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Convert hex to base64

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Armin Friedl 2025-02-07 21:35:45 +01:00
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79
.gitignore vendored Normal file
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# Created by https://www.toptal.com/developers/gitignore/api/zig,emacs,linux
# Edit at https://www.toptal.com/developers/gitignore?templates=zig,emacs,linux
### Emacs ###
# -*- mode: gitignore; -*-
*~
\#*\#
/.emacs.desktop
/.emacs.desktop.lock
*.elc
auto-save-list
tramp
.\#*
# Org-mode
.org-id-locations
*_archive
# flymake-mode
*_flymake.*
# eshell files
/eshell/history
/eshell/lastdir
# elpa packages
/elpa/
# reftex files
*.rel
# AUCTeX auto folder
/auto/
# cask packages
.cask/
dist/
# Flycheck
flycheck_*.el
# server auth directory
/server/
# projectiles files
.projectile
# directory configuration
.dir-locals.el
# network security
/network-security.data
### Linux ###
# temporary files which can be created if a process still has a handle open of a deleted file
.fuse_hidden*
# KDE directory preferences
.directory
# Linux trash folder which might appear on any partition or disk
.Trash-*
# .nfs files are created when an open file is removed but is still being accessed
.nfs*
### zig ###
# Zig programming language
.zig-cache/
zig-out/
build/
build-*/
docgen_tmp/
.idea
# End of https://www.toptal.com/developers/gitignore/api/zig,emacs,linux

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build.zig Normal file
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const std = @import("std");
// Although this function looks imperative, note that its job is to
// declaratively construct a build graph that will be executed by an external
// runner.
pub fn build(b: *std.Build) void {
// Standard target options allows the person running `zig build` to choose
// what target to build for. Here we do not override the defaults, which
// means any target is allowed, and the default is native. Other options
// for restricting supported target set are available.
const target = b.standardTargetOptions(.{});
// Standard optimization options allow the person running `zig build` to select
// between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
// set a preferred release mode, allowing the user to decide how to optimize.
const optimize = b.standardOptimizeOption(.{});
const lib = b.addStaticLibrary(.{
.name = "matasano",
// In this case the main source file is merely a path, however, in more
// complicated build scripts, this could be a generated file.
.root_source_file = b.path("src/root.zig"),
.target = target,
.optimize = optimize,
});
// This declares intent for the library to be installed into the standard
// location when the user invokes the "install" step (the default step when
// running `zig build`).
b.installArtifact(lib);
const exe = b.addExecutable(.{
.name = "matasano",
.root_source_file = b.path("src/main.zig"),
.target = target,
.optimize = optimize,
});
// This declares intent for the executable to be installed into the
// standard location when the user invokes the "install" step (the default
// step when running `zig build`).
b.installArtifact(exe);
// This *creates* a Run step in the build graph, to be executed when another
// step is evaluated that depends on it. The next line below will establish
// such a dependency.
const run_cmd = b.addRunArtifact(exe);
// By making the run step depend on the install step, it will be run from the
// installation directory rather than directly from within the cache directory.
// This is not necessary, however, if the application depends on other installed
// files, this ensures they will be present and in the expected location.
run_cmd.step.dependOn(b.getInstallStep());
// This allows the user to pass arguments to the application in the build
// command itself, like this: `zig build run -- arg1 arg2 etc`
if (b.args) |args| {
run_cmd.addArgs(args);
}
// This creates a build step. It will be visible in the `zig build --help` menu,
// and can be selected like this: `zig build run`
// This will evaluate the `run` step rather than the default, which is "install".
const run_step = b.step("run", "Run the app");
run_step.dependOn(&run_cmd.step);
// Creates a step for unit testing. This only builds the test executable
// but does not run it.
const lib_unit_tests = b.addTest(.{
.root_source_file = b.path("src/root.zig"),
.target = target,
.optimize = optimize,
});
const run_lib_unit_tests = b.addRunArtifact(lib_unit_tests);
const exe_unit_tests = b.addTest(.{
.root_source_file = b.path("src/main.zig"),
.target = target,
.optimize = optimize,
});
const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests);
// Similar to creating the run step earlier, this exposes a `test` step to
// the `zig build --help` menu, providing a way for the user to request
// running the unit tests.
const test_step = b.step("test", "Run unit tests");
test_step.dependOn(&run_lib_unit_tests.step);
test_step.dependOn(&run_exe_unit_tests.step);
}

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build.zig.zon Normal file
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.{
// This is the default name used by packages depending on this one. For
// example, when a user runs `zig fetch --save <url>`, this field is used
// as the key in the `dependencies` table. Although the user can choose a
// different name, most users will stick with this provided value.
//
// It is redundant to include "zig" in this name because it is already
// within the Zig package namespace.
.name = "matasano",
// This is a [Semantic Version](https://semver.org/).
// In a future version of Zig it will be used for package deduplication.
.version = "0.0.0",
// This field is optional.
// This is currently advisory only; Zig does not yet do anything
// with this value.
//.minimum_zig_version = "0.11.0",
// This field is optional.
// Each dependency must either provide a `url` and `hash`, or a `path`.
// `zig build --fetch` can be used to fetch all dependencies of a package, recursively.
// Once all dependencies are fetched, `zig build` no longer requires
// internet connectivity.
.dependencies = .{
// See `zig fetch --save <url>` for a command-line interface for adding dependencies.
//.example = .{
// // When updating this field to a new URL, be sure to delete the corresponding
// // `hash`, otherwise you are communicating that you expect to find the old hash at
// // the new URL.
// .url = "https://example.com/foo.tar.gz",
//
// // This is computed from the file contents of the directory of files that is
// // obtained after fetching `url` and applying the inclusion rules given by
// // `paths`.
// //
// // This field is the source of truth; packages do not come from a `url`; they
// // come from a `hash`. `url` is just one of many possible mirrors for how to
// // obtain a package matching this `hash`.
// //
// // Uses the [multihash](https://multiformats.io/multihash/) format.
// .hash = "...",
//
// // When this is provided, the package is found in a directory relative to the
// // build root. In this case the package's hash is irrelevant and therefore not
// // computed. This field and `url` are mutually exclusive.
// .path = "foo",
// // When this is set to `true`, a package is declared to be lazily
// // fetched. This makes the dependency only get fetched if it is
// // actually used.
// .lazy = false,
//},
},
// Specifies the set of files and directories that are included in this package.
// Only files and directories listed here are included in the `hash` that
// is computed for this package. Only files listed here will remain on disk
// when using the zig package manager. As a rule of thumb, one should list
// files required for compilation plus any license(s).
// Paths are relative to the build root. Use the empty string (`""`) to refer to
// the build root itself.
// A directory listed here means that all files within, recursively, are included.
.paths = .{
"build.zig",
"build.zig.zon",
"src",
// For example...
//"LICENSE",
//"README.md",
},
}

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src/base64.zig Normal file
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const std = @import("std");
const builtin = @import("builtin");
const native_endian = builtin.cpu.arch.endian();
const charset = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
/// Encode a byte buffer with base64. Caller must free the result.
pub fn encode(alloc: std.mem.Allocator, buf: []const u8) ![]u8 {
var out = std.ArrayList(u8).init(alloc);
defer out.deinit();
var in_idx: usize = 0;
var out_idx: usize = 0;
while (in_idx < buf.len) {
const b1 = buf[in_idx];
const b2 = if (in_idx + 1 < buf.len) buf[in_idx + 1] else 0;
const b3 = if (in_idx + 2 < buf.len) buf[in_idx + 2] else 0;
// top 6 bit of b1
try out.append(charset[(b1 >> 2) & 0b111_111]);
// last 4 bit of b1 + top 4 bit of b2 & 0b111_111
// -> last 2 bit of b1 + top 4 bit of b2
try out.append(charset[((b1 << 4) | (b2 >> 4)) & 0b111_111]);
if (in_idx + 1 < buf.len) {
// last 6 bit of b2 + top 2 bit of b3 & 0b111_111
// -> last 4 bit of b2 + top 2 bit of b3
try out.append(charset[((b2 << 2) | (b3 >> 6)) & 0b111_111]);
} else {
try out.append('=');
}
if (in_idx + 2 < buf.len) {
// last 6 bit of b3
try out.append(charset[b3 & 0b111_111]);
} else {
try out.append('=');
}
in_idx += 3;
out_idx += 4;
}
return out.toOwnedSlice();
}
/// Decode a base64 string to a byte buffer. Caller must free the result.
pub fn decode(alloc: std.mem.Allocator, buf: []const u8) ![]u8 {
var out = std.ArrayList(u8).init(alloc);
defer out.deinit();
var in_idx: usize = 0;
var out_idx: usize = 0;
while (in_idx < buf.len) {
// Decode 4 Base64 characters to 3 bytes
const c1 = try to_bin(buf[in_idx]);
const c2 = try to_bin(buf[in_idx + 1]);
const c3 = try to_bin(buf[in_idx + 2]);
const c4 = try to_bin(buf[in_idx + 3]);
// note that we can assume that the u8 is actually just a u6
// and the high 2 bit are always 0
//
// also the terms all, top, and bottom refer to the 6 relevant
// bit only
// all bit of c1 at top of byte + top 2 bit of c2 at bottom
try out.append((c1 << 2) | (c2 >> 4));
// bottom 4 bit of c2 + top 4 bit of c3
try out.append(((c2 & 0b0000_1111) << 4) | (c3 >> 2));
if (c3 != 0xff and c4 != 0xff) {
// bottom 2 bit of c3 + all 6 bits of c4
try out.append(((c3 & 0b0000_0011) << 6) | c4);
} else if (c3 != 0xff and c4 == 0xff) {
// chop off 2 bits, i.e. just don't add last 2 bits of c3
// and c4 is ignored anyways since it is the padding
} else if (c3 == 0xff and c4 == 0xff) {
// chop off 4 bits. this means the last 2 6-bit values
// produced only 8-bit output instead of 12. That means we
// can just drop the last byte, why:
// for the last byte we used 4 bit of c2 and 4 bit of c3
// c3 is the padding so can be dropped
// the 2 padding bytes mean we can drop 4 bit of the
// non-padding values, which is exactly the 4 bits
// we used from c2
_ = out.pop();
} else {
return error.InvalidPadding;
}
in_idx += 4;
out_idx += 3;
}
return out.toOwnedSlice();
}
// Tailor-made helper function for `decode`. This is likely not
// usefuly anywhere else ever due to idiosyncrasies.
//
// Converts a char from b64 charset back to the corresponding binary
// value.
//
// This yields actually just a 6 byte value but u8 is easier to
// calculate with, the caller must handle this correctly and never use
// the highest 2 bit of the returned u8.
//
// The only exception to this is the padding '=' which is
// returned as 0xff and must be handled specially. This is a
// hack to simplify the code in `decode`.
fn to_bin(char: u8) !u8 {
return switch (char) {
'A'...'Z' => char - 'A',
'a'...'z' => char - 'a' + 26,
'0'...'9' => char - '0' + 52,
'+' => 62,
'/' => 63,
'=' => 0xff,
else => error.InvalidBase64Character,
};
}
test "b64 decode" {
const data = [_][2][]const u8{
.{ &[_]u8{0x00}, "AA==" },
.{ &[_]u8{0xFF}, "/w==" },
.{ &[_]u8{ 0x01, 0x02, 0x03 }, "AQID" },
.{ &[_]u8{ 0xFE, 0xFE, 0xFE }, "/v7+" },
.{ &[_]u8{ 0x7F, 0x7F, 0x7F, 0x7F }, "f39/fw==" },
.{ &[_]u8{ 0x7F, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F }, "f39/f39/" },
.{ &[_]u8{ 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE }, "/v7+/v7+/g==" },
.{ &[_]u8{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 }, "AAAAAAAAAAE=" },
};
for (data) |d| {
const res = try decode(std.testing.allocator, d[1]);
defer std.testing.allocator.free(res);
try std.testing.expectEqualSlices(u8, d[0], res);
}
}
test "b64 encode" {
const data = [_][2][]const u8{
.{ &[_]u8{0x00}, "AA==" },
.{ &[_]u8{0xFF}, "/w==" },
.{ &[_]u8{ 0x01, 0x02, 0x03 }, "AQID" },
.{ &[_]u8{ 0xFE, 0xFE, 0xFE }, "/v7+" },
.{ &[_]u8{ 0x7F, 0x7F, 0x7F, 0x7F }, "f39/fw==" },
.{ &[_]u8{ 0x7F, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F }, "f39/f39/" },
.{ &[_]u8{ 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE }, "/v7+/v7+/g==" },
.{ &[_]u8{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 }, "AAAAAAAAAAE=" },
};
for (data) |d| {
const res = try encode(std.testing.allocator, d[0]);
defer std.testing.allocator.free(res);
try std.testing.expectEqualStrings(d[1], res);
}
}

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const std = @import("std");
const Allocator = std.mem.Allocator;
/// Convert hex string to binary byte array. Caller must free the
/// result.
pub fn decode(allocator: Allocator, hex: []const u8) ![]u8 {
if (hex.len % 2 != 0) return error.InvalidInputLength;
var out = try allocator.alloc(u8, hex.len / 2);
errdefer allocator.free(out);
const hexToByte = struct {
fn f(h: u8) !u4 {
return switch (h) {
'0'...'9' => @intCast(h - '0'),
'A'...'F' => @intCast(h - 'A' + 10),
'a'...'f' => @intCast(h - 'a' + 10),
else => return error.InvalidHex,
};
}
}.f;
var i: usize = 0;
while (i < hex.len) : (i += 2) {
const hi: u4 = try hexToByte(hex[i]);
const lo: u4 = try hexToByte(hex[i + 1]);
out[i / 2] = (@as(u8, hi) << 4) | lo;
}
return out;
}
/// Convert binary byte array to hex string. Caller must free the
/// result.
pub fn encode(allocator: Allocator, bin: []const u8) ![]u8 {
var out = try allocator.alloc(u8, bin.len * 2);
errdefer allocator.free(out);
for (bin, 0..) |b, i| {
const hi: u8 = (b >> 4) & 0b0000_1111;
const lo: u8 = b & 0b0000_1111;
out[i * 2] = if (hi < 10) hi + '0' else hi - 10 + 'A';
out[i * 2 + 1] = if (lo < 10) lo + '0' else lo - 10 + 'A';
}
return out;
}
test "encode" {
const allocator = std.testing.allocator;
const hex_bytes = [_][2][]const u8{
.{ "AB", &[_]u8{0b1010_1011} },
.{ "00", &[_]u8{0b0000_0000} },
.{ "FF", &[_]u8{0b1111_1111} },
.{ "5C", &[_]u8{0b0101_1100} },
.{ "5CF0", &[_]u8{ 0b0101_1100, 0b1111_0000 } },
.{ "5CF0FF00ABABAB00", &[_]u8{
0b0101_1100,
0b1111_0000,
0b1111_1111,
0b0000_0000,
0b1010_1011,
0b1010_1011,
0b1010_1011,
0b0000_0000,
} },
};
for (hex_bytes) |hex_byte| {
const res = try encode(allocator, hex_byte[1]);
defer allocator.free(res);
try std.testing.expectEqualSlices(u8, hex_byte[0], res);
}
}
test "decode" {
const allocator = std.testing.allocator;
const hex_bytes = [_][2][]const u8{
.{ "AB", &[_]u8{0b1010_1011} },
.{ "00", &[_]u8{0b0000_0000} },
.{ "FF", &[_]u8{0b1111_1111} },
.{ "5C", &[_]u8{0b0101_1100} },
.{ "5CF0", &[_]u8{ 0b0101_1100, 0b1111_0000 } },
.{ "5CF0FF00ABABAB00", &[_]u8{
0b0101_1100,
0b1111_0000,
0b1111_1111,
0b0000_0000,
0b1010_1011,
0b1010_1011,
0b1010_1011,
0b0000_0000,
} },
};
for (hex_bytes) |hex_byte| {
const res = try decode(allocator, hex_byte[0]);
defer allocator.free(res);
try std.testing.expectEqualSlices(u8, hex_byte[1], res);
}
}

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const std = @import("std");
const b64 = @import("base64.zig");
const hex = @import("hex.zig");
pub fn main() !void {
var gpa = std.heap.GeneralPurposeAllocator(.{}){};
const allocator = gpa.allocator();
const args = try std.process.argsAlloc(allocator);
defer std.process.argsFree(allocator, args);
const stdout = std.io.getStdOut().writer();
if (std.mem.eql(u8, args[1], "b64")) {
if (std.mem.eql(u8, args[2], "-d")) {
const result = try b64.decode(allocator, args[3]);
defer allocator.free(result);
try stdout.print("{s}", .{result});
}
if (std.mem.eql(u8, args[2], "-e")) {
const buf = try hex.decode(allocator, args[3]);
defer allocator.free(buf);
const result = try b64.encode(allocator, buf);
defer allocator.free(result);
try stdout.print("{s}", .{result});
}
}
}

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src/root.zig Normal file
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const std = @import("std");
const testing = std.testing;
export fn add(a: i32, b: i32) i32 {
return a + b;
}
test "basic add functionality" {
try testing.expect(add(3, 7) == 10);
}