Patent ID: 7424112

Claim:
A method comprising: generating intermediate ciphertext from syntax compliant plaintext; post-processing the intermediate ciphertext to determine if there are any illegal symbols in the intermediate ciphertext; responsive to identifying an illegal symbol, switching the illegal symbol with a corresponding plaintext symbol to create a switched corresponding plaintext symbol; and responsive to switching the illegal symbol with a corresponding plaintext symbol: (a) decrypting symbol(s) backwards from the switched plaintext symbol to a preceding delimiting symbol of the intermediate ciphertext to detect any symbol that cannot be decrypted to a syntax compliant symbol; (b) responsive to detecting a symbol that cannot be decrypted to a syntax compliant symbol, replacing the symbol and all symbol(s) between the symbol and the switched corresponding plaintext symbol, with a respective corresponding plaintext symbol; and (c) if the symbol was not a preceding delimiting symbol, repeating steps (a) and (b), wherein operations of post-processing the intermediate ciphertext and one or more iterations of switching the illegal symbol with a corresponding plaintext symbol generate syntax compliant ciphertext from non-syntax compliant ciphertext.