const std = @import("../std.zig");
const sha2 = std.crypto.hash.sha2;
pub fn Composition(comptime H1: type, comptime H2: type) type {
return struct {
const Self = @This();
H1: H1,
H2: H2,
pub const digest_length = H1.digest_length;
pub const block_length = H1.block_length;
pub const Options = struct {
H1: H1.Options = .{},
H2: H2.Options = .{},
};
pub fn init(options: Options) Self {
return Self{ .H1 = H1.init(options.H1), .H2 = H2.init(options.H2) };
}
pub fn hash(b: []const u8, out: *[digest_length]u8, options: Options) void {
var d = Self.init(options);
d.update(b);
d.final(out);
}
pub fn update(d: *Self, b: []const u8) void {
d.H2.update(b);
}
pub fn final(d: *Self, out: *[digest_length]u8) void {
var H2_digest: [H2.digest_length]u8 = undefined;
d.H2.final(&H2_digest);
d.H1.update(&H2_digest);
d.H1.final(out);
}
};
}
pub const Sha256oSha256 = Composition(sha2.Sha256, sha2.Sha256);
pub const Sha384oSha384 = Composition(sha2.Sha384, sha2.Sha384);
pub const Sha512oSha512 = Composition(sha2.Sha512, sha2.Sha512);
test "Hash composition" {
const Sha256 = sha2.Sha256;
const msg = "test";
var out: [Sha256oSha256.digest_length]u8 = undefined;
Sha256oSha256.hash(msg, &out, .{});
var t: [Sha256.digest_length]u8 = undefined;
Sha256.hash(msg, &t, .{});
var out2: [Sha256.digest_length]u8 = undefined;
Sha256.hash(&t, &out2, .{});
try std.testing.expectEqualSlices(u8, &out, &out2);
}