HMAC(k, m)
is computed as HMAC(H(k), m).
This property is sometimes raised as a possible weakness of HMAC in password-hashing scenarios: it has been demonstrated that it's possible to find a long ASCII string and a random value whose hash will be also an ASCII string, and both values will produce the same HMAC output.[9][10]|journal=
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(help)Unlike SHA-1 and SHA-2, Keccak does not have the length-extension weakness, hence does not need the HMAC nested construction. Instead, MAC computation can be performed by simply prepending the message with the key.
although it doesn't affect applications such as HMAC where collisions aren't important
The strongest attack known against HMAC is based on the frequency of collisions for the hash function H ('birthday attack') [PV,BCK2], and is totally impractical for minimally reasonable hash functions.
This paper proves that HMAC is a PRF under the sole assumption that the compression function is a PRF. This recovers a proof based guarantee since no known attacks compromise the pseudorandomness of the compression function, and it also helps explain the resistance-to-attack that HMAC has shown even when implemented with hash functions whose (weak) collision resistance is compromised.
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(help)sha256
will be set.Encrypt
MethodReturn:An associative array with 'salt', 'password', 'hash' keyswhich vaule of 'hash' is concatenation of 'salt' and 'password'.
Return:An object (stdClass) with 'salt', 'password', 'hash' propertieswhich vaule of 'hash' is concatenation of 'salt' and 'password'.
$good_hash
which has been fetched from database to generate $password
hash while $good_hash
could be salt or hash (concatenation of salt and password).Return:An associative array with 'salt', 'password', 'hash' keyswhich vaule of 'hash' is concatenation of 'salt' and 'password'.
$good_hash
which has been fetched from database to generate $password
hash while $good_hash
could be salt or hash (concatenation of salt and password).Return:An object (stdClass) with 'salt', 'password', 'hash' propertieswhich vaule of 'hash' is concatenation of 'salt' and 'password'.
salt
and password
indexes/properties are 128-bit|16-byte|32-char hash value by default. so hash
would be double (256-bit).pbkdf2
library into your controller:$pbkdf2['password']
as user's password and storing $pbkdf2['salt']
in seperate column for lateral using$pbkdf2['hash']
as user's password which has been recommended; no need to store user's salt
seperately.pbkdf2
library into your controller:user.php
exists, which returns an associative array contains user's password
and whatever-you-need from database using posted username
.salt
and password
which called hash
is used as user's password. the encrypt method select the salt
automatically.salt
in database separately, you MUST pass the salt
as second parameter to encrypt method.