Hot answers tagged

76

Summary: it was marginally better on older drives, but doesn't matter now. Multiple passes erase a tree with overkill but miss the rest of the forest. Use encryption. The origin lies in work by Peter Gutmann, who showed that there is some memory in a disk bit: a zero that's been overwritten with a zero can be distinguished from a one that's been overwritten ...


45

Google has access (obviously). The police will have access if they have a valid search warrant. A national security letter will give the FBI secret access. Various three-letter agencies may have access, depending on how they're doing at circumventing Google's encryption. (Google started encrypting its internal traffic after it was revealed that the NSA was ...


44

Quick-formatting a hard disk simply erases the filesystem's structures and tables and writes new ones in place, giving the illusion of a brand new disk. Old data is simply overwritten as and when needed, but it still remains on the disk. File carving utilities can go through the disk data and recover fragments of files, then stitch them back together without ...


31

The only NIST approved method to securely erase a hard drive is by utilizing the secure erase internal command - documented at the Center for Magnetic Recording Research (CMRR) - and that is what everyone should be doing. It is an ATA command, and covers (S)ATA interfaces. After that, you can optionally degauss the drive to erase the firmware itself. Lots ...


26

From Wikipedia: An initialization vector has different security requirements than a key, so the IV usually does not need to be secret. However, in most cases, it is important that an initialization vector is never reused under the same key. For CBC and CFB, reusing an IV leaks some information about the first block of plaintext, and about any common ...


20

According to the articles linked below 1-2 wipes will be enough. For any modern PRML/EPRML drive, a few passes of random scrubbing is the best you can do. As the paper says, “A good scrubbing with random data will do about as well as can be expected“. This was true in 1996, and is still true now. “ Even if some data is left unerased or recoverable ...


19

There is a well-known reference article by Peter Gutmann on the subject. However, that article is a bit old (15 years) and newer harddisks might not operate as is described. Some data may fail to be totally obliterated by a single write due to two phenomena: We want to write a bit (0 or 1) but the physical signal is analog. Data is stored by manipulating ...


19

Back then, tapes were just binary data on a magnetic film, with no "hidden" channels or out-of-band capabilities. Manufacturers that claimed to make tape-to-tape recording impossible often just made the tape look different, to deter would-be pirates. A regular tape recorder module was usually used to read them, so making "special" tapes couldn't really work. ...


18

From a theoretical standpoint the idea of total drive destruction may be the only way of destroying data on a hard drive fully. From a practical standpoint, I've not seen any evidence that it's possible to recover meaningful data from a standard hard drive (ie, not taking SSDs or other devices that use wear levelling or similar technologies) after a once ...


18

Overwriting the data is either insufficient or useless, depending on how things are done internally by the device itself. Flash memory has a limited life, expressed in terms of read/write cycles. To sum it up, you can have one block of data full of zeros; bits can be changed from zero to one individually, but the reset to zero can be done only for a complete ...


18

The reason you write '0' instead of '1' has to do with the way magnetic storage encodes the 0 and the 1. a long explanation of it can be found on Wikipedia under Run-length_limited. In short RLL is the methodology used to store the '1' and '0' and it is more complex than just to store the bit values themselves. On a side note to make the drive more like it ...


16

The most sensible approach is to assume you cant rely on their privacy - it isn't their responsibility, although there are some services whose selling point is securing this data. If you take that stance, as long as you encrypt all data before it goes to the cloud you can be safe (decide on what level of encryption you need in order to be safe) This ...


15

What about something like Verbatim's Archival Grade Gold DVD-R>? It gives 4 GB storage. They claim a life of "up to 100 years" but I find no independent verification. Frankly I'm skeptical. But maybe you can boost your chances by just burning the same data on to multiple disks and hope any failures are uncorrelated? I'd buy disks from different lots or ...


14

I will try to answer your question as specifically as possible. I contacted Intel tech support to ask them exactly this question: Is the AES key on the Intel 520 encrypted with the ATA password. After weeks of back and forth, I finally received an explicit confirmation from them. I quote: Yes, ATA password is used to encrypt the encryption keys stores ...


14

Never hardcode passwords or crypto keys in your program. The general rule of thumb is: the only credentials you should store on a user's machine are credentials associated with that user, e.g., credentials that enable that user to log into his/her account. You should not store your developer credentials on the user's machine. That's not safe. You have to ...


14

Not instantly. Although, that's what I want to believe. What you could do is the following. Download the Truecrypt version 7.1a and create an encrypted storage file (option 1 from the wizard) and choose 3 algorithm based encryption with a SHA-512 key. Put all your sensitive files in here and upload the encrypted file to Google Drive. When you want to work ...


13

If I recall correctly, some games even managed to defeat direct tape-to-tape copying. In principle, this couldn't be possible, as the audio track on the tape contained all the information required. In practice, by using a custom loader which operated on data files encoded at a higher frequency than the standard Spectrum data files, low-quality consumer-...


12

I would say no its not suitable for storing criticial information, From the sound of their terms Google essentially owns everyting you upload as well as anything derivitive of your data as well. Here is an excerpt from the verge.com explaining the differences of the 3 major players, notice Google is very liberal with what they can do with your data. ...


12

As storage technologies change over time, using different encodings and remappings to deal with sector errors, the best way to permanently erase data changes also. Very smart people have expended enormous amounts of time and effort arguing over this problem. Most of them end up at the same bottom line, which is: the only method you can truly trust is ...


11

If you're talking about a Windows desktop application, you should use the CryptProtectData API, which stores the credentials in protected memory regions and encrypts them with a key that is part of the user profile. This is the standard protection mechanism for Windows applications. On Linux you could look into using the GNOME keyring or KDE wallet, and OS ...


10

Do you need to erase the data, or do you need to persuade other people that the data has been erased? (I will only talk about 'entire disk' wiping on conventional drives; I'm not talking about wiping single files or slack space or SSDs.) As far as I am aware there is no software package that claims to be able to recover data that has had a single overwrite....


10

No. The API keys need to be stored in cleartext. They are not passwords: they are cryptographic keys. These keys are used for things like authenticating requests (using SHA1-HMAC). The server needs to know the crypto key to apply the cryptographic algorithms. Therefore, the API key needs to be stored in cleartext on the server. If the server stored ...


10

Technically, according to PCI SSC you can hold onto CVV and other sensitive authentication data until authorization has occurred. In other words the restriction on storing sensitive authentication data applies to post authentication/processing storage. Here is a document from the PCI SSC about data storage requirments. See the "Technical Guidelines for PCI ...


9

Keeping information in RAM can enhance security, if done right and if the requirements allow it. I'm going to show two security architectures where keeping the data in RAM provides a security benefit. These are fairly specific scenarios; most of the time keeping data in RAM doesn't help. Protection against file dump attacks Consider a web application that ...


9

Consider this from an Information Management or Information Assurance question rather than an Information Protection question. To the question if a service provider's level of security is "safe" (sufficient and appropriate), the answer is YES and NO - depending on the level of protection the specific information requires. My suggestion is you create three ...


9

Hashing is not storage; it irreversibly destroys data. We can get away with calling password hashing as "password storage" because when we actually need the password, we have a handy human operator to type it in. Indeed, when we hash the password we do not store the password, but only a token sufficient to verify the typed-in password. An API key must be ...


9

Any data you upload to Google Drive (or Skydrive, or Dropbox for that matter) should be considered duplicated by the NSA. Apart from arbitrary queries from the aforementioned secret service, law enforcement agencies from any country may gain access to them through legal means (subpoenas and so on). And of course, Google engineers could in theory browse your ...


8

In my opinion, you don't. The salt cannot be used directly to get the clear PAN back, so it is not subject to requirement 3.5.


7

Yes, TrueCrypt volumes look like random data. This is mentioned in the Plausible deniability section of the TrueCrypt FAQ. The FAQ even mentions that having just erased a disk is an excuse for having a volume full of random data. I hate to call it a plausible excuse because as a rule people don't keep such volumes around. If your disk is seized and found to ...


7

Those good old days. When I was young I copied some Spectrum games and had to work my way around copy preventions schemes. Tape-to-tape copying is described in other answers. I was interested in digital copies for the best results. Data on the tape in standard format was essentially just a series of bytes. With a few standard statements (LOAD, SAVE) you ...



Only top voted, non community-wiki answers of a minimum length are eligible