Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>It seems what you need is fairly simple. (Although finding an elegant mathematical solution to this problem may be fun it's really not necessary) SHA-256 is a 32 byte long array. The letters and numbers you see are just the hexadecimal representation of the array. Since a Hex digit requires 4 bits of data each combination of two letters or numbers (or letters and numbers) represents 1 byte. This is why you need a 64 long character string to represent a 32 byte array.</p> <p>To my knowledge WinRar has a password limit of 177 characters and 7z has no limitation. Theoretically you could use your original 64 character SHA-256 representation as a password. The generated password is very strong since it has 16^64 == 2^256 combinations.</p> <p>However as it happens - a shorter password but a lot stronger can be generated using Base64 encoding (Wikipedia is a good place to start). With Base64 your 32 bytes array can be represented as a 43 character long password comprised of uppercase and lowercase letters as well as 9 digits and the + and / characters. So you get 64^43 > 2^256.</p> <p>You can easily convert the Base64 string back to the hash.</p> <p><strong>As a side note:</strong> You should notice that since AES256 uses a 256 bit key it's actually quite useless to generate a stronger password since in that case the attacker can just attack the key and neglect the password so using the SHA-256 is really enough. But I like the fact that we can generate a 43 character long password stronger than the 64 character long one.</p> <p><strong>And yet another side note:</strong> Depending on the type of characters the compressor you will use accepts as a password character you could design your own Base128 encoding and lower the number of characters to 37.</p> <p>Also I would suggest using 7z as it is both fast, very capable and last but not least open source.</p>
    singulars
    1. This table or related slice is empty.
    1. POMathematics of Hashing with numbers and letters
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USSebastian Cabot
    1. USSebastian Cabot
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POMathematics of Hashing with numbers and letters
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    1. COActually, the Base64 password will still have 256 bits of entropy, just like the hexadecimal one, since it's derived from a 256-bit hash. Yes, 43*6 = 258 > 256, but the two extra bits will simply be zero.
      singulars
      1. PO
      1. USIlmari Karonen
    2. CO@IlmariKaronen - Why you might be right but regarding the password you are actually wrong. The Base64 password is generated through a table. For that reason the resulting password is not just a different representation of the same bits. It a new bit string which is 344 bits long. So unless you attack the original hash that was used to produce it you get a much greater entropy. Your point is really valid only if you know how the password was generated in the first place.
      singulars
      1. PO
      1. USSebastian Cabot
    3. CORecognizing base64-encoded data tends to be pretty easy, especially if you have more than one sample.
      singulars
      1. PO
      1. USIlmari Karonen
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload