From: Stephan Mueller Date: Sun, 17 Aug 2014 15:37:34 +0000 (+0200) Subject: crypto: drbg - replace int2byte with cpu_to_be X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=72f3e00dd67ec449199a8844bc012a4fa1e0340a;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git crypto: drbg - replace int2byte with cpu_to_be The DRBG requires the conversion of an integer into a string representation of that integer. The previous implementation converted the given integer byte-wise. However, the kernel offers the cpu_to_be function which already re-arranges the memory representation of an integer such that it applies when interpreting the same memory as character string. The change therefore uses an integer-cast / union of the target character array together with the cpu_to_be function to convert an integer into its string representation. Tests show that the Hash and CTR DRBG implementations (the HMAC DRBG does not require such conversion) is about 10% faster (or requires less computing power, respectively). Signed-off-by: Stephan Mueller Signed-off-by: Herbert Xu --- diff --git a/crypto/drbg.c b/crypto/drbg.c index 7894db9ca90b..d86c67792e61 100644 --- a/crypto/drbg.c +++ b/crypto/drbg.c @@ -302,20 +302,19 @@ static bool drbg_fips_continuous_test(struct drbg_state *drbg, * Convert an integer into a byte representation of this integer. * The byte representation is big-endian * - * @buf buffer holding the converted integer * @val value to be converted - * @buflen length of buffer + * @buf buffer holding the converted integer -- caller must ensure that + * buffer size is at least 32 bit */ #if (defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR)) -static inline void drbg_int2byte(unsigned char *buf, uint64_t val, - size_t buflen) +static inline void drbg_cpu_to_be32(__u32 val, unsigned char *buf) { - unsigned char *byte; - uint64_t i; + struct s { + __u32 conv; + }; + struct s *conversion = (struct s *) buf; - byte = buf + (buflen - 1); - for (i = 0; i < buflen; i++) - *(byte--) = val >> (i * 8) & 0xff; + conversion->conv = cpu_to_be32(val); } /* @@ -483,10 +482,10 @@ static int drbg_ctr_df(struct drbg_state *drbg, /* 10.4.2 step 2 -- calculate the entire length of all input data */ list_for_each_entry(seed, seedlist, list) inputlen += seed->len; - drbg_int2byte(&L_N[0], inputlen, 4); + drbg_cpu_to_be32(inputlen, &L_N[0]); /* 10.4.2 step 3 */ - drbg_int2byte(&L_N[4], bytes_to_return, 4); + drbg_cpu_to_be32(bytes_to_return, &L_N[4]); /* 10.4.2 step 5: length is L_N, input_string, one byte, padding */ padlen = (inputlen + sizeof(L_N) + 1) % (drbg_blocklen(drbg)); @@ -517,7 +516,7 @@ static int drbg_ctr_df(struct drbg_state *drbg, * holds zeros after allocation -- even the increment of i * is irrelevant as the increment remains within length of i */ - drbg_int2byte(iv, i, 4); + drbg_cpu_to_be32(i, iv); /* 10.4.2 step 9.2 -- BCC and concatenation with temp */ ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list); if (ret) @@ -862,7 +861,7 @@ static int drbg_hash_df(struct drbg_state *drbg, /* 10.4.1 step 3 */ input[0] = 1; - drbg_int2byte(&input[1], (outlen * 8), 4); + drbg_cpu_to_be32((outlen * 8), &input[1]); /* 10.4.1 step 4.1 -- concatenation of data for input into hash */ drbg_string_fill(&data, input, 5); @@ -1023,7 +1022,10 @@ static int drbg_hash_generate(struct drbg_state *drbg, { int len = 0; int ret = 0; - unsigned char req[8]; + union { + unsigned char req[8]; + __u64 req_int; + } u; unsigned char prefix = DRBG_PREFIX3; struct drbg_string data1, data2; LIST_HEAD(datalist); @@ -1053,8 +1055,8 @@ static int drbg_hash_generate(struct drbg_state *drbg, drbg->scratchpad, drbg_blocklen(drbg)); drbg_add_buf(drbg->V, drbg_statelen(drbg), drbg->C, drbg_statelen(drbg)); - drbg_int2byte(req, drbg->reseed_ctr, sizeof(req)); - drbg_add_buf(drbg->V, drbg_statelen(drbg), req, 8); + u.req_int = cpu_to_be64(drbg->reseed_ctr); + drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8); out: memset(drbg->scratchpad, 0, drbg_blocklen(drbg));