Oliver Pinter
2012-Jun-10 22:37 UTC
blf uses only 2^4 round for passwd encoding?! [Re: Default password hash]
http://svnweb.freebsd.org/base/head/secure/lib/libcrypt/crypt-blowfish.c?revision=231986&view=markup 145 static const char *magic = "$2a$04$"; 146 147 /* Defaults */ 148 minr = 'a'; 149 logr = 4; 150 rounds = 1 << logr; 151 152 /* If it starts with the magic string, then skip that */ 153 if(!strncmp(salt, magic, strlen(magic))) { 154 salt += strlen(magic); 155 } grep 04 /etc/master.passwd: root:$2a$04$XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX:0:0::0:0:XXX:/root:/bin/csh xxxx:$2a$04$XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX:100X:100X::0:0:XXXXXXXXXXXXX:/home/xxxx:/bin/tcsh 16 rounds in 2012? It is not to weak?! On 6/8/12, Dag-Erling Sm?rgrav <des@des.no> wrote:> We still have MD5 as our default password hash, even though known-hash > attacks against MD5 are relatively easy these days. We've supported > SHA256 and SHA512 for many years now, so how about making SHA512 the > default instead of MD5, like on most Linux distributions? > > Index: etc/login.conf > ==================================================================> --- etc/login.conf (revision 236616) > +++ etc/login.conf (working copy) > @@ -23,7 +23,7 @@ > # AND SEMANTICS'' section of getcap(3) for more escape sequences). > > default:\ > - :passwd_format=md5:\ > + :passwd_format=sha512:\ > :copyright=/etc/COPYRIGHT:\ > :welcome=/etc/motd:\ > :setenv=MAIL=/var/mail/$,BLOCKSIZE=K,FTP_PASSIVE_MODE=YES:\ > > DES > -- > Dag-Erling Sm?rgrav - des@des.no > _______________________________________________ > freebsd-security@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-security > To unsubscribe, send any mail to "freebsd-security-unsubscribe@freebsd.org" >
RW
2012-Jun-10 23:24 UTC
blf uses only 2^4 round for passwd encoding?! [Re: Default password hash]
On Mon, 11 Jun 2012 00:37:30 +0200 Oliver Pinter wrote:> 16 rounds in 2012? It is not to weak?!It's hard to say. Remember that blowfish was designed as a cipher not a hash. It's designed to be fast, but to still resist known plaintext attacks at the beginning of the ciphertext. It was also designed to work directly with a passphrase because there was a history of programmers abusing DES by using simple ascii passwords as keys. For these reasons initialization is deliberately expensive, effectively it already contains an element of passphrase hashing.