Because the rainbow table is based on computed hashes, salts will effectively prevent table values from matching the values stored in the system's SAM. However, if the attacker somehow knows the salt values, then it may be possible to modify the cracking algorithm to account for the password salts.
Are rainbow tables a relevant threat? Rainbow tables are an efficient way to crack large numbers of passwords through pre-generated data sets of password hashes. However, rainbow tables are still fairly slow to generate, and are specific to the given password hash and password type they were designed to crack.
Disadvantages: One main and most common problem when dealing with Rainbow Table Attacks is the fact that these tables need to be stored in a huge memory (Hard Disks). Sometimes Terabytes are needed, resulting in an increased maintenance cost.
Rainbow tables require large amounts of storage space and can take a long time to generate, but their primary shortcoming is that they may be ineffective against password hashing that uses salting.
The faster the hash function is, the less reason there is to use a rainbow table. After all, the rainbow table is just a time-storage trade-off (you're reducing time by using more storage). So since hash functions are only getting faster, the benefit of a rainbow table is diminished.
A rainbow table attack is a password cracking method that uses a special table (a “rainbow table”) to crack the password hashes in a database. Applications don't store passwords in plaintext, but instead encrypt passwords using hashes.
To crack a password, or for rainbow table attacks, large numbers of hashes are run through a dataset and then through multiple reduction stages to split them into smaller components that are linked to plaintext characters. The plaintext passwords are then stored in the table next to their hashes.
A salt randomizes each hash by adding random data that is unique to each user to their password hash, so even the same password has a unique hash. If someone tried to compare hashes in a rainbow table to those in a database, none of the hashes would match, even if the passwords were the same.
Experts say the best defense against rainbow tables is to "salt" passwords, which is the practice of appending a random value to the password before it is encrypted.
The main difference between a brute force attack and a rainbow table attack is that there is precomputed data involved with a rainbow table when trying to crack passwords whereas there is no precomputed data when a brute force is to be performed.
Experiments performed on large problems with a 128-core computer perfectly match the theoretical ex- pectations. We construct a rainbow table for a space N = 242 in approx- imately 8 hours instead of 50 hours for the usual way to generate a table.
John the Ripper (JTR) is a free, open-source software tool used by hackers, both ethical and otherwise, for password cracking. The software is typically used in a UNIV/Linux and Mac OS X environment where it can detect weak passwords.
Hash tables are great very simple passwords. (For example, you might use a hash table to scan a database for passwords that match one of the top 10,000 most commonly used passwords. Rainbow tables, on the other hand, are great for trying to crack the hashes of tougher or more complex passwords.
A salt is a randomized, considerably large value generated when you use a secure random number generator or random bit generator. Salts get stored with each password hash value on your server, thus creating unique hash values for passwords.
A rainbow table stores all the one-way hashes of plaintext passwords from 1 character in length to 7 or maybe 8 characters in length.
A strong password is a unique word or phrase a hacker cannot easily guess or crack. Here are the main traits of a reliable, secure password: At least 12 characters long (the longer, the better). Has a combination of upper and lowercase letters, numbers, punctuation, and special symbols.
To summarize what I understand, the salt makes the hashed password more complex, thus making it much less likely to exist in a precomputed rainbow table.
You can't "reverse" password hashes. You can't "unhash" or "dehash" passwords. You can't "reverse" or "invert" MD5, SHA256, bcrypt, SHA1, or similar hashes, salted or unsalted. You (usually) can't "decode" passwords, "decrypt" password hashes or "reverse" or "unscramble" password hashes at all.
Hashcat — The Fastest Password Cracker to Crack Complex Passwords. Hashcat identifies itself as the world's fastest password-cracking tool. Empowered with GPU acceleration, it outperforms John the Ripper in terms of speed.
A rainbow table is a large, precomputed table designed to cache the output of cryptographic hash functions to decrypt hashed passwords into plaintext. Rainbow tables were invented by IT expert Philippe Oechslin, who published a paper on his work in 2003.
To calculate the sample space of a password, we can use the following formula: S = C ^ N. Where S is the total number of possible passwords, the sample space, C is the number of characters in the pool of characters available to us, and N is the number of characters our password has.
There are 948 entries in a table stored. Each entry consists of a 8 character password (for simplicity, assume each character is 1 Byte) and a 128-bit MD5 hash value. That is at least 146,000 TB. This is not practical.
A full rainbow table of hashed-keys with its associated hashes would required 16 ^ 32 entries. This calculation was derived by knowing that a hashed-key is 32 bits in length and each bit is represented in hexadecimal (16 variations).