postgres_protocol_sm3/password/
mod.rs

1//! Functions to encrypt a password in the client.
2//!
3//! This is intended to be used by client applications that wish to
4//! send commands like `ALTER USER joe PASSWORD 'pwd'`. The password
5//! need not be sent in cleartext if it is encrypted on the client
6//! side. This is good because it ensures the cleartext password won't
7//! end up in logs pg_stat displays, etc.
8
9use crate::authentication::sasl;
10use base64::display::Base64Display;
11use base64::engine::general_purpose::STANDARD;
12use hmac::{Hmac, Mac};
13use md5::Md5;
14use sm3::Sm3;
15use rand::RngCore;
16use sha2::digest::FixedOutput;
17use sha2::{Digest, Sha256};
18
19#[cfg(test)]
20mod test;
21
22const SCRAM_DEFAULT_ITERATIONS: u32 = 4096;
23const SCRAM_DEFAULT_SALT_LEN: usize = 16;
24
25/// Hash password using SCRAM-SHA-256 with a randomly-generated
26/// salt.
27///
28/// The client may assume the returned string doesn't contain any
29/// special characters that would require escaping in an SQL command.
30pub fn scram_sha_256(password: &[u8]) -> String {
31    let mut salt: [u8; SCRAM_DEFAULT_SALT_LEN] = [0; SCRAM_DEFAULT_SALT_LEN];
32    let mut rng = rand::thread_rng();
33    rng.fill_bytes(&mut salt);
34    scram_sha_256_salt(password, salt)
35}
36
37// Internal implementation of scram_sha_256 with a caller-provided
38// salt. This is useful for testing.
39pub(crate) fn scram_sha_256_salt(password: &[u8], salt: [u8; SCRAM_DEFAULT_SALT_LEN]) -> String {
40    // Prepare the password, per [RFC
41    // 4013](https://tools.ietf.org/html/rfc4013), if possible.
42    //
43    // Postgres treats passwords as byte strings (without embedded NUL
44    // bytes), but SASL expects passwords to be valid UTF-8.
45    //
46    // Follow the behavior of libpq's PQencryptPasswordConn(), and
47    // also the backend. If the password is not valid UTF-8, or if it
48    // contains prohibited characters (such as non-ASCII whitespace),
49    // just skip the SASLprep step and use the original byte
50    // sequence.
51    let prepared: Vec<u8> = match std::str::from_utf8(password) {
52        Ok(password_str) => {
53            match stringprep::saslprep(password_str) {
54                Ok(p) => p.into_owned().into_bytes(),
55                // contains invalid characters; skip saslprep
56                Err(_) => Vec::from(password),
57            }
58        }
59        // not valid UTF-8; skip saslprep
60        Err(_) => Vec::from(password),
61    };
62
63    // salt password
64    let salted_password = sasl::hi(&prepared, &salt, SCRAM_DEFAULT_ITERATIONS);
65
66    // client key
67    let mut hmac = Hmac::<Sha256>::new_from_slice(&salted_password)
68        .expect("HMAC is able to accept all key sizes");
69    hmac.update(b"Client Key");
70    let client_key = hmac.finalize().into_bytes();
71
72    // stored key
73    let mut hash = Sha256::default();
74    hash.update(client_key.as_slice());
75    let stored_key = hash.finalize_fixed();
76
77    // server key
78    let mut hmac = Hmac::<Sha256>::new_from_slice(&salted_password)
79        .expect("HMAC is able to accept all key sizes");
80    hmac.update(b"Server Key");
81    let server_key = hmac.finalize().into_bytes();
82
83    format!(
84        "SCRAM-SHA-256${}:{}${}:{}",
85        SCRAM_DEFAULT_ITERATIONS,
86        Base64Display::new(&salt, &STANDARD),
87        Base64Display::new(&stored_key, &STANDARD),
88        Base64Display::new(&server_key, &STANDARD)
89    )
90}
91
92/// **Not recommended, as MD5 is not considered to be secure.**
93///
94/// Hash password using MD5 with the username as the salt.
95///
96/// The client may assume the returned string doesn't contain any
97/// special characters that would require escaping.
98pub fn md5(password: &[u8], username: &str) -> String {
99    // salt password with username
100    let mut salted_password = Vec::from(password);
101    salted_password.extend_from_slice(username.as_bytes());
102
103    let mut hash = Md5::new();
104    hash.update(&salted_password);
105    let digest = hash.finalize();
106    format!("md5{:x}", digest)
107}
108/// Hash password using SM3 with the username as the salt.
109///
110/// The client may assume the returned string doesn't contain any
111/// special characters that would require escaping.
112pub fn sm3(password: &[u8], username: &str) -> String {
113    // salt password with username
114    let mut salted_password = Vec::from(password);
115    salted_password.extend_from_slice(username.as_bytes());
116
117    let mut hash = Sm3::new();
118    hash.update(&salted_password);
119    let digest = hash.finalize();
120    format!("sm3{:x}", digest)
121}
postgres_protocol_sm3/password/mod.rs

postgres_protocol_sm3/password/
mod.rs
