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rust: Split AES into three parts, setup, process data and finish

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Might want to re-use the setup/finish code for streaming data and/or DMA.
This commit is contained in:
Wladimir J. van der Laan 2020-04-30 15:36:14 +00:00
parent 68ddf3b1bc
commit e080a03821
1 changed files with 64 additions and 36 deletions
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90
rust/k210-shared/src/soc/aes.rs
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@ -30,30 +30,16 @@ fn write4pad(arr: &mut [u8], ofs: usize, val: u32) {
arr[ofs..ofs+n].copy_from_slice(&val.to_le_bytes()[0..n]);
}
/** AES operation (encrypt or decrypt) using hardware engine. Takes a &mut
* AES as only one operation can be active at a time.
*
* Supported modes:
*
* Mode Keybits Extra input Extra output
* ---- --------------- ------------------------ ----------------
* ECB 128 / 192 / 256 no IV
* CBC 128 / 192 / 256 128 bit IV
* GCM 128 / 192 / 256 96 bit IV + ? bytes AAD) 128 bit tag (optional)
*/
pub fn run(
fn setup(
aes: &mut pac::AES,
cipher_mode: cipher_mode,
encrypt_sel: encrypt_sel,
key: &[u8],
iv: &[u8],
aad: &[u8],
ind: &[u8],
outd: &mut [u8],
tag: &mut [u8],
)
{
assert!(ind.len() != 0);
len: usize,
) {
assert!(len != 0);
match cipher_mode {
cipher_mode::ECB => assert!(iv.len() == 0 && aad.len() == 0),
cipher_mode::CBC => assert!(iv.len() == 16 && aad.len() == 0),
@ -89,7 +75,7 @@ pub fn run(
aes.encrypt_sel.write(|w|
w.encrypt_sel().variant(encrypt_sel));
aes.aad_num.write(|w| w.bits((aad.len() as u32).wrapping_sub(1)));
aes.pc_num.write(|w| w.bits((ind.len() as u32).wrapping_sub(1)));
aes.pc_num.write(|w| w.bits((len as u32).wrapping_sub(1)));
// Turn on engine
aes.en.write(|w|
@ -103,21 +89,16 @@ pub fn run(
aes.aad_data.write(|w| w.bits(read4pad(aad, i * 4)));
}
// Send and receive plaintext/ciphertext
let mut iptr = 0;
let mut optr = 0;
while optr < ind.len() {
while iptr < ind.len() && aes.data_in_flag.read().data_in_flag() == DATA_IN_FLAG_A::CAN_INPUT {
aes.text_data.write(|w| w.bits(read4pad(ind, iptr)));
iptr += 4;
}
while aes.data_out_flag.read().data_out_flag() == DATA_OUT_FLAG_A::CAN_OUTPUT {
write4pad(outd, optr, aes.out_data.read().bits());
optr += 4;
}
}
if cipher_mode == cipher_mode::GCM && tag.len() != 0 {
fn finish(
aes: &mut pac::AES,
cipher_mode: cipher_mode,
tag: &mut [u8],
) {
unsafe {
if cipher_mode == cipher_mode::GCM {
// Read and store tag, if requested
// TODO: the engine also supports writing a tag through gcm_in_tag
// and verifying it, presumably in linear time.
@ -134,11 +115,13 @@ pub fn run(
atomic::compiler_fence(Ordering::SeqCst)
}
if tag.len() != 0 {
for i in 0..4 {
let val = aes.gcm_out_tag[3 - i].read().bits();
tag[i*4..i*4+4].copy_from_slice(&val.to_be_bytes());
}
}
}
// Wait until AES engine finished
while aes.finish.read().finish() != FINISH_A::FINISHED {
@ -146,3 +129,48 @@ pub fn run(
}
}
}
/** AES operation (encrypt or decrypt) using hardware engine. Takes a &mut
* AES as only one operation can be active at a time.
*
* Supported modes:
*
* Mode Keybits Extra input Extra output
* ---- --------------- ------------------------ ----------------
* ECB 128 / 192 / 256 no IV
* CBC 128 / 192 / 256 128 bit IV
* GCM 128 / 192 / 256 96 bit IV + ? bytes AAD) 128 bit tag (optional)
*/
pub fn run(
aes: &mut pac::AES,
cipher_mode: cipher_mode,
encrypt_sel: encrypt_sel,
key: &[u8],
iv: &[u8],
aad: &[u8],
ind: &[u8],
outd: &mut [u8],
tag: &mut [u8],
)
{
setup(aes, cipher_mode, encrypt_sel, key, iv, aad, ind.len());
unsafe {
// Send and receive plaintext/ciphertext
let mut iptr = 0;
let mut optr = 0;
while optr < ind.len() {
while iptr < ind.len() && aes.data_in_flag.read().data_in_flag() == DATA_IN_FLAG_A::CAN_INPUT {
aes.text_data.write(|w| w.bits(read4pad(ind, iptr)));
iptr += 4;
}
while aes.data_out_flag.read().data_out_flag() == DATA_OUT_FLAG_A::CAN_OUTPUT {
write4pad(outd, optr, aes.out_data.read().bits());
optr += 4;
}
}
}
finish(aes, cipher_mode, tag);
}