From 4469e8ebb2f370794c88aa51d528d1d899d29ddc Mon Sep 17 00:00:00 2001 From: erankor Date: Mon, 7 Dec 2015 12:01:09 +0200 Subject: movenc: support cenc (common encryption) support writing encrypted mp4 using aes-ctr, conforming to ISO/IEC 23001-7. 3 new parameters were added: - encryption_scheme - allowed values are none (default) and cenc-aes-ctr - encryption_key - 128 bit encryption key (hex) - encryption_kid - 128 bit encryption key identifier (hex) Signed-off-by: Michael Niedermayer --- libavformat/movenccenc.c | 415 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 415 insertions(+) create mode 100644 libavformat/movenccenc.c (limited to 'libavformat/movenccenc.c') diff --git a/libavformat/movenccenc.c b/libavformat/movenccenc.c new file mode 100644 index 0000000000..b91294f706 --- /dev/null +++ b/libavformat/movenccenc.c @@ -0,0 +1,415 @@ +/* + * MOV CENC (Common Encryption) writer + * Copyright (c) 2015 Eran Kornblau + * + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ +#include "movenccenc.h" +#include "libavutil/intreadwrite.h" +#include "avio_internal.h" +#include "movenc.h" +#include "avc.h" + +static int auxiliary_info_alloc_size(MOVMuxCencContext* ctx, int size) +{ + size_t new_alloc_size; + + if (ctx->auxiliary_info_size + size > ctx->auxiliary_info_alloc_size) { + new_alloc_size = FFMAX(ctx->auxiliary_info_size + size, ctx->auxiliary_info_alloc_size * 2); + if (av_reallocp(&ctx->auxiliary_info, new_alloc_size)) { + return AVERROR(ENOMEM); + } + + ctx->auxiliary_info_alloc_size = new_alloc_size; + } + + return 0; +} + +static int auxiliary_info_write(MOVMuxCencContext* ctx, + const uint8_t *buf_in, int size) +{ + int ret; + + ret = auxiliary_info_alloc_size(ctx, size); + if (ret) { + return ret; + } + memcpy(ctx->auxiliary_info + ctx->auxiliary_info_size, buf_in, size); + ctx->auxiliary_info_size += size; + + return 0; +} + +static int auxiliary_info_add_subsample(MOVMuxCencContext* ctx, + uint16_t clear_bytes, uint32_t encrypted_bytes) +{ + uint8_t* p; + int ret; + + if (!ctx->use_subsamples) { + return 0; + } + + ret = auxiliary_info_alloc_size(ctx, 6); + if (ret) { + return ret; + } + + p = ctx->auxiliary_info + ctx->auxiliary_info_size; + + AV_WB16(p, clear_bytes); + p += sizeof(uint16_t); + + AV_WB32(p, encrypted_bytes); + + ctx->auxiliary_info_size += 6; + ctx->subsample_count++; + + return 0; +} + +/** + * Encrypt the input buffer and write using avio_write + */ +static void mov_cenc_write_encrypted(MOVMuxCencContext* ctx, AVIOContext *pb, + const uint8_t *buf_in, int size) +{ + uint8_t chunk[4096]; + const uint8_t* cur_pos = buf_in; + int size_left = size; + int cur_size; + + while (size_left > 0) { + cur_size = FFMIN(size_left, sizeof(chunk)); + av_aes_ctr_crypt(ctx->aes_ctr, chunk, cur_pos, cur_size); + avio_write(pb, chunk, cur_size); + cur_pos += cur_size; + size_left -= cur_size; + } +} + +/** + * Start writing a packet + */ +static int mov_cenc_start_packet(MOVMuxCencContext* ctx) +{ + int ret; + + /* write the iv */ + ret = auxiliary_info_write(ctx, av_aes_ctr_get_iv(ctx->aes_ctr), AES_CTR_IV_SIZE); + if (ret) { + return ret; + } + + if (!ctx->use_subsamples) { + return 0; + } + + /* write a zero subsample count */ + ctx->auxiliary_info_subsample_start = ctx->auxiliary_info_size; + ctx->subsample_count = 0; + ret = auxiliary_info_write(ctx, (uint8_t*)&ctx->subsample_count, sizeof(ctx->subsample_count)); + if (ret) { + return ret; + } + + return 0; +} + +/** + * Finalize a packet + */ +static int mov_cenc_end_packet(MOVMuxCencContext* ctx) +{ + size_t new_alloc_size; + + av_aes_ctr_increment_iv(ctx->aes_ctr); + + if (!ctx->use_subsamples) { + ctx->auxiliary_info_entries++; + return 0; + } + + /* add the auxiliary info entry size*/ + if (ctx->auxiliary_info_entries >= ctx->auxiliary_info_sizes_alloc_size) { + new_alloc_size = ctx->auxiliary_info_entries * 2 + 1; + if (av_reallocp(&ctx->auxiliary_info_sizes, new_alloc_size)) { + return AVERROR(ENOMEM); + } + + ctx->auxiliary_info_sizes_alloc_size = new_alloc_size; + } + ctx->auxiliary_info_sizes[ctx->auxiliary_info_entries] = + AES_CTR_IV_SIZE + ctx->auxiliary_info_size - ctx->auxiliary_info_subsample_start; + ctx->auxiliary_info_entries++; + + /* update the subsample count*/ + AV_WB16(ctx->auxiliary_info + ctx->auxiliary_info_subsample_start, ctx->subsample_count); + + return 0; +} + +int ff_mov_cenc_write_packet(MOVMuxCencContext* ctx, AVIOContext *pb, + const uint8_t *buf_in, int size) +{ + int ret; + + ret = mov_cenc_start_packet(ctx); + if (ret) { + return ret; + } + + ret = auxiliary_info_add_subsample(ctx, 0, size); + if (ret) { + return ret; + } + + mov_cenc_write_encrypted(ctx, pb, buf_in, size); + + ret = mov_cenc_end_packet(ctx); + if (ret) { + return ret; + } + + return 0; +} + +int ff_mov_cenc_avc_parse_nal_units(MOVMuxCencContext* ctx, AVIOContext *pb, + const uint8_t *buf_in, int size) +{ + const uint8_t *p = buf_in; + const uint8_t *end = p + size; + const uint8_t *nal_start, *nal_end; + int ret; + + ret = mov_cenc_start_packet(ctx); + if (ret) { + return ret; + } + + size = 0; + nal_start = ff_avc_find_startcode(p, end); + for (;;) { + while (nal_start < end && !*(nal_start++)); + if (nal_start == end) + break; + + nal_end = ff_avc_find_startcode(nal_start, end); + + avio_wb32(pb, nal_end - nal_start); + avio_w8(pb, *nal_start); + mov_cenc_write_encrypted(ctx, pb, nal_start + 1, nal_end - nal_start - 1); + + auxiliary_info_add_subsample(ctx, 5, nal_end - nal_start - 1); + + size += 4 + nal_end - nal_start; + nal_start = nal_end; + } + + ret = mov_cenc_end_packet(ctx); + if (ret) { + return ret; + } + + return size; +} + +int ff_mov_cenc_avc_write_nal_units(AVFormatContext *s, MOVMuxCencContext* ctx, + int nal_length_size, AVIOContext *pb, const uint8_t *buf_in, int size) +{ + int nalsize; + int ret; + int j; + + ret = mov_cenc_start_packet(ctx); + if (ret) { + return ret; + } + + while (size > 0) { + /* parse the nal size */ + if (size < nal_length_size + 1) { + av_log(s, AV_LOG_ERROR, "CENC-AVC: remaining size %d smaller than nal length+type %d\n", + size, nal_length_size + 1); + return -1; + } + + avio_write(pb, buf_in, nal_length_size + 1); + + nalsize = 0; + for (j = 0; j < nal_length_size; j++) { + nalsize = (nalsize << 8) | *buf_in++; + } + size -= nal_length_size; + + /* encrypt the nal body */ + if (nalsize <= 0 || nalsize > size) { + av_log(s, AV_LOG_ERROR, "CENC-AVC: nal size %d remaining %d\n", nalsize, size); + return -1; + } + + mov_cenc_write_encrypted(ctx, pb, buf_in + 1, nalsize - 1); + buf_in += nalsize; + size -= nalsize; + + auxiliary_info_add_subsample(ctx, nal_length_size + 1, nalsize - 1); + } + + ret = mov_cenc_end_packet(ctx); + if (ret) { + return ret; + } + + return 0; +} + +/* TODO: reuse this function from movenc.c */ +static int64_t update_size(AVIOContext *pb, int64_t pos) +{ + int64_t curpos = avio_tell(pb); + avio_seek(pb, pos, SEEK_SET); + avio_wb32(pb, curpos - pos); /* rewrite size */ + avio_seek(pb, curpos, SEEK_SET); + + return curpos - pos; +} + +static int mov_cenc_write_senc_tag(MOVMuxCencContext* ctx, AVIOContext *pb, + int64_t* auxiliary_info_offset) +{ + int64_t pos = avio_tell(pb); + + avio_wb32(pb, 0); /* size */ + ffio_wfourcc(pb, "senc"); + avio_wb32(pb, ctx->use_subsamples ? 0x02 : 0); /* version & flags */ + avio_wb32(pb, ctx->auxiliary_info_entries); /* entry count */ + *auxiliary_info_offset = avio_tell(pb); + avio_write(pb, ctx->auxiliary_info, ctx->auxiliary_info_size); + return update_size(pb, pos); +} + +static int mov_cenc_write_saio_tag(AVIOContext *pb, int64_t auxiliary_info_offset) +{ + int64_t pos = avio_tell(pb); + uint8_t version; + + avio_wb32(pb, 0); /* size */ + ffio_wfourcc(pb, "saio"); + version = auxiliary_info_offset > 0xffffffff ? 1 : 0; + avio_w8(pb, version); + avio_wb24(pb, 0); /* flags */ + avio_wb32(pb, 1); /* entry count */ + if (version) { + avio_wb64(pb, auxiliary_info_offset); + } else { + avio_wb32(pb, auxiliary_info_offset); + } + return update_size(pb, pos); +} + +static int mov_cenc_write_saiz_tag(MOVMuxCencContext* ctx, AVIOContext *pb) +{ + int64_t pos = avio_tell(pb); + avio_wb32(pb, 0); /* size */ + ffio_wfourcc(pb, "saiz"); + avio_wb32(pb, 0); /* version & flags */ + avio_w8(pb, ctx->use_subsamples ? 0 : AES_CTR_IV_SIZE); /* default size*/ + avio_wb32(pb, ctx->auxiliary_info_entries); /* entry count */ + if (ctx->use_subsamples) { + avio_write(pb, ctx->auxiliary_info_sizes, ctx->auxiliary_info_entries); + } + return update_size(pb, pos); +} + +void ff_mov_cenc_write_stbl_atoms(MOVMuxCencContext* ctx, AVIOContext *pb) +{ + int64_t auxiliary_info_offset; + + mov_cenc_write_senc_tag(ctx, pb, &auxiliary_info_offset); + mov_cenc_write_saio_tag(pb, auxiliary_info_offset); + mov_cenc_write_saiz_tag(ctx, pb); +} + +static int mov_cenc_write_schi_tag(AVIOContext *pb, uint8_t* kid) +{ + int64_t pos = avio_tell(pb); + avio_wb32(pb, 0); /* size */ + ffio_wfourcc(pb, "schi"); + + avio_wb32(pb, 32); /* size */ + ffio_wfourcc(pb, "tenc"); + avio_wb32(pb, 0); /* version & flags */ + avio_wb24(pb, 1); /* is encrypted */ + avio_w8(pb, AES_CTR_IV_SIZE); /* iv size */ + avio_write(pb, kid, CENC_KID_SIZE); + + return update_size(pb, pos); +} + +int ff_mov_cenc_write_sinf_tag(MOVTrack* track, AVIOContext *pb, uint8_t* kid) +{ + int64_t pos = avio_tell(pb); + avio_wb32(pb, 0); /* size */ + ffio_wfourcc(pb, "sinf"); + + /* frma */ + avio_wb32(pb, 12); /* size */ + ffio_wfourcc(pb, "frma"); + avio_wl32(pb, track->tag); + + /* schm */ + avio_wb32(pb, 20); /* size */ + ffio_wfourcc(pb, "schm"); + avio_wb32(pb, 0); /* version & flags */ + ffio_wfourcc(pb, "cenc"); /* scheme type*/ + avio_wb32(pb, 0x10000); /* scheme version */ + + /* schi */ + mov_cenc_write_schi_tag(pb, kid); + + return update_size(pb, pos); +} + +int ff_mov_cenc_init(MOVMuxCencContext* ctx, uint8_t* encryption_key, + int use_subsamples, int bitexact) +{ + int ret; + + ctx->aes_ctr = av_aes_ctr_alloc(); + if (!ctx->aes_ctr) { + return AVERROR(ENOMEM); + } + + ret = av_aes_ctr_init(ctx->aes_ctr, encryption_key); + if (ret != 0) { + return ret; + } + + if (!bitexact) { + av_aes_ctr_set_random_iv(ctx->aes_ctr); + } + + ctx->use_subsamples = use_subsamples; + + return 0; +} + +void ff_mov_cenc_free(MOVMuxCencContext* ctx) +{ + av_aes_ctr_free(ctx->aes_ctr); +} -- cgit v1.2.3