44 lines
1.3 KiB
C
44 lines
1.3 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis */
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/* SPDX-License-Identifier: Unlicense */
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#include "tomcrypt_private.h"
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/**
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@file x25519_shared_secret.c
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Create a X25519 shared secret, Steffen Jaeckel
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*/
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#ifdef LTC_CURVE25519
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/**
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Create a X25519 shared secret.
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@param private_key The private X25519 key in the pair
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@param public_key The public X25519 key in the pair
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@param out [out] The destination of the shared data
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@param outlen [in/out] The max size and resulting size of the shared data.
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@return CRYPT_OK if successful
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*/
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int x25519_shared_secret(const curve25519_key *private_key,
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const curve25519_key *public_key,
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unsigned char *out, unsigned long *outlen)
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{
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LTC_ARGCHK(private_key != NULL);
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LTC_ARGCHK(public_key != NULL);
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LTC_ARGCHK(out != NULL);
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LTC_ARGCHK(outlen != NULL);
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if (public_key->pka != LTC_PKA_X25519) return CRYPT_PK_INVALID_TYPE;
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if (private_key->type != PK_PRIVATE) return CRYPT_PK_INVALID_TYPE;
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if (*outlen < 32uL) {
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*outlen = 32uL;
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return CRYPT_BUFFER_OVERFLOW;
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}
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tweetnacl_crypto_scalarmult(out, private_key->priv, public_key->pub);
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*outlen = 32uL;
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return CRYPT_OK;
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}
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#endif
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