From 62e0abe7591489c563c3d4380054050af9cb4838 Mon Sep 17 00:00:00 2001 From: Martin Willi Date: Fri, 17 Apr 2015 14:19:37 +0200 Subject: [PATCH] ikev2: Include fragment number into message ID passed to IV gen When using a cipher with sequential IVs, we never must pass an identical IV to the IV generator. To avoid it when using IKEv2 fragmentation, use the lower bits of the 64-bit message ID as the fragment number. --- src/libcharon/encoding/payloads/encrypted_payload.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/src/libcharon/encoding/payloads/encrypted_payload.c b/src/libcharon/encoding/payloads/encrypted_payload.c index 04372fdf0..d1a267836 100644 --- a/src/libcharon/encoding/payloads/encrypted_payload.c +++ b/src/libcharon/encoding/payloads/encrypted_payload.c @@ -502,6 +502,8 @@ METHOD(encrypted_payload_t, encrypt, status_t, generator = generator_create(); plain = generate(this, generator); assoc = append_header(this, assoc); + /* lower 32-bits are for fragment number, if used */ + mid <<= 32; status = encrypt_content("encrypted payload", this->aead, mid, plain, assoc, &this->encrypted); generator->destroy(generator); @@ -932,6 +934,9 @@ METHOD(encrypted_payload_t, frag_encrypt, status_t, } free(this->encrypted.ptr); assoc = append_header_frag(this, assoc); + /* IKEv2 message IDs are not unique if fragmentation is used, hence include + * the fragment number to make it unique */ + mid = mid << 32 | this->fragment_number; status = encrypt_content("encrypted fragment payload", this->aead, mid, this->plain, assoc, &this->encrypted); free(assoc.ptr);