Where Does ADB Store Keys and Backups?
ADB keeps its host key pair in ~/.android/adbkey, while backup archives land wherever your -f flag pointed.
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ADB splits its files by role. The host key pair that your phone trusts lives in a fixed dot folder in your home directory, created automatically on first server start. Backup archives are the opposite: they go exactly where your -f flag says, defaulting to the current directory.
That split explains two classic confusions. A new key pair means the phone prompts for authorization again, and a missing .ab file usually means the terminal was in a different folder than assumed.
Where Android Debug Bridge stores this, by platform
%USERPROFILE%\.android\adbkey
Host private key with adbkey.pub beside it. Delete both and restart the server to trigger a fresh authorization prompt on the phone. Backup .ab files default to the folder the terminal was in when you ran adb backup.
~/.android/adbkey
Same key pair layout. The ANDROID_SDK_HOME variable can relocate the whole .android folder. Point -f at an explicit path like ~/backups/phone.ab so archives never land somewhere surprising.
~/.android/adbkey
Same arrangement. An .ab file is a compressed tar with a 24 byte header, so standard unzip tools choke on it; use an abe style extractor or strip the header first.
Frequently asked questions
where did my adb backup file go
Wherever your shell was standing. Without -f, adb backup writes backup.ab into the current directory. Rerun with adb backup -f ~/phone.ab to put the next one somewhere deliberate.
why is my phone asking to authorize adb again
The host key changed. A fresh ~/.android/adbkey was generated, or you switched users or machines. Accept the prompt on the phone and the new key is remembered.
how do i open an ab backup file
Strip the 24 byte header and decompress the rest as gzip into a tar, or use an Android Backup Extractor jar. Encrypted backups need the password you set when creating them.
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