Bitcoin Wallet for Android – permission denied decrypting the wallet backup file using OpenSSL

I’ve followed the advice found on the https://github.com/bitcoin-wallet/bitcoin-wallet/blob/master/wallet/README.recover.md, but I’m having issues decrypted a wallet backup file

When I run below line

openssl enc -d -aes-256-cbc -md md5 -a -in Bitcoin-wallet-backup-2017-12-25 > bitcoin-wallet-decrypted-backup

I got below error message

$ openssl enc -d -aes-256-cbc -md md5 -a -in bitcoin-wallet-backup-2017-12-25 > bitcoin-wallet-decrypted-backup 
bitcoin-wallet-backup-2017-12-25: Permission denied 
140623991867032:error:0200100D:system library:fopen:Permission denied:bss_file.c:398:fopen('bitcoin-wallet-backup-2017-12-25','r') 
140623991867032:error:20074002:BIO routines:FILE_CTRL:system lib:bss_file.c:400:

Is there something wrong?