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//! `crypto_pwhash_scryptsalsa208sha256`, a particular combination of Scrypt, Salsa20/8 //! and SHA-256 use ffi; use libc::c_ulonglong; use randombytes::randombytes_into; /// Number of bytes in a `Salt`. pub const SALTBYTES: usize = ffi::crypto_pwhash_scryptsalsa208sha256_SALTBYTES as usize; /// Number of bytes in a `HashedPassword`. pub const HASHEDPASSWORDBYTES: usize = ffi::crypto_pwhash_scryptsalsa208sha256_STRBYTES as usize; /// All `HashedPasswords` start with this string. pub const STRPREFIX: &[u8] = ffi::crypto_pwhash_scryptsalsa208sha256_STRPREFIX; /// Safe base line for `OpsLimit` for interactive password hashing. pub const OPSLIMIT_INTERACTIVE: OpsLimit = OpsLimit(ffi::crypto_pwhash_scryptsalsa208sha256_OPSLIMIT_INTERACTIVE as usize); /// Safe base line for `MemLimit` for interactive password hashing. pub const MEMLIMIT_INTERACTIVE: MemLimit = MemLimit(ffi::crypto_pwhash_scryptsalsa208sha256_MEMLIMIT_INTERACTIVE as usize); /// `OpsLimit` for highly sensitive data. pub const OPSLIMIT_SENSITIVE: OpsLimit = OpsLimit(ffi::crypto_pwhash_scryptsalsa208sha256_OPSLIMIT_SENSITIVE as usize); /// `MemLimit` for highly sensitive data. pub const MEMLIMIT_SENSITIVE: MemLimit = MemLimit(ffi::crypto_pwhash_scryptsalsa208sha256_MEMLIMIT_SENSITIVE as usize); /// `OpsLimit` represents the maximum number of computations to perform when /// using the functions in this module. /// /// A high `OpsLimit` will make the functions /// require more CPU cycles #[derive(Copy, Clone)] pub struct OpsLimit(pub usize); /// `MemLimit` represents the maximum amount of RAM that the functions in this /// module will use, in bytes. /// /// It is highly recommended to allow the functions to use /// at least 16 megabytes. #[derive(Copy, Clone)] pub struct MemLimit(pub usize); new_type! { /// `Salt` used for password hashing public Salt(SALTBYTES); } new_type! { /// `HashedPassword`is a password verifier generated from a password /// /// A `HashedPassword` is zero-terminated, includes only ASCII characters and can /// be conveniently stored into SQL databases and other data stores. No /// additional information has to be stored in order to verify the password. public HashedPassword(HASHEDPASSWORDBYTES); } /// `gen_salt()` randombly generates a new `Salt` for key derivation /// /// THREAD SAFETY: `gen_salt()` is thread-safe provided that you have called /// `sodiumoxide::init()` once before using any other function from sodiumoxide. pub fn gen_salt() -> Salt { let mut salt = Salt([0; SALTBYTES]); randombytes_into(&mut salt.0); salt } /// The `derive_key()` function derives a key from a password and a `Salt` /// /// The computed key is stored into key. /// /// `opslimit` represents a maximum amount of computations to perform. Raising /// this number will make the function require more CPU cycles to compute a key. /// /// `memlimit` is the maximum amount of RAM that the function will use, in /// bytes. It is highly recommended to allow the function to use at least 16 /// megabytes. /// /// For interactive, online operations, `OPSLIMIT_INTERACTIVE` and /// `MEMLIMIT_INTERACTIVE` provide a safe base line for these two /// parameters. However, using higher values may improve security. /// /// For highly sensitive data, `OPSLIMIT_SENSITIVE` and `MEMLIMIT_SENSITIVE` can /// be used as an alternative. But with these parameters, deriving a key takes /// more than 10 seconds on a 2.8 Ghz Core i7 CPU and requires up to 1 gigabyte /// of dedicated RAM. /// /// The salt should be unpredictable. `gen_salt()` is the easiest way to create a `Salt`. /// /// Keep in mind that in order to produce the same key from the same password, /// the same salt, and the same values for opslimit and memlimit have to be /// used. /// /// The function returns `Ok(key)` on success and `Err(())` if the computation didn't /// complete, usually because the operating system refused to allocate the /// amount of requested memory. pub fn derive_key<'a>( key: &'a mut [u8], passwd: &[u8], salt: &Salt, OpsLimit(opslimit): OpsLimit, MemLimit(memlimit): MemLimit, ) -> Result<&'a [u8], ()> { if unsafe { ffi::crypto_pwhash_scryptsalsa208sha256( key.as_mut_ptr(), key.len() as c_ulonglong, passwd.as_ptr() as *const _, passwd.len() as c_ulonglong, salt.0.as_ptr(), opslimit as c_ulonglong, memlimit, ) } == 0 { Ok(key) } else { Err(()) } } /// `derive_key_interactive()` is a shortcut function for `derive_key()` with /// interactive limits (i.e. using `derive_key()` with `OPSLIMIT_INTERACTIVE` /// and `MEMLIMIT_INTERACTIVE`) pub fn derive_key_interactive<'a>( key: &'a mut [u8], passwd: &[u8], salt: &Salt, ) -> Result<&'a [u8], ()> { derive_key( key, passwd, salt, OPSLIMIT_INTERACTIVE, MEMLIMIT_INTERACTIVE, ) } /// `derive_key_sensitive()` is a shortcut function for `derive_key()` with /// sensitive limits (i.e. using `derive_key()` with `OPSLIMIT_SENSITIVE` /// and `MEMLIMIT_SENSITIVE`) pub fn derive_key_sensitive<'a>( key: &'a mut [u8], passwd: &[u8], salt: &Salt, ) -> Result<&'a [u8], ()> { derive_key(key, passwd, salt, OPSLIMIT_SENSITIVE, MEMLIMIT_SENSITIVE) } /// The `pwhash()` returns a `HashedPassword` which /// includes: /// /// - the result of a memory-hard, CPU-intensive hash function applied to the password /// `passwd` /// - the automatically generated salt used for the /// previous computation /// - the other parameters required to verify the password: opslimit and memlimit /// /// `OPSLIMIT_INTERACTIVE` and `MEMLIMIT_INTERACTIVE` are safe baseline /// values to use for `opslimit` and `memlimit`. /// /// The function returns `Ok(hashed_password)` on success and `Err(())` if it didn't complete /// successfully pub fn pwhash( passwd: &[u8], OpsLimit(opslimit): OpsLimit, MemLimit(memlimit): MemLimit, ) -> Result<HashedPassword, ()> { let mut hp = HashedPassword([0; HASHEDPASSWORDBYTES]); if unsafe { ffi::crypto_pwhash_scryptsalsa208sha256_str( hp.0.as_mut_ptr() as *mut _, passwd.as_ptr() as *const _, passwd.len() as c_ulonglong, opslimit as c_ulonglong, memlimit, ) } == 0 { Ok(hp) } else { Err(()) } } /// `pwhash_interactive()` is a shortcut function for `pwhash()` with /// interactive limits (i.e. using `pwhash()` with `OPSLIMIT_INTERACTIVE` /// and `MEMLIMIT_INTERACTIVE`) pub fn pwhash_interactive(passwd: &[u8]) -> Result<HashedPassword, ()> { pwhash(passwd, OPSLIMIT_INTERACTIVE, MEMLIMIT_INTERACTIVE) } /// `pwhash_sensitive()` is a shortcut function for `pwhash()` with /// sensitive limits (i.e. using `pwhash()` with `OPSLIMIT_SENSITIVE` /// and `MEMLIMIT_SENSITIVE`) pub fn pwhash_sensitive(passwd: &[u8]) -> Result<HashedPassword, ()> { pwhash(passwd, OPSLIMIT_SENSITIVE, MEMLIMIT_SENSITIVE) } /// `pwhash_verify()` verifies that the password `str_` is a valid password /// verification string (as generated by `pwhash()`) for `passwd` /// /// It returns `true` if the verification succeeds, and `false` on error. pub fn pwhash_verify(hp: &HashedPassword, passwd: &[u8]) -> bool { unsafe { ffi::crypto_pwhash_scryptsalsa208sha256_str_verify( hp.0.as_ptr() as *const _, passwd.as_ptr() as *const _, passwd.len() as c_ulonglong, ) == 0 } } #[cfg(test)] mod test { use super::*; #[test] fn test_derive_key() { let mut kb = [0u8; 32]; let salt = Salt([ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, ]); let pw = b"Correct Horse Battery Staple"; // test vector generated by using libsodium let key_expected = [ 0xf1, 0xbb, 0xb8, 0x7c, 0x43, 0x36, 0x5b, 0x03, 0x3b, 0x9a, 0xe8, 0x3e, 0x05, 0xef, 0xad, 0x25, 0xdb, 0x8d, 0x83, 0xb8, 0x3d, 0xb1, 0xde, 0xe3, 0x6b, 0xdb, 0xf5, 0x4d, 0xcd, 0x3a, 0x1a, 0x11, ]; let key = derive_key( &mut kb, pw, &salt, OPSLIMIT_INTERACTIVE, MEMLIMIT_INTERACTIVE, ) .unwrap(); assert_eq!(key, key_expected); } #[test] fn test_pwhash_verify() { use randombytes::randombytes; for i in 0..32usize { let pw = randombytes(i); let pwh = pwhash(&pw, OPSLIMIT_INTERACTIVE, MEMLIMIT_INTERACTIVE).unwrap(); assert!(pwhash_verify(&pwh, &pw)); } } #[test] fn test_pwhash_verify_tamper() { use randombytes::randombytes; for i in 0..16usize { let mut pw = randombytes(i); let pwh = pwhash(&pw, OPSLIMIT_INTERACTIVE, MEMLIMIT_INTERACTIVE).unwrap(); for j in 0..pw.len() { pw[j] ^= 0x20; assert!(!pwhash_verify(&pwh, &pw)); pw[j] ^= 0x20; } } } #[cfg(feature = "serde")] #[test] fn test_serialisation() { use randombytes::randombytes; use test_utils::round_trip; for i in 0..32usize { let pw = randombytes(i); let pwh = pwhash(&pw, OPSLIMIT_INTERACTIVE, MEMLIMIT_INTERACTIVE).unwrap(); let salt = gen_salt(); round_trip(pwh); round_trip(salt); } } }