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1308e022e1
Some files talk about the MIT license. This code was contributed under CLA and was relicensed to the OpenSSL licence when imported. Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de> (Merged from https://github.com/openssl/openssl/pull/5105)
233 lines
8.4 KiB
C
233 lines
8.4 KiB
C
/*
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* Copyright 2017 The OpenSSL Project Authors. All Rights Reserved.
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* Copyright 2015-2016 Cryptography Research, Inc.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*
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* Originally written by Mike Hamburg
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*/
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#ifndef __DECAF_ED448_H__
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#define __DECAF_ED448_H__ 1
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#include "point_448.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/** Number of bytes in an EdDSA public key. */
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#define DECAF_EDDSA_448_PUBLIC_BYTES 57
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/** Number of bytes in an EdDSA private key. */
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#define DECAF_EDDSA_448_PRIVATE_BYTES DECAF_EDDSA_448_PUBLIC_BYTES
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/** Number of bytes in an EdDSA private key. */
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#define DECAF_EDDSA_448_SIGNATURE_BYTES (DECAF_EDDSA_448_PUBLIC_BYTES + DECAF_EDDSA_448_PRIVATE_BYTES)
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/** Does EdDSA support non-contextual signatures? */
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#define DECAF_EDDSA_448_SUPPORTS_CONTEXTLESS_SIGS 0
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/** EdDSA encoding ratio. */
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#define DECAF_448_EDDSA_ENCODE_RATIO 4
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/** EdDSA decoding ratio. */
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#define DECAF_448_EDDSA_DECODE_RATIO (4 / 4)
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/**
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* @brief EdDSA key generation. This function uses a different (non-Decaf)
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* encoding.
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*
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* @param [out] pubkey The public key.
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* @param [in] privkey The private key.
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*/
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decaf_error_t decaf_ed448_derive_public_key (
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uint8_t pubkey[DECAF_EDDSA_448_PUBLIC_BYTES],
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const uint8_t privkey[DECAF_EDDSA_448_PRIVATE_BYTES]
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);
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/**
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* @brief EdDSA signing.
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*
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* @param [out] signature The signature.
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* @param [in] privkey The private key.
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* @param [in] pubkey The public key.
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* @param [in] message The message to sign.
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* @param [in] message_len The length of the message.
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* @param [in] prehashed Nonzero if the message is actually the hash of something you want to sign.
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* @param [in] context A "context" for this signature of up to 255 bytes.
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* @param [in] context_len Length of the context.
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*
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* @warning For Ed25519, it is unsafe to use the same key for both prehashed and non-prehashed
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* messages, at least without some very careful protocol-level disambiguation. For Ed448 it is
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* safe. The C++ wrapper is designed to make it harder to screw this up, but this C code gives
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* you no seat belt.
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*/
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decaf_error_t decaf_ed448_sign (
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uint8_t signature[DECAF_EDDSA_448_SIGNATURE_BYTES],
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const uint8_t privkey[DECAF_EDDSA_448_PRIVATE_BYTES],
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const uint8_t pubkey[DECAF_EDDSA_448_PUBLIC_BYTES],
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const uint8_t *message,
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size_t message_len,
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uint8_t prehashed,
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const uint8_t *context,
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size_t context_len
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) __attribute__((nonnull(1,2,3)));
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/**
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* @brief EdDSA signing with prehash.
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*
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* @param [out] signature The signature.
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* @param [in] privkey The private key.
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* @param [in] pubkey The public key.
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* @param [in] hash The hash of the message. This object will not be modified by the call.
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* @param [in] context A "context" for this signature of up to 255 bytes. Must be the same as what was used for the prehash.
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* @param [in] context_len Length of the context.
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*
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* @warning For Ed25519, it is unsafe to use the same key for both prehashed and non-prehashed
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* messages, at least without some very careful protocol-level disambiguation. For Ed448 it is
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* safe. The C++ wrapper is designed to make it harder to screw this up, but this C code gives
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* you no seat belt.
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*/
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decaf_error_t decaf_ed448_sign_prehash (
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uint8_t signature[DECAF_EDDSA_448_SIGNATURE_BYTES],
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const uint8_t privkey[DECAF_EDDSA_448_PRIVATE_BYTES],
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const uint8_t pubkey[DECAF_EDDSA_448_PUBLIC_BYTES],
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const uint8_t hash[64],
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const uint8_t *context,
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size_t context_len
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) __attribute__((nonnull(1,2,3,4)));
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/**
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* @brief EdDSA signature verification.
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*
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* Uses the standard (i.e. less-strict) verification formula.
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*
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* @param [in] signature The signature.
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* @param [in] pubkey The public key.
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* @param [in] message The message to verify.
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* @param [in] message_len The length of the message.
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* @param [in] prehashed Nonzero if the message is actually the hash of something you want to verify.
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* @param [in] context A "context" for this signature of up to 255 bytes.
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* @param [in] context_len Length of the context.
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*
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* @warning For Ed25519, it is unsafe to use the same key for both prehashed and non-prehashed
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* messages, at least without some very careful protocol-level disambiguation. For Ed448 it is
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* safe. The C++ wrapper is designed to make it harder to screw this up, but this C code gives
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* you no seat belt.
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*/
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decaf_error_t decaf_ed448_verify (
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const uint8_t signature[DECAF_EDDSA_448_SIGNATURE_BYTES],
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const uint8_t pubkey[DECAF_EDDSA_448_PUBLIC_BYTES],
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const uint8_t *message,
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size_t message_len,
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uint8_t prehashed,
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const uint8_t *context,
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uint8_t context_len
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) __attribute__((nonnull(1,2)));
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/**
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* @brief EdDSA signature verification.
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*
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* Uses the standard (i.e. less-strict) verification formula.
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*
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* @param [in] signature The signature.
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* @param [in] pubkey The public key.
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* @param [in] hash The hash of the message. This object will not be modified by the call.
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* @param [in] context A "context" for this signature of up to 255 bytes. Must be the same as what was used for the prehash.
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* @param [in] context_len Length of the context.
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*
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* @warning For Ed25519, it is unsafe to use the same key for both prehashed and non-prehashed
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* messages, at least without some very careful protocol-level disambiguation. For Ed448 it is
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* safe. The C++ wrapper is designed to make it harder to screw this up, but this C code gives
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* you no seat belt.
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*/
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decaf_error_t decaf_ed448_verify_prehash (
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const uint8_t signature[DECAF_EDDSA_448_SIGNATURE_BYTES],
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const uint8_t pubkey[DECAF_EDDSA_448_PUBLIC_BYTES],
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const uint8_t hash[64],
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const uint8_t *context,
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uint8_t context_len
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) __attribute__((nonnull(1,2)));
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/**
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* @brief EdDSA point encoding. Used internally, exposed externally.
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* Multiplies by DECAF_448_EDDSA_ENCODE_RATIO first.
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*
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* The multiplication is required because the EdDSA encoding represents
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* the cofactor information, but the Decaf encoding ignores it (which
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* is the whole point). So if you decode from EdDSA and re-encode to
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* EdDSA, the cofactor info must get cleared, because the intermediate
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* representation doesn't track it.
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*
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* The way libdecaf handles this is to multiply by
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* DECAF_448_EDDSA_DECODE_RATIO when decoding, and by
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* DECAF_448_EDDSA_ENCODE_RATIO when encoding. The product of these
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* ratios is always exactly the cofactor 4, so the cofactor
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* ends up cleared one way or another. But exactly how that shakes
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* out depends on the base points specified in RFC 8032.
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*
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* The upshot is that if you pass the Decaf/Ristretto base point to
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* this function, you will get DECAF_448_EDDSA_ENCODE_RATIO times the
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* EdDSA base point.
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*
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* @param [out] enc The encoded point.
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* @param [in] p The point.
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*/
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void curve448_point_mul_by_ratio_and_encode_like_eddsa (
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uint8_t enc[DECAF_EDDSA_448_PUBLIC_BYTES],
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const curve448_point_t p
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);
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/**
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* @brief EdDSA point decoding. Multiplies by DECAF_448_EDDSA_DECODE_RATIO,
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* and ignores cofactor information.
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*
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* See notes on curve448_point_mul_by_ratio_and_encode_like_eddsa
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*
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* @param [out] enc The encoded point.
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* @param [in] p The point.
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*/
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decaf_error_t curve448_point_decode_like_eddsa_and_mul_by_ratio (
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curve448_point_t p,
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const uint8_t enc[DECAF_EDDSA_448_PUBLIC_BYTES]
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);
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/**
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* @brief EdDSA to ECDH public key conversion
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* Deserialize the point to get y on Edwards curve,
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* Convert it to u coordinate on Montgomery curve.
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*
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* @warning This function does not check that the public key being converted
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* is a valid EdDSA public key (FUTURE?)
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*
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* @param[out] x The ECDH public key as in RFC7748(point on Montgomery curve)
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* @param[in] ed The EdDSA public key(point on Edwards curve)
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*/
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void decaf_ed448_convert_public_key_to_x448 (
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uint8_t x[DECAF_X448_PUBLIC_BYTES],
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const uint8_t ed[DECAF_EDDSA_448_PUBLIC_BYTES]
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);
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/**
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* @brief EdDSA to ECDH private key conversion
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* Using the appropriate hash function, hash the EdDSA private key
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* and keep only the lower bytes to get the ECDH private key
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*
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* @param[out] x The ECDH private key as in RFC7748
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* @param[in] ed The EdDSA private key
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*/
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decaf_error_t decaf_ed448_convert_private_key_to_x448 (
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uint8_t x[DECAF_X448_PRIVATE_BYTES],
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const uint8_t ed[DECAF_EDDSA_448_PRIVATE_BYTES]
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);
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#ifdef __cplusplus
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} /* extern "C" */
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#endif
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#endif /* __DECAF_ED448_H__ */
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