diff options
Diffstat (limited to 'g10/pubkey-enc.c')
| -rw-r--r-- | g10/pubkey-enc.c | 68 |
1 files changed, 38 insertions, 30 deletions
diff --git a/g10/pubkey-enc.c b/g10/pubkey-enc.c index 2f8fb45f4..0fcd9c21c 100644 --- a/g10/pubkey-enc.c +++ b/g10/pubkey-enc.c @@ -38,8 +38,10 @@ int get_session_key( PKT_pubkey_enc *k, DEK *dek ) { - int i, j, c, rc = 0; - MPI dek_frame = mpi_alloc_secure(40); + int rc = 0; + MPI plain_dek = NULL; + byte *frame = NULL; + unsigned n, nframe; u16 csum, csum2; PKT_secret_cert *skc = m_alloc_clear( sizeof *skc ); @@ -58,7 +60,8 @@ get_session_key( PKT_pubkey_enc *k, DEK *dek ) skey.g = skc->d.elg.g; skey.y = skc->d.elg.y; skey.x = skc->d.elg.x; - elg_decrypt( dek_frame, k->d.elg.a, k->d.elg.b, &skey ); + plain_dek = mpi_alloc_secure( mpi_get_nlimbs(skey.p) ); + elg_decrypt( plain_dek, k->d.elg.a, k->d.elg.b, &skey ); memset( &skey, 0, sizeof skey ); } #ifdef HAVE_RSA_CIPHER @@ -74,7 +77,8 @@ get_session_key( PKT_pubkey_enc *k, DEK *dek ) skey.q = skc->d.rsa.rsa_q; skey.d = skc->d.rsa.rsa_d; skey.u = skc->d.rsa.rsa_u; - rsa_secret( dek_frame, k->d.rsa.rsa_integer, &skey ); + plain_dek = mpi_alloc_secure( mpi_get_nlimbs(skey.n) ); + rsa_secret( plain_dek, k->d.rsa.rsa_integer, &skey ); memset( &skey, 0, sizeof skey ); } #endif/*HAVE_RSA_CIPHER*/ @@ -83,9 +87,10 @@ get_session_key( PKT_pubkey_enc *k, DEK *dek ) goto leave; } free_secret_cert( skc ); skc = NULL; + frame = mpi_get_buffer( plain_dek, &nframe, NULL ); + mpi_free( plain_dek ); plain_dek = NULL; - - /* Now get the DEK (data encryption key) from the dek_frame + /* Now get the DEK (data encryption key) from the frame * * Old versions encode the DEK in in this format (msb is left): * @@ -101,51 +106,53 @@ get_session_key( PKT_pubkey_enc *k, DEK *dek ) * CSUM */ if( DBG_CIPHER ) - log_mpidump("DEK frame:", dek_frame ); - for(i=0; mpi_getbyte(dek_frame, i) != -1; i++ ) + log_hexdump("DEK frame:", frame, nframe ); + for(n=0; n < nframe && !frame[n]; n++ ) /* skip leading zeroes */ ; - for(i--; i >= 0 && !(c=mpi_getbyte(dek_frame, i)); i--) - ; /* Skip leading zeroes */ - if( i < 16 ) + if( n + 7 > nframe ) { rc = G10ERR_WRONG_SECKEY; goto leave; } - if( c == 1 && mpi_getbyte(dek_frame,0) == 2 ) { + if( frame[n] == 1 && frame[nframe-1] == 2 ) { log_error("old encoding of DEK is not supported\n"); rc = G10ERR_CIPHER_ALGO; goto leave; } - if( c != 2 ) /* somethink is wrong */ + if( frame[n] != 2 ) /* somethink is wrong */ { rc = G10ERR_WRONG_SECKEY; goto leave; } - /* look for the zero byte */ - for(i--; i > 4 ; i-- ) - if( !mpi_getbyte(dek_frame,i) ) - break; - if( i <= 4 ) /* zero byte not found */ + for(n++; n < nframe && frame[n]; n++ ) /* skip the random bytes */ + ; + n++; /* and the zero byte */ + if( n + 4 > nframe ) { rc = G10ERR_WRONG_SECKEY; goto leave; } - /* next byte indicates the used cipher */ - switch( mpi_getbyte(dek_frame, --i ) ) { + + dek->keylen = nframe - (n+1) - 2; + dek->algo = frame[n++]; + switch( dek->algo ) { case CIPHER_ALGO_IDEA: rc = G10ERR_NI_CIPHER; goto leave; case CIPHER_ALGO_BLOWFISH: - if( i != 22 ) /* length of blowfish is 20 (+2 bytes checksum) */ + if( dek->keylen != 20 ) { rc = G10ERR_WRONG_SECKEY; goto leave; } - dek->algo = CIPHER_ALGO_BLOWFISH; break; case CIPHER_ALGO_BLOWFISH128: - if( i != 18 ) /* length of blowfish-128 is 16 (+2 bytes checksum) */ + if( dek->keylen != 16 ) + { rc = G10ERR_WRONG_SECKEY; goto leave; } + break; + case CIPHER_ALGO_CAST: + if( dek->keylen < 5 || dek->keylen > 16 ) { rc = G10ERR_WRONG_SECKEY; goto leave; } - dek->algo = CIPHER_ALGO_BLOWFISH128; break; default: + dek->algo = 0; rc = G10ERR_CIPHER_ALGO; goto leave; } /* copy the key to DEK and compare the checksum */ - csum = mpi_getbyte(dek_frame, 1) << 8; - csum |= mpi_getbyte(dek_frame, 0); - dek->keylen = i - 2; - for( i--, csum2=0, j=0; i > 1; i-- ) - csum2 += dek->key[j++] = mpi_getbyte(dek_frame, i); + csum = frame[nframe-2] << 8; + csum |= frame[nframe-1]; + memcpy( dek->key, frame+n, dek->keylen ); + for( csum2=0, n=0; n < dek->keylen; n++ ) + csum2 += dek->key[n]; if( csum != csum2 ) { rc = G10ERR_WRONG_SECKEY; goto leave; @@ -154,7 +161,8 @@ get_session_key( PKT_pubkey_enc *k, DEK *dek ) log_hexdump("DEK is:", dek->key, dek->keylen ); leave: - mpi_free(dek_frame); + mpi_free(plain_dek); + m_free(frame); if( skc ) free_secret_cert( skc ); return rc; |