One of the ciphers implementing AES algorithm is $-$aes$-128-$cbc$.$ What does the number $128$ represent? Supported ciphers: $-$aes$-128-$cbc $-$aes$-128-$cfb$8-$aes$-128-$ofb $-$aes$-192-$cfb$1-$aes$-192-$ecb $-$aes$-256-$cfb $-$aes$-256-$ctr $-$aes $128-$aes$192-$wrap $-$aria$-128-$cbc $-$aria$-128-$cfb$8-$aria$-128-$ofb $-$aria$-192-$cfb$1-$aria$-192-$ecb $-$aria$-256-$cfb $-$aria$-256-$ctr $-$aria$128-$bf $-$bf$-$ecb $-$camellia$-128-$cbc $-$camellia$-128-$cfb$8-$camellia$-128-$ofb $-$camellia$-192-$cfb$1-$camellia$-192-$ecb $-$camellia$-256-$cfb $-$camellia$-256-$ctr $-$Camellia$128-$cast $-$cast$5-$cfb $-$aes$-128-$cfb $-$aes$-128-$ctr $-$aes$-192-$cbc $-$aes$-192-$cfb$8-$aes$-192-$ofb $-$aes$-256-$cfb$1-$aes$-256-$ecb $-$aes$128-$wrap $-$aes$256-$aria$-128-$cfb $-$aria$-128-$ctr $-$aria$-192-$cbc $-$aria$-192-$cfb$8-$aria$-192-$ofb $-$aria$-256-$cfb$1-$aria$-256-$ecb $-$aria$192-$bf$-$cbc $-$bf$-$ofb $-$camellia$-128-$cfb $-$camellia$-128-$ctr $-$camellia$-192-$cbc $-$camellia$-192-$cfb$8-$camellia$-192-$ofb $-$camellia$-256-$cfb$1-$camellia$-256-$ecb $-$camellia$192-$cast$-$cbc $-$cast$5-$ecb $-$aes$-128-$cfb$1-$aes$-128-$ecb $-$aes$-192-$cfb $-$aes$-192-$ctr $-$aes$-256-$cbc $-$aes$-256-$cfb$8-$aes$-256-$ofb $-$aes $192-$aes$256-$wrap $-$aria$-128-$cfb$1-$aria$-128-$ecb $-$aria$-192-$cfb $-$aria$-192-$ctr $-$aria$-256-$cbc $-$aria$-256-$cfb$8-$aria$-256-$ofb $-$aria $256-$bf$-$cfb $-$blowfish $-$camellia$-128-$cfb$1-$camellia$-128-$ecb $-$camellia$-192-$cfb $-$camellia$-192-$ctr $-$camellia$-256-$cbc $-$camellia$-256-$cfb$8-$camellia$-256-$ofb $-$camellia$256-$cast$5-$cbc $-$cast$-$ofb