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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 <lukas@wunner.de> Tested-by: Lukas Wunner <lukas@wunner.de> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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@ -222,9 +222,8 @@ static int ecdsa_ecc_ctx_reset(struct ecc_ctx *ctx)
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static int ecdsa_set_pub_key(struct crypto_akcipher *tfm, const void *key, unsigned int keylen)
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{
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struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);
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unsigned int digitlen, ndigits;
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const unsigned char *d = key;
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const u64 *digits = (const u64 *)&d[1];
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unsigned int ndigits;
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int ret;
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ret = ecdsa_ecc_ctx_reset(ctx);
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@ -238,12 +237,17 @@ static int ecdsa_set_pub_key(struct crypto_akcipher *tfm, const void *key, unsig
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return -EINVAL;
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keylen--;
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ndigits = (keylen >> 1) / sizeof(u64);
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digitlen = keylen >> 1;
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ndigits = DIV_ROUND_UP(digitlen, sizeof(u64));
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if (ndigits != ctx->curve->g.ndigits)
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return -EINVAL;
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ecc_swap_digits(digits, ctx->pub_key.x, ndigits);
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ecc_swap_digits(&digits[ndigits], ctx->pub_key.y, ndigits);
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d++;
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ecc_digits_from_bytes(d, digitlen, ctx->pub_key.x, ndigits);
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ecc_digits_from_bytes(&d[digitlen], digitlen, ctx->pub_key.y, ndigits);
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ret = ecc_is_pubkey_valid_full(ctx->curve, &ctx->pub_key);
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ctx->pub_key_set = ret == 0;
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@ -56,6 +56,27 @@ static inline void ecc_swap_digits(const void *in, u64 *out, unsigned int ndigit
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out[i] = get_unaligned_be64(&src[ndigits - 1 - i]);
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}
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/**
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* ecc_digits_from_bytes() - Create ndigits-sized digits array from byte array
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* @in: Input byte array
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* @nbytes Size of input byte array
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* @out Output digits array
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* @ndigits: Number of digits to create from byte array
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*/
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static inline void ecc_digits_from_bytes(const u8 *in, unsigned int nbytes,
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u64 *out, unsigned int ndigits)
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{
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unsigned int o = nbytes & 7;
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__be64 msd = 0;
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if (o) {
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memcpy((u8 *)&msd + sizeof(msd) - o, in, o);
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out[--ndigits] = be64_to_cpu(msd);
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in += o;
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}
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ecc_swap_digits(in, out, ndigits);
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}
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/**
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* ecc_is_key_valid() - Validate a given ECDH private key
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*
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