static int mxf_decrypt_triplet(AVFormatContext *s, AVPacket *pkt, KLVPacket *klv) { static const uint8_t checkv[16] = {0x43, 0x48, 0x55, 0x4b, 0x43, 0x48, 0x55, 0x4b, 0x43, 0x48, 0x55, 0x4b, 0x43, 0x48, 0x55, 0x4b}; MXFContext *mxf = s->priv_data; AVIOContext *pb = s->pb; int64_t end = avio_tell(pb) + klv->length; uint64_t size; uint64_t orig_size; uint64_t plaintext_size; uint8_t ivec[16]; uint8_t tmpbuf[16]; int index; if (!mxf->aesc && s->key && s->keylen == 16) { mxf->aesc = av_malloc(av_aes_size); if (!mxf->aesc) return -1; av_aes_init(mxf->aesc, s->key, 128, 1); } // crypto context avio_skip(pb, klv_decode_ber_length(pb)); // plaintext offset klv_decode_ber_length(pb); plaintext_size = avio_rb64(pb); // source klv key klv_decode_ber_length(pb); avio_read(pb, klv->key, 16); if (!IS_KLV_KEY(klv, mxf_essence_element_key)) return -1; index = mxf_get_stream_index(s, klv); if (index < 0) return -1; // source size klv_decode_ber_length(pb); orig_size = avio_rb64(pb); if (orig_size < plaintext_size) return -1; // enc. code size = klv_decode_ber_length(pb); if (size < 32 || size - 32 < orig_size) return -1; avio_read(pb, ivec, 16); avio_read(pb, tmpbuf, 16); if (mxf->aesc) av_aes_crypt(mxf->aesc, tmpbuf, tmpbuf, 1, ivec, 1); if (memcmp(tmpbuf, checkv, 16)) av_log(s, AV_LOG_ERROR, "probably incorrect decryption key\n"); size -= 32; av_get_packet(pb, pkt, size); size -= plaintext_size; if (mxf->aesc) av_aes_crypt(mxf->aesc, &pkt->data[plaintext_size], &pkt->data[plaintext_size], size >> 4, ivec, 1); pkt->size = orig_size; pkt->stream_index = index; avio_skip(pb, end - avio_tell(pb)); return 0; }