Class: Rex::Proto::Kerberos::Crypto::Des3CbcSha1
Constant Summary
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- SEED_SIZE =
21
- BLOCK_SIZE =
8
- PADDING_SIZE =
8
- MAC_SIZE =
20
- HASH_FUNCTION =
'SHA1'
Instance Method Summary
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Methods included from Asn1Utils
#truncate_nulls_after_asn1
#add_ones_complement, #checksum, #decrypt, #encrypt, #gss_unwrap, #gss_wrap, #rotate_right
Instance Method Details
#decrypt_asn1(ciphertext, key, msg_type) ⇒ Object
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# File 'lib/rex/proto/kerberos/crypto/des3_cbc_sha1.rb', line 32
def decrypt_asn1(ciphertext, key, msg_type)
result = decrypt(ciphertext, key, msg_type)
padding_removed = truncate_nulls_after_asn1(result)
end
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#expand(seed) ⇒ Object
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# File 'lib/rex/proto/kerberos/crypto/des3_cbc_sha1.rb', line 63
def expand(seed)
def parity(b)
b &= ~1
b | (b.digits(2).count(1) + 1) % 2
end
raise Rex::Proto::Kerberos::Model::Error::KerberosError unless seed.length == 7
firstbytes = seed.map {|b| parity(b & ~1)}
tmp = 7.times.map { |i| (seed[i] & 1) << i+1 }
lastbyte = parity(tmp.sum)
keybytes = firstbytes + [lastbyte]
if _is_weak_des_key(keybytes)
keybytes[7] = keybytes[7] ^ 0xF0
end
keybytes
end
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#parity(b) ⇒ Object
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# File 'lib/rex/proto/kerberos/crypto/des3_cbc_sha1.rb', line 64
def parity(b)
b &= ~1
b | (b.digits(2).count(1) + 1) % 2
end
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#string_to_key(string, salt, params: nil) ⇒ String
Derive an encryption key based on a password and salt for the given cipher type
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# File 'lib/rex/proto/kerberos/crypto/des3_cbc_sha1.rb', line 22
def string_to_key(string, salt, params: nil)
raise Rex::Proto::Kerberos::Model::Error::KerberosError, 'Params not supported for DES' unless params == nil
utf8_encoded = (string + salt).encode('UTF-8').bytes
k = random_to_key(nfold(utf8_encoded, 21))
k = k.pack('C*')
result = derive(k, 'kerberos'.encode('UTF-8'))
result
end
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