mxf aes decryption support, patch by Reimar, simplified to only look for first...

mxf aes decryption support, patch by Reimar, simplified to only look for first crypto context, will be extended once we get files with multiple cryptocontext, and hope that they won't have broken container ul

Originally committed as revision 7925 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mxf.c

@@ -46,6 +46,7 @@
 //#define DEBUG
 
 #include "avformat.h"
+#include "aes.h"
 
 typedef uint8_t UID[16];
 
@@ -60,8 +61,16 @@ enum MXFMetadataSetType {
     Descriptor,
     Track,
     EssenceContainerData,
+    CryptoContext,
 };
 
+typedef struct MXFCryptoContext {
+    UID uid;
+    enum MXFMetadataSetType type;
+    UID context_uid;
+    UID source_container_ul;
+} MXFCryptoContext;
+
 typedef struct MXFStructuralComponent {
     UID uid;
     enum MXFMetadataSetType type;
@@ -137,6 +146,7 @@ typedef struct MXFContext {
     int metadata_sets_count;
     const uint8_t *sync_key;
     AVFormatContext *fc;
+    struct AVAES *aesc;
 } MXFContext;
 
 typedef struct KLVPacket {
@@ -173,6 +183,7 @@ static const uint8_t mxf_header_partition_pack_key[]       = { 0x06,0x0e,0x2b,0x
 static const uint8_t mxf_essence_element_key[]             = { 0x06,0x0e,0x2b,0x34,0x01,0x02,0x01,0x01,0x0d,0x01,0x03,0x01 };
 /* complete keys to match */
 static const uint8_t mxf_encrypted_triplet_key[]           = { 0x06,0x0e,0x2b,0x34,0x02,0x04,0x01,0x07,0x0d,0x01,0x03,0x01,0x02,0x7e,0x01,0x00 };
+static const uint8_t mxf_encrypted_essence_container[]     = { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x07,0x0d,0x01,0x03,0x01,0x02,0x0b,0x01,0x00 };
 
 #define IS_KLV_KEY(x, y) (!memcmp(x, y, sizeof(y)))
 
@@ -245,6 +256,63 @@ static int mxf_get_d10_aes3_packet(ByteIOContext *pb, AVStream *st, AVPacket *pk
     return 0;
 }
 
+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;
+    ByteIOContext *pb = &s->pb;
+    offset_t end = url_ftell(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);
+        av_aes_init(mxf->aesc, s->key, 128, 1);
+    }
+    // crypto context
+    url_fskip(pb, klv_decode_ber_length(pb));
+    // plaintext offset
+    klv_decode_ber_length(pb);
+    plaintext_size = get_be64(pb);
+    // source klv key
+    klv_decode_ber_length(pb);
+    get_buffer(pb, klv->key, 16);
+    if (!IS_KLV_KEY(klv, mxf_essence_element_key)) goto err_out;
+    index = mxf_get_stream_index(s, klv);
+    if (index < 0) goto err_out;
+    // source size
+    klv_decode_ber_length(pb);
+    orig_size = get_be64(pb);
+    if (orig_size < plaintext_size) goto err_out;
+    // enc. code
+    size = klv_decode_ber_length(pb);
+    if (size < 32 || size - 32 < orig_size) goto err_out;
+    get_buffer(pb, ivec, 16);
+    get_buffer(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;
+    url_fskip(pb, end - url_ftell(pb));
+    return 0;
+
+err_out:
+    url_fskip(pb, end - url_ftell(pb));
+    return -1;
+}
+
 static int mxf_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     MXFContext *mxf = s->priv_data;
@@ -259,9 +327,13 @@ static int mxf_read_packet(AVFormatContext *s, AVPacket *pkt)
         PRINT_KEY("read packet", klv.key);
 #endif
         if (IS_KLV_KEY(klv.key, mxf_encrypted_triplet_key)) {
+            int res = mxf_decrypt_triplet(s, pkt, &klv);
             mxf->sync_key = mxf_encrypted_triplet_key;
-            av_log(s, AV_LOG_ERROR, "encrypted triplet not supported\n");
-            return -1;
+            if (res < 0) {
+                av_log(s, AV_LOG_ERROR, "invalid encoded triplet\n");
+                return -1;
+            }
+            return 0;
         }
         if (IS_KLV_KEY(klv.key, mxf_essence_element_key)) {
             int index = mxf_get_stream_index(s, &klv);
@@ -294,6 +366,19 @@ static int mxf_add_metadata_set(MXFContext *mxf, void *metadata_set)
     return 0;
 }
 
+static int mxf_read_metadata_cryptographic_context(MXFCryptoContext *cryptocontext, ByteIOContext *pb, int tag)
+{
+    switch(tag) {
+    case 0xFFFE:
+        get_buffer(pb, cryptocontext->context_uid, 16);
+        break;
+    case 0xFFFD:
+        get_buffer(pb, cryptocontext->source_container_ul, 16);
+        break;
+    }
+    return 0;
+}
+
 static int mxf_read_metadata_content_storage(MXFContext *mxf, ByteIOContext *pb, int tag)
 {
     switch (tag) {
@@ -601,6 +686,7 @@ static int mxf_parse_structural_metadata(MXFContext *mxf)
         MXFTrack *temp_track = NULL;
         MXFDescriptor *descriptor = NULL;
         MXFStructuralComponent *component = NULL;
+        UID *essence_container_ul = NULL;
         const MXFCodecUL *codec_ul = NULL;
         const MXFCodecUL *container_ul = NULL;
         AVStream *st;
@@ -697,6 +783,19 @@ static int mxf_parse_structural_metadata(MXFContext *mxf)
         PRINT_KEY("essence codec     ul", descriptor->essence_codec_ul);
         PRINT_KEY("essence container ul", descriptor->essence_container_ul);
 #endif
+        essence_container_ul = &descriptor->essence_container_ul;
+        /* HACK: replacing the original key with mxf_encrypted_essence_container
+         * is not allowed according to s429-6, try to find correct information anyway */
+        if (IS_KLV_KEY(essence_container_ul, mxf_encrypted_essence_container)) {
+            av_log(mxf->fc, AV_LOG_INFO, "broken encrypted mxf file\n");
+            for (k = 0; k < mxf->metadata_sets_count; k++) {
+                MXFMetadataSet *metadata = mxf->metadata_sets[k];
+                if (metadata->type == CryptoContext) {
+                    essence_container_ul = &((MXFCryptoContext *)metadata)->source_container_ul;
+                    break;
+                }
+            }
+        }
         /* TODO: drop PictureEssenceCoding and SoundEssenceCompression, only check EssenceContainer */
         codec_ul = mxf_get_codec_ul(mxf_codec_uls, &descriptor->essence_codec_ul);
         st->codec->codec_id = codec_ul->id;
@@ -705,7 +804,7 @@ static int mxf_parse_structural_metadata(MXFContext *mxf)
             st->codec->extradata_size = descriptor->extradata_size;
         }
         if (st->codec->codec_type == CODEC_TYPE_VIDEO) {
-            container_ul = mxf_get_codec_ul(mxf_picture_essence_container_uls, &descriptor->essence_container_ul);
+            container_ul = mxf_get_codec_ul(mxf_picture_essence_container_uls, essence_container_ul);
             if (st->codec->codec_id == CODEC_ID_NONE)
                 st->codec->codec_id = container_ul->id;
             st->codec->width = descriptor->width;
@@ -713,7 +812,7 @@ static int mxf_parse_structural_metadata(MXFContext *mxf)
             st->codec->bits_per_sample = descriptor->bits_per_sample; /* Uncompressed */
             st->need_parsing = 2; /* only parse headers */
         } else if (st->codec->codec_type == CODEC_TYPE_AUDIO) {
-            container_ul = mxf_get_codec_ul(mxf_sound_essence_container_uls, &descriptor->essence_container_ul);
+            container_ul = mxf_get_codec_ul(mxf_sound_essence_container_uls, essence_container_ul);
             if (st->codec->codec_id == CODEC_ID_NONE)
                 st->codec->codec_id = container_ul->id;
             st->codec->channels = descriptor->channels;
@@ -759,6 +858,7 @@ static const MXFMetadataReadTableEntry mxf_metadata_read_table[] = {
     { { 0x06,0x0E,0x2B,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x47,0x00 }, mxf_read_metadata_generic_descriptor, sizeof(MXFDescriptor), Descriptor }, /* AES3 */
     { { 0x06,0x0E,0x2B,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x3A,0x00 }, mxf_read_metadata_track, sizeof(MXFTrack), Track }, /* Static Track */
     { { 0x06,0x0E,0x2B,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x3B,0x00 }, mxf_read_metadata_track, sizeof(MXFTrack), Track }, /* Generic Track */
+    { { 0x06,0x0E,0x2B,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x04,0x01,0x02,0x02,0x00,0x00 }, mxf_read_metadata_cryptographic_context, sizeof(MXFCryptoContext), CryptoContext },
     { { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 }, NULL, 0, AnyType },
 };
 
@@ -823,7 +923,8 @@ static int mxf_read_header(AVFormatContext *s, AVFormatParameters *ap)
 #ifdef DEBUG
         PRINT_KEY("read header", klv.key);
 #endif
-        if (IS_KLV_KEY(klv.key, mxf_essence_element_key)) {
+        if (IS_KLV_KEY(klv.key, mxf_encrypted_triplet_key) ||
+            IS_KLV_KEY(klv.key, mxf_essence_element_key)) {
             /* FIXME avoid seek */
             url_fseek(&s->pb, klv.offset, SEEK_SET);
             break;
@@ -868,6 +969,7 @@ static int mxf_read_close(AVFormatContext *s)
         av_freep(&mxf->metadata_sets[i]);
     }
     av_freep(&mxf->metadata_sets);
+    av_freep(&mxf->aesc);
     return 0;
 }
 

libavutil/Makefile

@@ -18,6 +18,7 @@ OBJS= mathematics.o \
       tree.o \
       lzo.o \
       random.o \
+      aes.o \
 
 HEADERS = avutil.h common.h mathematics.h integer.h rational.h \
           intfloat_readwrite.h md5.h adler32.h log.h fifo.h lzo.h \