support x25519 init

Created a mess in previous commit.
This commit is contained in:
Halil Durak
2026-01-13 19:46:42 +03:00
parent 7ae3e8cb47
commit 1699a92822

View File

@@ -35,7 +35,16 @@ const SubtleCrypto = @This();
/// Don't optimize away the type.
_pad: bool = false,
const Params = struct {
const Algorithm = union(enum) {
/// For RSASSA-PKCS1-v1_5, RSA-PSS, or RSA-OAEP: pass an RsaHashedKeyGenParams object.
rsa_hashed_key_gen: RsaHashedKeyGen,
/// For HMAC: pass an HmacKeyGenParams object.
hmac_key_gen: HmacKeyGen,
/// Can be Ed25519 or X25519.
name: []const u8,
/// Can be Ed25519 or X25519.
object: struct { name: []const u8 },
/// https://developer.mozilla.org/en-US/docs/Web/API/RsaHashedKeyGenParams
const RsaHashedKeyGen = struct {
name: []const u8,
@@ -63,208 +72,6 @@ const Params = struct {
};
};
/// NOTE: I think we can use extern union and cast this to intended algorithm
/// by `name` field. Not sure if it'd make difference memory/performance wise.
const Algorithm = union(enum) {
rsa_hashed_key_gen: Params.RsaHashedKeyGen,
hmac_key_gen: Params.HmacKeyGen,
};
/// Returns the desired digest by its name.
fn getDigest(name: []const u8) error{Invalid}!*const crypto.EVP_MD {
const digest = std.meta.stringToEnum(enum {
@"SHA-1",
@"SHA-256",
@"SHA-384",
@"SHA-512",
}, name) orelse return error.Invalid;
return switch (digest) {
.@"SHA-1" => crypto.EVP_sha1(),
.@"SHA-256" => crypto.EVP_sha256(),
.@"SHA-384" => crypto.EVP_sha384(),
.@"SHA-512" => crypto.EVP_sha512(),
};
}
/// Represents a cryptographic key obtained from one of the SubtleCrypto methods
/// generateKey(), deriveKey(), importKey(), or unwrapKey().
pub const CryptoKey = struct {
/// Algorithm being used.
_type: Type,
/// Whether the key is extractable.
_extractable: bool,
/// Bit flags of `usages`; see `Usages` type.
_usages: u8,
_key: []const u8,
_digest: *const crypto.EVP_MD,
pub const Type = enum(u8) { hmac, rsa };
/// Changing the names of fields would affect bitmask creation.
pub const Usages = struct {
// zig fmt: off
pub const encrypt = 0x001;
pub const decrypt = 0x002;
pub const sign = 0x004;
pub const verify = 0x008;
pub const deriveKey = 0x010;
pub const deriveBits = 0x020;
pub const wrapKey = 0x040;
pub const unwrapKey = 0x080;
// zig fmt: on
};
pub fn init(
algorithm: Algorithm,
extractable: bool,
key_usages: []const []const u8,
page: *Page,
) !*CryptoKey {
// TODO.
return switch (algorithm) {
.hmac_key_gen => |hmac| initHMAC(hmac, extractable, key_usages, page),
else => @panic("NYI"),
};
}
/// Create a bitmask out of `key_usages`.-
fn createUsagesMask(usages: []const []const u8) !u8 {
const decls = @typeInfo(Usages).@"struct".decls;
var mask: u8 = 0;
iter_usages: for (usages) |usage| {
inline for (decls) |decl| {
if (std.mem.eql(u8, decl.name, usage)) {
mask |= @field(Usages, decl.name);
continue :iter_usages;
}
}
// Unknown usage if got here, report error.
return error.SyntaxError;
}
return mask;
}
inline fn canSign(self: *const CryptoKey) bool {
return self._usages & Usages.sign != 0;
}
inline fn canVerify(self: *const CryptoKey) bool {
return self._usages & Usages.verify != 0;
}
fn initHMAC(
algorithm: Params.HmacKeyGen,
extractable: bool,
key_usages: []const []const u8,
page: *Page,
) !*CryptoKey {
const hash = switch (algorithm.hash) {
.string => |str| str,
.object => |obj| obj.name,
};
// Find digest.
const digest = try getDigest(hash);
// Calculate usages mask and check if its correct.
const usages_mask = try createUsagesMask(key_usages);
const block_size: usize = blk: {
// Caller provides this in bits, not bytes.
if (algorithm.length) |length| {
break :blk length / 8;
}
// Prefer block size of the hash function instead.
break :blk crypto.EVP_MD_block_size(digest);
};
const key = try page.arena.alloc(u8, block_size);
errdefer page.arena.free(key);
// HMAC is simply CSPRNG.
const res = crypto.RAND_bytes(key.ptr, key.len);
std.debug.assert(res == 1);
return page._factory.create(CryptoKey{
._type = .hmac,
._extractable = extractable,
._usages = usages_mask,
._key = key,
._digest = digest,
});
}
fn signHMAC(self: *const CryptoKey, data: []const u8, page: *Page) !js.ArrayBuffer {
if (!self.canSign()) {
return error.InvalidAccessError;
}
const buffer = try page.arena.alloc(u8, crypto.EVP_MD_size(self._digest));
errdefer page.arena.free(buffer);
var out_len: u32 = 0;
// Try to sign.
const signed = crypto.HMAC(
self._digest,
@ptrCast(self._key.ptr),
self._key.len,
data.ptr,
data.len,
buffer.ptr,
&out_len,
);
if (signed != null) {
return js.ArrayBuffer{ .values = buffer[0..out_len] };
}
// Not DOM exception, failed on our side.
return error.Invalid;
}
fn verifyHMAC(
self: *const CryptoKey,
signature: []const u8,
data: []const u8,
page: *Page,
) !js.Promise {
if (!self.canVerify()) {
return error.InvalidAccessError;
}
var buffer: [crypto.EVP_MAX_MD_BLOCK_SIZE]u8 = undefined;
var out_len: u32 = 0;
// Try to sign.
const signed = crypto.HMAC(
self._digest,
@ptrCast(self._key.ptr),
self._key.len,
data.ptr,
data.len,
&buffer,
&out_len,
);
if (signed != null) {
// CRYPTO_memcmp compare in constant time so prohibits time-based attacks.
const res = crypto.CRYPTO_memcmp(signed, @ptrCast(signature.ptr), signature.len);
return page.js.resolvePromise(res == 0);
}
return page.js.resolvePromise(false);
}
pub const JsApi = struct {
pub const bridge = js.Bridge(CryptoKey);
pub const Meta = struct {
pub const name = "CryptoKey";
pub var class_id: bridge.ClassId = undefined;
pub const prototype_chain = bridge.prototypeChain();
};
};
};
/// Generate a new key (for symmetric algorithms) or key pair (for public-key algorithms).
pub fn generateKey(
_: *const SubtleCrypto,
@@ -273,11 +80,11 @@ pub fn generateKey(
key_usages: []const []const u8,
page: *Page,
) !js.Promise {
const key = CryptoKey.init(algorithm, extractable, key_usages, page) catch |err| {
const key_or_pair = CryptoKey.init(algorithm, extractable, key_usages, page) catch |err| {
return page.js.rejectPromise(@errorName(err));
};
return page.js.resolvePromise(key);
return page.js.resolvePromise(key_or_pair);
}
/// Exports a key: that is, it takes as input a CryptoKey object and gives you
@@ -358,6 +165,296 @@ pub fn verify(
};
}
/// Returns the desired digest by its name.
fn getDigest(name: []const u8) error{Invalid}!*const crypto.EVP_MD {
if (std.mem.eql(u8, "SHA-256", name)) {
return crypto.EVP_sha256();
}
if (std.mem.eql(u8, "SHA-384", name)) {
return crypto.EVP_sha384();
}
if (std.mem.eql(u8, "SHA-512", name)) {
return crypto.EVP_sha512();
}
if (std.mem.eql(u8, "SHA-1", name)) {
return crypto.EVP_sha1();
}
return error.Invalid;
}
const KeyOrPair = union(enum) { key: *CryptoKey, pair: CryptoKeyPair };
/// https://developer.mozilla.org/en-US/docs/Web/API/CryptoKeyPair
const CryptoKeyPair = struct {
privateKey: *CryptoKey,
publicKey: *CryptoKey,
};
/// Represents a cryptographic key obtained from one of the SubtleCrypto methods
/// generateKey(), deriveKey(), importKey(), or unwrapKey().
pub const CryptoKey = struct {
/// Algorithm being used.
_type: Type,
/// Whether the key is extractable.
_extractable: bool,
/// Bit flags of `usages`; see `Usages` type.
_usages: u8,
_key: []const u8,
_digest: *const crypto.EVP_MD,
pub const Type = enum(u8) { hmac, rsa, x25519 };
/// Changing the names of fields would affect bitmask creation.
pub const Usages = struct {
// zig fmt: off
pub const encrypt = 0x001;
pub const decrypt = 0x002;
pub const sign = 0x004;
pub const verify = 0x008;
pub const deriveKey = 0x010;
pub const deriveBits = 0x020;
pub const wrapKey = 0x040;
pub const unwrapKey = 0x080;
// zig fmt: on
};
pub fn init(
algorithm: Algorithm,
extractable: bool,
key_usages: []const []const u8,
page: *Page,
) !KeyOrPair {
return switch (algorithm) {
.hmac_key_gen => |hmac| initHMAC(hmac, extractable, key_usages, page),
.name => |name| {
if (std.mem.eql(u8, "X25519", name)) {
return initX25519(extractable, key_usages, page);
}
return error.NotSupported;
},
.object => |object| {
// Ditto.
const name = object.name;
if (std.mem.eql(u8, "X25519", name)) {
return initX25519(extractable, key_usages, page);
}
return error.NotSupported;
},
else => @panic("NYI"),
};
}
/// Create a bitmask out of `key_usages`.
/// `0` is equal to `SyntaxError`.
fn createUsagesMask(usages: []const []const u8) u8 {
const decls = @typeInfo(Usages).@"struct".decls;
var mask: u8 = 0;
iter_usages: for (usages) |usage| {
inline for (decls) |decl| {
if (std.mem.eql(u8, decl.name, usage)) {
mask |= @field(Usages, decl.name);
continue :iter_usages;
}
}
// Unknown usage if got here.
return 0;
}
return mask;
}
inline fn canSign(self: *const CryptoKey) bool {
return self._usages & Usages.sign != 0;
}
inline fn canVerify(self: *const CryptoKey) bool {
return self._usages & Usages.verify != 0;
}
// HMAC.
fn initHMAC(
algorithm: Algorithm.HmacKeyGen,
extractable: bool,
key_usages: []const []const u8,
page: *Page,
) !KeyOrPair {
const hash = switch (algorithm.hash) {
.string => |str| str,
.object => |obj| obj.name,
};
// Find digest.
const digest = try getDigest(hash);
// Calculate usages mask and check if its correct.
const usages_mask = createUsagesMask(key_usages);
if (usages_mask == 0) {
return error.SyntaxError;
}
const block_size: usize = blk: {
// Caller provides this in bits, not bytes.
if (algorithm.length) |length| {
break :blk length / 8;
}
// Prefer block size of the hash function instead.
break :blk crypto.EVP_MD_block_size(digest);
};
const key = try page.arena.alloc(u8, block_size);
errdefer page.arena.free(key);
// HMAC is simply CSPRNG.
const res = crypto.RAND_bytes(key.ptr, key.len);
std.debug.assert(res == 1);
const crypto_key = try page._factory.create(CryptoKey{
._type = .hmac,
._extractable = extractable,
._usages = usages_mask,
._key = key,
._digest = digest,
});
return .{ .key = crypto_key };
}
fn signHMAC(self: *const CryptoKey, data: []const u8, page: *Page) !js.ArrayBuffer {
if (!self.canSign()) {
return error.InvalidAccessError;
}
const buffer = try page.call_arena.alloc(u8, crypto.EVP_MD_size(self._digest));
errdefer page.call_arena.free(buffer);
var out_len: u32 = 0;
// Try to sign.
const signed = crypto.HMAC(
self._digest,
@ptrCast(self._key.ptr),
self._key.len,
data.ptr,
data.len,
buffer.ptr,
&out_len,
);
if (signed != null) {
return js.ArrayBuffer{ .values = buffer[0..out_len] };
}
// Not DOM exception, failed on our side.
return error.Invalid;
}
fn verifyHMAC(
self: *const CryptoKey,
signature: []const u8,
data: []const u8,
page: *Page,
) !js.Promise {
if (!self.canVerify()) {
return error.InvalidAccessError;
}
var buffer: [crypto.EVP_MAX_MD_BLOCK_SIZE]u8 = undefined;
var out_len: u32 = 0;
// Try to sign.
const signed = crypto.HMAC(
self._digest,
@ptrCast(self._key.ptr),
self._key.len,
data.ptr,
data.len,
&buffer,
&out_len,
);
if (signed != null) {
// CRYPTO_memcmp compare in constant time so prohibits time-based attacks.
const res = crypto.CRYPTO_memcmp(signed, @ptrCast(signature.ptr), signature.len);
return page.js.resolvePromise(res == 0);
}
return page.js.resolvePromise(false);
}
// X25519.
fn initX25519(
extractable: bool,
key_usages: []const []const u8,
page: *Page,
) !KeyOrPair {
// This code has too many allocations here and there, might be nice to
// gather them together with a single alloc call. Not sure if factory
// pattern is suitable for it though.
// Calculate usages; only matters for private key.
// Only deriveKey() and deriveBits() be used for X25519.
var mask: u8 = 0;
iter_usages: for (key_usages) |usage| {
inline for ([_][]const u8{ "deriveKey", "deriveBits" }) |name| {
if (std.mem.eql(u8, name, usage)) {
mask |= @field(Usages, name);
continue :iter_usages;
}
}
// Unknown usage if got here.
return error.SyntaxError;
}
// Cannot be empty.
if (mask == 0) {
return error.SyntaxError;
}
const public_value = try page.arena.alloc(u8, crypto.X25519_PUBLIC_VALUE_LEN);
errdefer page.arena.free(public_value);
const private_key = try page.arena.alloc(u8, crypto.X25519_PRIVATE_KEY_LEN);
errdefer page.arena.free(private_key);
// There's no info about whether this can fail; so I assume it cannot.
crypto.X25519_keypair(@ptrCast(public_value), @ptrCast(private_key));
const private = try page._factory.create(CryptoKey{
._type = .x25519,
._extractable = extractable,
._usages = mask,
._key = private_key,
// FIXME: This is unnecessary for X25519.
._digest = crypto.EVP_sha1(),
});
errdefer page._factory.destroy(private);
const public = try page._factory.create(CryptoKey{
._type = .x25519,
._extractable = extractable,
// Always empty for public key.
._usages = 0,
._key = public_value,
// FIXME: This is unnecessary for X25519.
._digest = crypto.EVP_sha1(),
});
errdefer page._factory.destroy(public);
return .{ .pair = .{ .privateKey = private, .publicKey = public } };
}
pub const JsApi = struct {
pub const bridge = js.Bridge(CryptoKey);
pub const Meta = struct {
pub const name = "CryptoKey";
pub var class_id: bridge.ClassId = undefined;
pub const prototype_chain = bridge.prototypeChain();
};
};
};
pub const JsApi = struct {
pub const bridge = js.Bridge(SubtleCrypto);