Support AES-192/256 PACE (fixes reading Portuguese Cartão de Cidadão) - #50
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FerroLx wants to merge 1 commit into
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Support AES-192/256 PACE (fixes reading Portuguese Cartão de Cidadão)#50FerroLx wants to merge 1 commit into
FerroLx wants to merge 1 commit into
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Two AES key-length bugs prevented PACE with AES-192/256, which the current Portuguese Cartão de Cidadão (and other modern eMRTDs) negotiate: 1. proto/pace.dart decryptNonce hard-coded the nonce cipher to AESChiperSelector.getChiper(size: KEY_LENGTH.s128), ignoring the negotiated keyLength. With an AES-256 k_pi (32 bytes) this raised "key length must be 128 bits". Use the in-scope `keyLength`. 2. crypto/aes.dart AESChiperSelector.getChiper returned AESCipher128() for the KEY_LENGTH.s192 case (copy-paste error). Return AESCipher192(). Note: this also needs pointycastle's CMac AES-256 IV fix (CMac.init sizing the zero IV to key length instead of block size) for the PACE mutual-auth CMAC and secure-messaging MAC to work end to end.
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Problem
PACE fails on eMRTDs that negotiate AES-192/256 (e.g. the current Portuguese
Cartão de Cidadão), due to two AES key-length bugs.
Fixes
1.
proto/pace.dart—decryptNoncehard-coded the nonce cipher to AES-128:ignoring the negotiated
keyLengthalready in scope. With an AES-256k_pi(32 bytes)this raises "key length must be 128 bits". Fixed to
getChiper(size: keyLength).2.
crypto/aes.dart—AESChiperSelector.getChiperreturnedAESCipher128()for theKEY_LENGTH.s192case (copy-paste error). Fixed toAESCipher192().Dependency
End-to-end AES-256 PACE also requires the pointycastle
CMac.initIV fix(sizes the zero IV to key length instead of cipher block size) for the mutual-auth
CMAC and secure-messaging MAC. See bcgit/pc-dart.
Testing
Verified by successfully reading a real Portuguese Cartão de Cidadão (PACE, AES-256)
over NFC end-to-end (EF.SOD + DG1 + DG2) with both fixes applied.