| diff --git a/scapy/layers/ipsec.py b/scapy/layers/ipsec.py |
| index 69e7ae3b..99373466 100644 |
| --- a/scapy/layers/ipsec.py |
| +++ b/scapy/layers/ipsec.py |
| @@ -518,12 +517,16 @@ class AuthAlgo(object): |
| else: |
| return self.mac(key, self.digestmod(), default_backend()) |
| |
| - def sign(self, pkt, key): |
| + def sign(self, pkt, key, trailer=None): |
| """ |
| Sign an IPsec (ESP or AH) packet with this algo. |
| |
| @param pkt: a packet that contains a valid encrypted ESP or AH layer |
| @param key: the authentication key, a byte string |
| + @param trailer: additional data appended to the packet for ICV |
| + calculation, but not trnasmitted with the packet. |
| + For example, the high order bits of the exteneded |
| + sequence number. |
| |
| @return: the signed packet |
| """ |
| @@ -539,11 +542,13 @@ class AuthAlgo(object): |
| elif pkt.haslayer(AH): |
| clone = zero_mutable_fields(pkt.copy(), sending=True) |
| mac.update(raw(clone)) |
| + if trailer: |
| + mac.update(trailer) |
| pkt[AH].icv = mac.finalize()[:self.icv_size] |
| |
| return pkt |
| |
| - def verify(self, pkt, key): |
| + def verify(self, pkt, key, trailer): |
| """ |
| Check that the integrity check value (icv) of a packet is valid. |
| |
| @@ -574,6 +579,8 @@ class AuthAlgo(object): |
| clone = zero_mutable_fields(pkt.copy(), sending=False) |
| |
| mac.update(raw(clone)) |
| + if trailer: |
| + mac.update(trailer) # bytearray(4)) #raw(trailer)) |
| computed_icv = mac.finalize()[:self.icv_size] |
| |
| # XXX: Cannot use mac.verify because the ICV can be truncated |
| @@ -757,7 +764,8 @@ class SecurityAssociation(object): |
| SUPPORTED_PROTOS = (IP, IPv6) |
| |
| def __init__(self, proto, spi, seq_num=1, crypt_algo=None, crypt_key=None, |
| - auth_algo=None, auth_key=None, tunnel_header=None, nat_t_header=None): |
| + auth_algo=None, auth_key=None, tunnel_header=None, nat_t_header=None, |
| + use_esn=False): |
| """ |
| @param proto: the IPsec proto to use (ESP or AH) |
| @param spi: the Security Parameters Index of this SA |
| @@ -771,6 +779,7 @@ class SecurityAssociation(object): |
| to encapsulate the encrypted packets. |
| @param nat_t_header: an instance of a UDP header that will be used |
| for NAT-Traversal. |
| + @param use_esn: Use Extended Sequence Numbers |
| """ |
| |
| if proto not in (ESP, AH, ESP.name, AH.name): |
| @@ -782,6 +791,7 @@ class SecurityAssociation(object): |
| |
| self.spi = spi |
| self.seq_num = seq_num |
| + self.use_esn = use_esn |
| |
| if crypt_algo: |
| if crypt_algo not in CRYPT_ALGOS: |
| @@ -827,6 +837,17 @@ class SecurityAssociation(object): |
| raise TypeError('packet spi=0x%x does not match the SA spi=0x%x' % |
| (pkt.spi, self.spi)) |
| |
| + def build_seq_num(self, num): |
| + # only lower order bits are transmitted |
| + # higher order bits are used in the ICV |
| + lower = num & 0xffffffff |
| + upper = num >> 32 |
| + |
| + if self.use_esn: |
| + return lower, struct.pack(">I", upper) |
| + else: |
| + return lower, None |
| + |
| def _encrypt_esp(self, pkt, seq_num=None, iv=None): |
| |
| if iv is None: |
| @@ -835,7 +856,8 @@ class SecurityAssociation(object): |
| if len(iv) != self.crypt_algo.iv_size: |
| raise TypeError('iv length must be %s' % self.crypt_algo.iv_size) |
| |
| - esp = _ESPPlain(spi=self.spi, seq=seq_num or self.seq_num, iv=iv) |
| + low_seq_num, high_seq_num = self.build_seq_num(seq_num or self.seq_num) |
| + esp = _ESPPlain(spi=self.spi, seq=low_seq_num, iv=iv) |
| |
| if self.tunnel_header: |
| tunnel = self.tunnel_header.copy() |
| @@ -857,7 +879,7 @@ class SecurityAssociation(object): |
| esp = self.crypt_algo.pad(esp) |
| esp = self.crypt_algo.encrypt(self, esp, self.crypt_key) |
| |
| - self.auth_algo.sign(esp, self.auth_key) |
| + self.auth_algo.sign(esp, self.auth_key, high_seq_num) |
| |
| if self.nat_t_header: |
| nat_t_header = self.nat_t_header.copy() |
| @@ -884,7 +906,8 @@ class SecurityAssociation(object): |
| |
| def _encrypt_ah(self, pkt, seq_num=None): |
| |
| - ah = AH(spi=self.spi, seq=seq_num or self.seq_num, |
| + low_seq_num, high_seq_num = self.build_seq_num(seq_num or self.seq_num) |
| + ah = AH(spi=self.spi, seq=low_seq_num, |
| icv = b"\x00" * self.auth_algo.icv_size) |
| |
| if self.tunnel_header: |
| @@ -924,7 +947,8 @@ class SecurityAssociation(object): |
| else: |
| ip_header.plen = len(ip_header.payload) + len(ah) + len(payload) |
| |
| - signed_pkt = self.auth_algo.sign(ip_header / ah / payload, self.auth_key) |
| + signed_pkt = self.auth_algo.sign(ip_header / ah / payload, |
| + self.auth_key, high_seq_num) |
| |
| # sequence number must always change, unless specified by the user |
| if seq_num is None: |
| @@ -955,11 +979,12 @@ class SecurityAssociation(object): |
| |
| def _decrypt_esp(self, pkt, verify=True): |
| |
| + low_seq_num, high_seq_num = self.build_seq_num(self.seq_num) |
| encrypted = pkt[ESP] |
| |
| if verify: |
| self.check_spi(pkt) |
| - self.auth_algo.verify(encrypted, self.auth_key) |
| + self.auth_algo.verify(encrypted, self.auth_key, high_seq_num) |
| |
| esp = self.crypt_algo.decrypt(self, encrypted, self.crypt_key, |
| self.crypt_algo.icv_size or |
| @@ -998,9 +1023,11 @@ class SecurityAssociation(object): |
| |
| def _decrypt_ah(self, pkt, verify=True): |
| |
| + low_seq_num, high_seq_num = self.build_seq_num(self.seq_num) |
| + |
| if verify: |
| self.check_spi(pkt) |
| - self.auth_algo.verify(pkt, self.auth_key) |
| + self.auth_algo.verify(pkt, self.auth_key, high_seq_num) |
| |
| ah = pkt[AH] |
| payload = ah.payload |