It's also not necessary. We do have to change some debugging output. Signed-off-by: George Spelvin <linux@xxxxxxxxxxx> --- crypto/ansi_cprng.c | 39 ++++++++++++++++++++------------------- 1 file changed, 20 insertions(+), 19 deletions(-) diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c index c0a27288..6b844f13 100644 --- a/crypto/ansi_cprng.c +++ b/crypto/ansi_cprng.c @@ -35,19 +35,22 @@ #define PRNG_NEED_RESET 0x2 /* - * Note: DT is our counter value - * I is our intermediate value - * V is our seed vector + * Note: In addition to the fixed encryption key, there are three + * block-sized state buffers: + * 1. rand_data is the current output data (R in the spec). + * 2. V is our main state vector + * 3. DT is the current "data/time" used for seeding. The fact that + * this is a deterministic counter rather than an actual timestamp + * (with some small amount of seed entropy) means that this code is + * NOT an implmentation of X9.31. + * * See http://csrc.nist.gov/groups/STM/cavp/documents/rng/931rngext.pdf * for implementation details */ - - struct prng_context { spinlock_t prng_lock; unsigned char rand_data[DEFAULT_BLK_SZ]; unsigned char DT[DEFAULT_BLK_SZ]; - unsigned char I[DEFAULT_BLK_SZ]; unsigned char V[DEFAULT_BLK_SZ]; u32 rand_read_pos; /* Offset into rand_data[] */ struct crypto_cipher *tfm; @@ -93,13 +96,13 @@ static int _get_more_prng_bytes(struct prng_context *ctx, int cont_test) ctx); hexdump("Input DT: ", ctx->DT, DEFAULT_BLK_SZ); - hexdump("Input I: ", ctx->I, DEFAULT_BLK_SZ); hexdump("Input V: ", ctx->V, DEFAULT_BLK_SZ); /* * This algorithm is a 3 stage state machine */ for (i = 0; i < 3; i++) { + unsigned char const *input; unsigned char *output; switch (i) { @@ -108,9 +111,9 @@ static int _get_more_prng_bytes(struct prng_context *ctx, int cont_test) * Start by encrypting the counter value * This gives us an intermediate value I */ - memcpy(tmp, ctx->DT, DEFAULT_BLK_SZ); - output = ctx->I; - hexdump("tmp stage 0: ", tmp, DEFAULT_BLK_SZ); + input = ctx->DT; + output = tmp; + hexdump("input stage 0: ", ctx->DT, DEFAULT_BLK_SZ); break; case 1: /* @@ -120,9 +123,9 @@ static int _get_more_prng_bytes(struct prng_context *ctx, int cont_test) * in (no longer used) V until we have done the * anti-repetition compare. */ - xor_vectors(ctx->I, ctx->V, tmp, DEFAULT_BLK_SZ); - hexdump("tmp stage 1: ", tmp, DEFAULT_BLK_SZ); - output = ctx->V; + xor_vectors(tmp, ctx->V, ctx->V, DEFAULT_BLK_SZ); + hexdump("input stage 1: ", ctx->V, DEFAULT_BLK_SZ); + input = output = ctx->V; break; case 2: /* @@ -148,15 +151,14 @@ static int _get_more_prng_bytes(struct prng_context *ctx, int cont_test) * Lastly xor the random data with I * and encrypt that to obtain a new secret vector V */ - xor_vectors(ctx->I, ctx->V, tmp, DEFAULT_BLK_SZ); - output = ctx->V; - hexdump("tmp stage 2: ", tmp, DEFAULT_BLK_SZ); + xor_vectors(tmp, ctx->V, ctx->V, DEFAULT_BLK_SZ); + hexdump("input stage 2: ", ctx->V, DEFAULT_BLK_SZ); + input = output = ctx->V; break; } - /* do the encryption */ - crypto_cipher_encrypt_one(ctx->tfm, output, tmp); + crypto_cipher_encrypt_one(ctx->tfm, output, input); } /* @@ -172,7 +174,6 @@ static int _get_more_prng_bytes(struct prng_context *ctx, int cont_test) ctx->rand_read_pos = 0; hexdump("Output DT: ", ctx->DT, DEFAULT_BLK_SZ); - hexdump("Output I: ", ctx->I, DEFAULT_BLK_SZ); hexdump("Output V: ", ctx->V, DEFAULT_BLK_SZ); hexdump("New Random Data: ", ctx->rand_data, DEFAULT_BLK_SZ); -- 2.1.3 -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
