Plugins – Lua Programming Reference

  • Last updated:
  • access_time Reading time:

Language

Lua plugins are run using the standard Lua 5.3 interpreter.

Plugins may use the following standard Lua 5.3 symbols:

  • assert
  • bit32
  • collectgarbage
  • coroutine
  • error
  • getmetatable
  • ipairs
  • load
  • math
  • next
  • pairs
  • pcall
  • rawequal
  • rawget
  • rawlen
  • rawset
  • select
  • setmetatable
  • string
  • table
  • tonumber
  • tostring
  • type
  • utf8
  • xpcall
  • _VERSION
  • _G

The following will be supported soon:

  • print
  • require

Support is not planned for the following:

  • loadfile
  • arg
  • debug
  • dofile
  • package
  • os
  • io

The following Self-Defending Key Management Service (KMS) defined symbols are also in scope, detailed below:

Invoking plugins

A plugin must define a function run.

When the plugin is invoked, run will be called with the following parameters:

  • input: The JSON data with which the plugin was invoked, decoded into a Lua object as in json.decode, or nil if no input data was supplied. 
  • url: The URL that was used to invoke the plugin, represented as a Lua table:
    • url.path: A Lua array of path components, for example, ['sys', 'v1', 'plugins', '08ce8c3e-50fc-4c95-a633-ca417e6f2828']. Users and apps may append arbitrary custom path components when invoking a plugin.
    • url.query: The query string (the part of the URL after ?), or nil if the URL does not include a query string.
  • method: The method used to invoke the plugin, either 'POST' or 'GET'.

The function run may accept any prefix of these arguments, for example:

  • function run() ... end
  • function run(input) ... end
  • function run(input, url, method) ... end

The function run may return the following:

  • nil: the plugin invocation returns successfully with no content.
  • An encodable Lua object: the object is encoded to JSON as in json.encode and returned.
  • nil and an Error: the plugin invocation errors as described in the Error section below.

The 'Blob' class

A Blob represents arbitrary binary data.

Fortanix Self-Defending KMS REST APIs use JSON and distinguish between

  • UTF-8 strings (e.g. key name), which use JSON strings, and
  • binary data (e.g. key material), which uses base64-encoded JSON strings.

JSON strings must be valid UTF-8, so in general raw binary data is not a valid JSON string.

Lua plugin APIs use Lua strings for UTF-8 strings and Blobs for binary data.

For interoperability with the JSON REST APIs, a base64-encoded Lua string may be used instead of a Blob where binary data is expected.

Constructors

Blob.from_bytes(string)

Constructs a Blob from a Lua string with raw binary data. Note that Lua strings do not need to be valid UTF-8.

E.g.: local blob = Blob.from_bytes('\1\2\255').

Blob.from_base64(string)

Constructs a Blob from base64-encoded data in a Lua string.

E.g.: local blob = Blob.from_base64('AQL/').

Blob.from_hex(string)

 Constructs a Blob from hex-encoded data in a Lua string.

E.g.: local blob = Blob.from_hex('0102FF').

Blob.from_base58(string)

 Constructs a Blob base58-encoded data in a Lua string.

E.g.: local blob = Blob.from_base58('LiA').

Blob.from_base58_check(string)

Constructs a Blob from base58-encoded data in a Lua string. Unlike plain base58, this also includes an SHA-256d checksum.

E.g.: local blob = Blob.from_base58_check('3DyWSpcNi').

Blob.random(num_bytes)

Constructs a random Blob with the given number of bytes. The bytes will be generated using Fortanix Self-Defending KMS's cryptographically secure random number generator.

Blob.random { bytes = num_bytes } and Blob.random { bits = num_bits } are also supported.

num_bytes must be a whole number; num_bits must be a multiple of 8.

Blob.pack(fmt, …)

This is equivalent to Blob.from_bytes(string.pack(fmt, ...)). See the documentation for string.pack.

E.g.: assert(Blob.pack('>i8', 0xDEADBEEF):hex() == '00000000DEADBEEF')

Methods

blob:unpack(fmt)

This is equivalent to string.unpack(fmt, blob:bytes()). See the documentation for string.unpack.

E.g.: assert(Blob.from_hex('00000000DEADBEEF'):unpack('>i8') == 0xDEADBEEF)

blob:bytes()

Returns a Lua string with the raw binary data.

E.g.: assert(blob:bytes() == '\1\2\255')

blob:base64()

Returns a Lua string with the base64-encoded binary data.

E.g.: assert(blob:base64() == 'AQL/')

blob:hex()

Returns a Lua string with the hex-encoded binary data.

E.g.: assert(blob:hex() == '0102FF')

blob:base58()

Returns a Lua string with the base58-encoded binary data.

E.g.: assert(blob:base58() == 'LiA')

blob:base58_check()

Returns a Lua string with the base58-encoding(including SHA-256d checksum) of the binary data.

E.g.: assert(blob:base58_check() == '3DyWSpcNi')

blob:slice(lo_byte, hi_byte)

Returns a blob consisting of the bytes between lo_byte and hi_byte, 1-indexed and inclusive. For example, Blob.from_bytes('\1\2\3\4'):slice(2, 3) == Blob.from_bytes('\2\3').

blob .. blob2

.. maybe used to concatenate two blobs, e.g. Blob.from_bytes('\1') .. Blob.from_bytes('\2') == Blob.from_bytes('\1\2').

#blob

# maybe used to get the number of bytes in the blob, e.g. assert(#Blob.from_bytes('\1\1\1') == 3).

blob & blob2, blob | blob2, blob ~ blob2

&, |, and ~ maybe used to take the bitwise and, the bitwise or, and the bitwise xor of two blobs. The blobs must be the same size, or else these operations will throw an exception.

~blob

~ may be used to take the bitwise not of a blob.

The 'cbor' module

cbor.encode(object)

cbor.encode encodes (serializes) a Lua object into a Blob containing binary data in the CBOR format.

Encodable Lua objects include:

  • nil, which encodes to null.
  • Lua numbers and booleans, which encode to CBOR numbers and booleans.
  • Blobs, which encode to CBOR byte strings.
  • Lua strings, which encode to CBOR text strings.
    • CBOR text string should be valid UTF-8, while Lua strings may contain arbitrary binary data. To encode a Lua string representing potentially non-UTF-8 binary data, use Blob.from_bytes(string).
  • Lua tables, which encode to CBOR maps or CBOR array.
    • A table is encoded as an array if the set of keys is {1, 2, .., n} for some n.

A Lua object may use a custom encoder by adding an encoder function __tocbor to the metatable. There is no corresponding way to use a custom decoder.

For example,

null = setmetatable({}, { __tocbor = function(self) return cbor.encode(nil) end })

cbor.decode(data)

cbor.decode decodes (deserializes) a blob containing CBOR binary data, returning a Lua object that encodes to the given CBOR as defined in cbor.encode. CBOR byte strings decode to Blobs and CBOR nil decodes to null. The other CBOR types decode to primitive strings, numbers, booleans, and tables.

The 'json' module

json.encode(object)

json.encode encodes (serializes) a Lua object into Lua string containing JSON data.

json.encode(object) returns the JSON corresponding to cbor.encode(object).

CBOR byte strings (Blobs) become base64-encoded JSON strings.

json.decode(data)

json.decode decodes (deserializes) a Lua string containing JSON data, returning a Lua object that encodes to the given JSON, as defined in json.encode.

JSON nil decodes to null. The other JSON types decode to primitive strings, numbers, booleans, and tables.

JSON strings always decode to Lua strings, including base64-encoded JSON strings.

For example, encoding a Blob to JSON and then decoding the JSON will produce a base64-encoded Lua string. To get the original Blob, apply Blob.from_base64 to the decoded string.

The function 'request'

request {method = method, url = request_url, headers = headers, body=request_body} executes an arbitrary REST API request over HTTPS. The server must present a publicly-trusted certificate.

method is the REST method name, POST, GET, PUT, etc.

request_url is the https URL. 

headersis a map of custom headers to be sent, e.g: headers{['Content-Type'] = "application/json"}. 

request_body is request data as a Lua string.

For example,

function run(input)
 local method = "POST" -- GET, PUT etc
 local request_url = "https://<rest-api-url>" 
 local headers = {['Content-Type'] = "application/json"}
 local request_body = json.encode({key = "value"})
 local response = request { method = method, url = request_url, headers = headers, body=request_body }
 return json.decode(response.body:bytes()) -- returns json output
end

The 'null' object

This is an object that encodes to CBOR or JSON null. This is returned on success in methods like sobject:delete() that return no data. We do not return nil here so that assert(sobject:delete()) works.

The 'Array' class

An Array is a table that always serializes to a JSON/CBOR array, not a map.

Non-numeric keys in an Array (more precisely, keys not included in ipairs) are ignored during serialization.

Motivation

The empty map {} and the empty array [] in JSON both deserialize to the empty Lua table {}.

The empty Lua table serializes to the empty map. Array() serializes to the empty array.

Constructors

Array() or Array {} is the empty array.

Array(table) returns setmetatable(table, Array).

E.g. assert(json.encode(Array { 1, 2, a = 3 }) == '[1,2]').

The 'Error' class

This class is used for errors from the plugin APIs. If an error occurs, a function will return two values: nil and the error (this is a standard Lua idiom). An error has two properties: an HTTP status code number status and message string. Custom errors may be constructed using Error.new { status = <code>, message = "<message>" }.

For example,

function run()
local result, error = Sobject { name = "nonexistent key" }
assert(result) == nil
assert(error.status = 404)
-- return a custom 401 Unauthorized error to the plugin invoker
  return nil, Error.new { status = 401, message = "custom error" }
end

The function 'principal'

principal() returns the EntityId of the entity that invoked the plugin.

For example,

function run()
if principal():type() ~= 'user'
return nil, Error.new { status = 401, message = "Plugin may only be invoked by users" }
end
end

The function 'this_plugin'

this_plugin() returns a plugin object corresponding to the plugin being invoked.

For example,

function run()
return "the name of this plugin is " .. this_plugin().name
end

The function 'require_approval_for'

The  require_approval_for(object) ensures that quorum approval is met for the object. It returns nil and an Error if quorum approval is not met.

The object can be of type Sobject, App, Group or Plugin.

This requires the plugin to be invoked as an approval request using the REST API.

POST /sys/v1/approval_requests
{
 "operation": "sys/v1/plugins/<plugin-UUID>",
 "body": "plugin-input-body"
}

Example plugin code:

function check(input)
  key = assert(Sobject { id = input })
  require_approval_for(key)
 end
function run(input)
 return key:encrypt { plain = Blob.random(16), mode = 'ECB' }
 end

Above will require quorum approval on the input key for the encryption operation.

The 'AuditLog' module

AuditLog.log { message = message, severity = severity }

Write an audit log entry associated with this plugin with the given message and severity.

severity maybe one of 'INFO', 'WARNING', 'ERROR', or 'CRITICAL'.

AuditLog.get_all { … }

Get audit log entries matching the requested filters. This corresponds to GET /sys/v1/logs in the REST API. Returns an array of audit log entries, or nil and an Error if the logs could not be fetched.

The 'Sobject' class

This represents a security object, transient or persisted. The properties of this object are described in the REST API docs (it is named KeyObject there). sobject.value and sobject.pub_key are Blobs (unless they are nil).

sobject.creator is an EntityId object.

Like apps, plugin may create transient keys by adding transient = true to the create, import, unwrap, derive, or agree request. These transient keys only exist during the invocation of the plugin. As soon as the plugin’s function run returns, they become invalid.

Constructors

Sobject { id = ‘<uuid>’ } or Sobject { kid = ‘<uuid>’ }

This return the persisted security object with the given UUID, or nil and an Error if no such object exists.

For example, 

local sobject = assert(Sobject { id = '123e4567-e89b-12d3-a456-426655440000' })

Sobject  { name = ‘key name’ }

This returns the persisted security object with the given name, or nil and an Error if no such object exists.

Sobject.create { … }

Create a security object. This corresponds to POST /crypto/v1/keys in the REST API. The arguments to this function are described in the REST API documentation for SobjectRequest. This returns the created Sobject, or nil and an Error if the object could not be created.

For example,

local sobject = assert(Sobject.create { name = "my key", obj_type = "AES", key_size = 128 })

Sobject.import { … }

Import a security object. This corresponds to PUT /crypto/v1/keys in the REST API. The arguments to this function are described in the REST API documentation for SobjectRequest. This returns the import Sobject, or nil and an Error if the object could not be imported.

For example,

local sobject = assert(Sobject.import { name = "my key", obj_type = "AES", value = Blob.random { bits = 128 } })

Methods

sobject:update { ... }

Update the properties of sobject. This corresponds to PATCH /crypto/v1/keys/<uuid> in the REST API. The arguments to this method are described in the REST API documentation for SobjectRequest. This method may not be called on a transient sobject. Returns null on success, or nil and an Error if the object could not be updated.

For example,

assert(sobject:update { name = "new key name" }) -- throw an exception if update fails

sobject:delete()

Delete the sobject. This corresponds to DELETE /crypto/v1/keys/<uuid> in the REST API. This method may not be called on a transient sobject. Returns null on success, or nil and an Error if the object could not be deleted.

For example,

assert(sobject:delete()) -- throw an exception if update fails

sobject:export()

Retrieve the value of sobject. This corresponds to GET /crypto/v1/keys/export in the REST API. This returns a Sobject which has a value property on success, or returns nil and an Error if the object could not be exported.

For example,

local exported_value = assert(Sobject { name = 'my key' }):export().value

sobject:digest()

Retrieve the digest (hash) of the value of sobject. This corresponds toPOST /crypto/v1/keys/digest in the REST API.

This returns an object corresponding to DigestResponse  from the REST API on success, or nil and an Error if the digest could not be computed. The returned digest is a Blob.

For example,

local sha256_hash = assert(Sobject { name = 'my key' }):digest().digest
return sha256_hash:hex()

sobject:descriptor()

Returns {  kid  =  "<uuid>"  } if sobject is persisted, or {  transient_key  =  blob  } if sobject is transient.

sobject:encrypt { ... }

Encrypt data using sobject. This corresponds to POST /crypto/v1/encrypt in the REST API. The arguments to this method are described in the REST API docs for EncryptRequest. Returns an object corresponding to EncryptResponse in the REST API on success, or nil and an Error if the data could not be encrypted. In the returned object, cipher and iv are Blobs.

For example,

local sobject = assert(Sobject { name = "my aes key" })
local encrypt_response = assert(sobject:encrypt { plain = Blob.from_bytes("hello world"), mode = 'CBC' })
return encrypt_response.cipher:base64() .. ':' .. encrypt_response.iv:base64()

sobject:decrypt { … }

Decrypt data using sobject. This corresponds to POST /crypto/v1/decrypt in the REST API. The arguments to this method are described in the REST API docs for DecryptRequest. Returns an object corresponding to DecryptResponse in the REST API on success, or nil and an Error if the data could not be encrypted.

In the retuned object, plain is a Blob.

For example,

function encrypt(blob)
local sobject = assert(Sobject { name = "my rsa key" })
return assert(sobject:decrypt { cipher = blob }).plain
end

sobject:sign { ... }

Sign data using sobject. This corresponds to POST /crypto/v1/sign in the REST API.

The arguments to this method are described in the REST API docs for SignRequest.

Returns an object corresponding to SignResponse in the REST API on success, or nil and an Error if the data could not be signed.

In the returned object, signature is a Blob.

For example,

local sobject = assert(Sobject { name = "my rsa key" })
local sign_response = assert(sobject:sign { data = Blob.from_bytes("hello world"), hash_alg = 'SHA256' })
return sign_response.signature

sobject:verify { ... }

Verify data signed by sobject. This corresponds to POST /crypto/v1/verify in the REST API.

The arguments to this method are described in the REST API docs for VerifyRequest.

Returns an object corresponding to VerifyResponse in the REST API on success, or nil and an Error if the validity of the signature could not be established.

Note that if the signature is determined to be invalid, the call will successfully return { result = false }.

For example,

local sobject = assert(Sobject { name = "my rsa key" })
local verify_response = assert(sobject:verify { data = Blob.from_bytes("hello world"), signature = signature, hash_alg = 'SHA256' })
assert(verify_response.result == true)

sobject:wrap { … }

 Use sobject to wrap another security object. This corresponds to POST /crypto/v1/wrapkey in the REST API. The arguments to this method are described in the REST API docs for WrapKeyRequestEx. The subject argument may be a descriptor (as described in the REST API) or a Sobject. Returns an object corresponding to WrapKeyResponse in the REST API on success, or nil and an Error if the sobject key could not be wrapped.

For example,

local wrapping_key = assert(Sobject { name = "AES wrapping key" })
local generated_key = assert(Sobject.create { obj_type = 'AES', key_size = 128, transient = true })
local wrap_response = assert(wrapping_key:wrap { subject = generated_key, mode = 'CBC' })
local result = wrap_response.wrapped_key:base64() .. ':' .. wrap_response.iv:base64()

sobject:unwrap { … }

Use sobject to unwrap and import a wrapped key. This corresponds to POST /crypto/v1/unwrapkey in the REST API. The arguments to this method are described in the REST API docs for UnwrapKeyRequest. Returns the unwrapped sobject, or nil and an Error if the wrapped key could not be unwrapped.

For example,

function run(input)
local wrapping_key = assert(Sobject { name = "RSA wrapping key" })
local unwrapped_key =
  assert(wrapping_key:unwrap { wrapped_key = input.wrapped_key, obj_type = 'AES', transient = true })
return unwrapped_key:encrypt(input.encrypt_request)
end

sobject:agree { … }

Perform a key agreement algorithm using the private key sobject and the public key from another party. This corresponds to POST /crypto/v1/agree in the REST API. The arguments to this method are described in the REST API for AgreeKeyRequest. The public_key argument may be a descriptor (as described in the REST API) or a Sobject.

Returns the agreed sobject, or nil and an Error if the key agreement could not be completed.

sobject:mac { … }

Use sobject to compute a cryptographic Message Authentication Code on a message. sobject must be a symmetric key. This corresponds to POST /crypto/v1/mac in the REST API. The arguments to this method are described in the REST API docs for MacGenerateRequest.

Returns an object corresponding to MacGenerateResponse from the REST API on success, or nil and an Error if the MAC could not be generated.

sobject:mac_verify { ... }

Use sobject to verify a cryptographic Message Authentication Code on a message. sobject must be a symmetric key. This corresponds to POST /crypto/v1/macverify in the REST API.

The arguments to this method are described in the REST API docs for MacVerifyRequest.

Returns an object corresponding to MacVerifyResponse from the REST API on success, or nil and an Error if the validity of the MAC could not be established.

Note that if the MAC is determined to be invalid, the call will successfully return { result = false }.

sobject:persist{ ... }

If the sobject is a transient key, this saves the key as a persisted sobject . This corresponds to GET crypto/v1/keys/persist in the REST API.

The arguments to this method are described in the REST API documentation for PersistTransientKeyRequest.

This returns a sobject which has a kid set, or returns nil and an Error if the object could not be persisted.

For example,

local transient_sobject = assert(Sobject.create { obj_type = "AES", key_size = 128, transient = true })
local persisted_sobject = transient_sobject:persist{ name = "My Key"}

sobject:derive()

This derives a new key from an existing sobject. This corresponds to GET crypto/v1/derive in the REST API.

The arguments to this method are described in the REST API documentation for DeriveKeyRequestEx.

This returns a sobject for the derived key, or returns nil and an Error if the key derivation fails.

For example,

local new_sobject = assert(Sobject { name = "My Key" }):derive {
 name = "New Key",
 key_size = 128,
 key_type = "AES",
 mechanism = {
 alg = "AES",
 plain = Blob.from_bytes("my seed value"),
 mode = "CBC"
 }
}

Sobject:issuer_dn()

If the object is a certificate, then returns an X509Name representing the certificate issuer.

Sobject:subject_dn()

If the object is a certificate, then returns an X509Name representing the certificate subject.

Sobject:get_extension(oid)

If the object is a certificate, then returns the value of the extension specified by the Oid argument.

E.g.: let extn = sobject:get_extension(Oid.from_str('subjectKeyIdentifier'))

Sobject:extension_oids()

If the object is a certificate, returns a list of OIDs which are used in the certificate.

E.g.: let extn_oids = sobject:extension_oids()

Sobject:verify_certificate(issuing_cert)

If the object is a certificate, then verifies the signature on the cert using the issuing certificate which is provided as an argument.

Sobject:ec_public_info()

If the object is an EC key, this returns information about the public part of the EC key.

Response object is {group = <EcGroup>, public_point = <Blob>}

Sobject:rsa_public_info()

If the object is an RSA key, this returns information about the public part of the RSA key.

Response object is {exponent = <Blob>, modulus = <Blob>, key_size = 1024}

The 'EntityId' class

This identifies an app, user, or plugin. It corresponds to CreatorType in the REST API docs.

Methods

entity_id:id()

Returns the UUID of the app, user, or plugin.

entity_id:type()

Returns "app", "user", or "plugin".

entity_id:entity()

Returns the appropriate App, User, or Plugin object, or nil and an Error if no such object exists.

For example,

local key = assert(Sobject { name = "my key" })
local creator = key.creator
return "Created by a " .. creator:type() .. " named " .. creator:entity().name

The 'App' class

This represents an app. The properties of this object are described in the REST API docs.

app.creator is an EntityId object.

Constructors

App { id = “<uuid>” }

This returns the app with the given UUID, or nil and an Error if no such app exists.

The 'Plugin' class

This represents a Plugin.

The properties of this object are described in the REST API docs.

plugin.creator is an EntityId object.

Constructors

Plugin { id = “<uuid>” }

This returns the plugin with the given UUID, or nil and an Error if no such object exists.

The 'User' class

This represents a User. The properties of this object are described in the REST API docs.

Constructors

User { id = “<uuid>” }

This returns the user with the given UUID, or nil and an Error if no such user exists.

The 'Group' class

This represents a Group. The properties of this object are described in the REST API docs.

Constructors

Group { id = “<uuid>” }

This returns the group with the given UUID, or nil and an Error if no such group exists.

The function 'digest'

Compute the digest (hash) of the given data using the given algorithm. This corresponds to POST /crypto/v1/digest from the REST API.

digest returns an object corresponding to DigestResponse from the REST API on success, or niland an Error if the digest could not be computed. The returned digest is a Blob.

For example,

local sha256_hash = assert(digest { data = Blob.from_bytes('Hello world'), alg = 'SHA256' }).digest
return sha256_hash:hex()

The 'BigNum' class

A BigNum represents an arbitrary-precision integer.

Constructors

BigNum.from_bytes_be(string)

Constructs a BigNum from a Lua string with big endian binary data.

E.g.: local bignum = BigNum.from_bytes_be('\x01\x00\x01').

BigNum.from_bytes_be(blob)

Constructs a BigNum from a Blob with the big endian binary data.

E.g.: local bignum = BigNum.from_bytes_be(Blob.from_bytes('\x01\x00\x01')).

Methods

bignum:to_bytes_be()

Returns a Blob with the big endian binary data.

E.g.: local bytes = bignum:to_bytes_be().

bignum:to_bytes_be_zero_pad(n)

Returns a Blob with big endian binary data, zero padding to n bytes.

E.g.: local bytes = bignum:to_bytes_be_zero_pad(16).

bignum:copy()

Returns a copy of bignum.

E.g.: local copy = bignum:copy().

bignum==bignum

Compare two bignums for equality

E.g.: local same = bignum1 == bignum2.

bignum < bignum

Test if one bignum is less than another

E.g.: local less = bignum1 < bignum2.

bignum <= bignum

Test if one bignum is less than or equal to another

E.g.: local lte = bignum1 <= bignum2.

bignum > bignum

Test if one bignum is greater than another

E.g.: local greater = bignum1 > bignum2.

bignum >= bignum

Test if one bignum is greater than or equal to another

E.g.: local gte = bignum1 >= bignum2.

bignum:add(bignum2)

Performs a signed addition of bignum2 to bignum and updates bignum to result.

E.g.: bignum:add(bignum2).

bignum + bignum2

Performs a signed addition of bignum2 to bignum and returns the result.

E.g.: local result = bignum + bignum2.

bignum:sub(bignum2)

Performs a signed subtraction of bignum2 from bignum and updates bignum to result.

E.g.: bignum:sub(bignum2).

bignum - bignum2

Performs a signed subtraction of bignum2 from bignum and returns the result.

E.g.: local result = bignum - bignum2.

bignum:mul(bignum2)

Performs a multiplication of bignum by bignum2 and updates bignum to result.

E.g.: bignum:mul(bignum2).

bignum * bignum2

Performs a multiplication of bignum by bignum2 and returns the result.

E.g.: local result = bignum * bignum2.

bignum:div()

Performs a division of bignum by bignum2 and updates bignum to result.

E.g.: bignum:div().

bignum / bignum2

Performs a division of bignum by bignum2 and returns result.

E.g.: local result = bignum / bignum2.

bignum:mod()

Performs a modular reduction of bignum for the base bignum2 and updates bignum to result.

E.g.: bignum:mod().

bignum % bignum2

Performs a modular reduction of bignum for the base bignum2 and returns result.

E.g.: local result = bignum % bignum2.

The 'Time' class

A Time represents current system time.

Constructors

Time.now_insecure()

Constructs a Time.

E.g.: local time = Time.now_insecure().

Methods

time:unix_epoch_seconds()

Returns a Lua number tcorresponding to current system time as seconds since 00:00:00 Jan 1, 1970 UTC.

E.g.: local secs = time:unix_epoch_seconds().

time:unix_epoch_nanoseconds()

Returns a Lua number corresponding to current system time as nanoseconds since 00:00:00 Jan 1, 1970 UTC.

E.g.: local nanosecs = time:unix_epoch_nanoseconds().

The 'Oid' class

An Oid represents an ASN.1 object identifier.

Constructors

Oid.from_str(str)

Load an OID from a string which can be either the usual dotted-decimal notation or a name (for some well known and commonly used OIDs).

E.g.: local cn = Oid.from_str('CN') E.g.: local email = Oid.from_str('1.2.840.113549.1.9.1')

Methods

Oid:to_str()

If the OID has a known value, return the string associated with it. Otherwise returns the dotted decimal value.

E.g.: assert(email:to_str() == 'emailAddress')

The 'x509Name' class

An X509Name represents an X.509 distinguished name, as used in certificates and signing requests.

Constructors

X509Name.from_der(der)

Load a DN from the binary DER encoding.

E.g.: local name = X509Name.from_der(der)

X509Name.new()

Create a new (empty) DN.

E.g.: local name = X509Name.new()

Methods

X509Name.to_str()

Return a readable string encoding for the DN.

X509Name.oids()

Return an array of OIDs specifying the values it contains

X509Name.get(oid)

If the specified OID is set in the DN, return the value. Otherwise returns nil.

X509Name.set(oid, value, string_type)

Set the OID to the provided value. The string_type field specifies how the string is encoded; for best interop use "utf8". Other accepted encodings are "printable", "numeric", and "ia5".

E.g.: name.set(oids.from_str('CN'), 'localhost', 'utf8')

The 'Pkcs10Csr' class

A Pkcs10Csr represents a certificate signing request as specified in PKCS 10.

Constructors

Pkcs10Csr.new(key_id, subject)

Pkcs10Csr.from_der(der)

Load a PKCS10 CSR from the binary DER value.

Methods

csr:to_der()

Returns a Blob with the DER encoding of the CSR.

csr:verify_signature()

Verify the self-signature on a CSR, returning true on success. This simply verifies that whoever generated the CSR does have access to the private key corresponding to the public key in the CSR. This does not authenticate the CSR in any way. However, this prevents certain forgery attacks that are otherwise possible.

csr:subject_dn()

 Return an X509Name of the subject set in the CSR.

csr:sign(ca_cert, ca_key_name, cert_lifetime, digest, serial_bits)

Sign a CSR, creating a new certificate object. The ca_cert should be a CA certificate Sobject. The ca_key_name should be the name of a key stored in Fortanix Self-Defending KMS which is associated with the issuing CA certificate. The certificate lifetime is given in seconds from the current time. digest the default value is SHA256 if not provided. serial_bits the default value is 160 if not provided.

The 'TbsCertificate' class

A TbsCertificate represents the body of a certificate without an associated signature. It allows creating a custom certificate without first creating a CSR.

Constructors

TbsCertificate.new(key_id, subject, skid, lifetime)

Methods

TbsCertificate:add_extension(oid, critical, value)

Add an extension to the TbsCertificate.

Each certificate extension is identified by an OID and is marked either critical or non-critical. During validation, any implementation that encounters a critical extension it cannot identify is required to reject the certificate. So ordinarily critical extensions are only used when the certificate cannot be safely validated without understanding the extension. If the extension is just for informative purposes it is usually non-critical.

TbsCertificate:to_der()

Returns a Blob with the DER encoding of the TbsCertificate.

TbsCertificate:sign(ca_cert, ca_key_name, serial_bits, digest)

Sign the TbsCertificate and return a new certificate object. The issuing certificate should be an sobject and the ca_key_name gives the name of the signing key which must be stored in Fortanix Self-Defending KMS. digest the default value is SHA256 if not provided. serial_bits the default value is 160 if not provided.

TbsCertificate:self-sign(signing_key, digest)

 Self-sign the TbsCertificate and return a new certificate object. The signing_key is the sobject of the signing key which must be stored in Fortanix Self-Defending KMS. For the correct self-signed certificate, the public key in the TbsCertificate (key_id in the constructor) must correspond to this signing key. digest the default value is SHA256 if not provided.

The 'EcGroup' class

An EcGroup represents some elliptic curve group supported in Fortanix Self-Defending KMS.

Constructors

EcGroup.SecP256R1, EcGroup.SecP256K1, ...

EcGroup supports construction via a enum-style syntax. Possible values are “Bp256R1”, “Bp384R1”, “Bp512R1”, “Curve25519”, “SecP192K1”, “SecP192R1”, “SecP224K1”, “SecP224R1”, “SecP256K1”, “SecP256R1”, “SecP384R1”, and “SecP521R1”.

 

EcGroup.from_name

This function constructs an EC group from a string (values matching the above-named enums). This is useful when the desired group is provided as a parameter by the invoker of a plugin.

Methods

EcGroup:name()

This function returns the name of the group.

EcGroup:generator()

This function returns an EcPoint which is the generator of this group.

EcGroup:point_from_components(x, y)

This function returns a new EcPointtaking BigNum components x and Y.

EcGroup:point_from_binary(v)

This function decodes an encoded EC point using the standard OS2ECP convention. Both compressed and uncompressed points are supported.

EcPoint

An EcPoint represents a particular point on an elliptic curve. It is constructed using the functions on EcGroup.

Methods

EcPoint:group()

This function returns the EcGroup that this point belongs to.

EcPoint:add(other)

This function performs point addition, adding two points and returning the resulting point.

EcPoint:mul(scalar)

This function performs point multiplication, multiplying a point by a scalar BigNum and returning the resulting point.

EcPoint:x()

This function returns the affine x coordinate of the point as a BigNum.

EcPoint:y()

This function returns the affine y coordinate of the point as a BigNum.

EcPoint:to_binary(compress)

This function returns the binary encoding of a point. If compress is false then uncompressed encoding is used. If compress is nil or true then point compression is used.

The 'DerEncoder' class

A DerEncoder provides ASN1 encoding functions which help in creating custom CSRs and Certificates.

Constructors

DerEncoder.new() 

Methods

DerEncoder:start_seq()

This begins a DER SEQUENCE which is nested with a call to end_seq(). The start_seq() and end_seq() must be correctly paired.

DerEncoder:end_seq()

This ends a DER SEQUENCE started by a start_seq() earlier.

DerEncoder:add_bool(b)

DerEncoder:add_int(i)

Supports both int and bignum types for input.

DerEncoder:add_oid(oid)

Input is Oid type.

DerEncoder:add_enum(i)

DerEncoder:add_string(s, encoding)

encoding parameter specifies how the string is tagged. Possible values are utf8, printable, numeric or ia5. The encoding is not verified for the input string by the system. Use utf8 unless required for format compatibility.

DerEncoder:add_octets(s)

Supports both Blob type and a hex string for input.

DerEncoder:add_raw(s)

Supports both Blob type and a hex string for input.

DerEncoder:implicit_context(tag)

This specifies that the next encoded value should be given an implicit context-specific tag.

DerEncoder:explicit_context(tag)

DerEncoder:value()

Returns a DER-encoded value as Blob. If calls to start_seq()  and end_seq() do not align, then function will return an error.

Example code

local oid = Oid.from_str('1.2.3.4')
 local val = DerEncoder.new():start_seq()
    :add_string("str", 'utf8')
    :add_string("str", 'printable')
    :add_string("dns", 'ia5')
    :add_string('1234', 'numeric')
    :add_bool(true)
    :add_octets("01020304")
    :add_oid(oid)
    :end_seq():value()
 return Blob.from_bytes(val):hex()