diff options
Diffstat (limited to 'g10/pkclist.c')
| -rw-r--r-- | g10/pkclist.c | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/g10/pkclist.c b/g10/pkclist.c index dbbcbbdd8..4e58f125c 100644 --- a/g10/pkclist.c +++ b/g10/pkclist.c @@ -512,3 +512,102 @@ build_pk_list( STRLIST remusr, PK_LIST *ret_pk_list, unsigned usage ) } +/**************** + * Return -1 if we could not find an algorithm. + */ +int +select_algo_from_prefs( PK_LIST pk_list, int preftype ) +{ + PK_LIST pkr; + u32 bits[8]; + byte *pref = NULL; + size_t npref; + int i, j; + int compr_hack=0; + int any; + + if( !pk_list ) + return -1; + + memset( bits, ~0, 8 * sizeof *bits ); + for( pkr = pk_list; pkr; pkr = pkr->next ) { + u32 mask[8]; + + memset( mask, 0, 8 * sizeof *mask ); + if( !pkr->pk->local_id ) + BUG(); /* if this occurs, we can use get_ownertrust to set it */ + if( preftype == PREFTYPE_SYM ) + bits[0] = (1<<2); /* 3DES is implicitly there */ + m_free(pref); + pref = get_pref_data( pkr->pk->local_id, pkr->pk->namehash, &npref); + any = 0; + if( pref ) { + /*log_hexdump("raw: ", pref, npref );*/ + for(i=0; i+1 < npref; i+=2 ) { + if( pref[i] == preftype ) { + mask[pref[i+1]/32] |= 1 << (pref[i+1]%32); + any = 1; + } + } + } + if( (!pref || !any) && preftype == PREFTYPE_COMPR ) { + mask[0] |= 3; /* asume no_compression and old pgp */ + compr_hack = 1; + } + + /*log_debug("mask=%08lX%08lX%08lX%08lX%08lX%08lX%08lX%08lX\n", + (ulong)mask[7], (ulong)mask[6], (ulong)mask[5], (ulong)mask[4], + (ulong)mask[3], (ulong)mask[2], (ulong)mask[1], (ulong)mask[0]);*/ + for(i=0; i < 8; i++ ) + bits[i] &= mask[i]; + /*log_debug("bits=%08lX%08lX%08lX%08lX%08lX%08lX%08lX%08lX\n", + (ulong)bits[7], (ulong)bits[6], (ulong)bits[5], (ulong)bits[4], + (ulong)bits[3], (ulong)bits[2], (ulong)bits[1], (ulong)bits[0]);*/ + } + /* usable algorithms are now in bits + * We now use the last key from pk_list to select + * the algorithm we want to use. there are no + * preferences for the last key, we select the one + * corresponding to first set bit. + */ + i = -1; + any = 0; + if( pref ) { + for(j=0; j+1 < npref; j+=2 ) { + if( pref[j] == preftype ) { + any = 1; + if( (bits[pref[j+1]/32] & (1<<(pref[j+1]%32))) ) { + i = pref[j+1]; + break; + } + } + } + } + if( !pref || !any ) { + for(j=0; j < 256; j++ ) + if( (bits[j/32] & (1<<(j%32))) ) { + i = j; + break; + } + } + /*log_debug("prefs of type %d: selected %d\n", preftype, i );*/ + if( compr_hack && !i ) { + /* selected no compression, but we should check whether + * algorithm 1 is also available (the ordering is not relevant + * in this case). */ + if( bits[0] & (1<<1) ) + i = 1; /* yep; we can use compression algo 1 */ + } + + if( preftype == PREFTYPE_SYM && i == CIPHER_ALGO_3DES ) { + i = CIPHER_ALGO_BLOWFISH; + if( opt.verbose ) + log_info("replacing 3DES by Blowfish\n"); + } + + + m_free(pref); + return i; +} + + |