3 ms·

reddit made this mistake early on and they learnt their lesson. They no longer store passwords in plain text. The popularity of a service does not guarantee th

by FraaJad 17y ago

reddit made this mistake early on and they learnt their lesson. They no longer store passwords in plain text. The popularity of a service does not guarantee that it's developers are covering all the bases. I'm glad Django stores all the passwords as a sha1 hash.

cperciva 17y ago
I'm glad Django stores all the passwords as a sha1 hash. This is better than storing plaintext passwords, but it still makes a brute-force attack very cheap. Use a well designed key derivation function which is expensive to attack. (And come to BSDCan'09 next week to hear me talk about this!)
- simonw 17y ago
  Django uses a salted hash - each password is stored with a random hash code unique to that password, e.g.: sha1$0ae33$b8a9502237851f302170e1bb207d4eb3f36d9a31 The 0ae33 is different for each stored password, and is used as part of the SHA1 hash. This means you have to brute force each account separately - you can't just use a pre-generated SHA1 lookup table. It sounds like you know your stuff though - if there's anything we could do to make this secure (while not depending on any libraries other than the Python standard library) please share!
  - tptacek 17y ago
    That's still not secure, because SHA1 is very fast. To get "secure" from that, you need to iterate the function several thousand times, or use bcrypt.
    - cperciva 17y ago
      Or use scrypt, which is far more secure than bcrypt. :-)
    - FooBarWidget 17y ago
      Do you have a website or blog entry which explains in detail why using bcrypt is more secure than hash+salt, and how one is supposed to properly store passwords with crypt? Is it because Blowfish is more computationally expensive, and if so, how by how much compared to SHA-1? How does it compare to using larger hashes such as SHA-512 and Whirlpool? Why Blowfish instead of AES?

3 ms·

reddit made this mistake early on and they learnt their lesson. They no longer store passwords in plain text. The popularity of a service does not guarantee th

by FraaJad 17y ago

cperciva 17y ago
I'm glad Django stores all the passwords as a sha1 hash. This is better than storing plaintext passwords, but it still makes a brute-force attack very cheap. Use a well designed key derivation function which is expensive to attack. (And come to BSDCan'09 next week to hear me talk about this!)
- simonw 17y ago
  Django uses a salted hash - each password is stored with a random hash code unique to that password, e.g.: sha1$0ae33$b8a9502237851f302170e1bb207d4eb3f36d9a31 The 0ae33 is different for each stored password, and is used as part of the SHA1 hash. This means you have to brute force each account separately - you can't just use a pre-generated SHA1 lookup table. It sounds like you know your stuff though - if there's anything we could do to make this secure (while not depending on any libraries other than the Python standard library) please share!
  - tptacek 17y ago
    That's still not secure, because SHA1 is very fast. To get "secure" from that, you need to iterate the function several thousand times, or use bcrypt.
    - cperciva 17y ago
      Or use scrypt, which is far more secure than bcrypt. :-)
    - FooBarWidget 17y ago
      Do you have a website or blog entry which explains in detail why using bcrypt is more secure than hash+salt, and how one is supposed to properly store passwords with crypt? Is it because Blowfish is more computationally expensive, and if so, how by how much compared to SHA-1? How does it compare to using larger hashes such as SHA-512 and Whirlpool? Why Blowfish instead of AES?