, ctx->len ) ); if( mbedtls_mpi_cmp_mpi( &T, &ctx->N ) >= 0 ) { ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA; goto cleanup; } if( f_rng != NULL ) { /* * Blinding * T = T * Vi mod N */ MBEDTLS_MPI_CHK( rsa_prepare_blinding( ctx, f_rng, p_rng ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T, &T, &ctx->Vi ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &T, &ctx->N ) ); /* * Exponent blinding */ MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &P1, &ctx->P, 1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &Q1, &ctx->Q, 1 ) ); #if defined(MBEDTLS_RSA_NO_CRT) /* * D_blind = ( P - 1 ) * ( Q - 1 ) * R + D */ MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, RSA_EXPONENT_BLINDING, f_rng, p_rng ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &D_blind, &P1, &Q1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &D_blind, &D_blind, &R ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &D_blind, &D_blind, &ctx->D ) ); D = &D_blind; #else /* * DP_blind = ( P - 1 ) * R + DP */ MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, RSA_EXPONENT_BLINDING, f_rng, p_rng ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &DP_blind, &P1, &R ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &DP_blind, &DP_blind, &ctx->DP ) ); DP = &DP_blind; /* * DQ_blind = ( Q - 1 ) * R + DQ */ MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, RSA_EXPONENT_BLINDING, f_rng, p_rng ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &DQ_blind, &Q1, &R ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &DQ_blind, &DQ_blind, &ctx->DQ ) ); DQ = &DQ_blind; #endif /* MBEDTLS_RSA_NO_CRT */ } #if defined(MBEDTLS_RSA_NO_CRT) MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T, &T, D, &ctx->N, &ctx->RN ) ); #else /* * Faster decryption using the CRT * * T1 = input ^ dP mod P * T2 = input ^ dQ mod Q */ MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T1, &T, DP, &ctx->P, &ctx->RP ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T2, &T, DQ, &ctx->Q, &ctx->RQ ) ); /* * T = (T1 - T2) * (Q^-1 mod P) mod P */ MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &T, &T1, &T2 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T1, &T, &ctx->QP ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &T1, &ctx->P ) ); /* * T = T2 + T * Q */ MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T1, &T, &ctx->Q ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &T, &T2, &T1 ) ); #endif /* MBEDTLS_RSA_NO_CRT */ if( f_rng != NULL ) { /* * Unblind * T = T * Vf mod N */ MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T, &T, &ctx->Vf ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &T, &ctx->N ) ); } olen = ctx->len; MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &T, output, olen ) ); cleanup: #if defined(MBEDTLS_THREADING_C) if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); #endif mbedtls_mpi_free( &T ); mbedtls_mpi_free( &T1 ); mbedtls_mpi_free( &T2 ); mbedtls_mpi_free( &P1 ); mbedtls_mpi_free( &Q1 ); mbedtls_mpi_free( &R ); if( f_rng != NULL ) { #if defined(MBEDTLS_RSA_NO_CRT) mbedtls_mpi_free( &D_blind ); #else mbedtls_mpi_free( &DP_blind ); mbedtls_mpi_free( &DQ_blind ); #endif } if( ret != 0 ) return( MBEDTLS_ERR_RSA_PRIVATE_FAILED + ret ); return( 0 ); } #if defined(MBEDTLS_PKCS1_V21) /** * Generate and apply the MGF1 operation (from PKCS#1 v2.1) to a buffer. * * \param dst buffer to mask * \param dlen length of destination buffer * \param src source of the mask generation * \param slen length of the source buffer * \param md_ctx message digest context to use */ static void mgf_mask( unsigned char *dst, size_t dlen, unsigned char *src, size_t slen, mbedtls_md_context_t *md_ctx ) { unsigned char mask[MBEDTLS_MD_MAX_SIZE]; unsigned char counter[4]; unsigned char *p; unsigned int hlen; size_t i, use_len; memset( mask, 0, MBEDTLS_MD_MAX_SIZE ); memset( counter, 0, 4 ); hlen = mbedtls_md_get_size( md_ctx->md_info ); /* Generate and apply dbMask */ p = dst; while( dlen > 0 ) { use_len = hlen; if( dlen < hlen ) use_len = dlen; mbedtls_md_starts( md_ctx ); mbedtls_md_update( md_ctx, src, slen ); mbedtls_md_update( md_ctx, counter, 4 ); mbedtls_md_finish( md_ctx, mask ); for( i = 0; i < use_len; ++i ) *p++ ^= mask[i]; counter[3]++; dlen -= use_len; } mbedtls_zeroize( mask, sizeof( mask ) ); } #endif /* MBEDTLS_PKCS1_V21 */ #if defined(MBEDTLS_PKCS1_V21) /* * Implementation of the PKCS#1 v2.1 RSAES-OAEP-ENCRYPT function */ int mbedtls_rsa_rsaes_oaep_encrypt( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, int mode, const unsigned char *label, size_t label_len, size_t ilen, const unsigned char *input, unsigned char *output ) { size_t olen; int ret; unsigned char *p = output; unsigned int hlen; const mbedtls_md_info_t *md_info; mbedtls_md_context_t md_ctx; if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); if( f_rng == NULL ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id ); if( md_info == NULL ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); olen = ctx->len; hlen = mbedtls_md_get_size( md_info ); /* first comparison checks for overflow */ if( ilen + 2 * hlen + 2 < ilen || olen < ilen + 2 * hlen + 2 ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); memset( output, 0, olen ); *p++ = 0; /* Generate a random octet string seed */ if( ( ret = f_rng( p_rng, p, hlen ) ) != 0 ) return( MBEDTLS_ERR_RSA_RNG_FAILED + ret ); p += hlen; /* Construct DB */ mbedtls_md( md_info, label, label_len, p ); p += hlen; p += olen - 2 * hlen - 2 - ilen; *p++ = 1; memcpy( p, input, ilen ); mbedtls_md_init( &md_ctx ); if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 ) { mbedtls_md_free( &md_ctx ); return( ret ); } /* maskedDB: Apply dbMask to DB */ mgf_mask( output + hlen + 1, olen - hlen - 1, output + 1, hlen, &md_ctx ); /* maskedSeed: Apply seedMask to seed */ mgf_mask( output + 1, hlen, output + hlen + 1, olen - hlen - 1, &md_ctx ); mbedtls_md_free( &md_ctx ); return( ( mode == MBEDTLS_RSA_PUBLIC ) ? mbedtls_rsa_public( ctx, output, output ) : mbedtls_rsa_private( ctx, f_rng, p_rng, output, output ) ); } #endif /* MBEDTLS_PKCS1_V21 */ #if defined(MBEDTLS_PKCS1_V15) /* * Implementation of the PKCS#1 v2.1 RSAES-PKCS1-V1_5-ENCRYPT function */ int mbedtls_rsa_rsaes_pkcs1_v15_encrypt( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, int mode, size_t ilen, const unsigned char *input, unsigned char *output ) { size_t nb_pad, olen; int ret; unsigned char *p = output; if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); // We don't check p_rng because it won't be dereferenced here if( f_rng == NULL || input == NULL || output == NULL ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); olen = ctx->len; /* first comparison checks for overflow */ if( ilen + 11 < ilen || olen < ilen + 11 ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); nb_pad = olen - 3 - ilen; *p++ = 0; if( mode == MBEDTLS_RSA_PUBLIC ) { *p++ = MBEDTLS_RSA_CRYPT; while( nb_pad-- > 0 ) { int rng_dl = 100; do { ret = f_rng( p_rng, p, 1 ); } while( *p == 0 && --rng_dl && ret == 0 ); /* Check if RNG failed to generate data */ if( rng_dl == 0 || ret != 0 ) return( MBEDTLS_ERR_RSA_RNG_FAILED + ret ); p++; } } else { *p++ = MBEDTLS_RSA_SIGN; while( nb_pad-- > 0 ) *p++ = 0xFF; } *p++ = 0; memcpy( p, input, ilen ); return( ( mode == MBEDTLS_RSA_PUBLIC ) ? mbedtls_rsa_public( ctx, output, output ) : mbedtls_rsa_private( ctx, f_rng, p_rng, output, output ) ); } #endif /* MBEDTLS_PKCS1_V15 */ /* * Add the message padding, then do an RSA operation */ int mbedtls_rsa_pkcs1_encrypt( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, int mode, size_t ilen, const unsigned char *input, unsigned char *output ) { switch( ctx->padding ) { #if defined(MBEDTLS_PKCS1_V15) case MBEDTLS_RSA_PKCS_V15: return mbedtls_rsa_rsaes_pkcs1_v15_encrypt( ctx, f_rng, p_rng, mode, ilen, input, output ); #endif #if defined(MBEDTLS_PKCS1_V21) case MBEDTLS_RSA_PKCS_V21: return mbedtls_rsa_rsaes_oaep_encrypt( ctx, f_rng, p_rng, mode, NULL, 0, ilen, input, output ); #endif default: return( MBEDTLS_ERR_RSA_INVALID_PADDING ); } } #if defined(MBEDTLS_PKCS1_V21) /* * Implementation of the PKCS#1 v2.1 RSAES-OAEP-DECRYPT function */ int mbedtls_rsa_rsaes_oaep_decrypt( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, int mode, const unsigned char *label, size_t label_len, size_t *olen, const unsigned char *input, unsigned char *output, size_t output_max_len ) { int ret; size_t ilen, i, pad_len; unsigned char *p, bad, pad_done; unsigned char buf[MBEDTLS_MPI_MAX_SIZE]; unsigned char lhash[MBEDTLS_MD_MAX_SIZE]; unsigned int hlen; const mbedtls_md_info_t *md_info; mbedtls_md_context_t md_ctx; /* * Parameters sanity checks */ if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); ilen = ctx->len; if( ilen < 16 || ilen > sizeof( buf ) ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id ); if( md_info == NULL ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); hlen = mbedtls_md_get_size( md_info ); // checking for integer underflow if( 2 * hlen + 2 > ilen ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); /* * RSA operation */ ret = ( mode == MBEDTLS_RSA_PUBLIC ) ? mbedtls_rsa_public( ctx, input, buf ) : mbedtls_rsa_private( ctx, f_rng, p_rng, input, buf ); if( ret != 0 ) goto cleanup; /* * Unmask data and generate lHash */ mbedtls_md_init( &md_ctx ); if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 ) { mbedtls_md_free( &md_ctx ); goto cleanup; } /* Generate lHash */ mbedtls_md( md_info, label, label_len, lhash ); /* seed: Apply seedMask to maskedSeed */ mgf_mask( buf + 1, hlen, buf + hlen + 1, ilen - hlen - 1, &md_ctx ); /* DB: Apply dbMask to maskedDB */ mgf_mask( buf + hlen + 1, ilen - hlen - 1, buf + 1, hlen, &md_ctx ); mbedtls_md_free( &md_ctx ); /* * Check contents, in "constant-time" */ p = buf; bad = 0; bad |= *p++; /* First byte must be 0 */ p += hlen; /* Skip seed */ /* Check lHash */ for( i = 0; i < hlen; i++ ) bad |= lhash[i] ^ *p++; /* Get zero-padding len, but always read till end of buffer * (minus one, for the 01 byte) */ pad_len = 0; pad_done = 0; for( i = 0; i < ilen - 2 * hlen - 2; i++ ) { pad_done |= p[i]; pad_len += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1; } p += pad_len; bad |= *p++ ^ 0x01; /* * The only information "leaked" is whether the padding was correct or not * (eg, no data is copied if it was not correct). This meets the * recommendations in PKCS#1 v2.2: an opponent cannot distinguish between * the different error conditions. */ if( bad != 0 ) { ret = MBEDTLS_ERR_RSA_INVALID_PADDING; goto cleanup; } if( ilen - ( p - buf ) > output_max_len ) { ret = MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE; goto cleanup; } *olen = ilen - (p - buf); memcpy( output, p, *olen ); ret = 0; cleanup: mbedtls_zeroize( buf, sizeof( buf ) ); mbedtls_zeroize( lhash, sizeof( lhash ) ); return( ret ); } #endif /* MBEDTLS_PKCS1_V21 */ #if defined(MBEDTLS_PKCS1_V15) /* * Implementation of the PKCS#1 v2.1 RSAES-PKCS1-V1_5-DECRYPT function */ int mbedtls_rsa_rsaes_pkcs1_v15_decrypt( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, int mode, size_t *olen, const unsigned char *input, unsigned char *output, size_t output_max_len) { int ret; size_t ilen, pad_count = 0, i; unsigned char *p, bad, pad_done = 0; unsigned char buf[MBEDTLS_MPI_MAX_SIZE]; if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); ilen = ctx->len; if( ilen < 16 || ilen > sizeof( buf ) ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); ret = ( mode == MBEDTLS_RSA_PUBLIC ) ? mbedtls_rsa_public( ctx, input, buf ) : mbedtls_rsa_private( ctx, f_rng, p_rng, input, buf ); if( ret != 0 ) goto cleanup; p = buf; bad = 0; /* * Check and get padding len in "constant-time" */ bad |= *p++; /* First byte must be 0 */ /* This test does not depend on secret data */ if( mode == MBEDTLS_RSA_PRIVATE ) { bad |= *p++ ^ MBEDTLS_RSA_CRYPT; /* Get padding len, but always read till end of buffer * (minus one, for the 00 byte) */ for( i = 0; i < ilen - 3; i++ ) { pad_done |= ((p[i] | (unsigned char)-p[i]) >> 7) ^ 1; pad_count += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1; } p += pad_count; bad |= *p++; /* Must be zero */ } else { bad |= *p++ ^ MBEDTLS_RSA_SIGN; /* Get padding len, but always read till end of buffer * (minus one, for the 00 byte) */ for( i = 0; i < ilen - 3; i++ ) { pad_done |= ( p[i] != 0xFF ); pad_count += ( pad_done == 0 ); } p += pad_count; bad |= *p++; /* Must be zero */ } bad |= ( pad_count < 8 ); if( bad ) { ret = MBEDTLS_ERR_RSA_INVALID_PADDING; goto cleanup; } if( ilen - ( p - buf ) > output_max_len ) { ret = MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE; goto cleanup; } *olen = ilen - (p - buf); memcpy( output, p, *olen ); ret = 0; cleanup: mbedtls_zeroize( buf, sizeof( buf ) ); return( ret ); } #endif /* MBEDTLS_PKCS1_V15 */ /* * Do an RSA operation, then remove the message padding */ int mbedtls_rsa_pkcs1_decrypt( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, int mode, size_t *olen, const unsigned char *input, unsigned char *output, size_t output_max_len) { switch( ctx->padding ) { #if defined(MBEDTLS_PKCS1_V15) case MBEDTLS_RSA_PKCS_V15: return mbedtls_rsa_rsaes_pkcs1_v15_decrypt( ctx, f_rng, p_rng, mode, olen, input, output, output_max_len ); #endif #if defined(MBEDTLS_PKCS1_V21) case MBEDTLS_RSA_PKCS_V21: return mbedtls_rsa_rsaes_oaep_decrypt( ctx, f_rng, p_rng, mode, NULL, 0, olen, input, output, output_max_len ); #endif default: return( MBEDTLS_ERR_RSA_INVALID_PADDING ); } } #if defined(MBEDTLS_PKCS1_V21) /* * Implementation of the PKCS#1 v2.1 RSASSA-PSS-SIGN function */ int mbedtls_rsa_rsassa_pss_sign( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, int mode, mbedtls_md_type_t md_alg, unsigned int hashlen, const unsigned char *hash, unsigned char *sig ) { size_t olen; unsigned char *p = sig; unsigned char salt[MBEDTLS_MD_MAX_SIZE]; unsigned int slen, hlen, offset = 0; int ret; size_t msb; const mbedtls_md_info_t *md_info; mbedtls_md_context_t md_ctx; if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); if( f_rng == NULL ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); olen = ctx->len; if( md_alg != MBEDTLS_MD_NONE ) { /* Gather length of hash to sign */ md_info = mbedtls_md_info_from_type( md_alg ); if( md_info == NULL ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); hashlen = mbedtls_md_get_size( md_info ); } md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id ); if( md_info == NULL ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); hlen = mbedtls_md_get_size( md_info ); slen = hlen; if( olen < hlen + slen + 2 ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); memset( sig, 0, olen ); /* Generate salt of length slen */ if( ( ret = f_rng( p_rng, salt, slen ) ) != 0 ) return( MBEDTLS_ERR_RSA_RNG_FAILED + ret ); /* Note: EMSA-PSS encoding is over the length of N - 1 bits */ msb = mbedtls_mpi_bitlen( &ctx->N ) - 1; p += olen - hlen * 2 - 2; *p++ = 0x01; memcpy( p, salt, slen ); p += slen; mbedtls_md_init( &md_ctx ); if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 ) { mbedtls_md_free( &md_ctx ); /* No need to zeroize salt: we didn't use it. */ return( ret ); } /* Generate H = Hash( M' ) */ mbedtls_md_starts( &md_ctx ); mbedtls_md_update( &md_ctx, p, 8 ); mbedtls_md_update( &md_ctx, hash, hashlen ); mbedtls_md_update( &md_ctx, salt, slen ); mbedtls_md_finish( &md_ctx, p ); mbedtls_zeroize( salt, sizeof( salt ) ); /* Compensate for boundary condition when applying mask */ if( msb % 8 == 0 ) offset = 1; /* maskedDB: Apply dbMask to DB */ mgf_mask( sig + offset, olen - hlen - 1 - offset, p, hlen, &md_ctx ); mbedtls_md_free( &md_ctx ); msb = mbedtls_mpi_bitlen( &ctx->N ) - 1; sig[0] &= 0xFF >> ( olen * 8 - msb ); p += hlen; *p++ = 0xBC; return( ( mode == MBEDTLS_RSA_PUBLIC ) ? mbedtls_rsa_public( ctx, sig, sig ) : mbedtls_rsa_private( ctx, f_rng, p_rng, sig, sig ) ); } #endif /* MBEDTLS_PKCS1_V21 */ #if defined(MBEDTLS_PKCS1_V15) /* * Implementation of the PKCS#1 v2.1 RSASSA-PKCS1-V1_5-SIGN function */ /* Construct a PKCS v1.5 encoding of a hashed message * * This is used both for signature generation and verification. * * Parameters: * - md_alg: Identifies the hash algorithm used to generate the given hash; * MBEDTLS_MD_NONE if raw data are signed. * - hashlen: Length of hash in case hashlen is MBEDTLS_MD_NONE. * - hash: Buffer containing the hashed message. * - sig_len: Length of the encoded message. * - dst: Buffer to hold the encoded message. * * Assumptions: * - hash has size hashlen if md_alg == MBEDTLS_MD_NONE. * - hash has size corresponding to md_alg if md_alg != MBEDTLS_MD_NONE. * - dst points to a buffer of size at least sig_len. * */ static int rsa_rsassa_pkcs1_v15_encode( mbedtls_md_type_t md_alg, unsigned int hashlen, const unsigned char *hash, size_t sig_len, unsigned char *dst ) { size_t oid_size = 0; size_t nb_pad = sig_len; unsigned char *p = dst; const char *oid = NULL; /* Are we signing hashed or raw data? */ if( md_alg != MBEDTLS_MD_NONE ) { const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( md_alg ); if( md_info == NULL ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); if( mbedtls_oid_get_oid_by_md( md_alg, &oid, &oid_size ) != 0 ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); hashlen = mbedtls_md_get_size( md_info ); /* Double-check that 8 + hashlen + oid_size can be used as a * 1-byte ASN.1 length encoding and that there's no overflow. */ if( 8 + hashlen + oid_size >= 0x80 || 10 + hashlen < hashlen || 10 + hashlen + oid_size < 10 + hashlen ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); /* * Static bounds check: * - Need 10 bytes for five tag-length pairs. * (Insist on 1-byte length encodings to protect against variants of * Bleichenbacher's forgery attack against lax PKCS#1v1.5 verification) * - Need hashlen bytes for hash * - Need oid_size bytes for hash alg OID. */ if( nb_pad < 10 + hashlen + oid_size ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); nb_pad -= 10 + hashlen + oid_size; } else { if( nb_pad < hashlen ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); nb_pad -= hashlen; } /* Signature header and padding delimiter */ if( nb_pad < 3 ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); nb_pad -= 3; /* Now nb_pad is the amount of memory to be filled * with padding; must be at least 8 bytes. */ if( nb_pad < 8 ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); /* Write signature header and padding */ *p++ = 0; *p++ = MBEDTLS_RSA_SIGN; memset( p, 0xFF, nb_pad ); p += nb_pad; *p++ = 0; /* Are we signing raw data? */ if( md_alg == MBEDTLS_MD_NONE ) { memcpy( p, hash, hashlen ); return( 0 ); } /* Signing hashed data, add corresponding ASN.1 structure * * DigestInfo ::= SEQUENCE { * digestAlgorithm DigestAlgorithmIdentifier, * digest Digest } * DigestAlgorithmIdentifier ::= AlgorithmIdentifier * Digest ::= OCTET STRING * * Schematic: * TAG-SEQ + LEN [ TAG-SEQ + LEN [ TAG-OID + LEN [ OID ] * TAG-NULL + LEN [ NULL ] ] * TAG-OCTET + LEN [ HASH ] ] */ *p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED; *p++ = 0x08 + oid_size + hashlen; *p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED; *p++ = 0x04 + oid_size; *p++ = MBEDTLS_ASN1_OID; *p++ = oid_size; memcpy( p, oid, oid_size ); p += oid_size; *p++ = MBEDTLS_ASN1_NULL; *p++ = 0x00; *p++ = MBEDTLS_ASN1_OCTET_STRING; *p++ = hashlen; memcpy( p, hash, hashlen ); p += hashlen; /* Just a sanity-check, should be automatic * after the initial bounds check. */ if( p != dst + sig_len ) { mbedtls_zeroize( dst, sig_len ); return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); } return( 0 ); } /* * Do an RSA operation to sign the message digest */ int mbedtls_rsa_rsassa_pkcs1_v15_sign( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, int mode, mbedtls_md_type_t md_alg, unsigned int hashlen, const unsigned char *hash, unsigned char *sig ) { int ret; unsigned char *sig_try = NULL, *verif = NULL; if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); /* * Prepare PKCS1-v1.5 encoding (padding and hash identifier) */ if( ( ret = rsa_rsassa_pkcs1_v15_encode( md_alg, hashlen, hash, ctx->len, sig ) ) != 0 ) return( ret ); /* * Call respective RSA primitive */ if( mode == MBEDTLS_RSA_PUBLIC ) { /* Skip verification on a public key operation */ return( mbedtls_rsa_public( ctx, sig, sig ) ); } /* Private key operation * * In order to prevent Lenstra's attack, make the signature in a * temporary buffer and check it before returning it. */ sig_try = mbedtls_calloc( 1, ctx->len ); if( sig_try == NULL ) return( MBEDTLS_ERR_MPI_ALLOC_FAILED ); verif = mbedtls_calloc( 1, ctx->len ); if( verif == NULL ) { mbedtls_free( sig_try ); return( MBEDTLS_ERR_MPI_ALLOC_FAILED ); } MBEDTLS_MPI_CHK( mbedtls_rsa_private( ctx, f_rng, p_rng, sig, sig_try ) ); MBEDTLS_MPI_CHK( mbedtls_rsa_public( ctx, sig_try, verif ) ); if( mbedtls_safer_memcmp( verif, sig, ctx->len ) != 0 ) { ret = MBEDTLS_ERR_RSA_PRIVATE_FAILED; goto cleanup; } memcpy( sig, sig_try, ctx->len ); cleanup: mbedtls_free( sig_try ); mbedtls_free( verif ); return( ret ); } #endif /* MBEDTLS_PKCS1_V15 */ /* * Do an RSA operation to sign the message digest */ int mbedtls_rsa_pkcs1_sign( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, int mode, mbedtls_md_type_t md_alg, unsigned int hashlen, const unsigned char *hash, unsigned char *sig ) { switch( ctx->padding ) { #if defined(MBEDTLS_PKCS1_V15) case MBEDTLS_RSA_PKCS_V15: return mbedtls_rsa_rsassa_pkcs1_v15_sign( ctx, f_rng, p_rng, mode, md_alg, hashlen, hash, sig ); #endif #if defined(MBEDTLS_PKCS1_V21) case MBEDTLS_RSA_PKCS_V21: return mbedtls_rsa_rsassa_pss_sign( ctx, f_rng, p_rng, mode, md_alg, hashlen, hash, sig ); #endif default: return( MBEDTLS_ERR_RSA_INVALID_PADDING ); } } #if defined(MBEDTLS_PKCS1_V21) /* * Implementation of the PKCS#1 v2.1 RSASSA-PSS-VERIFY function */ int mbedtls_rsa_rsassa_pss_verify_ext( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, int mode, mbedtls_md_type_t md_alg, unsigned int hashlen, const unsigned char *hash, mbedtls_md_type_t mgf1_hash_id, int expected_salt_len, const unsigned char *sig ) { int ret; size_t siglen; unsigned char *p; unsigned char result[MBEDTLS_MD_MAX_SIZE]; unsigned char zeros[8]; unsigned int hlen; size_t slen, msb; const mbedtls_md_info_t *md_info; mbedtls_md_context_t md_ctx; unsigned char buf[MBEDTLS_MPI_MAX_SIZE]; if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); siglen = ctx->len; if( siglen < 16 || siglen > sizeof( buf ) ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); ret = ( mode == MBEDTLS_RSA_PUBLIC ) ? mbedtls_rsa_public( ctx, sig, buf ) : mbedtls_rsa_private( ctx, f_rng, p_rng, sig, buf ); if( ret != 0 ) return( ret ); p = buf; if( buf[siglen - 1] != 0xBC ) return( MBEDTLS_ERR_RSA_INVALID_PADDING ); if( md_alg != MBEDTLS_MD_NONE ) { /* Gather length of hash to sign */ md_info = mbedtls_md_info_from_type( md_alg ); if( md_info == NULL ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); hashlen = mbedtls_md_get_size( md_info ); } md_info = mbedtls_md_info_from_type( mgf1_hash_id ); if( md_info == NULL ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); hlen = mbedtls_md_get_size( md_info ); slen = siglen - hlen - 1; /* Currently length of salt + padding */ memset( zeros, 0, 8 ); /* * Note: EMSA-PSS verification is over the length of N - 1 bits */ msb = mbedtls_mpi_bitlen( &ctx->N ) - 1; /* Compensate for boundary condition when applying mask */ if( msb % 8 == 0 ) { p++; siglen -= 1; } if( buf[0] >> ( 8 - siglen * 8 + msb ) ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); mbedtls_md_init( &md_ctx ); if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 ) { mbedtls_md_free( &md_ctx ); return( ret ); } mgf_mask( p, siglen - hlen - 1, p + siglen - hlen - 1, hlen, &md_ctx ); buf[0] &= 0xFF >> ( siglen * 8 - msb ); while( p < buf + siglen && *p == 0 ) p++; if( p == buf + siglen || *p++ != 0x01 ) { mbedtls_md_free( &md_ctx ); return( MBEDTLS_ERR_RSA_INVALID_PADDING ); } /* Actual salt len */ slen -= p - buf; if( expected_salt_len != MBEDTLS_RSA_SALT_LEN_ANY && slen != (size_t) expected_salt_len ) { mbedtls_md_free( &md_ctx ); return( MBEDTLS_ERR_RSA_INVALID_PADDING ); } /* * Generate H = Hash( M' ) */ mbedtls_md_starts( &md_ctx ); mbedtls_md_update( &md_ctx, zeros, 8 ); mbedtls_md_update( &md_ctx, hash, hashlen ); mbedtls_md_update( &md_ctx, p, slen ); mbedtls_md_finish( &md_ctx, result ); mbedtls_md_free( &md_ctx ); if( memcmp( p + slen, result, hlen ) == 0 ) return( 0 ); else return( MBEDTLS_ERR_RSA_VERIFY_FAILED ); } /* * Simplified PKCS#1 v2.1 RSASSA-PSS-VERIFY function */ int mbedtls_rsa_rsassa_pss_verify( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, int mode, mbedtls_md_type_t md_alg, unsigned int hashlen, const unsigned char *hash, const unsigned char *sig ) { mbedtls_md_type_t mgf1_hash_id = ( ctx->hash_id != MBEDTLS_MD_NONE ) ? (mbedtls_md_type_t) ctx->hash_id : md_alg; return( mbedtls_rsa_rsassa_pss_verify_ext( ctx, f_rng, p_rng, mode, md_alg, hashlen, hash, mgf1_hash_id, MBEDTLS_RSA_SALT_LEN_ANY, sig ) ); } #endif /* MBEDTLS_PKCS1_V21 */ #if defined(MBEDTLS_PKCS1_V15) /* * Implementation of the PKCS#1 v2.1 RSASSA-PKCS1-v1_5-VERIFY function */ int mbedtls_rsa_rsassa_pkcs1_v15_verify( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, int mode, mbedtls_md_type_t md_alg, unsigned int hashlen, const unsigned char *hash, const unsigned char *sig ) { int ret = 0; const size_t sig_len = ctx->len; unsigned char *encoded = NULL, *encoded_expected = NULL; if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 ) return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); /* * Prepare expected PKCS1 v1.5 encoding of hash. */ if( ( encoded = mbedtls_calloc( 1, sig_len ) ) == NULL || ( encoded_expected = mbedtls_calloc( 1, sig_len ) ) == NULL ) { ret = MBEDTLS_ERR_MPI_ALLOC_FAILED; goto cleanup; } if( ( ret = rsa_rsassa_pkcs1_v15_encode( md_alg, hashlen, hash, sig_len, encoded_expected ) ) != 0 ) goto cleanup; /* * Apply RSA primitive to get what should be PKCS1 encoded hash. */ ret = ( mode == MBEDTLS_RSA_PUBLIC ) ? mbedtls_rsa_public( ctx, sig, encoded ) : mbedtls_rsa_private( ctx, f_rng, p_rng, sig, encoded ); if( ret != 0 ) goto cleanup; /* * Compare */ if( ( ret = mbedtls_safer_memcmp( encoded, encoded_expected, sig_len ) ) != 0 ) { ret = MBEDTLS_ERR_RSA_VERIFY_FAILED; goto cleanup; } cleanup: if( encoded != NULL ) { mbedtls_zeroize( encoded, sig_len ); mbedtls_free( encoded ); } if( encoded_expected != NULL ) { mbedtls_zeroize( encoded_expected, sig_len ); mbedtls_free( encoded_expected ); } return( ret ); } #endif /* MBEDTLS_PKCS1_V15 */ /* * Do an RSA operation and check the message digest */ int mbedtls_rsa_pkcs1_verify( mbedtls_rsa_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, int mode, mbedtls_md_type_t md_alg, unsigned int hashlen, const unsigned char *hash, const unsigned char *sig ) { switch( ctx->padding ) { #if defined(MBEDTLS_PKCS1_V15) case MBEDTLS_RSA_PKCS_V15: return mbedtls_rsa_rsassa_pkcs1_v15_verify( ctx, f_rng, p_rng, mode, md_alg, hashlen, hash, sig ); #endif #if defined(MBEDTLS_PKCS1_V21) case MBEDTLS_RSA_PKCS_V21: return mbedtls_rsa_rsassa_pss_verify( ctx, f_rng, p_rng, mode, md_alg, hashlen, hash, sig ); #endif default: return( MBEDTLS_ERR_RSA_INVALID_PADDING ); } } /* * Copy the components of an RSA key */ int mbedtls_rsa_copy( mbedtls_rsa_context *dst, const mbedtls_rsa_context *src ) { int ret; dst->ver = src->ver; dst->len = src->len; MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->N, &src->N ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->E, &src->E ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->D, &src->D ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->P, &src->P ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Q, &src->Q ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->DP, &src->DP ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->DQ, &src->DQ ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->QP, &src->QP ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RN, &src->RN ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RP, &src->RP ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RQ, &src->RQ ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Vi, &src->Vi ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Vf, &src->Vf ) ); dst->padding = src->padding; dst->hash_id = src->hash_id; cleanup: if( ret != 0 ) mbedtls_rsa_free( dst ); return( ret ); } /* * Free the components of an RSA key */ void mbedtls_rsa_free( mbedtls_rsa_context *ctx ) { mbedtls_mpi_free( &ctx->Vi ); mbedtls_mpi_free( &ctx->Vf ); mbedtls_mpi_free( &ctx->RQ ); mbedtls_mpi_free( &ctx->RP ); mbedtls_mpi_free( &ctx->RN ); mbedtls_mpi_free( &ctx->QP ); mbedtls_mpi_free( &ctx->DQ ); mbedtls_mpi_free( &ctx->DP ); mbedtls_mpi_free( &ctx->Q ); mbedtls_mpi_free( &ctx->P ); mbedtls_mpi_free( &ctx->D ); mbedtls_mpi_free( &ctx->E ); mbedtls_mpi_free( &ctx->N ); #if defined(MBEDTLS_THREADING_C) mbedtls_mutex_free( &ctx->mutex ); #endif } #if defined(MBEDTLS_SELF_TEST) #include "mbedtls/sha1.h" /* * Example RSA-1024 keypair, for test purposes */ #define KEY_LEN 128 #define RSA_N "9292758453063D803DD603D5E777D788" \ "8ED1D5BF35786190FA2F23EBC0848AEA" \ "DDA92CA6C3D80B32C4D109BE0F36D6AE" \ "7130B9CED7ACDF54CFC7555AC14EEBAB" \ "93A89813FBF3C4F8066D2D800F7C38A8" \ "1AE31942917403FF4946B0A83D3D3E05" \ "EE57C6F5F5606FB5D4BC6CD34EE0801A" \ "5E94BB77B07507233A0BC7BAC8F90F79" #define RSA_E "10001" #define RSA_D "24BF6185468786FDD303083D25E64EFC" \ "66CA472BC44D253102F8B4A9D3BFA750" \ "91386C0077937FE33FA3252D28855837" \ "AE1B484A8A9A45F7EE8C0C634F99E8CD" \ "DF79C5CE07EE72C7F123142198164234" \ "CABB724CF78B8173B9F880FC86322407" \ "AF1FEDFDDE2BEB674CA15F3E81A1521E" \ "071513A1E85B5DFA031F21ECAE91A34D" #define RSA_P "C36D0EB7FCD285223CFB5AABA5BDA3D8" \ "2C01CAD19EA484A87EA4377637E75500" \ "FCB2005C5C7DD6EC4AC023CDA285D796" \ "C3D9E75E1EFC42488BB4F1D13AC30A57" #define RSA_Q "C000DF51A7C77AE8D7C7370C1FF55B69" \ "E211C2B9E5DB1ED0BF61D0D9899620F4" \ "910E4168387E3C30AA1E00C339A79508" \ "8452DD96A9A5EA5D9DCA68DA636032AF" #define RSA_DP "C1ACF567564274FB07A0BBAD5D26E298" \ "3C94D22288ACD763FD8E5600ED4A702D" \ "F84198A5F06C2E72236AE490C93F07F8" \ "3CC559CD27BC2D1CA488811730BB5725" #define RSA_DQ "4959CBF6F8FEF750AEE6977C155579C7" \ "D8AAEA56749EA28623272E4F7D0592AF" \ "7C1F1313CAC9471B5C523BFE592F517B" \ "407A1BD76C164B93DA2D32A383E58357" #define RSA_QP "9AE7FBC99546432DF71896FC239EADAE" \ "F38D18D2B2F0E2DD275AA977E2BF4411" \ "F5A3B2A5D33605AEBBCCBA7FEB9F2D2F" \ "A74206CEC169D74BF5A8C50D6F48EA08" #define PT_LEN 24 #define RSA_PT "\xAA\xBB\xCC\x03\x02\x01\x00\xFF\xFF\xFF\xFF\xFF" \ "\x11\x22\x33\x0A\x0B\x0C\xCC\xDD\xDD\xDD\xDD\xDD" #if defined(MBEDTLS_PKCS1_V15) static int myrand( void *rng_state, unsigned char *output, size_t len ) { #if !defined(__OpenBSD__) size_t i; if( rng_state != NULL ) rng_state = NULL; for( i = 0; i < len; ++i ) output[i] = rand(); #else if( rng_state != NULL ) rng_state = NULL; arc4random_buf( output, len ); #endif /* !OpenBSD */ return( 0 ); } #endif /* MBEDTLS_PKCS1_V15 */ /* * Checkup routine */ int mbedtls_rsa_self_test( int verbose ) { int ret = 0; #if defined(MBEDTLS_PKCS1_V15) size_t len; mbedtls_rsa_context rsa; unsigned char rsa_plaintext[PT_LEN]; unsigned char rsa_decrypted[PT_LEN]; unsigned char rsa_ciphertext[KEY_LEN]; #if defined(MBEDTLS_SHA1_C) unsigned char sha1sum[20]; #endif mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, 0 ); rsa.len = KEY_LEN; MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &rsa.N , 16, RSA_N ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &rsa.E , 16, RSA_E ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &rsa.D , 16, RSA_D ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &rsa.P , 16, RSA_P ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &rsa.Q , 16, RSA_Q ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &rsa.DP, 16, RSA_DP ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &rsa.DQ, 16, RSA_DQ ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &rsa.QP, 16, RSA_QP ) ); if( verbose != 0 ) mbedtls_printf( " RSA key validation: " ); if( mbedtls_rsa_check_pubkey( &rsa ) != 0 || mbedtls_rsa_check_privkey( &rsa ) != 0 ) { if( verbose != 0 ) mbedtls_printf( "failed\n" ); return( 1 ); } if( verbose != 0 ) mbedtls_printf( "passed\n PKCS#1 encryption : " ); memcpy( rsa_plaintext, RSA_PT, PT_LEN ); if( mbedtls_rsa_pkcs1_encrypt( &rsa, myrand, NULL, MBEDTLS_RSA_PUBLIC, PT_LEN, rsa_plaintext, rsa_ciphertext ) != 0 ) { if( verbose != 0 ) mbedtls_printf( "failed\n" ); return( 1 ); } if( verbose != 0 ) mbedtls_printf( "passed\n PKCS#1 decryption : " ); if( mbedtls_rsa_pkcs1_decrypt( &rsa, myrand, NULL, MBEDTLS_RSA_PRIVATE, &len, rsa_ciphertext, rsa_decrypted, sizeof(rsa_decrypted) ) != 0 ) { if( verbose != 0 ) mbedtls_printf( "failed\n" ); return( 1 ); } if( memcmp( rsa_decrypted, rsa_plaintext, len ) != 0 ) { if( verbose != 0 ) mbedtls_printf( "failed\n" ); return( 1 ); } if( verbose != 0 ) mbedtls_printf( "passed\n" ); #if defined(MBEDTLS_SHA1_C) if( verbose != 0 ) mbedtls_printf( " PKCS#1 data sign : " ); mbedtls_sha1( rsa_plaintext, PT_LEN, sha1sum ); if( mbedtls_rsa_pkcs1_sign( &rsa, myrand, NULL, MBEDTLS_RSA_PRIVATE, MBEDTLS_MD_SHA1, 0, sha1sum, rsa_ciphertext ) != 0 ) { if( verbose != 0 ) mbedtls_printf( "failed\n" ); return( 1 ); } if( verbose != 0 ) mbedtls_printf( "passed\n PKCS#1 sig. verify: " ); if( mbedtls_rsa_pkcs1_verify( &rsa, NULL, NULL, MBEDTLS_RSA_PUBLIC, MBEDTLS_MD_SHA1, 0, sha1sum, rsa_ciphertext ) != 0 ) { if( verbose != 0 ) mbedtls_printf( "failed\n" ); return( 1 ); } if( verbose != 0 ) mbedtls_printf( "passed\n" ); #endif /* MBEDTLS_SHA1_C */ if( verbose != 0 ) mbedtls_printf( "\n" ); cleanup: mbedtls_rsa_free( &rsa ); #else /* MBEDTLS_PKCS1_V15 */ ((void) verbose); #endif /* MBEDTLS_PKCS1_V15 */ return( ret ); } #endif /* MBEDTLS_SELF_TEST */ #endif /* MBEDTLS_RSA_C */