From d67c96fb97b5811e15c881d5cb72e293faa5f8e1 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 --- include/crypto/internal/ecc.h | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'include/crypto/internal') diff --git a/include/crypto/internal/ecc.h b/include/crypto/internal/ecc.h index 4f6c1a68882f..ab722a8986b7 100644 --- a/include/crypto/internal/ecc.h +++ b/include/crypto/internal/ecc.h @@ -56,6 +56,27 @@ static inline void ecc_swap_digits(const void *in, u64 *out, unsigned int ndigit out[i] = get_unaligned_be64(&src[ndigits - 1 - i]); } +/** + * ecc_digits_from_bytes() - Create ndigits-sized digits array from byte array + * @in: Input byte array + * @nbytes Size of input byte array + * @out Output digits array + * @ndigits: Number of digits to create from byte array + */ +static inline void ecc_digits_from_bytes(const u8 *in, unsigned int nbytes, + u64 *out, unsigned int ndigits) +{ + unsigned int o = nbytes & 7; + __be64 msd = 0; + + if (o) { + memcpy((u8 *)&msd + sizeof(msd) - o, in, o); + out[--ndigits] = be64_to_cpu(msd); + in += o; + } + ecc_swap_digits(in, out, ndigits); +} + /** * ecc_is_key_valid() - Validate a given ECDH private key * -- cgit v1.2.3