olm/javascript/olm_pk.js

function PkEncryption() {
    var size = Module['_olm_pk_encryption_size']();
    this.buf = malloc(size);
    this.ptr = Module['_olm_pk_encryption'](this.buf);
}

function pk_encryption_method(wrapped) {
    return function() {
        var result = wrapped.apply(this, arguments);
        if (result === OLM_ERROR) {
            var message = Pointer_stringify(
                Module['_olm_pk_encryption_last_error'](arguments[0])
            );
            throw new Error("OLM." + message);
        }
        return result;
    }
}

PkEncryption.prototype['free'] = function() {
    Module['_olm_clear_pk_encryption'](this.ptr);
    free(this.ptr);
}

PkEncryption.prototype['set_recipient_key'] = restore_stack(function(key) {
    var key_array = array_from_string(key);
    var key_buffer = stack(key_array);
    pk_encryption_method(Module['_olm_pk_encryption_set_recipient_key'])(
        this.ptr, key_buffer, key_array.length
    );
});

PkEncryption.prototype['encrypt'] = restore_stack(function(
    plaintext
) {
    var plaintext_buffer, ciphertext_buffer, plaintext_length;
    try {
        plaintext_length = Module['lengthBytesUTF8'](plaintext)
        plaintext_buffer = malloc(plaintext_length + 1);
        Module['stringToUTF8'](plaintext, plaintext_buffer, plaintext_length + 1);
        var random_length = pk_encryption_method(
            Module['_olm_pk_encrypt_random_length']
        )();
        var random = random_stack(random_length);
        var ciphertext_length = pk_encryption_method(
            Module['_olm_pk_ciphertext_length']
        )(this.ptr, plaintext_length);
        ciphertext_buffer = malloc(ciphertext_length + NULL_BYTE_PADDING_LENGTH);
        var mac_length = pk_encryption_method(
            Module['_olm_pk_mac_length']
        )(this.ptr);
        var mac_buffer = stack(mac_length + NULL_BYTE_PADDING_LENGTH);
        Module['setValue'](
            mac_buffer+mac_length,
            0, "i8"
        );
        var ephemeral_length = pk_encryption_method(
            Module['_olm_pk_key_length']
        )();
        var ephemeral_buffer = stack(ephemeral_length + NULL_BYTE_PADDING_LENGTH);
        Module['setValue'](
            ephemeral_buffer+ephemeral_length,
            0, "i8"
        );
        pk_encryption_method(Module['_olm_pk_encrypt'])(
            this.ptr,
            plaintext_buffer, plaintext_length,
            ciphertext_buffer, ciphertext_length,
            mac_buffer, mac_length,
            ephemeral_buffer, ephemeral_length,
            random, random_length
        );
        // UTF8ToString requires a null-terminated argument, so add the
        // null terminator.
        Module['setValue'](
            ciphertext_buffer+ciphertext_length,
            0, "i8"
        );
        return {
            "ciphertext": Module['UTF8ToString'](ciphertext_buffer),
            "mac": Pointer_stringify(mac_buffer),
            "ephemeral": Pointer_stringify(ephemeral_buffer)
        };
    } finally {
        if (plaintext_buffer !== undefined) {
            // don't leave a copy of the plaintext in the heap.
            bzero(plaintext_buffer, plaintext_length + 1);
            free(plaintext_buffer);
        }
        if (ciphertext_buffer !== undefined) {
            free(ciphertext_buffer);
        }
    }
});


function PkDecryption() {
    var size = Module['_olm_pk_decryption_size']();
    this.buf = malloc(size);
    this.ptr = Module['_olm_pk_decryption'](this.buf);
}

function pk_decryption_method(wrapped) {
    return function() {
        var result = wrapped.apply(this, arguments);
        if (result === OLM_ERROR) {
            var message = Pointer_stringify(
                Module['_olm_pk_decryption_last_error'](arguments[0])
            );
            throw new Error("OLM." + message);
        }
        return result;
    }
}

PkDecryption.prototype['free'] = function() {
    Module['_olm_clear_pk_decryption'](this.ptr);
    free(this.ptr);
}

PkDecryption.prototype['generate_key'] = restore_stack(function () {
    var random_length = pk_decryption_method(
        Module['_olm_pk_generate_key_random_length']
    )();
    var random_buffer = random_stack(random_length);
    var pubkey_length = pk_encryption_method(
        Module['_olm_pk_key_length']
    )();
    var pubkey_buffer = stack(pubkey_length + NULL_BYTE_PADDING_LENGTH);
    pk_decryption_method(Module['_olm_pk_generate_key'])(
        this.ptr,
        pubkey_buffer, pubkey_length,
        random_buffer, random_length
    );
    return Pointer_stringify(pubkey_buffer);
});

PkDecryption.prototype['decrypt'] = restore_stack(function (
    ephemeral_key, mac, ciphertext
) {
    var plaintext_buffer, ciphertext_buffer, plaintext_max_length;
    try {
        ciphertext_length = Module['lengthBytesUTF8'](ciphertext)
        ciphertext_buffer = malloc(ciphertext_length + 1);
        Module['stringToUTF8'](ciphertext, ciphertext_buffer, ciphertext_length + 1);
        var ephemeralkey_array = array_from_string(ephemeral_key);
        var ephemeralkey_buffer = stack(ephemeralkey_array);
        var mac_array = array_from_string(mac);
        var mac_buffer = stack(mac_array);
        plaintext_max_length = pk_decryption_method(Module['_olm_pk_max_plaintext_length'])(
            this.ptr,
            ciphertext_length
        );
        plaintext_buffer = malloc(plaintext_max_length + NULL_BYTE_PADDING_LENGTH);
        var plaintext_length = pk_decryption_method(Module['_olm_pk_decrypt'])(
            this.ptr,
            ephemeralkey_buffer, ephemeralkey_array.length,
            mac_buffer, mac_array.length,
            ciphertext_buffer, ciphertext_length,
            plaintext_buffer, plaintext_max_length
        );
        // UTF8ToString requires a null-terminated argument, so add the
        // null terminator.
        Module['setValue'](
            plaintext_buffer+plaintext_length,
            0, "i8"
        );
        return Module['UTF8ToString'](plaintext_buffer);
    } finally {
        if (plaintext_buffer !== undefined) {
            // don't leave a copy of the plaintext in the heap.
            bzero(plaintext_buffer, plaintext_length + 1);
            free(plaintext_buffer);
        }
        if (ciphertext_buffer !== undefined) {
            free(ciphertext_buffer);
        }
    }
})