Fiddle::Pointer is a class to handle C pointers
The base exception for JSON errors.
Provides symmetric algorithms for encryption and decryption. The algorithms that are available depend on the particular version of OpenSSL that is installed.
A list of supported algorithms can be obtained by
puts OpenSSL::Cipher.ciphers
Cipher There are several ways to create a Cipher instance. Generally, a Cipher algorithm is categorized by its name, the key length in bits and the cipher mode to be used. The most generic way to create a Cipher is the following
cipher = OpenSSL::Cipher.new('<name>-<key length>-<mode>')
That is, a string consisting of the hyphenated concatenation of the individual components name, key length and mode. Either all uppercase or all lowercase strings may be used, for example:
cipher = OpenSSL::Cipher.new('aes-128-cbc')
Encryption and decryption are often very similar operations for symmetric algorithms, this is reflected by not having to choose different classes for either operation, both can be done using the same class. Still, after obtaining a Cipher instance, we need to tell the instance what it is that we intend to do with it, so we need to call either
cipher.encrypt
or
cipher.decrypt
on the Cipher instance. This should be the first call after creating the instance, otherwise configuration that has already been set could get lost in the process.
Symmetric encryption requires a key that is the same for the encrypting and for the decrypting party and after initial key establishment should be kept as private information. There are a lot of ways to create insecure keys, the most notable is to simply take a password as the key without processing the password further. A simple and secure way to create a key for a particular Cipher is
cipher = OpenSSL::Cipher.new('aes-256-cfb') cipher.encrypt key = cipher.random_key # also sets the generated key on the Cipher
If you absolutely need to use passwords as encryption keys, you should use Password-Based Key Derivation Function 2 (PBKDF2) by generating the key with the help of the functionality provided by OpenSSL::PKCS5.pbkdf2_hmac_sha1 or OpenSSL::PKCS5.pbkdf2_hmac.
Although there is Cipher#pkcs5_keyivgen, its use is deprecated and it should only be used in legacy applications because it does not use the newer PKCS#5 v2 algorithms.
The cipher modes CBC, CFB, OFB and CTR all need an “initialization vector”, or short, IV. ECB mode is the only mode that does not require an IV, but there is almost no legitimate use case for this mode because of the fact that it does not sufficiently hide plaintext patterns. Therefore
You should never use ECB mode unless you are absolutely sure that you absolutely need it
Because of this, you will end up with a mode that explicitly requires an IV in any case. Although the IV can be seen as public information, i.e. it may be transmitted in public once generated, it should still stay unpredictable to prevent certain kinds of attacks. Therefore, ideally
Always create a secure random IV for every encryption of your Cipher
A new, random IV should be created for every encryption of data. Think of the IV as a nonce (number used once) - it’s public but random and unpredictable. A secure random IV can be created as follows
cipher = ... cipher.encrypt key = cipher.random_key iv = cipher.random_iv # also sets the generated IV on the Cipher
Although the key is generally a random value, too, it is a bad choice as an IV. There are elaborate ways how an attacker can take advantage of such an IV. As a general rule of thumb, exposing the key directly or indirectly should be avoided at all cost and exceptions only be made with good reason.
Cipher#final ECB (which should not be used) and CBC are both block-based modes. This means that unlike for the other streaming-based modes, they operate on fixed-size blocks of data, and therefore they require a “finalization” step to produce or correctly decrypt the last block of data by appropriately handling some form of padding. Therefore it is essential to add the output of OpenSSL::Cipher#final to your encryption/decryption buffer or you will end up with decryption errors or truncated data.
Although this is not really necessary for streaming-mode ciphers, it is still recommended to apply the same pattern of adding the output of Cipher#final there as well - it also enables you to switch between modes more easily in the future.
data = "Very, very confidential data" cipher = OpenSSL::Cipher.new('aes-128-cbc') cipher.encrypt key = cipher.random_key iv = cipher.random_iv encrypted = cipher.update(data) + cipher.final ... decipher = OpenSSL::Cipher.new('aes-128-cbc') decipher.decrypt decipher.key = key decipher.iv = iv plain = decipher.update(encrypted) + decipher.final puts data == plain #=> true
Data (AEAD) If the OpenSSL version used supports it, an Authenticated Encryption mode (such as GCM or CCM) should always be preferred over any unauthenticated mode. Currently, OpenSSL supports AE only in combination with Associated Data (AEAD) where additional associated data is included in the encryption process to compute a tag at the end of the encryption. This tag will also be used in the decryption process and by verifying its validity, the authenticity of a given ciphertext is established.
This is superior to unauthenticated modes in that it allows to detect if somebody effectively changed the ciphertext after it had been encrypted. This prevents malicious modifications of the ciphertext that could otherwise be exploited to modify ciphertexts in ways beneficial to potential attackers.
An associated data is used where there is additional information, such as headers or some metadata, that must be also authenticated but not necessarily need to be encrypted. If no associated data is needed for encryption and later decryption, the OpenSSL library still requires a value to be set - “” may be used in case none is available.
An example using the GCM (Galois/Counter Mode). You have 16 bytes key, 12 bytes (96 bits) nonce and the associated data auth_data. Be sure not to reuse the key and nonce pair. Reusing an nonce ruins the security guarantees of GCM mode.
cipher = OpenSSL::Cipher.new('aes-128-gcm').encrypt cipher.key = key cipher.iv = nonce cipher.auth_data = auth_data encrypted = cipher.update(data) + cipher.final tag = cipher.auth_tag # produces 16 bytes tag by default
Now you are the receiver. You know the key and have received nonce, auth_data, encrypted and tag through an untrusted network. Note that GCM accepts an arbitrary length tag between 1 and 16 bytes. You may additionally need to check that the received tag has the correct length, or you allow attackers to forge a valid single byte tag for the tampered ciphertext with a probability of 1/256.
raise "tag is truncated!" unless tag.bytesize == 16 decipher = OpenSSL::Cipher.new('aes-128-gcm').decrypt decipher.key = key decipher.iv = nonce decipher.auth_tag = tag decipher.auth_data = auth_data decrypted = decipher.update(encrypted) + decipher.final puts data == decrypted #=> true
OpenSSL::Digest allows you to compute message digests (sometimes interchangeably called “hashes”) of arbitrary data that are cryptographically secure, i.e. a Digest implements a secure one-way function.
One-way functions offer some useful properties. E.g. given two distinct inputs the probability that both yield the same output is highly unlikely. Combined with the fact that every message digest algorithm has a fixed-length output of just a few bytes, digests are often used to create unique identifiers for arbitrary data. A common example is the creation of a unique id for binary documents that are stored in a database.
Another useful characteristic of one-way functions (and thus the name) is that given a digest there is no indication about the original data that produced it, i.e. the only way to identify the original input is to “brute-force” through every possible combination of inputs.
These characteristics make one-way functions also ideal companions for public key signature algorithms: instead of signing an entire document, first a hash of the document is produced with a considerably faster message digest algorithm and only the few bytes of its output need to be signed using the slower public key algorithm. To validate the integrity of a signed document, it suffices to re-compute the hash and verify that it is equal to that in the signature.
You can get a list of all digest algorithms supported on your system by running this command in your terminal:
openssl list -digest-algorithms
Among the OpenSSL 1.1.1 supported message digest algorithms are:
SHA224, SHA256, SHA384, SHA512, SHA512-224 and SHA512-256
SHA3-224, SHA3-256, SHA3-384 and SHA3-512
BLAKE2s256 and BLAKE2b512
Each of these algorithms can be instantiated using the name:
digest = OpenSSL::Digest.new('SHA256')
“Breaking” a message digest algorithm means defying its one-way function characteristics, i.e. producing a collision or finding a way to get to the original data by means that are more efficient than brute-forcing etc. Most of the supported digest algorithms can be considered broken in this sense, even the very popular MD5 and SHA1 algorithms. Should security be your highest concern, then you should probably rely on SHA224, SHA256, SHA384 or SHA512.
data = File.binread('document') sha256 = OpenSSL::Digest.new('SHA256') digest = sha256.digest(data)
data1 = File.binread('file1') data2 = File.binread('file2') data3 = File.binread('file3') sha256 = OpenSSL::Digest.new('SHA256') sha256 << data1 sha256 << data2 sha256 << data3 digest = sha256.digest
Digest instance data1 = File.binread('file1') sha256 = OpenSSL::Digest.new('SHA256') digest1 = sha256.digest(data1) data2 = File.binread('file2') sha256.reset digest2 = sha256.digest(data2)
Generic error, common for all classes under OpenSSL module
Generic Error for all of OpenSSL::BN (big num)
Document-class: OpenSSL::HMAC
OpenSSL::HMAC allows computing Hash-based Message Authentication Code (HMAC). It is a type of message authentication code (MAC) involving a hash function in combination with a key. HMAC can be used to verify the integrity of a message as well as the authenticity.
OpenSSL::HMAC has a similar interface to OpenSSL::Digest.
key = "key" data = "message-to-be-authenticated" mac = OpenSSL::HMAC.hexdigest("SHA256", key, data) #=> "cddb0db23f469c8bf072b21fd837149bd6ace9ab771cceef14c9e517cc93282e"
data1 = File.binread("file1") data2 = File.binread("file2") key = "key" hmac = OpenSSL::HMAC.new(key, 'SHA256') hmac << data1 hmac << data2 mac = hmac.digest
If an object defines encode_with, then an instance of Psych::Coder will be passed to the method when the object is being serialized. The Coder automatically assumes a Psych::Nodes::Mapping is being emitted. Other objects like Sequence and Scalar may be emitted if seq= or scalar= are called, respectively.
Psych::Handler is an abstract base class that defines the events used when dealing with Psych::Parser. Clients who want to use Psych::Parser should implement a class that inherits from Psych::Handler and define events that they can handle.
Psych::Handler defines all events that Psych::Parser can possibly send to event handlers.
See Psych::Parser for more details
YAML event parser class. This class parses a YAML document and calls events on the handler that is passed to the constructor. The events can be used for things such as constructing a YAML AST or deserializing YAML documents. It can even be fed back to Psych::Emitter to emit the same document that was parsed.
See Psych::Handler for documentation on the events that Psych::Parser emits.
Here is an example that prints out ever scalar found in a YAML document:
# Handler for detecting scalar values class ScalarHandler < Psych::Handler def scalar value, anchor, tag, plain, quoted, style puts value end end parser = Psych::Parser.new(ScalarHandler.new) parser.parse(yaml_document)
Here is an example that feeds the parser back in to Psych::Emitter. The YAML document is read from STDIN and written back out to STDERR:
parser = Psych::Parser.new(Psych::Emitter.new($stderr)) parser.parse($stdin)
Psych uses Psych::Parser in combination with Psych::TreeBuilder to construct an AST of the parsed YAML document.
Scan scalars for built in types
This class works in conjunction with Psych::Parser to build an in-memory parse tree that represents a YAML document.
parser = Psych::Parser.new Psych::TreeBuilder.new parser.parse('--- foo') tree = parser.handler.root
See Psych::Handler for documentation on the event methods used in this class.
This class handles only scanner events, which are dispatched in the ‘right’ order (same with input).
ResolutionError is the error class for socket name resolution.
OLEProperty is a helper class of Property with arguments, used by ‘olegen.rb`-generated files.
Raised when OLE processing failed.
EX:
obj = WIN32OLE.new("NonExistProgID")
raises the exception:
WIN32OLE::RuntimeError: unknown OLE server: `NonExistProgID'
HRESULT error code:0x800401f3
Invalid class string
The superclass for all exceptions raised by Ruby/zlib.
The following exceptions are defined as subclasses of Zlib::Error. These exceptions are raised when zlib library functions return with an error status.
Subclass of Zlib::Error when zlib returns a Z_DATA_ERROR.
Usually if a stream was prematurely freed.