In message <000001c2aa3d$ed41bab0$7c03fdcb@the9note> on Mon, 23 Dec 2002 13:44:06
+0900, 김덕우\(Deokwu, Kim\) <[EMAIL PROTECTED]> said:
thenine> void AES_ctr128_encrypt(const unsigned char *in, unsigned char *out,
thenine> const unsigned long length, const AES_KEY *key,
thenine> unsigned char counter[AES_BLOCK_SIZE],
thenine> unsigned char ecount_buf[AES_BLOCK_SIZE],
thenine> unsigned int *num)
thenine>
thenine> The 'in' and 'out' is plaintext(ciphertext) and ciphertext(plaintext).
thenine> The 'key' is key value. The 'length' is block length value...
thenine> But I don't know the other value...(And How to decrypt the ciphertext?
thenine> The other mode use a value of 'AES_ENCRYPT' or 'AES_DECRYPT'.)
Since the counter mode requires certain temporary values to be held
between calls, you need to provide them. Those are two buffers (which
need to be initialised with '\0's) and a block offset indicator (so
the counter mode can be used as a stream cipher), which also needs to
be initialised to 0.
You decrypt with the encrypt function, since the encryption per se
really is just an XOR operation.
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