Forum Discussion
Kevin_Stewart
Employee
EmployeeAES functions
Hello Devcentral gurus,
Does anyone know the specifics of the AES functions and how they work. Specifically, look at the following code snippet:
set testkey "test"
set testdat...
I know this is an old thread, but I wanted to answer the question from Scott about the key length above for anyone else landing here.
The AES::key command generates object represented as a list with 3 elements or a string in the format "AES (128 | 192 | 256) <32, 48, 64 HEX digits respectively>".
when RULE_INIT {
set secret_key [AES::key 128]
log local0. " of chars of key is [string length $secret_key]"
log local0. "Key as list: [list $secret_key]"
log local0. "Key as string: $secret_key"
}
Jul 8 06:01:51 info tmm1[4989]: Rule aes-key : of chars of key is 40
Jul 8 06:01:51 info tmm1[4989]: Rule aes-key : Key as list: {AES 128 679152125086aacfbc35ef2b1ede5abf}
Jul 8 06:01:51 info tmm1[4989]: Rule aes-key : Key as string: AES 128 679152125086aacfbc35ef2b1ede5abf
When specifying a key to the AES::encrypt or AES::decrypt commands it can either be a key object as generated by AES::key or a passphrase. If you generate a key using AES::key (or a string with the correct format) it will use that key for encryption and decryption.
A string that does not match the above format will be interpreted as a passphrase and will be used (along with random salt) to generate a key. This is where AES::decrypt is affected by ID224113.
So the extra 8 bytes you see in the string length is the "AES 128 " part of the string.
Hope this helps.
Jason