Coding Horrors: You can gather all your technical debt into one easy framework!

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ninjeff: Jan 19, 2004

zootm posted:

I don't disagree with that in general but due to Java's general suckiness, passing in a dynamic value like this as a parameter is non-trivial. Unless you want to pass in an implementation of some obscene interface called BlockDispersalCalculator or something, you're stuck. It is a language limitation though, what you suggest is generally sensible.

Not that this is relevant to the whole "scripting vs hardcoded" discussion, but in this case (determining how many items drop from a block) it seemslike you could just have a minimum and maximum count for each block type and that would cover every reasonable case.

# ? Feb 17, 2011 18:25

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# ? May 16, 2024 09:22

zootm: Aug 8, 2006; We used to be better friends.

Ugg boots posted:

Correct me if I'm wrong, but by passing in a dynamic value you don't mean passing in an enum value do you?

I mean a value that can change on subsequent calls (i.e. a value defined by a function, rather than a simple value).

Having said that ninjeff's suggestion (which I would quote if I wasn't on a mobile phone) above makes perfect sense assuming people don't want to screw with the distribution.

# ? Feb 18, 2011 09:39

shrughes: Oct 11, 2008; (call/cc call/cc)

What's the output of this program on your system?

code:

#include <iostream>
#include <map>

int cnt = 0;
struct F {
    ~F() { cnt++; }
};


int main() {
    std::map<int, F> m;
    m[5] = F();
    m.erase(5);
    std::cout << cnt << std::endl;
}

On mine, it's 4.

# ? Feb 21, 2011 03:07

TOO SCSI FOR MY CAT: Oct 12, 2008; this is what happens when you take UI design away from engineers and give it to a bunch of hipster art student "designers"

shrughes posted:

What's the output of this program on your system?

On mine, it's 4.

Should be 4 on any standards-compliant compiler; what number were you expecting?

# ? Feb 21, 2011 03:35

ToxicFrog: Apr 26, 2008

^^ Why is that? Shouldn't only one F be created, and thus, only one destroyed?

# ? Feb 21, 2011 03:36

TOO SCSI FOR MY CAT: Oct 12, 2008; this is what happens when you take UI design away from engineers and give it to a bunch of hipster art student "designers"

ToxicFrog posted:

^^ Why is that? Shouldn't only one F be created, and thus, only one destroyed?

If map::operator[] is called with a missing key, it automatically inserts a default value with that key before returning its reference. Inserting requires construction of a std::pair<int, F>. The behavior should be something like:

1. call map::operator[] , it constructs a temporary pair, inserts it, then unstacks the temp values (two F deletions)

2. temporary F is created, then assigned to reference returned from operator[], then unstacks the temporary (third F deletion)

3. map::erase() removes the value from the map (fourth F deletion)

# ? Feb 21, 2011 03:53

shrughes: Oct 11, 2008; (call/cc call/cc)

Janin posted:

Should be 4 on any standards-compliant compiler; what number were you expecting?

I would expect it to be 2. One for the std::pair field on a tree node, and one for the temporary in main(). There's no reason for it to be higher. (And if the standard says it must be identical to m.insert(make_pair(5, F())).first->second then the standard is a coding horror.)

# ? Feb 21, 2011 03:53

TOO SCSI FOR MY CAT: Oct 12, 2008; this is what happens when you take UI design away from engineers and give it to a bunch of hipster art student "designers"

shrughes posted:

I would expect it to be 2. There's no reason for it to be higher. (And if the standard says it must be identical to m.insert(make_pair(5, F())).first->second then the standard is a coding horror.)

man, considering the vast and ever-expanding list of horrors that is C++, it's just not worth getting worked up over a few extra data copies.

# ? Feb 21, 2011 03:55

rjmccall: Sep 7, 2007; no worries friend; Fun Shoe

One gets created when evaluating the RHS of the assignment; another gets created when evaluating the LHS of the assignment (i.e., creating an object to assign into). It's not possible to elide copy-assignments, so that's the bare minimum.

libstdc++'s std::map requires two more temporaries because it actually implements operator[] in terms of insert(it, value_type(key, mapped_type())) when the key isn't found, which creates a temporary key and *two* temporary values.

EDIT: beaten quite badly.

# ? Feb 21, 2011 04:04

ohgodwhat: Aug 6, 2005

http://sourcesale.com/projects/2357-Encryption-Static-Library

I haven't seen the source code for it, but the description is bad enough. This is supposed to be a form of encryption?

quote:

The library gets a password from an array and uses it to create a much bigger array. Then it gets a byte from the data to be encrypted and adds that with a value within the larger array. To use this for file encryption I recommend using the while loop and loop through the file sending data to the library one byte at a time until the file ends.

# ? Feb 21, 2011 18:07

POKEMAN SAM: Jul 8, 2004

ryanmfw posted:

http://sourcesale.com/projects/2357-Encryption-Static-Library

I haven't seen the source code for it, but the description is bad enough. This is supposed to be a form of encryption?

Hah, that's awesome. Here's a preview of the code from that page

code:

  dat -  keytemp[keycount];
    keycount += 1;
	if (keycount > 1048576) {
		keycount = 1;
	}

return dat;
}




}


/////////////////////////////////////////////////////////////////////////////////////

void keygenerate() //calculates keytemp 
{
	extern unsigned short int passtemp[512];	//refers to passtemp in program

# ? Feb 21, 2011 18:49

gibbed: Apr 10, 2006

Ugg boots posted:

Hah, that's awesome. Here's a preview of the code from that page

I RE'd a little bit of the testalib.exe and it appeared to just be XORing the content with a generated table based on the key (this is just from a quick look though, I could be wrong). So yeah, crappy obfuscation.

# ? Feb 21, 2011 19:14

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

gibbed posted:

I RE'd a little bit of the testalib.exe and it appeared to just be XORing the content with a generated table based on the key (this is just from a quick look though, I could be wrong). So yeah, crappy obfuscation.

That's how AES-CTR and AES-OFB work, except the table is so fantastically large it's impractical to store.

# ? Feb 22, 2011 05:44

Scaevolus: Apr 16, 2007

BonzoESC posted:

That's how AES-CTR and AES-OFB work, except the table is so fantastically large it's impractical to store.

Yes, stream ciphers work by XOR-ing a suitably random stream of bits with a message stream.

# ? Feb 22, 2011 06:18

Malloc Voidstar: May 7, 2007; Fuck the cowboys. Unf. Fuck em hard.

mysql>�select�aes_encrypt('hello',�'')�=�aes_encrypt('hello',�'4re35na2aTaVasAy4re35na2aTaVasAy'); +-------------------------------------------------------------------------------------+ |�aes_encrypt('hello',�'')�=�aes_encrypt('hello',�'4re35na2aTaVasAy4re35na2aTaVasAy')�| +-------------------------------------------------------------------------------------+ |��1�| +-------------------------------------------------------------------------------------+

http://bazaar.launchpad.net/~mysql/mysql-server/mysql-5.5/view/head:/mysys/my_aes.c

# ? Feb 23, 2011 01:11

Opinion Haver: Apr 9, 2007

Aleksei Vasiliev posted:

mysql>�select�aes_encrypt('hello',�'')�=�aes_encrypt('hello',�'4re35na2aTaVasAy4re35na2aTaVasAy'); +-------------------------------------------------------------------------------------+ |�aes_encrypt('hello',�'')�=�aes_encrypt('hello',�'4re35na2aTaVasAy4re35na2aTaVasAy')�| +-------------------------------------------------------------------------------------+ |��1�| +-------------------------------------------------------------------------------------+

http://bazaar.launchpad.net/~mysql/mysql-server/mysql-5.5/view/head:/mysys/my_aes.c

I don't get it.

vvv oh, hurr.

Opinion Haver fucked around with this message at 01:37 on Feb 23, 2011

# ? Feb 23, 2011 01:21

bobthecheese: Jun 7, 2006; Although I've never met Martha Stewart, I'll probably never birth her child.

Aleksei Vasiliev posted:

mysql>�select�aes_encrypt('hello',�'')�=�aes_encrypt('hello',�'4re35na2aTaVasAy4re35na2aTaVasAy'); +-------------------------------------------------------------------------------------+ |�aes_encrypt('hello',�'')�=�aes_encrypt('hello',�'4re35na2aTaVasAy4re35na2aTaVasAy')�| +-------------------------------------------------------------------------------------+ |��1�| +-------------------------------------------------------------------------------------+

http://bazaar.launchpad.net/~mysql/mysql-server/mysql-5.5/view/head:/mysys/my_aes.c

Is that a case of an accidental collision, or a pre-defined default key?

yaoi prophet posted:

I don't get it

it means that encrypting something with '4re35na2aTaVasAy4re35na2aTaVasAy' as a key has the same result as not using a key at all.

bobthecheese fucked around with this message at 01:25 on Feb 23, 2011

# ? Feb 23, 2011 01:23

TOO SCSI FOR MY CAT: Oct 12, 2008; this is what happens when you take UI design away from engineers and give it to a bunch of hipster art student "designers"

bobthecheese posted:

Is that a case of an accidental collision, or a pre-defined default key?

If the key length is >128 bits, MySQL reduces it by XOR. "4re35na2aTaVasAy4re35na2aTaVasAy" is just "4re35na2aTaVasAy" twice, so it reduces to 0 (the same as ""). You can get the same result by doubling (or quadrupling, etc) any 16-character string.

# ? Feb 23, 2011 03:20

bobthecheese: Jun 7, 2006; Although I've never met Martha Stewart, I'll probably never birth her child.

Janin posted:

If the key length is >128 bits, MySQL reduces it by XOR. "4re35na2aTaVasAy4re35na2aTaVasAy" is just "4re35na2aTaVasAy" twice, so it reduces to 0 (the same as ""). You can get the same result by doubling (or quadrupling, etc) any 16-character string.

Oh, wow, that IS a horror.

# ? Feb 23, 2011 03:22

spiritual bypass: Feb 19, 2008; Grimey Drawer

I can't wait for Oracle to finally kill MySQL

# ? Feb 23, 2011 03:33

Kelson: Jan 23, 2005

Aleksei Vasiliev posted:

mysql>�select�aes_encrypt('hello',�'')�=�aes_encrypt('hello',�'4re35na2aTaVasAy4re35na2aTaVasAy'); +-------------------------------------------------------------------------------------+ |�aes_encrypt('hello',�'')�=�aes_encrypt('hello',�'4re35na2aTaVasAy4re35na2aTaVasAy')�| +-------------------------------------------------------------------------------------+ |��1�| +-------------------------------------------------------------------------------------+

http://bazaar.launchpad.net/~mysql/mysql-server/mysql-5.5/view/head:/mysys/my_aes.c

I'm not sure I'm following where that value arises from the link. In my_aes_create_key, I see that it leaves rkey 0'd out if key_length is 0, but it looks like rijndaelKeySetup* (wherever that's defined) then sets "4re...". Am I missing something?

# ? Feb 23, 2011 04:13

TOO SCSI FOR MY CAT: Oct 12, 2008; this is what happens when you take UI design away from engineers and give it to a bunch of hipster art student "designers"

Kelson posted:

I'm not sure I'm following where that value arises from the link. In my_aes_create_key, I see that it leaves rkey 0'd out if key_length is 0, but it looks like rijndaelKeySetup* (wherever that's defined) then sets "4re...". Am I missing something?

read my post

# ? Feb 23, 2011 05:50

Kelson: Jan 23, 2005

Janin posted:

read my post

I did. I didn't say "I don't understand what is happening". Instead, "I'm not following where that value arises from the link."

# ? Feb 23, 2011 12:14

gibbed: Apr 10, 2006

BonzoESC posted:

That's how AES-CTR and AES-OFB work, except the table is so fantastically large it's impractical to store.

Well yes, but this self-implemented junk is terrible.

# ? Feb 23, 2011 12:29

POKEMAN SAM: Jul 8, 2004

gibbed posted:

Well yes, but this self-implemented junk is terrible.

It's like, yeah I kinda know how hash functions work, but I sure as poo poo won't try to write one myself!

# ? Feb 23, 2011 16:46

Dessert Rose: May 17, 2004; awoken in control of a lucid deep dream...

Kelson posted:

I did. I didn't say "I don't understand what is happening". Instead, "I'm not following where that value arises from the link."

code:

  for (ptr= rkey, sptr= key; sptr < key_end; ptr++,sptr++)
  {
    if (ptr == rkey_end)
      ptr= rkey;  /*  Just loop over tmp_key until we used all key */
    *ptr^= (uint8) *sptr;
  }

# ? Feb 23, 2011 16:59

Kelson: Jan 23, 2005

Ryouga Inverse posted:

code:

  for (ptr= rkey, sptr= key; sptr < key_end; ptr++,sptr++)
  {
    if (ptr == rkey_end)
      ptr= rkey;  /*  Just loop over tmp_key until we used all key */
    *ptr^= (uint8) *sptr;
  }

That's what I thought at first, except key_length is presumably 0 for the empty string. That means key_end = key + 0, which is really just key. Which skips the for(sptr = key;sptr < key;sptr++) loop?

If that weren't the case, the value would be whatever happened to be in the "invalid" memory block key pointed towards (which may change between runs).

# ? Feb 24, 2011 04:07

ShoulderDaemon: Oct 9, 2003; support goon fund; Taco Defender

Kelson posted:

That's what I thought at first, except key_length is presumably 0 for the empty string. That means key_end = key + 0, which is really just key. Which skips the for(sptr = key;sptr < key;sptr++) loop?

If that weren't the case, the value would be whatever happened to be in the "invalid" memory block key pointed towards (which may change between runs).

Correct, except the memory block isn't invalid in that case, it's explicitly initialized to zero by the bzero call prior to the block.

The value Aleksei Vasiliev chose doesn't come from the code, it's arbitrary. It just happens to have the property that when XORed over itself in 16-byte chunks it becomes zero. The key "4re35na2aTaVasAy4re35na2aTaVasAy" is the same as the key "" is the same as the key "0123456789abcdef0123456789abcdef" is the same as the key "abcdefghijklmnopabcdefghijklmnop" is the same as the key "aaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbb" and so on and so on.

ShoulderDaemon fucked around with this message at 04:35 on Feb 24, 2011

# ? Feb 24, 2011 04:32

Kelson: Jan 23, 2005

ShoulderDaemon posted:

Correct, except the memory block isn't invalid in that case, it's explicitly initialized to zero by the bzero call prior to the block.

Really?

code:

static int my_aes_create_key(KEYINSTANCE *aes_key, enum encrypt_dir direction, const char *key, int key_length)
{
  uint8 rkey[AES_KEY_LENGTH/8];	 /* The real key to be used for encryption */
  uint8 *rkey_end=rkey+AES_KEY_LENGTH/8; /* Real key boundary */
  uint8 *ptr;			/* Start of the real key*/
  const char *sptr;			/* Start of the working key */
  const char *key_end=key+key_length;	/* Working key boundary*/
  bzero((char*) rkey,AES_KEY_LENGTH/8);      /* Set initial key  */

  for (ptr= rkey, sptr= key; sptr < key_end; ptr++,sptr++)
  {
    if (ptr == rkey_end)
      ptr= rkey;  /*  Just loop over tmp_key until we used all key */
    *ptr^= (uint8) *sptr;
  }
  ...
}

If key_length is 0, the for loop never executes (no xor takes place in my_aes_create_key) which leaves rkey bzero'd. If mysql was retarded and key_length somehow weren't 0 in the empty-key instance above, it'd xor *sptr into rkey, which is "invalid" memory (sptr = key; sptr < key+key_length) not the bzero'd buffer (ptr = rkey; bzero(rkey, AES_KEY_LENGTH/8)).

ShoulderDaemon posted:

The value Aleksei Vasiliev chose doesn't come from the code, it's arbitrary. It just happens to have the property that when XORed over itself in 16-byte chunks it becomes zero. The key "4re35na2aTaVasAy4re35na2aTaVasAy" is the same as the key "" is the same as the key "0123456789abcdef0123456789abcdef" is the same as the key "abcdefghijklmnopabcdefghijklmnop" is the same as the key "aaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbb" and so on and so on.

I believe "4re35na2aTaVasAy" is xor'd into each 16-byte chunk; where is that value in the code above? I may certainly be missing something, I'm just asking what. It appears to be in code not shown in the link (such as within rijndaelKeySetupEnc(aes_key->rk, rkey, AES_KEY_LENGTH)). No?

# ? Feb 24, 2011 12:28

Malloc Voidstar: May 7, 2007; Fuck the cowboys. Unf. Fuck em hard.

*key is a pointer to the password
rkey is an array of length 16 (AES_KEY_LENGTH = 128, /8 = 16. see my_aes.h for the define)
rkey is the actual key that will be used to encrypt/decrypt

��for�(ptr=�rkey,�sptr=�key;�sptr�<�key_end;�ptr++,sptr++) ��{ ��if�(ptr�==�rkey_end) ��ptr=�rkey;��/*��Just�loop�over�tmp_key�until�we�used�all�key�*/ ��*ptr^=�(uint8)�*sptr; ��}

sptr = the password pointer

it first zeroes the realkey, if the given password is 0-length then it's done creating the realkey, the loop doesn't run

if not, then it will iterate through the realkey[16] for as many bytes as there are in the password, XORing as it goes. that's this line: *ptr^= (uint8) *sptr;.( ^= is XOR-assignment). if it hits the realkey's end, then it will reset to the beginning of the array. the password index is not changed.

did this help

(also I'm a Java programmer so my explanation might be totally wrong :v:

)

# ? Feb 24, 2011 14:25

Hammerite: Mar 9, 2007; And you don't remember what I said here, either, but it was pompous and stupid.; Jade Ear Joe

I don't see what the problem is. Just use "4re35na2aTaVasAy4re35na2aTaVasAy4re35na2aTaVasAy" and you'll be fine. :eng101:

# ? Feb 24, 2011 16:34

ShoulderDaemon: Oct 9, 2003; support goon fund; Taco Defender

Kelson posted:

If key_length is 0, the for loop never executes (no xor takes place in my_aes_create_key) which leaves rkey bzero'd.

Correct.

Kelson posted:

If mysql was retarded and key_length somehow weren't 0 in the empty-key instance above, it'd xor *sptr into rkey, which is "invalid" memory (sptr = key; sptr < key+key_length) not the bzero'd buffer (ptr = rkey; bzero(rkey, AES_KEY_LENGTH/8)).

This does not happen; key_length is zero in the empty-key instance.

Kelson posted:

I believe "4re35na2aTaVasAy" is xor'd into each 16-byte chunk; where is that value in the code above?

Incorrect. The "4re35na2aTaVasAy" is not an artifact of the code, it's just something Aleksei Vasiliev chose arbitrarily. "4re35na2aTaVasAy" is not special.

The only thing that's special about about the key that Aleksei Vasiliev chose is that it consists of a 16-character string, repeated an even number of times. Any such key will be equivalent to the all-zeroes key or the empty key.

Kelson posted:

I may certainly be missing something, I'm just asking what. It appears to be in code not shown in the link (such as within rijndaelKeySetupEnc(aes_key->rk, rkey, AES_KEY_LENGTH)). No?

Nowhere within any of the MySQL code or its support libraries will you find "4re35na2aTaVasAy". It's not a value that comes from the code. It's just a value that Aleksei Vasiliev picked to demonstrate the problem.

# ? Feb 24, 2011 17:49

Opinion Haver: Apr 9, 2007

code:

mysql> select aes_encrypt('hello', '') = aes_encrypt('hello', 'arbitrarypasswrdarbitrarypasswrd');
+-------------------------------------------------------------------------------------+
| aes_encrypt('hello', '') = aes_encrypt('hello', 'arbitrarypasswrdarbitrarypasswrd') |
+-------------------------------------------------------------------------------------+
|                                                                                   1 |
+-------------------------------------------------------------------------------------+

See?

# ? Feb 24, 2011 18:08

NotShadowStar: Sep 20, 2000

Sheet nigga, that's all you had to say!

# ? Feb 24, 2011 18:55

Randomosity: Sep 21, 2003; My stalker WAS watching me...

ToxicFrog posted:

Who the gently caress uses floats to store monetary amounts

At the risk of sounding stupid, what's that preferred way?

VVV hah, I understand how floats are stored and their implicit fuzziness. I meant which variable type or some other method.

Randomosity fucked around with this message at 19:57 on Feb 24, 2011

# ? Feb 24, 2011 19:50

pseudorandom name: May 6, 2007

Certainly not a format incapable of storing exact values.

# ? Feb 24, 2011 19:52

spiritual bypass: Feb 19, 2008; Grimey Drawer

Store an integer containing cents; doubles are just big floats.

# ? Feb 24, 2011 19:58

Incoherence: May 22, 2004; POYO AND TEAR

rt4 posted:

Store an integer containing cents; doubles are just big floats.

[insert Office Space plot summary here]

# ? Feb 24, 2011 20:04

dis astranagant: Dec 14, 2006

Randomosity posted:

At the risk of sounding stupid, what's that preferred way?

VVV hah, I understand how floats are stored and their implicit fuzziness. I meant which variable type or some other method.

There are decimal data types in many languages and the ones that don't probably have a library for it. Anyone working with money should probably use them (especially if they could be audited).

# ? Feb 24, 2011 20:21

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# ? May 16, 2024 09:22

Scaevolus: Apr 16, 2007

That's not how aes_encrypt works, though. It expects to get a (random) 128-bit string.

It should probably be noted in the documentation, but I don't see how this is a horror.

# ? Feb 24, 2011 21:19

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > The Cavern of COBOL > Coding Horrors: You can gather all your technical debt into one easy framework!

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