From c95f28e4efbe38a3c4bb2d09289287452486fa8c Mon Sep 17 00:00:00 2001 From: Stefan Berger Date: Thu, 4 Apr 2024 10:18:45 -0400 Subject: crypto: ecdsa - Convert byte arrays with key coordinates to digits For NIST P192/256/384 the public key's x and y parameters could be copied directly from a given array since both parameters filled 'ndigits' of digits (a 'digit' is a u64). For support of NIST P521 the key parameters need to have leading zeros prepended to the most significant digit since only 2 bytes of the most significant digit are provided. Therefore, implement ecc_digits_from_bytes to convert a byte array into an array of digits and use this function in ecdsa_set_pub_key where an input byte array needs to be converted into digits. Suggested-by: Lukas Wunner Tested-by: Lukas Wunner Reviewed-by: Jarkko Sakkinen Signed-off-by: Stefan Berger Signed-off-by: Herbert Xu --- crypto/ecdsa.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) (limited to 'crypto/ecdsa.c') diff --git a/crypto/ecdsa.c b/crypto/ecdsa.c index 3f9ec273..e819d098 100644 --- a/crypto/ecdsa.c +++ b/crypto/ecdsa.c @@ -222,9 +222,8 @@ static int ecdsa_ecc_ctx_reset(struct ecc_ctx *ctx) static int ecdsa_set_pub_key(struct crypto_akcipher *tfm, const void *key, unsigned int keylen) { struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm); + unsigned int digitlen, ndigits; const unsigned char *d = key; - const u64 *digits = (const u64 *)&d[1]; - unsigned int ndigits; int ret; ret = ecdsa_ecc_ctx_reset(ctx); @@ -238,12 +237,17 @@ static int ecdsa_set_pub_key(struct crypto_akcipher *tfm, const void *key, unsig return -EINVAL; keylen--; - ndigits = (keylen >> 1) / sizeof(u64); + digitlen = keylen >> 1; + + ndigits = DIV_ROUND_UP(digitlen, sizeof(u64)); if (ndigits != ctx->curve->g.ndigits) return -EINVAL; - ecc_swap_digits(digits, ctx->pub_key.x, ndigits); - ecc_swap_digits(&digits[ndigits], ctx->pub_key.y, ndigits); + d++; + + ecc_digits_from_bytes(d, digitlen, ctx->pub_key.x, ndigits); + ecc_digits_from_bytes(&d[digitlen], digitlen, ctx->pub_key.y, ndigits); + ret = ecc_is_pubkey_valid_full(ctx->curve, &ctx->pub_key); ctx->pub_key_set = ret == 0; -- cgit v1.2.3