It's more legible, and the code is 15 bytes smaller (i386).
Signed-off-by: George Spelvin <linux@xxxxxxxxxxx>
---
crypto/ansi_cprng.c | 87 ++++++++++++++++++++---------------------------------
1 file changed, 32 insertions(+), 55 deletions(-)
I'm not really sure why this was implemented this convoluted way
in the first place. Did crypto_cipher_encrypt_one() used to be
an enormous inline function?
diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c
index de13e741..09bb1252 100644
--- a/crypto/ansi_cprng.c
+++ b/crypto/ansi_cprng.c
@@ -94,67 +94,44 @@ static int _get_more_prng_bytes(struct prng_context *ctx, bool cont_test)
hexdump("Input V: ", ctx->V, DEFAULT_BLK_SZ);
/*
- * This algorithm is a 3 stage state machine
+ * Start by encrypting the counter value.
+ * This gives us an intermediate value I.
*/
- for (i = 0; i < 3; i++) {
- unsigned char const *input;
- unsigned char *output;
+ crypto_cipher_encrypt_one(ctx->tfm, tmp, ctx->DT);
+ hexdump("input I: ", tmp, DEFAULT_BLK_SZ);
- switch (i) {
- case 0:
- /*
- * Start by encrypting the counter value
- * This gives us an intermediate value I
- */
- input = ctx->DT;
- output = tmp;
- hexdump("input stage 0: ", input, DEFAULT_BLK_SZ);
- break;
- case 1:
- /*
- * Next xor I with our secret vector V.
- * Encrypt that result to obtain our pseudo random
- * data which we output. It is kept temporarily
- * in (no longer used) V until we have done the
- * anti-repetition compare.
- */
- xor_block(tmp, ctx->V);
- input = output = ctx->V;
- hexdump("input stage 1: ", input, DEFAULT_BLK_SZ);
- break;
- case 2:
- /*
- * First check that we didn't produce the same
- * random data that we did last time around.
- */
- if (!memcmp(ctx->V, ctx->rand_data, DEFAULT_BLK_SZ)) {
- if (cont_test) {
- panic("cprng %p Failed repetition check!\n",
- ctx);
- }
-
- printk(KERN_ERR
- "ctx %p Failed repetition check!\n",
- ctx);
-
- ctx->flags |= PRNG_NEED_RESET;
- return -EINVAL;
- }
- memcpy(ctx->rand_data, ctx->V, DEFAULT_BLK_SZ);
+ /*
+ * Next xor I with our secret vector V.
+ * Encrypt that result to obtain our pseudo random data which
+ * we output. It is kept temporarily in (no longer used)
+ * V until we have done the anti-repetition compare.
+ */
+ xor_block(tmp, ctx->V);
+ hexdump("input stage 1: ", ctx->V, DEFAULT_BLK_SZ);
+ crypto_cipher_encrypt_one(ctx->tfm, ctx->V, ctx->V);
- /*
- * Lastly xor the random data with I
- * and encrypt that to obtain a new secret vector V
- */
- xor_block(tmp, ctx->V);
- input = output = ctx->V;
- hexdump("input stage 2: ", input, DEFAULT_BLK_SZ);
- break;
+ /*
+ * Check that we didn't produce the same random data
+ * that we did last time around.
+ */
+ if (!memcmp(ctx->V, ctx->rand_data, DEFAULT_BLK_SZ)) {
+ if (cont_test) {
+ panic("cprng %p Failed repetition check!\n", ctx);
}
- /* do the encryption */
- crypto_cipher_encrypt_one(ctx->tfm, output, input);
+ printk(KERN_ERR "ctx %p Failed repetition check!\n", ctx);
+ ctx->flags |= PRNG_NEED_RESET;
+ return -EINVAL;
}
+ memcpy(ctx->rand_data, ctx->V, DEFAULT_BLK_SZ);
+
+ /*
+ * Lastly xor the random data with I and encrypt that to
+ * obtain a new secret vector V
+ */
+ xor_block(tmp, ctx->V);
+ hexdump("input stage 2: ", ctx->V, DEFAULT_BLK_SZ);
+ crypto_cipher_encrypt_one(ctx->tfm, ctx->V, ctx->V);
/*
* Now update our DT value
--
2.1.3
--
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