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|
const std = @import("std");
const builtin = std.builtin;
const mem = std.mem;
const argon2 = std.crypto.pwhash.argon2;
const ed25519 = std.crypto.sign.Ed25519;
const xx32 = std.hash.XxHash32;
pub const pawprint = struct {
pub const Context = struct {
alloc: mem.Allocator,
io: std.Io,
};
pub const identity = struct {
pub const UnlockError = error{
ChecksumMismatch,
};
const salt_len = 16;
pub fn passphrase_kdf(
ctx: *const Context,
salt: [salt_len]u8,
passphrase: []const u8,
) ![36]u8 {
var derived: [36]u8 = undefined;
try argon2.kdf(
ctx.alloc,
&derived,
passphrase,
&salt,
argon2.Params.sensitive_2id,
argon2.Mode.argon2id,
ctx.io,
);
return derived;
}
pub const Locked = struct {
bytes: [36]u8,
salt: [salt_len]u8,
pub fn unlock(
self: *const Locked,
ctx: *const Context,
passphrase: []const u8,
) !Unlocked {
var seed = try passphrase_kdf(ctx, self.salt, passphrase);
for (0..36) |i| {
seed[i] ^= self.bytes[i];
}
const csum = xx32.hash(0, seed[0..32]);
var csum_bytes: [4]u8 = undefined;
mem.writeInt(u32, &csum_bytes, csum, builtin.Endian.little);
if (!mem.eql(u8, &csum_bytes, seed[32..36])) {
return UnlockError.ChecksumMismatch;
}
return Unlocked{
.keypair = try ed25519.KeyPair.generateDeterministic(
seed[0..32].*,
),
};
}
pub fn drop(self: *volatile Locked) void {
self.* = std.mem.zeroes(Locked);
}
};
pub const Unlocked = struct {
keypair: ed25519.KeyPair,
pub fn generate(io: std.Io) Unlocked {
return Unlocked{
.keypair = ed25519.KeyPair.generate(io),
};
}
pub fn lock(
self: *const Unlocked,
ctx: *const Context,
passphrase: []const u8,
) !Locked {
var salt: [salt_len]u8 = undefined;
try ctx.io.randomSecure(&salt);
const derived = try passphrase_kdf(ctx, salt, passphrase);
var locked = Locked{
.bytes = derived,
.salt = salt,
};
const seed = self.keypair.secret_key.seed();
for (0..32) |i| {
locked.bytes[i] ^= seed[i];
}
const csum = xx32.hash(0, seed);
var csum_bytes: [4]u8 = undefined;
mem.writeInt(u32, &csum_bytes, csum, builtin.Endian.little);
for (0..4) |i| {
locked.bytes[i + 32] ^= csum_bytes[i];
}
return locked;
}
pub fn drop(self: *volatile Unlocked) void {
self.* = std.mem.zeroes(Unlocked);
}
};
};
};
test "lock and unlock identity" {
const ctx = pawprint.Context{
.alloc = std.testing.allocator,
.io = std.testing.io,
};
const ident = pawprint.identity.Unlocked.generate(ctx.io);
const locked = try ident.lock(&ctx, "foobar123");
const unlocked = try locked.unlock(&ctx, "foobar123");
try std.testing.expectEqualDeep(ident, unlocked);
}
test "unlock with wrong passphrase" {
const ctx = pawprint.Context{
.alloc = std.testing.allocator,
.io = std.testing.io,
};
const ident = pawprint.identity.Unlocked.generate(ctx.io);
const locked = try ident.lock(&ctx, "foobar123");
const unlocked = locked.unlock(&ctx, "barbaz456");
try std.testing.expectEqual(
unlocked,
pawprint.identity.UnlockError.ChecksumMismatch,
);
}
test "drop unlocked identity" {
const ctx = pawprint.Context{
.alloc = std.testing.allocator,
.io = std.testing.io,
};
var ident = pawprint.identity.Unlocked.generate(ctx.io);
ident.drop();
try std.testing.expectEqual(
mem.zeroes(pawprint.identity.Unlocked),
ident,
);
}
test "drop locked identity" {
const ctx = pawprint.Context{
.alloc = std.testing.allocator,
.io = std.testing.io,
};
const ident = pawprint.identity.Unlocked.generate(ctx.io);
var locked = try ident.lock(&ctx, "foobar123");
locked.drop();
try std.testing.expectEqual(
mem.zeroes(pawprint.identity.Locked),
locked,
);
}
|
