jonasschneider

[22:32] <sokrates> does having a "perfect" PRNG trivially lead to perfect symmetric crypto?
[22:33] <sokrates> imagine this situation: A and B both have a copy of this perfect PRNG
[22:33] <sokrates> they both seed it with the shared key
[22:33] <catid> in the OTP sense yes i believe so
[22:33] <sokrates> and then alice simply XORs the PRNG's output with the plaintext
[22:34] <catid> but you can still misuse that kind of cipher construction: you can reuse the PRNG seed to encrypt the same data twice
[22:34] <Riastradh> If the key was chosen uniformly at random and the PRNG's output is indistinguishable from uniform random, then yes.  This is how stream ciphers work.
[22:34] <catid> or the seed can have insufficient randomness itself
[22:34] == Platyp [~flatline@2607:f470:22:8:beae:c5ff:fe5a:903f] has joined ##crypto
[22:35] <catid> an online game cheater can filter out all packets with length = 53 to stop something from going through, even though they cannot decrypt the data

jonasschneider

Keybase proof

I hereby claim:

• I am jonasschneider on github.
• I am jonasschneider (https://keybase.io/jonasschneider) on keybase.
• I have a public key whose fingerprint is 0D07 E065 758B 05EB E9C0 9DFD AC7F 2AEB 434F 894A

To claim this, I am signing this object:

jonasschneider

/*!
 *
 * stagas - need more 303
 *
 */

var bpm = 125;
var tuning = 440;
var transpose = -1;

jonasschneider

Okay, this is getting ugly. For some reeeally unknown reason, this segfaults:
$ run_fis pry -rpg -e 'PG.connect({:host=>"127.0.0.1"})'
while this doesn't:
$ run_fis pry -rpg -e 'puts PG.connect({dbname: "fis"})'

I suspect it has something to do with authentication methods; while the first one uses TCP sockets and therefore can't use Linux SO_GETPEERCRED auth,
the other one can. Oh well.

--- a/vendor/bundle/ruby/2.1.0/gems/sequel-4.9.0/lib/sequel/adapters/postgres.rb	2014-08-26 20:31:38.000000000 +0000
+++ b/vendor/bundle/ruby/2.1.0/gems/sequel-4.9.0/lib/sequel/adapters/postgres.rb	2014-08-26 20:31:53.000000000 +0000

jonasschneider

diff --git a/target-i386/seg_helper.c b/target-i386/seg_helper.c
index c98eeb4..fc72e4f 100644
--- a/target-i386/seg_helper.c
+++ b/target-i386/seg_helper.c
@@ -866,19 +866,24 @@ static void do_interrupt64(CPUX86State *env, int intno, int is_int,
     }
 
     if (load_segment(env, &e1, &e2, selector) != 0) {
+        qemu_log_mask(CPU_LOG_RESET, "XXXX load_segment\n");
         raise_exception_err(env, EXCP0D_GPF, selector & 0xfffc);

jonasschneider

vagrant@vagrant-ubuntu-trusty-64:/vagrant/mod$ nm --undefined-only a.out
                 U abort
                 U ceil
                 U ceilf
                 U exp
                 U exp2
                 U exp2f
                 U expf
                 U fflush
                 U floor

jonasschneider

[main] INFO spark.servlet.SparkFilter - StaticResourceHandler configured with folder = /public
Running in servlet container -- configuring from servlet context (usually from web.xml)
null
DB: CREATE TABLE IF NOT EXISTS experiment(id TEXT PRIMARY KEY     NOT NULL, description    TEXT    DEFAULT '',  budget       INT,  preview_click_count    INT,  hit_mturkid    TEXT,  finished       INT,  softfinished   INT,  answer_payment    INT,  rating_payment    INT ,  basic_payment    INT,  statsid        TEXT,  ratingviewclass TEXT,  sqltime       TIMESTAMP   DEFAULT CURRENT_TIMESTAMP   NOT NULL,  bonus_payment    INT,  tags           INT,  qualifications    INT,  hit_title      INT,  max_answers_per_assignment    INT,  max_ratings_per_assignment    INT,  hit_description    INT);
DB: CREATE TABLE IF NOT EXISTS  qualification(id TEXT PRIMARY KEY     NOT NULL, text     TEXT  ,  experimentid   TEXT     NOT NULL); 
DB: CREATE TABLE IF NOT EXISTS  tag(id TEXT PRIMARY KEY     NOT NULL, text     TEXT   ,  experimentid   TEXT  

jonasschneider

# Overhead  Command         Shared Object
# ........  .......  ....................  .....................................................................................................................
#
    93.16%  zbackup  libc-2.19.so          [.] memset
            |
            --- memset
               |
               |--99.99%-- std::string::append(unsigned long, char)
               |          google::protobuf::io::StringOutputStream::Next(void**, int*)
               |          google::protobuf::io::CodedOutputStream::Refresh()

jonasschneider

From ce4f2a8c91510d7032ab441c37f3b78de7cc72cb Mon Sep 17 00:00:00 2001
From: Jonas Schneider <mail@jonasschneider.com>
Date: Tue, 10 Mar 2015 23:48:42 +0100
Subject: [PATCH] backup_creator: naively buffer a couple of instructions to
 avoid using the slow StringOutputStream

---
 backup_creator.cc | 36 +++++++++++++++++++++++++++++++++++-
 backup_creator.hh |  4 ++++
 2 files changed, 39 insertions(+), 1 deletion(-)

jonasschneider

From bdd045842757f316123d295e4d71591b71e00b7f Mon Sep 17 00:00:00 2001
From: Jonas Schneider <mail@jonasschneider.com>
Date: Wed, 11 Mar 2015 10:25:35 +0100
Subject: [PATCH] Improve backup performance by initializing the
 CodedOutputStream only once.

---
 backup_creator.cc | 2 +-
 backup_creator.hh | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)