class Net::SSH::Transport::CipherFactory
Implements a factory of OpenSSL
cipher algorithms.
Constants
Public Class Methods
get(name, options = {})
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Retrieves a new instance of the named algorithm. The new instance will be initialized using an iv and key generated from the given iv, key, shared, hash and digester values. Additionally, the cipher will be put into encryption or decryption mode, based on the value of the encrypt
parameter.
# File lib/net/ssh/transport/cipher_factory.rb, line 46 def self.get(name, options = {}) ossl_name = SSH_TO_OSSL[name] or raise NotImplementedError, "unimplemented cipher `#{name}'" return IdentityCipher if ossl_name == "none" cipher = OpenSSL::Cipher.new(ossl_name) cipher.send(options[:encrypt] ? :encrypt : :decrypt) cipher.padding = 0 if name =~ /-ctr(@openssh.org)?$/ if ossl_name !~ /-ctr/ cipher.extend(Net::SSH::Transport::CTR) else cipher = Net::SSH::Transport::OpenSSLAESCTR.new(cipher) end end cipher.iv = Net::SSH::Transport::KeyExpander.expand_key(cipher.iv_len, options[:iv], options) key_len = cipher.key_len cipher.key_len = key_len cipher.key = Net::SSH::Transport::KeyExpander.expand_key(key_len, options[:key], options) return cipher end
get_lengths(name, options = {})
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Returns a two-element array containing the [ key-length, block-size ] for the named cipher algorithm. If the cipher algorithm is unknown, or is “none”, 0 is returned for both elements of the tuple. if :iv_len option is supplied the third return value will be ivlen
# File lib/net/ssh/transport/cipher_factory.rb, line 77 def self.get_lengths(name, options = {}) ossl_name = SSH_TO_OSSL[name] if ossl_name.nil? || ossl_name == "none" result = [0, 0] result << 0 if options[:iv_len] else cipher = OpenSSL::Cipher.new(ossl_name) key_len = cipher.key_len cipher.key_len = key_len block_size = case ossl_name when /\-ctr/ Net::SSH::Transport::OpenSSLAESCTR.block_size else cipher.block_size end result = [key_len, block_size] result << cipher.iv_len if options[:iv_len] end result end
supported?(name)
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Returns true if the underlying OpenSSL
library supports the given cipher, and false otherwise.
# File lib/net/ssh/transport/cipher_factory.rb, line 34 def self.supported?(name) ossl_name = SSH_TO_OSSL[name] or raise NotImplementedError, "unimplemented cipher `#{name}'" return true if ossl_name == "none" return OpenSSL::Cipher.ciphers.include?(ossl_name) end