Goal

copy Signal from an old phone to a new phone without storing the content.

Prerequisites

• ADB with root on both phones
• attached to a linux via USB on both phones
• Signal installed on new phone but not started (or data wiped)

Steps

• List devices

olly@lnx:~$ adb devices
List of devices attached
oldDevice device (source)
newDevice device (target)

• Enable root shell

olly@lnx:~$ adb -s oldDevice root
olly@lnx:~$ adb -s newDevice root

• Show old permission

olly@lnx:~$ adb -s oldDevice shell ls -alZ /data/data/org.thoughtcrime.securesms/
total 160
drwxrwx--x 12 u0_a88 u0_a88 u:object_r:app_data_file:s0:c512,c768 4096 2018-01-01 00:00 .
drwxrwx--x 161 system system u:object_r:system_data_file:s0 1337 2018-01-01 00:00 ..
drwxrwx--x 2 u0_a88 u0_a88 u:object_r:app_data_file:s0:c512,c768 4096 2018-01-01 00:00 app_captures
drwxrwx--x 2 u0_a88 u0_a88 u:object_r:app_data_file:s0:c512,c768 4096 2018-01-01 00:00 app_download_internal
drwxrwx--x 2 u0_a88 u0_a88 u:object_r:app_data_file:s0:c512,c768 1337 2018-01-01 00:00 app_parts
drwxrwx--x 2 u0_a88 u0_a88 u:object_r:app_data_file:s0:c512,c768 4096 2018-01-01 00:00 app_textures
drwxrwx--x 2 u0_a88 u0_a88 u:object_r:app_data_file:s0:c512,c768 4096 2018-01-01 00:00 app_webview
drwxrwx--x 4 u0_a88 u0_a88 u:object_r:app_data_file:s0:c512,c768 4096 2018-01-01 00:00 cache
drwxrwx--x 2 u0_a88 u0_a88 u:object_r:app_data_file:s0:c512,c768 4096 2018-01-01 00:00 code_cache
drwxrwx--x 2 u0_a88 u0_a88 u:object_r:app_data_file:s0:c512,c768 4096 2018-01-01 00:00 databases
drwxrwx--x 6 u0_a88 u0_a88 u:object_r:app_data_file:s0:c512,c768 4096 2018-01-01 00:00 files
lrwxrwxrwx 1 root root ? 46 2018-01-01 00:00 lib -> /data/app/org.thoughtcrime.securesms-2/lib/arm
drwxrwx--x 2 u0_a88 u0_a88 u:object_r:app_data_file:s0:c512,c768 4096 2018-01-01 00:00 shared_prefs

• Show new permission

olly@lnx:~$ adb -s newDevice shell ls -alZ /data/data/org.thoughtcrime.securesms/
total 16
drwx------ 2 u0_a82 u0_a82 u:object_r:app_data_file:s0:c512,c768 4096 2018-01-01 00:00 .
drwxrwx--x 154 system system u:object_r:system_data_file:s0 1337 2018-01-01 00:00 ..
lrwxrwxrwx 1 root root u:object_r:app_data_file:s0 46 2018-01-01 00:00 lib -> /data/app/org.thoughtcrime.securesms-1/lib/arm

• Copy data

olly@lnx:~$ adb -s oldDevice shell cd /data/data/org.thoughtcrime.securesms/ \&\& find . -maxdepth 1 -mindepth 1 -not -type l \| tar cpf - --files-from - | adb -s newDevice shell tar xpf - -C /data/data/org.thoughtcrime.securesms

• Copy key material

olly@lnx:~$ adb -s oldDevice shell tar cpf - /data/misc/keystore/user_0/.10088_chr_USRSKEY_SignalSecret | adb -s newDevice shell tar xpf - -C /data/misc/keystore/user_0/.10082_chr_USRSKEY_SignalSecret
olly@lnx:~$ adb -s oldDevice shell tar cpf - /data/misc/keystore/user_0/10088_USRSKEY_SignalSecret | adb -s newDevice shell tar xpf - -C /data/misc/keystore/user_0/10082_USRSKEY_SignalSecret

• Adapt permissions

olly@lnx:~$ adb -s newDevice shell cd /data/data/org.thoughtcrime.securesms/ \&\& find . -maxdepth 1 -mindepth 1 -not -type l -exec chown u0_a82:u0_a82 {} -R \;
olly@lnx:~$ adb -s newDevice shell chown u0_a82:u0_a82_cache /data/data/org.thoughtcrime.securesms/cache -R

olly@lnx:~$ adb -s newDevice shell chown keystore:keystore /data/misc/keystore/user_0/.10082_chr_USRSKEY_SignalSecret
olly@lnx:~$ adb -s newDevice shell chown keystore:keystore /data/misc/keystore/user_0/10082_USRSKEY_SignalSecret

• Adapt SELinux

olly@lnx:~$ adb -s newDevice shell cd /data/data/org.thoughtcrime.securesms/ \&\& find . -maxdepth 1 -mindepth 1 -not -type l -exec chcon u:object_r:app_data_file:s0:c512,c768 {} -R \;