mirror of
https://github.com/oxen-io/session-android.git
synced 2024-11-25 11:05:25 +00:00
98 lines
2.8 KiB
C++
98 lines
2.8 KiB
C++
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#include "SrtpStream.h"
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#include <android/log.h>
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#include <unistd.h>
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#define AES_BLOCK_SIZE 16
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#define TAG "SrtpStream"
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SrtpStream::SrtpStream(SrtpStreamParameters *parameters) :
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parameters(parameters)
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{}
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SrtpStream::~SrtpStream() {
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if (parameters != NULL) {
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delete parameters;
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}
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}
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int SrtpStream::init() {
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if (AES_set_encrypt_key(parameters->cipherKey, SRTP_AES_KEY_SIZE * 8, &key) != 0) {
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__android_log_print(ANDROID_LOG_WARN, TAG, "Failed to set AES key!");
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return -1;
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}
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return 0;
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}
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void SrtpStream::setIv(int64_t logicalSequence, uint32_t ssrc, uint8_t *salt, uint8_t *iv) {
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memset(iv, 0, AES_BLOCK_SIZE);
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memcpy(iv, salt, SRTP_SALT_SIZE);
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iv[6] ^= (uint8_t)(ssrc >> 8);
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iv[7] ^= (uint8_t)(ssrc);
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iv[8] ^= (uint8_t)(logicalSequence >> 40);
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iv[9] ^= (uint8_t)(logicalSequence >> 32);
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iv[10] ^= (uint8_t)(logicalSequence >> 24);
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iv[11] ^= (uint8_t)(logicalSequence >> 16);
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iv[12] ^= (uint8_t)(logicalSequence >> 8);
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iv[13] ^= (uint8_t)(logicalSequence);
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}
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int SrtpStream::decrypt(RtpPacket &packet, int64_t logicalSequence) {
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uint8_t iv[AES_BLOCK_SIZE];
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uint8_t ecount[AES_BLOCK_SIZE];
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uint8_t ourMac[SRTP_MAC_SIZE];
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uint32_t num = 0;
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uint32_t digest = 0;
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setIv(logicalSequence, packet.getSsrc(), parameters->salt, iv);
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memset(ecount, 0, sizeof(ecount));
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if (packet.getPayloadLen() < (SRTP_MAC_SIZE + 1)) {
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__android_log_print(ANDROID_LOG_WARN, TAG, "Packet shorter than MAC!");
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return -1;
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}
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HMAC(EVP_sha1(), parameters->macKey, SRTP_MAC_KEY_SIZE,
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(uint8_t*)packet.getSerializedPacket(), packet.getSerializedPacketLen() - SRTP_MAC_SIZE, ourMac, &digest);
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if (memcmp(ourMac, packet.getSerializedPacket() + packet.getSerializedPacketLen() - SRTP_MAC_SIZE,
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SRTP_MAC_SIZE) != 0)
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{
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__android_log_print(ANDROID_LOG_WARN, TAG, "MAC comparison failed!");
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return -1;
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}
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packet.setPayloadLen(packet.getPayloadLen() - SRTP_MAC_SIZE);
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AES_ctr128_encrypt((uint8_t*)packet.getPayload(), (uint8_t*)packet.getPayload(),
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packet.getPayloadLen(), &key, iv, ecount, &num);
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return 0;
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}
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int SrtpStream::encrypt(RtpPacket &packet, int64_t logicalSequence) {
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uint8_t iv[AES_BLOCK_SIZE];
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uint8_t ecount[AES_BLOCK_SIZE];
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uint32_t num = 0;
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uint32_t digest = 0;
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setIv(logicalSequence, packet.getSsrc(), parameters->salt, iv);
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memset(ecount, 0, sizeof(ecount));
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AES_ctr128_encrypt((uint8_t*)packet.getPayload(), (uint8_t*)packet.getPayload(), packet.getPayloadLen(), &key, iv, ecount, &num);
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HMAC(EVP_sha1(), parameters->macKey, SRTP_MAC_KEY_SIZE,
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(uint8_t*)packet.getSerializedPacket(), packet.getSerializedPacketLen(),
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(uint8_t*)packet.getSerializedPacket() + packet.getSerializedPacketLen(), &digest);
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packet.setPayloadLen(packet.getPayloadLen() + SRTP_MAC_SIZE);
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return 0;
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}
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