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extmod/moducryptolib: Add AES-CTR support for axTLS builds.

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Yonatan Goldschmidt 2019-04-28 23:57:11 +03:00 committed by Damien George
parent ef9843653b
commit 32ba679924
1 changed files with 27 additions and 0 deletions
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27
extmod/moducryptolib.c
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@ -139,6 +139,33 @@ STATIC void aes_process_cbc_impl(AES_CTX_IMPL *ctx, const uint8_t *in, uint8_t *
AES_cbc_decrypt(ctx, in, out, in_len);
}
}
#if MICROPY_PY_UCRYPTOLIB_CTR
// axTLS doesn't have CTR support out of the box. This implements the counter part using the ECB primitive.
STATIC void aes_process_ctr_impl(AES_CTX_IMPL *ctx, const uint8_t *in, uint8_t *out, size_t in_len, struct ctr_params *ctr_params) {
size_t n = ctr_params->offset;
uint8_t *const counter = ctx->iv;
while (in_len--) {
if (n == 0) {
aes_process_ecb_impl(ctx, counter, ctr_params->encrypted_counter, true);
// increment the 128-bit counter
for (int i = 15; i >= 0; --i) {
if (++counter[i] != 0) {
break;
}
}
}
*out++ = *in++ ^ ctr_params->encrypted_counter[n];
n = (n + 1) & 0xf;
}
ctr_params->offset = n;
}
#endif
#endif
#if MICROPY_SSL_MBEDTLS