I also noticed problems using an RSA key in AndFTP and found one way out which might also work for you. To use the private key in AndFTP, it must be readable with openssl, e.g.: $ openssl rsa -in rsa-mobil-private.txt -noout -text Private-Key: (1024 bit) modulus: 00:d4:78:17:b5:56:44:2f:4a:1c:56:03:...