ECC and RSA > 2048 is indeed supported. However, you have to switch the applet into the correct key mode before importing an existing key, see flexsecure-applets/docs/applets/1-pgp.md at master · DangerousThings/flexsecure-applets · GitHub . You can use the tool at SmartPGP/bin at master · github-af/SmartPGP · GitHub . Tested algorithms include: p256, p384, p521 and rsa2048, rsa3072, rsa4096 .