munch

-module(munch).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/munch.gleam").
-export([init_md5/0, init_sha1/0, init_sha256/0, init_sha224/0, init_sha512/0, init_sha384/0, digest/1, update/2, new_hash/1, hash/2, digest_bits/1, update_bits/2, hash_bits/2, new_hmac/2, hmac/3, hmac_bits/3, secure_compare/2, sign_message/3, verify_signed_message/3, strong_random_bytes/1]).
-export_type([hash_algorithm/0]).

-if(?OTP_RELEASE >= 27).
-define(MODULEDOC(Str), -moduledoc(Str)).
-define(DOC(Str), -doc(Str)).
-else.
-define(MODULEDOC(Str), -compile([])).
-define(DOC(Str), -compile([])).
-endif.

?MODULEDOC(
    " Cryptographic hash functions and related utilities.\n"
    "\n"
    " <style>\n"
    "   small {\n"
    "     font-size: 0.7em;\n"
    "     opacity: 0.75;\n"
    "   }\n"
    "   .goto-top {\n"
    "     display: block;\n"
    "     font-size: 0.85em;\n"
    "     text-align: right;\n"
    "   }\n"
    "   h4 {\n"
    "     margin-bottom: 0;\n"
    "     + p {\n"
    "       margin-top: 0;\n"
    "     }\n"
    "   }\n"
    " </style>\n"
    " <script>\n"
    " (callback => document.readyState !== 'loading' ? callback() : document.addEventListener('DOMContentLoaded', callback, { once: true }))(() => {\n"
    "   const list = document.querySelector('.sidebar > ul:last-of-type')\n"
    "   const sortedLists = document.createDocumentFragment()\n"
    "   const sortedMembers = document.createDocumentFragment()\n"
    "\n"
    "   for (const header of document.querySelectorAll('main > h4')) {\n"
    "     sortedLists.append((() => {\n"
    "       const node = document.createElement('h3')\n"
    "       node.append(header.textContent)\n"
    "       return node\n"
    "     })())\n"
    "     sortedMembers.append((() => {\n"
    "       const node = document.createElement('h2')\n"
    "       node.append(header.textContent)\n"
    "       return node\n"
    "     })())\n"
    "\n"
    "     const sortedList = document.createElement('ul')\n"
    "     sortedLists.append(sortedList)\n"
    "\n"
    "     for (const anchor of header.nextElementSibling.querySelectorAll('a')) {\n"
    "       const href = anchor.getAttribute('href')\n"
    "       const member = document.querySelector(`.member:has(h2 > a[href=\"${href}\"])`)\n"
    "       const sidebar = list.querySelector(`li:has(a[href=\"${href}\"])`)\n"
    "       sortedList.append(sidebar)\n"
    "       sortedMembers.append(member)\n"
    "     }\n"
    "   }\n"
    "\n"
    "   document.querySelector('.sidebar').insertBefore(sortedLists, list)\n"
    "   document.querySelector('.module-members:has(#module-values)').insertBefore(sortedMembers, document.querySelector('#module-values').nextSibling)\n"
    "\n"
    "   const goToTop = document.createElement('a')\n"
    "   goToTop.classList.add('goto-top')\n"
    "   goToTop.setAttribute('href', '#')\n"
    "   goToTop.textContent = 'Back to top ↑'\n"
    "   for (const member of document.querySelectorAll('.member')) {\n"
    "     member.insertBefore(goToTop.cloneNode(true), null)\n"
    "   }\n"
    " })\n"
    " </script>\n"
    "\n"
    " #### Hash Algorithms\n"
    " [md5](#md5 \"The MD5 hash algorithm\"),\n"
    " [sha1](#sha1 \"The SHA-1 hash algorithm\"),\n"
    " [sha224](#sha224 \"The SHA-224 hash algorithm\"),\n"
    " [sha256](#sha256 \"The SHA-256 hash algorithm\"),\n"
    " [sha384](#sha384 \"The SHA-384 hash algorithm\"),\n"
    " [sha512](#sha512 \"The SHA-512 hash algorithm\")\n"
    "\n"
    " #### Block API\n"
    " [hash](#hash \"Hash a UTF-8 encoded string\"),\n"
    " [hash_bits](#hash_bits \"Hash a bit string\"),\n"
    " [hmac](#hmac \"Authenticate a UTF-8 encoded string\"),\n"
    " [hmac_bits](#hmac_bits \"Authenticate a bit string\")\n"
    "\n"
    " #### Stream API\n"
    " [new_hash](#new_hash \"Start a streaming hash\"),\n"
    " [new_hmac](#new_hmac \"Start a streaming HMAC\"),\n"
    " [update](#update \"Add a UTF-8 encoded string\"),\n"
    " [update_bits](#update_bits \"Add binary data\"),\n"
    " [digest](#digest \"Return the base16 encoded digest\"),\n"
    " [digest_bits](#digest_bits \"Return the binary digest\")\n"
    "\n"
    " #### Utils\n"
    " [secure_compare](#secure_compare \"Compare two binaries in constant time\"),\n"
    " [sign_message](#sign_message \"Sign a message\"),\n"
    " [verify_signed_message](#verify_signed_message \"Verify a signed message\"),\n"
    " [strong_random_bytes](#strong_random_bytes \"Generate cryptographically secure random bytes\")\n"
).

-opaque hash_algorithm() :: {hash_algorithm,
        fun(() -> munch@internal@hash:hash()),
        integer(),
        binary()}.

-file("src/munch.gleam", 133).
-spec init_md5() -> munch@internal@hash:hash().
init_md5() ->
    gleam@result:lazy_unwrap(
        munch@internal@native:md5(),
        fun munch@internal@md5:new/0
    ).

-file("src/munch.gleam", 149).
-spec init_sha1() -> munch@internal@hash:hash().
init_sha1() ->
    gleam@result:lazy_unwrap(
        munch@internal@native:sha1(),
        fun munch@internal@sha1:new/0
    ).

-file("src/munch.gleam", 173).
-spec init_sha256() -> munch@internal@hash:hash().
init_sha256() ->
    gleam@result:lazy_unwrap(
        munch@internal@native:sha256(),
        fun munch@internal@sha256:new/0
    ).

-file("src/munch.gleam", 161).
-spec init_sha224() -> munch@internal@hash:hash().
init_sha224() ->
    gleam@result:lazy_unwrap(
        munch@internal@native:sha224(),
        fun munch@internal@sha256:new224/0
    ).

-file("src/munch.gleam", 197).
-spec init_sha512() -> munch@internal@hash:hash().
init_sha512() ->
    gleam@result:lazy_unwrap(
        munch@internal@native:sha512(),
        fun munch@internal@sha512:new/0
    ).

-file("src/munch.gleam", 185).
-spec init_sha384() -> munch@internal@hash:hash().
init_sha384() ->
    gleam@result:lazy_unwrap(
        munch@internal@native:sha384(),
        fun munch@internal@sha512:new384/0
    ).

-file("src/munch.gleam", 368).
?DOC(
    " Finalizes a streaming hash or HMAC calculation and returns its base16\n"
    " encoded digest.\n"
    "\n"
    " See `new_hash` and `new_hmac` for more information and examples.\n"
).
-spec digest(munch@internal@hash:hash()) -> binary().
digest(Hash) ->
    gleam_stdlib:base16_encode(munch@internal@hash:finish(Hash)).

-file("src/munch.gleam", 350).
?DOC(
    " Adds a UTF-8 encoded string to a streaming hash or HMAC calculation.\n"
    "\n"
    " See `new_hash` and `new_hmac` for more information and examples.\n"
).
-spec update(munch@internal@hash:hash(), binary()) -> munch@internal@hash:hash().
update(Hash, Str) ->
    munch@internal@hash:update(Hash, <<Str/binary>>).

-file("src/munch.gleam", 321).
?DOC(
    " Initializes the state for a streaming hash digest calculation.\n"
    "\n"
    " Add data using `update_bits` or `update`, then retrieve the digest using\n"
    " `digest_bits` or `digest`.\n"
    "\n"
    " This is useful for hashing streams or large amounts of data without loading\n"
    " all of it into memory at once.\n"
    "\n"
    " ## Examples\n"
    "\n"
    " ```gleam\n"
    " import munch\n"
    "\n"
    " let digest =\n"
    "   munch.new_hash(munch.sha512)\n"
    "   |> munch.update(\"data to hash\")\n"
    "   |> munch.update(\"more data\")\n"
    "   |> munch.digest\n"
    " ```\n"
).
-spec new_hash(hash_algorithm()) -> munch@internal@hash:hash().
new_hash(Algorithm) ->
    (erlang:element(2, Algorithm))().

-file("src/munch.gleam", 216).
?DOC(
    " Computes the base16 encoded digest of a UTF-8 encoded string.\n"
    "\n"
    " ## Examples\n"
    "\n"
    " ```gleam\n"
    " import munch\n"
    "\n"
    " assert munch.hash(munch.sha256, \"a\")\n"
    "   == \"CA978112CA1BBDCAFAC231B39A23DC4DA786EFF8147C4E72B9807785AFEE48BB\"\n"
    " ```\n"
    "\n"
    " To hash content in multiple chunks, see the `new_hash` function.\n"
).
-spec hash(hash_algorithm(), binary()) -> binary().
hash(Algorithm, String) ->
    _pipe = Algorithm,
    _pipe@1 = new_hash(_pipe),
    _pipe@2 = update(_pipe@1, String),
    digest(_pipe@2).

-file("src/munch.gleam", 359).
?DOC(
    " Finalizes a streaming hash or HMAC calculation and returns its binary\n"
    " digest.\n"
    "\n"
    " See `new_hash` and `new_hmac` for more information and examples.\n"
).
-spec digest_bits(munch@internal@hash:hash()) -> bitstring().
digest_bits(Hash) ->
    munch@internal@hash:finish(Hash).

-file("src/munch.gleam", 342).
?DOC(
    " Adds binary data to a streaming hash or HMAC calculation.\n"
    "\n"
    " See `new_hash` and `new_hmac` for more information and examples.\n"
).
-spec update_bits(munch@internal@hash:hash(), bitstring()) -> munch@internal@hash:hash().
update_bits(Hash, Bits) ->
    munch@internal@hash:update(Hash, Bits).

-file("src/munch.gleam", 242).
?DOC(
    " Computes the binary digest of a bit string.\n"
    "\n"
    " ## Returns\n"
    "\n"
    " The digest as a `BitArray`.\n"
    "\n"
    " ## Examples\n"
    "\n"
    " ```gleam\n"
    " import gleam/bit_array\n"
    " import munch\n"
    "\n"
    " assert munch.hash_bits(munch.sha256, <<\"a\":utf8>>)\n"
    "   |> bit_array.base16_encode\n"
    "   == \"CA978112CA1BBDCAFAC231B39A23DC4DA786EFF8147C4E72B9807785AFEE48BB\"\n"
    " ```\n"
    "\n"
    " To hash content in multiple chunks, see the `new_hash` function.\n"
).
-spec hash_bits(hash_algorithm(), bitstring()) -> bitstring().
hash_bits(Algorithm, Bits) ->
    _pipe = Algorithm,
    _pipe@1 = new_hash(_pipe),
    _pipe@2 = update_bits(_pipe@1, Bits),
    digest_bits(_pipe@2).

-file("src/munch.gleam", 333).
?DOC(
    " Initializes a streaming HMAC (hash-based message authentication code).\n"
    "\n"
    " Add data using `update_bits` or `update`, then retrieve the authentication\n"
    " code using `digest_bits` or `digest`.\n"
    "\n"
    " If the key does not contain a whole number of bytes, its final byte is\n"
    " padded with trailing zero bits before use.\n"
).
-spec new_hmac(hash_algorithm(), bitstring()) -> munch@internal@hash:hash().
new_hmac(Algorithm, Key) ->
    {hash_algorithm, Init, Block_size, _} = Algorithm,
    munch@internal@hmac:new(Init, Block_size, Key).

-file("src/munch.gleam", 263).
?DOC(
    " Computes the base16 encoded HMAC of UTF-8 encoded data using a UTF-8\n"
    " encoded key.\n"
    "\n"
    " ## Examples\n"
    "\n"
    " ```gleam\n"
    " import munch\n"
    "\n"
    " assert munch.hmac(\"message\", munch.sha256, \"key\")\n"
    "   == \"6E9EF29B75FFFC5B7ABAE527D58FDADB2FE42E7219011976917343065F58ED4A\"\n"
    " ```\n"
    "\n"
    " To authenticate content in multiple chunks, see the `new_hmac` function.\n"
).
-spec hmac(binary(), hash_algorithm(), binary()) -> binary().
hmac(Data, Algorithm, Key) ->
    _pipe = Algorithm,
    _pipe@1 = new_hmac(_pipe, <<Key/binary>>),
    _pipe@2 = update(_pipe@1, Data),
    digest(_pipe@2).

-file("src/munch.gleam", 288).
?DOC(
    " Computes the binary HMAC of a bit string.\n"
    "\n"
    " If the key does not contain a whole number of bytes, its final byte is\n"
    " padded with trailing zero bits before use.\n"
    "\n"
    " ## Examples\n"
    "\n"
    " ```gleam\n"
    " import gleam/bit_array\n"
    " import munch\n"
    "\n"
    " assert munch.hmac_bits(<<\"message\":utf8>>, munch.sha256, <<\"key\":utf8>>)\n"
    "   |> bit_array.base16_encode\n"
    "   == \"6E9EF29B75FFFC5B7ABAE527D58FDADB2FE42E7219011976917343065F58ED4A\"\n"
    " ```\n"
    "\n"
    " To authenticate content in multiple chunks, see the `new_hmac` function.\n"
).
-spec hmac_bits(bitstring(), hash_algorithm(), bitstring()) -> bitstring().
hmac_bits(Data, Algorithm, Key) ->
    _pipe = Algorithm,
    _pipe@1 = new_hmac(_pipe, Key),
    _pipe@2 = update_bits(_pipe@1, Data),
    digest_bits(_pipe@2).

-file("src/munch.gleam", 385).
-spec do_secure_compare(bitstring(), bitstring(), integer()) -> boolean().
do_secure_compare(Left, Right, Accumulator) ->
    case {Left, Right} of
        {<<X, Left@1/binary>>, <<Y, Right@1/binary>>} ->
            Accumulator@1 = munch@internal@bitwise:'bor'(
                Accumulator,
                munch@internal@bitwise:'xor'(X, Y)
            ),
            do_secure_compare(Left@1, Right@1, Accumulator@1);

        {_, _} ->
            (Left =:= Right) andalso (Accumulator =:= 0)
    end.

-file("src/munch.gleam", 378).
?DOC(
    " Compares two binaries in constant-time to avoid timing attacks.\n"
    "\n"
    " For more details see: http://codahale.com/a-lesson-in-timing-attacks/\n"
).
-spec secure_compare(bitstring(), bitstring()) -> boolean().
secure_compare(Left, Right) ->
    case erlang:byte_size(Left) =:= erlang:byte_size(Right) of
        true ->
            do_secure_compare(Left, Right, 0);

        false ->
            false
    end.

-file("src/munch.gleam", 455).
-spec signing_input(hash_algorithm(), bitstring()) -> binary().
signing_input(Algorithm, Message) ->
    {hash_algorithm, _, _, Protected} = Algorithm,
    erlang:list_to_binary(
        [gleam@bit_array:base64_url_encode(<<Protected/binary>>, false),
            <<"."/utf8>>,
            gleam@bit_array:base64_url_encode(Message, false)]
    ).

-file("src/munch.gleam", 408).
?DOC(
    " Signs a message which can later be verified using the\n"
    " `verify_signed_message` function to detect if the message has been tampered\n"
    " with.\n"
    "\n"
    " A web application could use this verifier to sign HTTP cookies. The data can\n"
    " be read by the user, but cannot be tampered with.\n"
).
-spec sign_message(bitstring(), bitstring(), hash_algorithm()) -> binary().
sign_message(Message, Secret, Algorithm) ->
    Input = signing_input(Algorithm, Message),
    Signature = hmac_bits(<<Input/binary>>, Algorithm, Secret),
    erlang:list_to_binary(
        [Input,
            <<"."/utf8>>,
            gleam@bit_array:base64_url_encode(Signature, false)]
    ).

-file("src/munch.gleam", 425).
?DOC(
    " Verifies a message created by the `sign_message` function.\n"
    "\n"
    " The hash algorithm must be the same one that was used to sign the message.\n"
).
-spec verify_signed_message(binary(), bitstring(), hash_algorithm()) -> {ok,
        bitstring()} |
    {error, nil}.
verify_signed_message(Message, Secret, Algorithm) ->
    gleam@result:'try'(case gleam@string:split(Message, <<"."/utf8>>) of
            [Protected, Payload, Signature] ->
                {ok, {Protected, Payload, Signature}};

            _ ->
                {error, nil}
        end, fun(_use0) ->
            {Protected@1, Payload@1, Signature@1} = _use0,
            Text = erlang:list_to_binary([Protected@1, <<"."/utf8>>, Payload@1]),
            gleam@result:'try'(
                gleam@bit_array:base64_url_decode(Payload@1),
                fun(Payload@2) ->
                    gleam@result:'try'(
                        gleam@bit_array:base64_url_decode(Signature@1),
                        fun(Signature@2) ->
                            gleam@result:'try'(
                                gleam@bit_array:base64_url_decode(Protected@1),
                                fun(Protected@2) ->
                                    {hash_algorithm, _, _, Signing_name} = Algorithm,
                                    case secure_compare(
                                        Protected@2,
                                        <<Signing_name/binary>>
                                    ) of
                                        true ->
                                            Challenge = hmac_bits(
                                                <<Text/binary>>,
                                                Algorithm,
                                                Secret
                                            ),
                                            case secure_compare(
                                                Challenge,
                                                Signature@2
                                            ) of
                                                true ->
                                                    {ok, Payload@2};

                                                false ->
                                                    {error, nil}
                                            end;

                                        false ->
                                            {error, nil}
                                    end
                                end
                            )
                        end
                    )
                end
            )
        end).

-file("src/munch.gleam", 478).
?DOC(
    " Generates a specified number of bytes randomly uniform 0..255, and returns\n"
    " the result in a binary.\n"
    "\n"
    " On Erlang this uses a cryptographically secure PRNG seeded and periodically\n"
    " mixed with operating system provided entropy. By default this is the\n"
    " `RAND_bytes` method from OpenSSL.\n"
    " <https://erlang.org/doc/man/crypto.html#strong_rand_bytes-1>\n"
    "\n"
    " On JavaScript the WebCrypto API is used.\n"
).
-spec strong_random_bytes(integer()) -> bitstring().
strong_random_bytes(Length) ->
    crypto:strong_rand_bytes(Length).