Generating the Cipher

Once the public key is retrieved and transmitted to the card user’s mobile, the application / device will need to generate a cipher - this should be a 24-character long random string. The mobile device should encrypt this cipher using the RSA public key, applying the AES encryption algorithm in CFB mode.

https://www.javainuse.com/rsagenerator

Enter Plain Text to Encrypt - store your own secret key that you will use for decryption of card secrets. In example: 123456789012345678904444

Enter Public/Private key - put here the public key from the get customer secure-key step.

MHwwDQYJKoZIhvcNAQEBBQADawAwaAJhAK0aDAVPR7arLZrjTibr1MsLxz6MgwnmjI963bLX1xsOqBtguO4IOHDqTc1t83zZXrikx6FWm4NS2SumXzeyYSA5PraQvemm/fwvFWwtroS3irP5wfAo6IxUh13+gp4+TwIDAQAB

Cipher type - RSA

Key Type - Public type