How I became a password cracker

Re:How I became a password cracker by alexkus on Monday March 25, 2013 @04:14AM (#5435952)

Most encryption algorithms (including block ciphers) can be used as a hashing algorithm for passwords.

Just encrypt a common known plaintext string and use the password as the encryption key. This is exactly how various hashing schemes like UNIX's crypt() (based on DES) work.

Knowing the plaintext (e.g. a set of NUL bytes) is useless as long as the encryption scheme doesn't have a weakness against known-plaintext attacks [EDIT] that allow you to recover the encryption key somehow.

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Re:How I became a password cracker by pjscott on Monday March 25, 2013 @01:55PM (#5438496)

Yes, and Blowfish (or rather, a variant of it with an expensive key schedule) is used as the main building block of Bcrypt in roughly the way you describe. That doesn't mean that Blowfish is Bcrypt.

I feel like such a pedantic dick for harping on this, but the distinction is worth making.

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Re:How I became a password cracker by chickopozo on Monday March 25, 2013 @05:44AM (#5436223)

Encryption does not provide Integrity (hash) or authentication (mac)

crypt(1) should be an example of how not to do hashing.

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Re:How I became a password cracker by alexkus on Monday March 25, 2013 @05:54AM (#5436241)

Perfectly true, but those points are irrelevant for password hashing.

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