Careful use of the other available buffers avoids the need for these, shrinking the context by 32 bytes.
Neither the debug output nor the FIPS-required anti-repetition check are changed in the slightest. Signed-off-by: George Spelvin <li...@horizon.com> --- crypto/ansi_cprng.c | 50 ++++++++++++++++++++++++-------------------------- 1 file changed, 24 insertions(+), 26 deletions(-) diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c index 325aa727d..2edac42e 100644 --- a/crypto/ansi_cprng.c +++ b/crypto/ansi_cprng.c @@ -37,19 +37,14 @@ /* * Note: DT is our counter value - * I is our intermediate value * V is our seed vector * 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 last_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_data_valid; struct crypto_cipher *tfm; @@ -97,27 +92,27 @@ 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 + * This gives us an intermediate value I (stored in tmp) */ - memcpy(tmp, ctx->DT, DEFAULT_BLK_SZ); - crypto_cipher_encrypt_one(ctx->tfm, ctx->I, tmp); - hexdump("I", ctx->I); + crypto_cipher_encrypt_one(ctx->tfm, tmp, ctx->DT); + hexdump("I", tmp); /* - * Next xor I with our secret vector V - * encrypt that result to obtain our - * pseudo random data which we output + * Next xor I with our secret vector V. Encrypt that result + * to obtain our pseudo random data which we output. But + * keep that output in ctx->V for the moment; we need the + * previous rand_data for ons more thing. */ - xor_vectors(ctx->I, ctx->V, tmp, DEFAULT_BLK_SZ); - hexdump("V^I", tmp); - crypto_cipher_encrypt_one(ctx->tfm, ctx->rand_data, tmp); - hexdump("R", ctx->rand_data); + xor_vectors(tmp, ctx->V, ctx->V, DEFAULT_BLK_SZ); + hexdump("V^I", ctx->V); + crypto_cipher_encrypt_one(ctx->tfm, ctx->V, ctx->V); + hexdump("R", ctx->V); /* - * First check that we didn't produce the same - * random data that we did last time around through this + * Check that we didn't produce the same random data that we + * did last time around. */ - if (!memcmp(ctx->rand_data, ctx->last_rand_data, DEFAULT_BLK_SZ)) { + if (!memcmp(ctx->V, ctx->rand_data, DEFAULT_BLK_SZ)) { if (cont_test) { panic("cprng %p Failed repetition check!\n", ctx); } @@ -127,15 +122,19 @@ static int _get_more_prng_bytes(struct prng_context *ctx, int cont_test) ctx->flags |= PRNG_NEED_RESET; return -EINVAL; } - memcpy(ctx->last_rand_data, ctx->rand_data, DEFAULT_BLK_SZ); + /* + * Okay, the new data is okay, copy it to the buffer. + */ + 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 + * Lastly xor the random data with I and encrypt that to obtain + * a new secret vector V. */ - xor_vectors(ctx->rand_data, ctx->I, tmp, DEFAULT_BLK_SZ); - hexdump("R^I", tmp); - crypto_cipher_encrypt_one(ctx->tfm, ctx->V, tmp); + xor_vectors(tmp, ctx->V, ctx->V, DEFAULT_BLK_SZ); + hexdump("R^I", ctx->V); + memzero_explicit(tmp, DEFAULT_BLK_SZ); + crypto_cipher_encrypt_one(ctx->tfm, ctx->V, ctx->V); hexdump("V'", ctx->V); /* @@ -272,7 +271,6 @@ static int reset_prng_context(struct prng_context *ctx, memset(ctx->DT, 0, DEFAULT_BLK_SZ); memset(ctx->rand_data, 0, DEFAULT_BLK_SZ); - memset(ctx->last_rand_data, 0, DEFAULT_BLK_SZ); ctx->rand_data_valid = DEFAULT_BLK_SZ; -- 2.1.3 -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
