CONVERSATION:
ABCDE FGHIJ KLMNO PQRST UUWXY Z
12345 678910 1112131415 1617181920 2122232425 26

STEP 1. Write out the message (HAIL ERIS) and put all the vowels at the end &(HLRSAIEI)

STEP 2. Reverse order (IEIASRLH)

STEP 3. Convert to numbers (9-5-9-1-19-18-12-8)

STEP 4. Put into numerical order (1-5-8-9-9-12-18-19)

STEP 5. Convert back to letters (AEHIILRS)

GUARANTEED TO BE 100% UNBREAKABLE.