How do I effectively use crypt()

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9 Answers

90%

crypt is one-way. When you get a password to test, you crypt it with the original salt and compare the encrypted values. By design, you have no way to recover the password after running it through crypt short of brute-force guessing until you find it. – Jeffrey Hantin Jul 21 '11 at 1:07 ,Since crypt() only uses the first two characters (or whatever CRYPT_SALT_LENGTH is) of the salt argument, passing in the encrypted password (of which the first characters are the salt originally used to encrypt it) does the right thing.,If your question is... Is it normal that with certain encryption ciphers you are returned with different encrypted strings for the same password/input? The answer is yes. Not to sure what you are refering to about salt. Salt it just salt. In the end it is a deturant and means nothing. Using passwords or encrypted forms of passwords as salt is not recommended, but using some random hash (base64) of a phrase is commonly used. Let me know if this doesn't any, and I'll try again., In the php.net example the stored password use not salt, when they test against the password they use user_input as the salt, perhaps this is an error in their documentation, I have seen this before. – user656925 Jul 21 '11 at 1:49

Prior to insertion on signup:

$pass = crypt('$pass', 'd4'); // after this I insert $pass into the mysql table
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88%

The key specifies the encryption algorithm used.,Data Encryption and Decryption Functions,A handle to the encryption key. An application obtains this handle by using either the CryptGenKey or the CryptImportKey function.,If the cipher is operating in a chaining mode, the next CryptEncrypt operation resets the cipher's feedback register to the KP_IV value of the key.

Syntax

BOOL CryptEncrypt(
   [ in ] HCRYPTKEY hKey,
   [ in ] HCRYPTHASH hHash,
   [ in ] BOOL Final,
   [ in ] DWORD dwFlags,
   [ in , out] BYTE * pbData,
   [ in , out] DWORD * pdwDataLen,
   [ in ] DWORD dwBufLen
);
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72%

In Unix computing, crypt or enigma is a utility program used for encryption. Due to the ease of breaking it, it is considered to be obsolete. ,Source code for crypt(1) from Version 6 Unix (implementation of Boris Hagelin's M-209 cryptographic machine),Source code for crypt(1) from Version 7 Unix (trivialised one-rotor Enigma-style machine),3 Breaking crypt(1) encryption

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65%

Using PHP's crypt() to store passwords,It is safe to store the salt together with the password hash. An attacker cannot use it to make a dictionary attack easier.,It is safe to store the salt together with the password hash. An attacker cannot use it to make a dictionary attack easier. ,Secure password hashing with bCrypt

Notice how the first 29 characters are the same as the salt string:

crypt('EgzamplPassword', '$2a$10$1qAz2wSx3eDc4rFv5tGb5t') >>
   '$2a$10$1qAz2wSx3eDc4rFv5tGb5e4jVuld5/KF2Kpy.B8D2XoC031sReFGi'

Notice also how anthing appended to the salt string argument has no effect on the result:

crypt('EgzamplPassword', '$2a$10$1qAz2wSx3eDc4rFv5tGb5t12345678901234567890') >>
   '$2a$10$1qAz2wSx3eDc4rFv5tGb5e4jVuld5/KF2Kpy.B8D2XoC031sReFGi'

crypt('EgzamplPassword', '$2a$10$1qAz2wSx3eDc4rFv5tGb5t$2a$10$1qAz2wSx3eDc4rFv5tGb5t') >>
   '$2a$10$1qAz2wSx3eDc4rFv5tGb5e4jVuld5/KF2Kpy.B8D2XoC031sReFGi'

And in particular, pass the value returned from crypt() back in as the salt argument:

crypt('EgzamplPassword', '$2a$10$1qAz2wSx3eDc4rFv5tGb5e4jVuld5/KF2Kpy.B8D2XoC031sReFGi') >>
   '$2a$10$1qAz2wSx3eDc4rFv5tGb5e4jVuld5/KF2Kpy.B8D2XoC031sReFGi'

Say we have a user table like this

create table user(
   id int,
   email varchar(255),
   password_hash varchar(64)
)

From a user account generation form, assume that we have (already sanitized) user input in $form->email and $form->password. We generate the hash:

$salt = openssl_random_pseudo_bytes(22);
$salt = '$2a$%13$'.strtr(base64_encode($salt), array('_' => '.', '~' => '/'));
$password_hash = crypt($form - > password, $salt);

At user logon assume we again have sanitized user input in $form->email and $form->password. To authenticate these against the accounts in user we select the password_hash field from table user where email = $form->email and, with that value in $password_hash

if ($password_hash === crypt($form - > password, $password_hash))
   // password is correct
else
// password is wrong
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75%

Checking a password is usually done by passing the plain-text password as word and the full results of a previous crypt() call, which should be the same as the results of this call.,Return a randomly generated salt of the specified method. If no method is given, the strongest method available as returned by methods() is used.,To generate a hash of a password using the strongest available method and check it against the original:,The crypt module defines the list of hashing methods (not all methods are available on all platforms):

import pwd
import crypt
import getpass
from hmac
import compare_digest as compare_hash

def login():
   username = input('Python login: ')
cryptedpasswd = pwd.getpwnam(username)[1]
if cryptedpasswd:
   if cryptedpasswd == 'x'
or cryptedpasswd == '*':
   raise ValueError('no support for shadow passwords')
cleartext = getpass.getpass()
return compare_hash(crypt.crypt(cleartext, cryptedpasswd), cryptedpasswd)
else :
   return True
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40%

The cipher method. For a list of available cipher methods, use openssl_get_cipher_methods(). , openssl_​get_​cipher_​methods , openssl_​get_​md_​methods , openssl_​cipher_​iv_​length

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22%

Encryption of the password: To generate a hash from the string, we use the password_hash() function.,Decryption of the password: To decrypt a password hash and retrieve the original string, we use the password_verify() function.,The password_verify() function verifies that the given hash matches the given password, generated by the password_hash() function. It returns true if the password and hash match, or false otherwise.,The password_hash() function creates a new password hash of the string using one of the available hashing algorithm. It returns the hash that is currently 60 character long, however, as new and stronger algorithms will be added to PHP, the length of the hash may increase. It is therefore recommended to allocate 255 characters for the column that may be used to store the hash in database.

Syntax:

string password_hash(string $password,
   mixed $algo, [array $options])

Syntax:

bool password_verify(string $password, string $hash)

Output:

Password Verified!
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60%

You may decrypt values using the decryptString method provided by the Crypt facade. If the value can not be properly decrypted, such as when the message authentication code is invalid, an Illuminate\Contracts\Encryption\DecryptException will be thrown:,You may encrypt a value using the encryptString method provided by the Crypt facade. All encrypted values are encrypted using OpenSSL and the AES-256-CBC cipher. Furthermore, all encrypted values are signed with a message authentication code (MAC). The integrated message authentication code will prevent the decryption of any values that have been tampered with by malicious users:,Laravel's encryption services provide a simple, convenient interface for encrypting and decrypting text via OpenSSL using AES-256 and AES-128 encryption. All of Laravel's encrypted values are signed using a message authentication code (MAC) so that their underlying value can not be modified or tampered with once encrypted.,Laravel Partners are elite shops providing top-notch Laravel development and consulting. Each of our partners can help you craft a beautiful, well-architected project.

You may encrypt a value using the encryptString method provided by the Crypt facade. All encrypted values are encrypted using OpenSSL and the AES-256-CBC cipher. Furthermore, all encrypted values are signed with a message authentication code (MAC). The integrated message authentication code will prevent the decryption of any values that have been tampered with by malicious users:

< ? php

namespace App\ Http\ Controllers;

use App\ Http\ Controllers\ Controller;
use App\ Models\ User;
use Illuminate\ Http\ Request;
use Illuminate\ Support\ Facades\ Crypt;

class DigitalOceanTokenController extends Controller {
   /**
    * Store a DigitalOcean API token for the user.
    *
    * @param  \Illuminate\Http\Request  $request
    * @return \Illuminate\Http\Response
    */
   public
   function storeSecret(Request $request) {
      $request - > user() - > fill([
         'token' => Crypt::encryptString($request - > token),
      ]) - > save();
   }
}
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48%

Statements that use AES_DECRYPT() are unsafe for statement-based replication. , Statements that use AES_ENCRYPT() or AES_DECRYPT() are unsafe for statement-based replication. , See the note regarding the MD5 algorithm at the beginning this section. , Calculates an MD5 128-bit checksum for the string. The value is returned as a string of 32 hexadecimal digits, or NULL if the argument was NULL. The return value can, for example, be used as a hash key. See the notes at the beginning of this section about storing hash values efficiently.

The str and crypt_str arguments can be any length, and padding is automatically added to str so it is a multiple of a block as required by block-based algorithms such as AES. This padding is automatically removed by the AES_DECRYPT() function. The length of crypt_str can be calculated using this formula:

16 * (trunc(string_length / 16) + 1)

For a key length of 128 bits, the most secure way to pass a key to the key_str argument is to create a truly random 128-bit value and pass it as a binary value. For example:

INSERT INTO t
VALUES(1, AES_ENCRYPT('text', UNHEX('F3229A0B371ED2D9441B830D21A390C3')));

A passphrase can be used to generate an AES key by hashing the passphrase. For example:

INSERT INTO t
VALUES(1, AES_ENCRYPT('text', UNHEX(SHA2('My secret passphrase', 512))));

A random string of bytes to use for the initialization vector can be produced by calling RANDOM_BYTES(16). For encryption modes that require an initialization vector, the same vector must be used for encryption and decryption.

mysql > SET block_encryption_mode = 'aes-256-cbc';
mysql > SET @key_str = SHA2('My secret passphrase', 512);
mysql > SET @init_vector = RANDOM_BYTES(16);
mysql > SET @crypt_str = AES_ENCRYPT('text', @key_str, @init_vector);
mysql > SELECT AES_DECRYPT(@crypt_str, @key_str, @init_vector); +
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- - +
|
AES_DECRYPT(@crypt_str, @key_str, @init_vector) |
   + -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- - +
   |
   text |
   + -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- - +
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