polarssl_rsa_verify_pss: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/polarssl_rsa_verify_pss - from package: libpolarssl-runtime

You may install the required package with command apt-get install {package}

Error in other languages:
polarssl_rsa_verify_pss: bevel nie gevind nie
polarssl_rsa_verify_pss: comandă negăsită
polarssl_rsa_verify_pss: comando não encontrado
polarssl_rsa_verify_pss: commande introuvable
polarssl_rsa_verify_pss: command not found
polarssl_rsa_verify_pss: käsku ei ole
polarssl_rsa_verify_pss: không tìm thấy lệnh
polarssl_rsa_verify_pss: komanda nerasta
polarssl_rsa_verify_pss: Kommando nicht gefunden.
polarssl_rsa_verify_pss: kommandot finns inte
polarssl_rsa_verify_pss: komut yok
polarssl_rsa_verify_pss: nie znaleziono polecenia
polarssl_rsa_verify_pss: níor aimsíodh an t-ordú
polarssl_rsa_verify_pss: no se encontró la orden
polarssl_rsa_verify_pss: no s'ha trobat l'ordre
polarssl_rsa_verify_pss: opdracht niet gevonden
polarssl_rsa_verify_pss: parancs nem található
polarssl_rsa_verify_pss: perintah tidak ditemukan
polarssl_rsa_verify_pss: príkaz nenájdený
polarssl_rsa_verify_pss: příkaz nenalezen
polarssl_rsa_verify_pss: команда не найдена
polarssl_rsa_verify_pss: командата не е открита
polarssl_rsa_verify_pss: 命令找不到
polarssl_rsa_verify_pss: コマンドが見つかりません