PSA_KEY_TYPE_PASSWORD macro

A low-entropy secret for password hashing or key derivation. This key type is suitable for passwords and passphrases which are typically intended to be memorizable by humans, and have a low entropy relative to their size. It can be used for randomly generated or derived keys with maximum or near-maximum entropy, but #PSA_KEY_TYPE_DERIVE is more suitable for such keys. It is not suitable for passwords with extremely low entropy, such as numerical PINs. These keys can be used as the #PSA_KEY_DERIVATION_INPUT_PASSWORD input of key derivation algorithms. Algorithms that accept such an input were designed to accept low-entropy secret and are known as password hashing or key stretching algorithms. These keys cannot be used as the #PSA_KEY_DERIVATION_INPUT_SECRET input of key derivation algorithms, as the algorithms that take such an input expect it to be high-entropy. The key policy determines which key derivation algorithm the key can be used for, among the permissible subset defined above.