1 files changed, 471 insertions, 0 deletions
diff --git a/ffmpeg/libavformat/srtp.c b/ffmpeg/libavformat/srtp.c
new file mode 100644
index 0000000..65309d0
--- /dev/null
+++ b/ffmpeg/libavformat/srtp.c
@@ -0,0 +1,471 @@
+/*
+ * SRTP encryption/decryption
+ * Copyright (c) 2012 Martin Storsjo
+ *
+ * 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 "libavutil/base64.h"
+#include "libavutil/aes.h"
+#include "libavutil/hmac.h"
+#include "libavutil/intreadwrite.h"
+#include "libavutil/log.h"
+#include "rtp.h"
+#include "srtp.h"
+
+void ff_srtp_free(struct SRTPContext *s)
+{
+    if (!s)
+        return;
+    av_freep(&s->aes);
+    if (s->hmac)
+        av_hmac_free(s->hmac);
+    s->hmac = NULL;
+}
+
+static void encrypt_counter(struct AVAES *aes, uint8_t *iv, uint8_t *outbuf,
+                            int outlen)
+{
+    int i, j, outpos;
+    for (i = 0, outpos = 0; outpos < outlen; i++) {
+        uint8_t keystream[16];
+        AV_WB16(&iv[14], i);
+        av_aes_crypt(aes, keystream, iv, 1, NULL, 0);
+        for (j = 0; j < 16 && outpos < outlen; j++, outpos++)
+            outbuf[outpos] ^= keystream[j];
+    }
+}
+
+static void derive_key(struct AVAES *aes, const uint8_t *salt, int label,
+                       uint8_t *out, int outlen)
+{
+    uint8_t input[16] = { 0 };
+    memcpy(input, salt, 14);
+    // Key derivation rate assumed to be zero
+    input[14 - 7] ^= label;
+    memset(out, 0, outlen);
+    encrypt_counter(aes, input, out, outlen);
+}
+
+int ff_srtp_set_crypto(struct SRTPContext *s, const char *suite,
+                       const char *params)
+{
+    uint8_t buf[30];
+
+    ff_srtp_free(s);
+
+    // RFC 4568
+    if (!strcmp(suite, "AES_CM_128_HMAC_SHA1_80") ||
+        !strcmp(suite, "SRTP_AES128_CM_HMAC_SHA1_80")) {
+        s->rtp_hmac_size = s->rtcp_hmac_size = 10;
+    } else if (!strcmp(suite, "AES_CM_128_HMAC_SHA1_32")) {
+        s->rtp_hmac_size = s->rtcp_hmac_size = 4;
+    } else if (!strcmp(suite, "SRTP_AES128_CM_HMAC_SHA1_32")) {
+        // RFC 5764 section 4.1.2
+        s->rtp_hmac_size  = 4;
+        s->rtcp_hmac_size = 10;
+    } else {
+        av_log(NULL, AV_LOG_WARNING, "SRTP Crypto suite %s not supported\n",
+                                     suite);
+        return AVERROR(EINVAL);
+    }
+    if (av_base64_decode(buf, params, sizeof(buf)) != sizeof(buf)) {
+        av_log(NULL, AV_LOG_WARNING, "Incorrect amount of SRTP params\n");
+        return AVERROR(EINVAL);
+    }
+    // MKI and lifetime not handled yet
+    s->aes  = av_aes_alloc();
+    s->hmac = av_hmac_alloc(AV_HMAC_SHA1);
+    if (!s->aes || !s->hmac)
+        return AVERROR(ENOMEM);
+    memcpy(s->master_key, buf, 16);
+    memcpy(s->master_salt, buf + 16, 14);
+
+    // RFC 3711
+    av_aes_init(s->aes, s->master_key, 128, 0);
+
+    derive_key(s->aes, s->master_salt, 0x00, s->rtp_key, sizeof(s->rtp_key));
+    derive_key(s->aes, s->master_salt, 0x02, s->rtp_salt, sizeof(s->rtp_salt));
+    derive_key(s->aes, s->master_salt, 0x01, s->rtp_auth, sizeof(s->rtp_auth));
+
+    derive_key(s->aes, s->master_salt, 0x03, s->rtcp_key, sizeof(s->rtcp_key));
+    derive_key(s->aes, s->master_salt, 0x05, s->rtcp_salt, sizeof(s->rtcp_salt));
+    derive_key(s->aes, s->master_salt, 0x04, s->rtcp_auth, sizeof(s->rtcp_auth));
+    return 0;
+}
+
+static void create_iv(uint8_t *iv, const uint8_t *salt, uint64_t index,
+                      uint32_t ssrc)
+{
+    uint8_t indexbuf[8];
+    int i;
+    memset(iv, 0, 16);
+    AV_WB32(&iv[4], ssrc);
+    AV_WB64(indexbuf, index);
+    for (i = 0; i < 8; i++) // index << 16
+        iv[6 + i] ^= indexbuf[i];
+    for (i = 0; i < 14; i++)
+        iv[i] ^= salt[i];
+}
+
+int ff_srtp_decrypt(struct SRTPContext *s, uint8_t *buf, int *lenptr)
+{
+    uint8_t iv[16] = { 0 }, hmac[20];
+    int len = *lenptr;
+    int av_uninit(seq_largest);
+    uint32_t ssrc, av_uninit(roc);
+    uint64_t index;
+    int rtcp, hmac_size;
+
+    // TODO: Missing replay protection
+
+    if (len < 2)
+        return AVERROR_INVALIDDATA;
+
+    rtcp = RTP_PT_IS_RTCP(buf[1]);
+    hmac_size = rtcp ? s->rtcp_hmac_size : s->rtp_hmac_size;
+
+    if (len < hmac_size)
+        return AVERROR_INVALIDDATA;
+
+    // Authentication HMAC
+    av_hmac_init(s->hmac, rtcp ? s->rtcp_auth : s->rtp_auth, sizeof(s->rtp_auth));
+    // If MKI is used, this should exclude the MKI as well
+    av_hmac_update(s->hmac, buf, len - hmac_size);
+
+    if (!rtcp) {
+        int seq = AV_RB16(buf + 2);
+        uint32_t v;
+        uint8_t rocbuf[4];
+
+        // RFC 3711 section 3.3.1, appendix A
+        seq_largest = s->seq_initialized ? s->seq_largest : seq;
+        v = roc = s->roc;
+        if (seq_largest < 32768) {
+            if (seq - seq_largest > 32768)
+                v = roc - 1;
+        } else {
+            if (seq_largest - 32768 > seq)
+                v = roc + 1;
+        }
+        if (v == roc) {
+            seq_largest = FFMAX(seq_largest, seq);
+        } else if (v == roc + 1) {
+            seq_largest = seq;
+            roc = v;
+        }
+        index = seq + (((uint64_t)v) << 16);
+
+        AV_WB32(rocbuf, roc);
+        av_hmac_update(s->hmac, rocbuf, 4);
+    }
+
+    av_hmac_final(s->hmac, hmac, sizeof(hmac));
+    if (memcmp(hmac, buf + len - hmac_size, hmac_size)) {
+        av_log(NULL, AV_LOG_WARNING, "HMAC mismatch\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    len -= hmac_size;
+    *lenptr = len;
+
+    if (len < 12)
+        return AVERROR_INVALIDDATA;
+
+    if (rtcp) {
+        uint32_t srtcp_index = AV_RB32(buf + len - 4);
+        len -= 4;
+        *lenptr = len;
+
+        ssrc = AV_RB32(buf + 4);
+        index = srtcp_index & 0x7fffffff;
+
+        buf += 8;
+        len -= 8;
+        if (!(srtcp_index & 0x80000000))
+            return 0;
+    } else {
+        int ext, csrc;
+        s->seq_initialized = 1;
+        s->seq_largest     = seq_largest;
+        s->roc             = roc;
+
+        csrc = buf[0] & 0x0f;
+        ext  = buf[0] & 0x10;
+        ssrc = AV_RB32(buf + 8);
+
+        buf += 12;
+        len -= 12;
+
+        buf += 4 * csrc;
+        len -= 4 * csrc;
+        if (len < 0)
+            return AVERROR_INVALIDDATA;
+
+        if (ext) {
+            if (len < 4)
+                return AVERROR_INVALIDDATA;
+            ext = (AV_RB16(buf + 2) + 1) * 4;
+            if (len < ext)
+                return AVERROR_INVALIDDATA;
+            len -= ext;
+            buf += ext;
+        }
+    }
+
+    create_iv(iv, rtcp ? s->rtcp_salt : s->rtp_salt, index, ssrc);
+    av_aes_init(s->aes, rtcp ? s->rtcp_key : s->rtp_key, 128, 0);
+    encrypt_counter(s->aes, iv, buf, len);
+
+    return 0;
+}
+
+int ff_srtp_encrypt(struct SRTPContext *s, const uint8_t *in, int len,
+                    uint8_t *out, int outlen)
+{
+    uint8_t iv[16] = { 0 }, hmac[20];
+    uint64_t index;
+    uint32_t ssrc;
+    int rtcp, hmac_size, padding;
+    uint8_t *buf;
+
+    if (len < 8)
+        return AVERROR_INVALIDDATA;
+
+    rtcp = RTP_PT_IS_RTCP(in[1]);
+    hmac_size = rtcp ? s->rtcp_hmac_size : s->rtp_hmac_size;
+    padding = hmac_size;
+    if (rtcp)
+        padding += 4; // For the RTCP index
+
+    if (len + padding > outlen)
+        return 0;
+
+    memcpy(out, in, len);
+    buf = out;
+
+    if (rtcp) {
+        ssrc = AV_RB32(buf + 4);
+        index = s->rtcp_index++;
+
+        buf += 8;
+        len -= 8;
+    } else {
+        int ext, csrc;
+        int seq = AV_RB16(buf + 2);
+
+        if (len < 12)
+            return AVERROR_INVALIDDATA;
+
+        ssrc = AV_RB32(buf + 8);
+
+        if (seq < s->seq_largest)
+            s->roc++;
+        s->seq_largest = seq;
+        index = seq + (((uint64_t)s->roc) << 16);
+
+        csrc = buf[0] & 0x0f;
+        ext = buf[0] & 0x10;
+
+        buf += 12;
+        len -= 12;
+
+        buf += 4 * csrc;
+        len -= 4 * csrc;
+        if (len < 0)
+            return AVERROR_INVALIDDATA;
+
+        if (ext) {
+            if (len < 4)
+                return AVERROR_INVALIDDATA;
+            ext = (AV_RB16(buf + 2) + 1) * 4;
+            if (len < ext)
+                return AVERROR_INVALIDDATA;
+            len -= ext;
+            buf += ext;
+        }
+    }
+
+    create_iv(iv, rtcp ? s->rtcp_salt : s->rtp_salt, index, ssrc);
+    av_aes_init(s->aes, rtcp ? s->rtcp_key : s->rtp_key, 128, 0);
+    encrypt_counter(s->aes, iv, buf, len);
+
+    if (rtcp) {
+        AV_WB32(buf + len, 0x80000000 | index);
+        len += 4;
+    }
+
+    av_hmac_init(s->hmac, rtcp ? s->rtcp_auth : s->rtp_auth, sizeof(s->rtp_auth));
+    av_hmac_update(s->hmac, out, buf + len - out);
+    if (!rtcp) {
+        uint8_t rocbuf[4];
+        AV_WB32(rocbuf, s->roc);
+        av_hmac_update(s->hmac, rocbuf, 4);
+    }
+    av_hmac_final(s->hmac, hmac, sizeof(hmac));
+
+    memcpy(buf + len, hmac, hmac_size);
+    len += hmac_size;
+    return buf + len - out;
+}
+
+#ifdef TEST
+#include <stdio.h>
+
+static const char *aes128_80_key = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmn";
+
+static const uint8_t rtp_aes128_80[] = {
+    // RTP header
+    0x80, 0xe0, 0x12, 0x34, 0x12, 0x34, 0x56, 0x78, 0x12, 0x34, 0x56, 0x78,
+    // encrypted payload
+    0x62, 0x69, 0x76, 0xca, 0xc5,
+    // HMAC
+    0xa1, 0xac, 0x1b, 0xb4, 0xa0, 0x1c, 0xd5, 0x49, 0x28, 0x99,
+};
+
+static const uint8_t rtcp_aes128_80[] = {
+    // RTCP header
+    0x81, 0xc9, 0x00, 0x07, 0x12, 0x34, 0x56, 0x78,
+    // encrypted payload
+    0x8a, 0xac, 0xdc, 0xa5, 0x4c, 0xf6, 0x78, 0xa6, 0x62, 0x8f, 0x24, 0xda,
+    0x6c, 0x09, 0x3f, 0xa9, 0x28, 0x7a, 0xb5, 0x7f, 0x1f, 0x0f, 0xc9, 0x35,
+    // RTCP index
+    0x80, 0x00, 0x00, 0x03,
+    // HMAC
+    0xe9, 0x3b, 0xc0, 0x5c, 0x0c, 0x06, 0x9f, 0xab, 0xc0, 0xde,
+};
+
+static const char *aes128_32_key = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmn";
+
+static const uint8_t rtp_aes128_32[] = {
+    // RTP header
+    0x80, 0xe0, 0x12, 0x34, 0x12, 0x34, 0x56, 0x78, 0x12, 0x34, 0x56, 0x78,
+    // encrypted payload
+    0x62, 0x69, 0x76, 0xca, 0xc5,
+    // HMAC
+    0xa1, 0xac, 0x1b, 0xb4,
+};
+
+static const uint8_t rtcp_aes128_32[] = {
+    // RTCP header
+    0x81, 0xc9, 0x00, 0x07, 0x12, 0x34, 0x56, 0x78,
+    // encrypted payload
+    0x35, 0xe9, 0xb5, 0xff, 0x0d, 0xd1, 0xde, 0x70, 0x74, 0x10, 0xaa, 0x1b,
+    0xb2, 0x8d, 0xf0, 0x20, 0x02, 0x99, 0x6b, 0x1b, 0x0b, 0xd0, 0x47, 0x34,
+    // RTCP index
+    0x80, 0x00, 0x00, 0x04,
+    // HMAC
+    0x5b, 0xd2, 0xa9, 0x9d,
+};
+
+static const char *aes128_80_32_key = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmn";
+
+static const uint8_t rtp_aes128_80_32[] = {
+    // RTP header
+    0x80, 0xe0, 0x12, 0x34, 0x12, 0x34, 0x56, 0x78, 0x12, 0x34, 0x56, 0x78,
+    // encrypted payload
+    0x62, 0x69, 0x76, 0xca, 0xc5,
+    // HMAC
+    0xa1, 0xac, 0x1b, 0xb4,
+};
+
+static const uint8_t rtcp_aes128_80_32[] = {
+    // RTCP header
+    0x81, 0xc9, 0x00, 0x07, 0x12, 0x34, 0x56, 0x78,
+    // encrypted payload
+    0xd6, 0xae, 0xc1, 0x58, 0x63, 0x70, 0xc9, 0x88, 0x66, 0x26, 0x1c, 0x53,
+    0xff, 0x5d, 0x5d, 0x2b, 0x0f, 0x8c, 0x72, 0x3e, 0xc9, 0x1d, 0x43, 0xf9,
+    // RTCP index
+    0x80, 0x00, 0x00, 0x05,
+    // HMAC
+    0x09, 0x16, 0xb4, 0x27, 0x9a, 0xe9, 0x92, 0x26, 0x4e, 0x10,
+};
+
+static void print_data(const uint8_t *buf, int len)
+{
+    int i;
+    for (i = 0; i < len; i++)
+        printf("%02x", buf[i]);
+    printf("\n");
+}
+
+static int test_decrypt(struct SRTPContext *srtp, const uint8_t *in, int len,
+                        uint8_t *out)
+{
+    memcpy(out, in, len);
+    if (!ff_srtp_decrypt(srtp, out, &len)) {
+        print_data(out, len);
+        return len;
+    } else
+        return -1;
+}
+
+static void test_encrypt(const uint8_t *data, int in_len, const char *suite,
+                         const char *key)
+{
+    struct SRTPContext enc = { 0 }, dec = { 0 };
+    int len;
+    char buf[1500];
+    ff_srtp_set_crypto(&enc, suite, key);
+    ff_srtp_set_crypto(&dec, suite, key);
+    len = ff_srtp_encrypt(&enc, data, in_len, buf, sizeof(buf));
+    if (!ff_srtp_decrypt(&dec, buf, &len)) {
+        if (len == in_len && !memcmp(buf, data, len))
+            printf("Decrypted content matches input\n");
+        else
+            printf("Decrypted content doesn't match input\n");
+    } else {
+        printf("Decryption failed\n");
+    }
+    ff_srtp_free(&enc);
+    ff_srtp_free(&dec);
+}
+
+int main(void)
+{
+    static const char *aes128_80_suite = "AES_CM_128_HMAC_SHA1_80";
+    static const char *aes128_32_suite = "AES_CM_128_HMAC_SHA1_32";
+    static const char *aes128_80_32_suite = "SRTP_AES128_CM_HMAC_SHA1_32";
+    static const char *test_key = "abcdefghijklmnopqrstuvwxyz1234567890ABCD";
+    uint8_t buf[1500];
+    struct SRTPContext srtp = { 0 };
+    int len;
+    ff_srtp_set_crypto(&srtp, aes128_80_suite, aes128_80_key);
+    len = test_decrypt(&srtp, rtp_aes128_80, sizeof(rtp_aes128_80), buf);
+    test_encrypt(buf, len, aes128_80_suite, test_key);
+    test_encrypt(buf, len, aes128_32_suite, test_key);
+    test_encrypt(buf, len, aes128_80_32_suite, test_key);
+    test_decrypt(&srtp, rtcp_aes128_80, sizeof(rtcp_aes128_80), buf);
+    test_encrypt(buf, len, aes128_80_suite, test_key);
+    test_encrypt(buf, len, aes128_32_suite, test_key);
+    test_encrypt(buf, len, aes128_80_32_suite, test_key);
+    ff_srtp_free(&srtp);
+
+    memset(&srtp, 0, sizeof(srtp)); // Clear the context
+    ff_srtp_set_crypto(&srtp, aes128_32_suite, aes128_32_key);
+    test_decrypt(&srtp, rtp_aes128_32, sizeof(rtp_aes128_32), buf);
+    test_decrypt(&srtp, rtcp_aes128_32, sizeof(rtcp_aes128_32), buf);
+    ff_srtp_free(&srtp);
+
+    memset(&srtp, 0, sizeof(srtp)); // Clear the context
+    ff_srtp_set_crypto(&srtp, aes128_80_32_suite, aes128_80_32_key);
+    test_decrypt(&srtp, rtp_aes128_80_32, sizeof(rtp_aes128_80_32), buf);
+    test_decrypt(&srtp, rtcp_aes128_80_32, sizeof(rtcp_aes128_80_32), buf);
+    ff_srtp_free(&srtp);
+    return 0;
+}
+#endif /* TEST */