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kdf

Apply scrypt to generate a key from a password.

scrypt is defined in RFC 7914.

allocator: mem.Allocator.

derived_key: Slice of appropriate size for generated key. Generally 16 or 32 bytes in length. May be uninitialized. All bytes will be overwritten. Maximum size is derived_key.len / 32 == 0xffff_ffff.

password: Arbitrary sequence of bytes of any length.

salt: Arbitrary sequence of bytes of any length.

params: Params.

scrypt.kdf

pub fn kdf(
    allocator: mem.Allocator,
    derived_key: []u8,
    password: []const u8,
    salt: []const u8,
    params: Params,
) KdfError!void

File

lib/std/crypto/scrypt.zig:178

Code

pub fn kdf(
    allocator: mem.Allocator,
    derived_key: []u8,
    password: []const u8,
    salt: []const u8,
    params: Params,
) KdfError!void {
    if (derived_key.len == 0) return KdfError.WeakParameters;
    if (derived_key.len / 32 > 0xffff_ffff) return KdfError.OutputTooLong;
    if (params.ln == 0 or params.r == 0 or params.p == 0) return KdfError.WeakParameters;

    const n64 = @as(u64, 1) << params.ln;
    if (n64 > max_size) return KdfError.WeakParameters;
    const n = @as(usize, @intCast(n64));
    if (@as(u64, params.r) * @as(u64, params.p) >= 1 << 30 or
        params.r > max_int / 128 / @as(u64, params.p) or
        params.r > max_int / 256 or
        n > max_int / 128 / @as(u64, params.r)) return KdfError.WeakParameters;

    const xy = try allocator.alignedAlloc(u32, .@"16", 64 * params.r);
    defer allocator.free(xy);
    const v = try allocator.alignedAlloc(u32, .@"16", 32 * n * params.r);
    defer allocator.free(v);
    var dk = try allocator.alignedAlloc(u8, .@"16", params.p * 128 * params.r);
    defer allocator.free(dk);

    try pwhash.pbkdf2(dk, password, salt, 1, HmacSha256);
    var i: u32 = 0;
    while (i < params.p) : (i += 1) {
        smix(@alignCast(dk[i * 128 * params.r ..]), params.r, n, v, xy);
    }
    try pwhash.pbkdf2(derived_key, password, dk, 1, HmacSha256);
}