crypto::salsa
crypto::salsa provides an implementation of the Salsa20 and XSalsa20 stream ciphers, per "Salsa20 specification" by Daniel J. Bernstein.
Use salsa20 to create a stream and either xsalsa20_init or salsa20_init to set handle, key and nonce of the appropriate size, NONCESZ for salsa20 or XNONCESZ for XSalsa20. After calling the appropriate init function, io::write may be used to encrypt blocks to the handle or io::read to decrypt blocks from the handle. The stream must be closed with io::close to wipe sensitive data from memory.
Writing blocks of length BLOCKSZ is not required. However, seeking the key stream with setctr only operates in units of BLOCKSZ.
This is a low-level module which implements cryptographic primitives. Direct use of cryptographic primitives is not recommended for non-experts, as incorrect use of these primitives can easily lead to the introduction of security vulnerabilities. Non-experts are advised to use the high-level operations available in the top-level crypto:: module.
Be advised that Hare's cryptography implementations have not been audited.
Index
Types
type stream = struct {
cipher::xorstream,
state: [16]u32,
xorbuf: [BLOCKSZ]u8,
xorused: size,
rounds: size,
};
Constants
def BLOCKSZ: size = 64;
def KEYSZ: size = 32;
def NONCESZ: size = 8;
def XNONCESZ: size = 24;
Functions
fn hsalsa20(out: []u8, key: []u8, nonce: []u8) void;
fn salsa20() stream;
fn salsa20_init(s: *stream, h: io::handle, key: []u8, nonce: []u8) void;
fn setctr(s: *stream, counter: u64) void;
fn xsalsa20_init(s: *stream, h: io::handle, key: []u8, nonce: []u8) void;
Types
type stream
Show undocumented member
type stream = struct {
cipher::xorstream,
state: [16]u32,
xorbuf: [BLOCKSZ]u8,
xorused: size,
rounds: size,
};
Constants
def BLOCKSZ
def BLOCKSZ: size = 64;
The block size of the Salsa cipher.
def KEYSZ
def KEYSZ: size = 32;
Size of a Salsa key, in bytes.
def NONCESZ
def NONCESZ: size = 8;
Size of the Salsa20 nonce, in bytes.
def XNONCESZ
def XNONCESZ: size = 24;
Size of the XSalsa20 nonce, in bytes.
Functions
fn hsalsa20
fn hsalsa20(out: []u8, key: []u8, nonce: []u8) void;
Derives a new key from 'key' and 'nonce' as used during XSalsa20 initialization. This function may only be used for specific purposes such as X25519 key derivation. Do not use if in doubt.
fn salsa20
fn salsa20() stream;
Create a Salsa20 or XSalsa20 stream. Must be initialized with either salsa20_init or xsalsa20_init, and must be closed with io::close after use to wipe sensitive data from memory.
fn salsa20_init
fn salsa20_init(s: *stream, h: io::handle, key: []u8, nonce: []u8) void;
Initialize a Salsa20 stream.
fn setctr
fn setctr(s: *stream, counter: u64) void;
Advances the key stream to "seek" to a future state by 'counter' times BLOCKSZ.
fn xsalsa20_init
fn xsalsa20_init(s: *stream, h: io::handle, key: []u8, nonce: []u8) void;
Initialize an XSalsa20 stream. XSalsa20 differs from Salsa20 via the use of a larger nonce parameter.