Encrypts data in a streaming fashion. Hand consecutive blocks of data to
the update method in
order to encrypt it. Returns the
encrypted data chunk. When done, the output of Cipher#final should be
additionally added to the result.
Parameters
data is a nonempty string. buffer is an optional string
to store the result.
static VALUE
ossl_cipher_update(int argc, VALUE *argv, VALUE self)
{
EVP_CIPHER_CTX *ctx;
unsigned char *in;
int in_len, out_len;
VALUE data, str;
rb_scan_args(argc, argv, "11", &data, &str);
StringValue(data);
in = (unsigned char *)RSTRING_PTR(data);
if ((in_len = RSTRING_LENINT(data)) == 0)
ossl_raise(rb_eArgError, "data must not be empty");
GetCipher(self, ctx);
out_len = in_len+EVP_CIPHER_CTX_block_size(ctx);
if (NIL_P(str)) {
str = rb_str_new(0, out_len);
} else {
StringValue(str);
rb_str_resize(str, out_len);
}
if (!EVP_CipherUpdate(ctx, (unsigned char *)RSTRING_PTR(str), &out_len, in, in_len))
ossl_raise(eCipherError, NULL);
assert(out_len < RSTRING_LEN(str));
rb_str_set_len(str, out_len);
return str;
}