In cryptography, key strengthening or key stretching refer to techniques used to make a possibly-weak key, typically a password or passphrase, more secure against a brute force attack by increasing the time it takes to test each possible key.
In cryptography, key strengthening or key stretching refer to techniques used to make a weak key such as a password or passphrase stronger, i.e. more costly to test combinations through brute force or a dictionary attack. They operate by increasing the time it takes to test each possible key.