Created
July 29, 2024 14:28
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random RC4 implementation I wrote at some point
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| pub const Rc4 = struct { | |
| s: [256]u8 = undefined, | |
| i: u8 = 0, | |
| j: u8 = 0, | |
| pub fn init(key: []const u8) Rc4 { | |
| var self = Rc4{}; | |
| for(&self.s, 0..) |*c, i| c.* = @intCast(i); | |
| { | |
| var i: u16 = 0; | |
| var j: u8 = 0; | |
| while(i < 255) : (i += 1) { | |
| j = j +% self.s[i] +% key[i % key.len]; | |
| std.mem.swap(u8, &self.s[i], &self.s[j]); | |
| } | |
| } | |
| return self; | |
| } | |
| pub fn get(self: *Rc4) u8 { | |
| self.i +%= 1; | |
| self.j +%= self.s[self.i]; | |
| std.mem.swap(u8, &self.s[self.i], &self.s[self.j]); | |
| return self.s[self.s[self.i] +% self.s[self.j]]; | |
| } | |
| pub fn deinit(self: *Rc4) void { | |
| std.crypto.utils.secureZero(u8, &self.s); | |
| self.j = 0; | |
| self.i = 0; | |
| } | |
| pub fn process(self: *Rc4, ciphertext: []u8, plaintext: []const u8) void { | |
| for(plaintext, 0..) |c, i| ciphertext[i] = c ^ self.get(); | |
| } | |
| }; | |
| test "Rc4" { | |
| var state = Rc4.init("Key"); | |
| defer state.deinit(); | |
| const plain = "Plaintext"; | |
| var dst: [plain.len]u8 = undefined; | |
| state.process(&dst, plain); | |
| try std.testing.expectEqual([_]u8{0xbb,0xf3,0x16,0xe8,0xd9,0x40,0xaf,0x0a,0xd3}, dst); | |
| } | |
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