1 files changed, 518 insertions, 0 deletions

diff --git a/src/nkeys.zig b/src/nkeys.zig
new file mode 100644
index 0000000..7ce44f9
--- /dev/null
+++ b/src/nkeys.zig
@@ -0,0 +1,518 @@
+const std = @import("std");
+const ascii = std.ascii;
+const base32 = @import("base32.zig");
+const crc16 = @import("crc16.zig");
+const crypto = std.crypto;
+const Ed25519 = crypto.sign.Ed25519;
+const mem = std.mem;
+const testing = std.testing;
+
+const Error = error{
+    InvalidPrefixByte,
+    InvalidEncoding,
+    InvalidSeed,
+    NoNKeySeedFound,
+    NoNKeyUserSeedFound,
+};
+
+pub fn fromText(text: []const u8) !Key {
+    if (!isValidEncoding(text)) return error.InvalidEncoding;
+    switch (text[0]) {
+        'S' => {
+            // It's a seed.
+            if (text.len != text_seed_len) return error.InvalidSeed;
+            return Key{ .seed_key_pair = try fromSeed(text[0..text_seed_len]) };
+        },
+        'P' => return error.InvalidEncoding, // unsupported for now
+        else => {
+            if (text.len != text_public_len) return error.InvalidEncoding;
+            return Key{ .public_key = try fromPublicKey(text[0..text_public_len]) };
+        },
+    }
+}
+
+pub const Key = union(enum) {
+    seed_key_pair: SeedKeyPair,
+    public_key: PublicKey,
+
+    const Self = @This();
+
+    pub fn publicKey(self: *const Self) !text_public {
+        return switch (self.*) {
+            .seed_key_pair => |*kp| try kp.publicKey(),
+            .public_key => |*pk| try pk.publicKey(),
+        };
+    }
+
+    pub fn intoPublicKey(self: *const Self) !PublicKey {
+        return switch (self.*) {
+            .seed_key_pair => |*kp| try kp.intoPublicKey(),
+            .public_key => |pk| pk,
+        };
+    }
+
+    pub fn verify(
+        self: *const Self,
+        msg: []const u8,
+        sig: [Ed25519.signature_length]u8,
+    ) !void {
+        return switch (self.*) {
+            .seed_key_pair => |*kp| try kp.verify(msg, sig),
+            .public_key => |*pk| try pk.verify(msg, sig),
+        };
+    }
+
+    pub fn wipe(self: *Self) void {
+        return switch (self.*) {
+            .seed_key_pair => |*kp| kp.wipe(),
+            .public_key => |*pk| pk.wipe(),
+        };
+    }
+};
+
+pub const KeyTypePrefixByte = enum(u8) {
+    seed = 18 << 3, // S
+    private = 15 << 3, // P
+    unknown = 23 << 3, // U
+};
+
+pub const PublicPrefixByte = enum(u8) {
+    account = 0, // A
+    cluster = 2 << 3, // C
+    operator = 14 << 3, // O
+    server = 13 << 3, // N
+    user = 20 << 3, // U
+
+    fn fromU8(b: u8) !PublicPrefixByte {
+        return switch (b) {
+            @enumToInt(PublicPrefixByte.server) => .server,
+            @enumToInt(PublicPrefixByte.cluster) => .cluster,
+            @enumToInt(PublicPrefixByte.operator) => .operator,
+            @enumToInt(PublicPrefixByte.account) => .account,
+            @enumToInt(PublicPrefixByte.user) => .user,
+            else => error.InvalidPrefixByte,
+        };
+    }
+};
+
+pub const SeedKeyPair = struct {
+    const Self = @This();
+
+    seed: text_seed,
+
+    pub fn init(prefix: PublicPrefixByte) !Self {
+        var raw_seed: [Ed25519.seed_length]u8 = undefined;
+        crypto.random.bytes(&raw_seed);
+        defer wipeBytes(&raw_seed);
+
+        var seed = try encodeSeed(prefix, &raw_seed);
+        return Self{ .seed = seed };
+    }
+
+    pub fn initFromSeed(seed: *const text_seed) !Self {
+        var decoded = try decodeSeed(seed);
+        defer decoded.wipe();
+
+        return Self{ .seed = seed.* };
+    }
+
+    fn rawSeed(self: *const Self) ![Ed25519.seed_length]u8 {
+        return (try decodeSeed(&self.seed)).seed;
+    }
+
+    fn keys(self: *const Self) !Ed25519.KeyPair {
+        return Ed25519.KeyPair.create(try rawSeed(self));
+    }
+
+    pub fn privateKey(self: *const Self) !text_private {
+        var kp = try self.keys();
+        defer wipeKeyPair(&kp);
+        return try encodePrivate(&kp.secret_key);
+    }
+
+    pub fn publicKey(self: *const Self) !text_public {
+        var decoded = try decodeSeed(&self.seed);
+        defer decoded.wipe();
+        var kp = try Ed25519.KeyPair.create(decoded.seed);
+        defer wipeKeyPair(&kp);
+        return try encodePublic(decoded.prefix, &kp.public_key);
+    }
+
+    pub fn intoPublicKey(self: *const Self) !PublicKey {
+        var decoded = try decodeSeed(&self.seed);
+        var kp = try Ed25519.KeyPair.create(decoded.seed);
+        defer wipeKeyPair(&kp);
+        return PublicKey{
+            .prefix = decoded.prefix,
+            .key = kp.public_key,
+        };
+    }
+
+    pub fn sign(
+        self: *const Self,
+        msg: []const u8,
+    ) ![Ed25519.signature_length]u8 {
+        var kp = try self.keys();
+        defer wipeKeyPair(&kp);
+        return try Ed25519.sign(msg, kp, null);
+    }
+
+    pub fn verify(
+        self: *const Self,
+        msg: []const u8,
+        sig: [Ed25519.signature_length]u8,
+    ) !void {
+        var kp = try self.keys();
+        defer wipeKeyPair(&kp);
+        try Ed25519.verify(sig, msg, kp.public_key);
+    }
+
+    pub fn wipe(self: *Self) void {
+        wipeBytes(&self.seed);
+    }
+
+    fn wipeKeyPair(kp: *Ed25519.KeyPair) void {
+        wipeBytes(&kp.secret_key);
+    }
+};
+
+fn wipeBytes(bs: []u8) void {
+    for (bs) |*b| b.* = 0;
+}
+
+pub const PublicKey = struct {
+    const Self = @This();
+
+    prefix: PublicPrefixByte,
+    key: [Ed25519.public_length]u8,
+
+    pub fn publicKey(self: *const Self) !text_public {
+        return try encodePublic(self.prefix, &self.key);
+    }
+
+    pub fn verify(
+        self: *const Self,
+        msg: []const u8,
+        sig: [Ed25519.signature_length]u8,
+    ) !void {
+        try Ed25519.verify(sig, msg, self.key);
+    }
+
+    pub fn wipe(self: *Self) void {
+        self.prefix = .user;
+        std.crypto.random.bytes(&self.key);
+    }
+};
+
+// One prefix byte, two CRC bytes
+const binary_private_size = 1 + Ed25519.secret_length + 2;
+// One prefix byte, two CRC bytes
+const binary_public_size = 1 + Ed25519.public_length + 2;
+// Two prefix bytes, two CRC bytes
+const binary_seed_size = 2 + Ed25519.seed_length + 2;
+
+pub const text_private_len = base32.encodedLen(binary_private_size);
+pub const text_public_len = base32.encodedLen(binary_public_size);
+pub const text_seed_len = base32.encodedLen(binary_seed_size);
+
+pub const text_private = [text_private_len]u8;
+pub const text_public = [text_public_len]u8;
+pub const text_seed = [text_seed_len]u8;
+
+pub fn encodePublic(prefix: PublicPrefixByte, key: *const [Ed25519.public_length]u8) !text_public {
+    return encode(1, key.len, &[_]u8{@enumToInt(prefix)}, key);
+}
+
+pub fn encodePrivate(key: *const [Ed25519.secret_length]u8) !text_private {
+    return encode(1, key.len, &[_]u8{@enumToInt(KeyTypePrefixByte.private)}, key);
+}
+
+fn EncodedKey(comptime prefix_len: usize, comptime data_len: usize) type {
+    return [base32.encodedLen(prefix_len + data_len + 2)]u8;
+}
+
+fn encode(
+    comptime prefix_len: usize,
+    comptime data_len: usize,
+    prefix: *const [prefix_len]u8,
+    data: *const [data_len]u8,
+) !EncodedKey(prefix_len, data_len) {
+    var buf: [prefix_len + data_len + 2]u8 = undefined;
+    defer wipeBytes(&buf);
+
+    mem.copy(u8, &buf, prefix[0..]);
+    mem.copy(u8, buf[prefix_len..], data[0..]);
+    var off = prefix_len + data_len;
+    var checksum = crc16.make(buf[0..off]);
+    mem.writeIntLittle(u16, buf[buf.len - 2 .. buf.len], checksum);
+
+    var text: EncodedKey(prefix_len, data_len) = undefined;
+    std.debug.assert(base32.encode(&buf, &text) == text.len);
+
+    return text;
+}
+
+pub fn encodeSeed(prefix: PublicPrefixByte, src: *const [Ed25519.seed_length]u8) !text_seed {
+    var full_prefix = [_]u8{
+        @enumToInt(KeyTypePrefixByte.seed) | (@enumToInt(prefix) >> 5),
+        (@enumToInt(prefix) & 0b00011111) << 3,
+    };
+    return encode(full_prefix.len, src.len, &full_prefix, src);
+}
+
+pub fn decodePrivate(text: *const text_private) ![Ed25519.secret_length]u8 {
+    var decoded = try decode(1, Ed25519.secret_length, text);
+    defer wipeBytes(&decoded.data);
+    if (decoded.prefix[0] != @enumToInt(KeyTypePrefixByte.private))
+        return error.InvalidPrefixByte;
+    return decoded.data;
+}
+
+pub fn decodePublic(prefix: PublicPrefixByte, text: *const text_public) ![Ed25519.public_length]u8 {
+    var decoded = try decode(1, Ed25519.public_length, text);
+    if (decoded.data[0] != @enumToInt(prefix))
+        return error.InvalidPrefixByte;
+    return decoded.data;
+}
+
+fn DecodedNKey(comptime prefix_len: usize, comptime data_len: usize) type {
+    return struct {
+        prefix: [prefix_len]u8,
+        data: [data_len]u8,
+    };
+}
+
+fn decode(
+    comptime prefix_len: usize,
+    comptime data_len: usize,
+    text: *const [base32.encodedLen(prefix_len + data_len + 2)]u8,
+) !DecodedNKey(prefix_len, data_len) {
+    var raw: [prefix_len + data_len + 2]u8 = undefined;
+    defer wipeBytes(&raw);
+    std.debug.assert((try base32.decode(text[0..], &raw)) == raw.len);
+
+    var checksum = mem.readIntLittle(u16, raw[raw.len - 2 .. raw.len]);
+    try crc16.validate(raw[0 .. raw.len - 2], checksum);
+
+    return DecodedNKey(prefix_len, data_len){
+        .prefix = raw[0..prefix_len].*,
+        .data = raw[prefix_len .. raw.len - 2].*,
+    };
+}
+
+pub const DecodedSeed = struct {
+    const Self = @This();
+
+    prefix: PublicPrefixByte,
+    seed: [Ed25519.seed_length]u8,
+
+    pub fn wipe(self: *Self) void {
+        self.prefix = .account;
+        wipeBytes(&self.seed);
+    }
+};
+
+pub fn decodeSeed(text: *const text_seed) !DecodedSeed {
+    var decoded = try decode(2, Ed25519.seed_length, text);
+    defer wipeBytes(&decoded.data); // gets copied
+
+    var key_ty_prefix = decoded.prefix[0] & 0b11111000;
+    var entity_ty_prefix = (decoded.prefix[0] & 0b00000111) << 5 | ((decoded.prefix[1] & 0b11111000) >> 3);
+
+    if (key_ty_prefix != @enumToInt(KeyTypePrefixByte.seed))
+        return error.InvalidSeed;
+
+    return DecodedSeed{
+        .prefix = try PublicPrefixByte.fromU8(entity_ty_prefix),
+        .seed = decoded.data,
+    };
+}
+
+pub fn fromPublicKey(text: *const text_public) !PublicKey {
+    var decoded = try decode(1, Ed25519.public_length, text);
+    defer wipeBytes(&decoded.data); // gets copied
+
+    return PublicKey{
+        .prefix = try PublicPrefixByte.fromU8(decoded.prefix[0]),
+        .key = decoded.data,
+    };
+}
+
+pub fn fromSeed(text: *const text_seed) !SeedKeyPair {
+    var res = try decodeSeed(text);
+    wipeBytes(&res.seed);
+    return SeedKeyPair{ .seed = text.* };
+}
+
+pub fn isValidEncoding(text: []const u8) bool {
+    if (text.len < 4) return false;
+    var made_crc: u16 = 0;
+    var dec = base32.Decoder{};
+    var crc_buf: [2]u8 = undefined;
+    var crc_buf_len: u8 = 0;
+    var expect_len: usize = base32.decodedLen(text.len);
+    var wrote_n_total: usize = 0;
+    for (text) |c, i| {
+        var b = (dec.read(c) catch return false) orelse continue;
+        wrote_n_total += 1;
+        if (crc_buf_len == 2) made_crc = crc16.update(made_crc, &.{crc_buf[0]});
+        crc_buf[0] = crc_buf[1];
+        crc_buf[1] = b;
+        if (crc_buf_len != 2) crc_buf_len += 1;
+    }
+    if (dec.out_off != 0 and wrote_n_total < expect_len) {
+        if (crc_buf_len == 2) made_crc = crc16.update(made_crc, &.{crc_buf[0]});
+        crc_buf[0] = crc_buf[1];
+        crc_buf[1] = dec.buf;
+        if (crc_buf_len != 2) crc_buf_len += 1;
+    }
+    if (crc_buf_len != 2) unreachable;
+    var got_crc = mem.readIntLittle(u16, &crc_buf);
+    return made_crc == got_crc;
+}
+
+pub fn isValidSeed(text: *const text_seed) bool {
+    var res = decodeSeed(text) catch return false;
+    wipeBytes(&res.seed);
+    return true;
+}
+
+pub fn isValidPublicKey(text: *const text_public, with_type: ?PublicPrefixByte) bool {
+    var res = decode(1, Ed25519.public_length, text) catch return false;
+    var public = PublicPrefixByte.fromU8(res.data[0]) catch return false;
+    return if (with_type) |ty| public == ty else true;
+}
+
+pub fn fromRawSeed(prefix: PublicPrefixByte, raw_seed: *const [Ed25519.seed_length]u8) !SeedKeyPair {
+    return SeedKeyPair{ .seed = try encodeSeed(prefix, raw_seed) };
+}
+
+pub fn getNextLine(text: []const u8, off: *usize) ?[]const u8 {
+    if (off.* <= text.len) return null;
+    var newline_pos = mem.indexOfPos(u8, text, off.*, "\n") orelse return null;
+    var start = off.*;
+    var end = newline_pos;
+    if (newline_pos > 0 and text[newline_pos - 1] == '\r') end -= 1;
+    off.* = newline_pos + 1;
+    return text[start..end];
+}
+
+// `line` must not contain CR or LF characters.
+pub fn isKeySectionBarrier(line: []const u8) bool {
+    return line.len >= 6 and mem.startsWith(u8, line, "---") and mem.endsWith(u8, line, "---");
+}
+
+pub fn areKeySectionContentsValid(contents: []const u8) bool {
+    const allowed_chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_-.=";
+
+    for (contents) |c| {
+        var is_c_allowed = false;
+        for (allowed_chars) |allowed_c| {
+            if (c == allowed_c) {
+                is_c_allowed = true;
+                break;
+            }
+        }
+        if (!is_c_allowed) return false;
+    }
+
+    return true;
+}
+
+pub fn findKeySection(text: []const u8, off: *usize) ?[]const u8 {
+    // Skip all space
+    // Lines end with \n, but \r\n is also fine
+    // Contents of the key may consist of abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_-.=
+    // However, if a line seems to be in the form of ---stuff---, the section is ended.
+    // A newline must be present at the end of the key footer
+    // See https://regex101.com/r/pEaqcJ/1 for a weird edge case in the github.com/nats-io/nkeys library
+    // Another weird edge case: https://regex101.com/r/Xmqj1h/1
+    while (true) {
+        var opening_line = getNextLine(text, off) orelse return null;
+        if (!isKeySectionBarrier(opening_line)) continue;
+
+        var contents_line = getNextLine(text, off) orelse return null;
+        if (!areKeySectionContentsValid(contents_line)) continue;
+
+        var closing_line = getNextLine(text, off) orelse return null;
+        if (!isKeySectionBarrier(closing_line)) continue;
+
+        return contents_line;
+    }
+}
+
+pub fn parseDecoratedJwt(contents: []const u8) ![]const u8 {
+    var current_off: usize = 0;
+    return findKeySection(contents, &current_off) orelse return contents;
+}
+
+fn validNKey(text: []const u8) bool {
+    var valid_prefix =
+        mem.startsWith(u8, text, "SO") or
+        mem.startsWith(u8, text, "SA") or
+        mem.startsWith(u8, text, "SU");
+    var valid_len = text.len >= text_seed_len;
+    return valid_prefix and valid_len;
+}
+
+fn findNKey(text: []const u8) ?[]const u8 {
+    var current_off: usize = 0;
+    while (true) {
+        var line = getNextLine(text, &current_off) orelse return null;
+        for (line) |c, i| {
+            if (!ascii.isSpace(c)) {
+                if (validNKey(line[i..])) return line[i..];
+                break;
+            }
+        }
+    }
+}
+
+pub fn parseDecoratedNKey(contents: []const u8) !SeedKeyPair {
+    var current_off: usize = 0;
+
+    var seed: ?[]const u8 = null;
+    if (findKeySection(contents, &current_off) != null)
+        seed = findKeySection(contents, &current_off);
+    if (seed != null)
+        seed = findNKey(contents) orelse return error.NoNKeySeedFound;
+    if (!validNKey(seed.?))
+        return error.NoNKeySeedFound;
+    return fromSeed(contents[0..text_seed_len]);
+}
+
+pub fn parseDecoratedUserNKey(contents: []const u8) !SeedKeyPair {
+    var key = try parseDecoratedNKey(contents);
+    if (!mem.startsWith(u8, &key.seed, "SU")) return error.NoNKeyUserSeedFound;
+    defer key.wipe();
+    return key;
+}
+
+test {
+    testing.refAllDecls(@This());
+    testing.refAllDecls(Key);
+    testing.refAllDecls(SeedKeyPair);
+    testing.refAllDecls(PublicKey);
+}
+
+test {
+    var key_pair = try SeedKeyPair.init(PublicPrefixByte.server);
+    defer key_pair.wipe();
+
+    var decoded_seed = try decodeSeed(&key_pair.seed);
+    var encoded_second_time = try encodeSeed(decoded_seed.prefix, &decoded_seed.seed);
+    try testing.expectEqualSlices(u8, &key_pair.seed, &encoded_second_time);
+    try testing.expect(isValidEncoding(&key_pair.seed));
+
+    var pub_key_str_a = try key_pair.publicKey();
+    var priv_key_str = try key_pair.privateKey();
+    try testing.expect(pub_key_str_a.len != 0);
+    try testing.expect(priv_key_str.len != 0);
+    try testing.expect(isValidEncoding(&pub_key_str_a));
+    try testing.expect(isValidEncoding(&priv_key_str));
+    wipeBytes(&priv_key_str);
+
+    var pub_key = try key_pair.intoPublicKey();
+    var pub_key_str_b = try pub_key.publicKey();
+    try testing.expectEqualSlices(u8, &pub_key_str_a, &pub_key_str_b);
+}