diff options
Diffstat (limited to 'board/cr50/dcrypto/p256.c')
| -rw-r--r-- | board/cr50/dcrypto/p256.c | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/board/cr50/dcrypto/p256.c b/board/cr50/dcrypto/p256.c index 6c923b4699..49c2fe4b2b 100644 --- a/board/cr50/dcrypto/p256.c +++ b/board/cr50/dcrypto/p256.c @@ -4,6 +4,7 @@ */ #include "dcrypto.h" +#include "endian.h" const p256_int SECP256r1_nMin2 = /* P-256 curve order - 2 */ { .a = { 0xfc632551 - 2, 0xf3b9cac2, 0xa7179e84, 0xbce6faad, -1, -1, 0, @@ -135,6 +136,34 @@ void p256_to_bin(const p256_int *src, uint8_t dst[P256_NBYTES]) #endif } +bool p256_from_be_bin_size(const uint8_t *src, size_t len, p256_int *dst) +{ + size_t i; + + /** + * Skip zero padding if input length is larger than P-256 size. + * This may happen with TPM2 commands receiving big-endian number + * with leading zeroes from external sources. + */ + while (len > P256_NBYTES) { + if (*src != 0) + return false; + len--; + src++; + } + + i = len; + /* Now add zero padding little-endian p256 if length is smaller. */ + while (i < P256_NBYTES) { + dst->b8[i] = 0; + i++; + } + reverse_bytes(dst->b8, src, len); + + /* Note: this code is correct only for little-endian platform. */ + return true; +} + void p256_from_bin(const uint8_t src[P256_NBYTES], p256_int *dst) { #if (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__) @@ -193,3 +222,69 @@ enum hmac_result p256_hmac_drbg_generate(struct drbg_ctx *ctx, p256_int *rnd) return result; } + +#ifndef P256_BIN_TEST +#define P256_BIN_TEST 0 +#endif + +#ifdef CRYPTO_TEST_SETUP + +#if P256_BIN_TEST +#include "console.h" + +static int cmd_p256_bin_test(int argc, char *argv[]) +{ + static const uint8_t i1[] = { + 0, 0, 0x10, 0x11, 0x12, 0x13, 0x20, 0x21, 0x22, + 0x23, 0x30, 0x31, 0x32, 0x33, 0x40, 0x41, 0x42, 0x43, + 0x50, 0x51, 0x52, 0x53, 0x60, 0x61, 0x62, 0x63, 0x70, + 0x71, 0x72, 0x73, 0x80, 0x81, 0x82, 0x83, 0x84 + }; + p256_int e = { .a = { 0x80818283, 0x70717273, 0x60616263, 0x50515253, + 0x40414243, 0x30313233, 0x20212223, + 0x10111213 } }; + + p256_int r; + bool passed = true; + bool result; + + /* zero padded */ + result = p256_from_be_bin_size(i1, 34, &r); + passed = result && (p256_cmp(&r, &e) == 0); + ccprintf("in=%ph\nout=%ph\n", HEX_BUF(i1, 34), HEX_BUF(&r, sizeof(r))); + + /* right sized. */ + memset(&r, 0, sizeof(r)); + result = p256_from_be_bin_size(i1 + 2, 32, &r); + passed = passed && (p256_cmp(&r, &e) == 0); + ccprintf("in=%ph\nout=%ph\n", HEX_BUF(i1 + 2, 32), + HEX_BUF(&r, sizeof(r))); + + /** + * Smaller big num, where padding high byte(s) with zeroes is needed. + * we do this by loading 31 byte starting 1 byte higher. + * This will result in same value as in 'e' except that the + * highest byte will be 0 (e.a[7] == 0x00111213). + */ + memset(&r, 0, sizeof(r)); + result = p256_from_be_bin_size(i1 + 3, 31, &r); + + /* Update expected result by clearing high byte */ + e.b8[31] = 0x00; + passed = passed && (p256_cmp(&r, &e) == 0); + ccprintf("in=%ph\nout=%ph\n", HEX_BUF(i1 + 3, 31), + HEX_BUF(&r, sizeof(r))); + + /* larger big num. */ + result = p256_from_be_bin_size(i1 + 2, 33, &r); + passed = passed && !result; + + ccprintf("p256_from_be_bin_size() test %s\n", + (passed) ? "PASSED" : "NOT PASSED"); + + return EC_SUCCESS; +} +DECLARE_SAFE_CONSOLE_COMMAND(p256_test, cmd_p256_bin_test, NULL, NULL); +#endif /* P256_BIN_TEST */ + +#endif /* CRYPTO_TEST_SETUP */ |