Dmitry Eremin-Solenikov dbaryshkov@gmail.com writes:
Add CFB variant with 8-bit segment size.
Thanks. I'm fine with separate functions like you do, that seems to be the most straightforward interface.
+void +cfb8_decrypt(const void *ctx, nettle_cipher_func *f,
size_t block_size, uint8_t *iv,size_t length, uint8_t *dst,const uint8_t *src)+{
- TMP_DECL(buffer, uint8_t, NETTLE_MAX_CIPHER_BLOCK_SIZE * 2);
- TMP_DECL(outbuf, uint8_t, NETTLE_MAX_CIPHER_BLOCK_SIZE * 2);
- TMP_ALLOC(buffer, block_size * 2);
- TMP_ALLOC(outbuf, block_size * 2);
- uint8_t i = 0;
- memcpy(buffer, iv, block_size);
- memcpy(buffer + block_size, src,
length < block_size ? length : block_size);- while (length)
- {
for (i = 0; i < length && i < block_size; i++)- f(ctx, block_size, outbuf + i, buffer + i);
if (src != dst)- memxor3(dst, src, outbuf, i);
else- memxor(dst, outbuf, i);
If there's no other reason to handle src == dst and src != dst separately in this function, I think it's better to use memxor3 unconditionally.
diff --git a/nettle.texinfo b/nettle.texinfo index aa374449c527..e610e74c79ab 100644
+@node CFB8, , CFB, Cipher modes +@comment node-name, next, previous, up +@subsection Cipher Feedback 8-bit mode
+@cindex Cipher Feedback 8-bit Mode +@cindex CFB8 Mode
+Cipher Feedback 8-bit mode (@acronym{CFB8}) transforms block cipher into a stream +cipher. The message is encrypted byte after byte, not requiring any padding.
Do you think it would help the reader if the CFB and CFB8 docs were merged into a single section?
Regards, /Niels