laforge has submitted this change. ( https://gerrit.osmocom.org/c/pysim/+/42287?usp=email )

Change subject: global_platform/scp: fix dek_encrypt/dek_decrypt for SCP02 ......................................................................

global_platform/scp: fix dek_encrypt/dek_decrypt for SCP02

The methods dek_encrypt/dek_decrypt use the wrong algorithm and the wrong key material. The algorithm should be 3DES rather then single DES and the key must be the DEK session key instead of the static DEK key from which the DEK session key is derived.

Related: SYS#7902 Change-Id: I3d0cc7378680b346fa39152c8b7074446d2c869d --- M pySim/global_platform/scp.py 1 file changed, 4 insertions(+), 2 deletions(-)

Approvals: fixeria: Looks good to me, but someone else must approve Jenkins Builder: Verified laforge: Looks good to me, approved

diff --git a/pySim/global_platform/scp.py b/pySim/global_platform/scp.py index e674766..124b4c5 100644 --- a/pySim/global_platform/scp.py +++ b/pySim/global_platform/scp.py @@ -266,11 +266,13 @@ super().__init__(*args, **kwargs)

def dek_encrypt(self, plaintext:bytes) -> bytes: - cipher = DES.new(self.card_keys.dek[:8], DES.MODE_ECB) + # See also GPC section B.1.1.2, E.4.7, and E.4.1 + cipher = DES3.new(self.sk.data_enc, DES.MODE_ECB) return cipher.encrypt(plaintext)

def dek_decrypt(self, ciphertext:bytes) -> bytes: - cipher = DES.new(self.card_keys.dek[:8], DES.MODE_ECB) + # See also GPC section B.1.1.2, E.4.7, and E.4.1 + cipher = DES3.new(self.sk.data_enc, DES.MODE_ECB) return cipher.decrypt(ciphertext)

def _compute_cryptograms(self, card_challenge: bytes, host_challenge: bytes):