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| -rw-r--r-- | src/ec25519_gf.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/src/ec25519_gf.c b/src/ec25519_gf.c index 91fa320..4914fa7 100644 --- a/src/ec25519_gf.c +++ b/src/ec25519_gf.c @@ -271,6 +271,10 @@ void ecc_25519_gf_recip(ecc_int256_t *out, const ecc_int256_t *in) { /** * Ensures some properties of a Galois field element to make it fit for use as a secret key * + * This sets the 255th bit and clears the 256th and the bottom three bits (so the key + * will be a multiple of 8). See Daniel J. Bernsteins paper "Curve25519: new Diffie-Hellman speed records." + * for the rationale of this. + * * The same pointers may be used for input and output. */ void ecc_25519_gf_sanitize_secret(ecc_int256_t *out, const ecc_int256_t *in) { |