sparkencrypt1 definition

Prefix: (bold, inverse, underline, inverse, inverse, clear, bold, color 00, color 00)
  02 16 1f 16 16 0f 02 03 30 30 03 30 30
Keys (given in decimal as two bytes from 00 to 15 encoding one nybble):
  03 xx xx 03 yy yy 0f

Key X: Top two bits specify an operation number from 0 to 3
Key Y: Value to use for the operation

The operations only change the bottom nybble of each character in the encrypted message,
and anything under character 0x20 is left completely alone. SE1 does *not* do any special
handling on UTF-8 or anything beyond 0x7f so it's advised to stick to regular ASCII chars.

Operations (encrypting):
0: xor with 15, add key Y
1: add key Y
2: xor with 15, subtract key Y
3: subtract key Y

Operations (decrypting):
0: subtract key Y, xor with 15
1: subtract key Y
2: add key Y, xor with 15
3: add key Y