class NETSNMP::Encryption::DES
Public Class Methods
new(priv_key, local: 0)
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# File lib/netsnmp/encryption/des.rb, line 8 def initialize(priv_key, local: 0) @priv_key = priv_key @local = local end
Public Instance Methods
decrypt(encrypted_data, salt:, **)
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# File lib/netsnmp/encryption/des.rb, line 30 def decrypt(encrypted_data, salt:, **) raise Error, "invalid priv salt received" unless (salt.length % 8).zero? raise Error, "invalid encrypted PDU received" unless (encrypted_data.length % 8).zero? cipher = OpenSSL::Cipher::DES.new(:CBC) cipher.padding = 0 iv = generate_decryption_key(salt) cipher.decrypt cipher.key = des_key cipher.iv = iv decrypted_data = cipher.update(encrypted_data) + cipher.final hlen, bodylen = OpenSSL::ASN1.traverse(decrypted_data) { |_, _, x, y, *| break x, y } decrypted_data.byteslice(0, hlen + bodylen) end
encrypt(decrypted_data, engine_boots:, **)
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# File lib/netsnmp/encryption/des.rb, line 13 def encrypt(decrypted_data, engine_boots:, **) cipher = OpenSSL::Cipher::DES.new(:CBC) iv, salt = generate_encryption_key(engine_boots) cipher.encrypt cipher.iv = iv cipher.key = des_key if (diff = decrypted_data.length % 8) != 0 decrypted_data << ("\x00" * (8 - diff)) end encrypted_data = cipher.update(decrypted_data) + cipher.final [encrypted_data, salt] end
Private Instance Methods
des_key()
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# File lib/netsnmp/encryption/des.rb, line 72 def des_key @priv_key[0, 8] end
generate_decryption_key(salt)
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# File lib/netsnmp/encryption/des.rb, line 67 def generate_decryption_key(salt) pre_iv = @priv_key[8, 8] pre_iv.xor(salt) end
generate_encryption_key(boots)
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8.1.1.1
# File lib/netsnmp/encryption/des.rb, line 51 def generate_encryption_key(boots) pre_iv = @priv_key[8, 8] salt = [0xff & (boots >> 24), 0xff & (boots >> 16), 0xff & (boots >> 8), 0xff & boots, 0xff & (@local >> 24), 0xff & (@local >> 16), 0xff & (@local >> 8), 0xff & @local].pack("c*") @local = @local == 0xffffffff ? 0 : @local + 1 iv = pre_iv.xor(salt) [iv, salt] end