f53c77648c
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de> (Merged from https://github.com/openssl/openssl/pull/5105)
207 lines
7.9 KiB
C
207 lines
7.9 KiB
C
/*
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* Copyright 2017-2018 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 __C448_ED448_H__
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# define __C448_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 EDDSA_448_PUBLIC_BYTES 57
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/* Number of bytes in an EdDSA private key. */
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# define EDDSA_448_PRIVATE_BYTES EDDSA_448_PUBLIC_BYTES
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/* Number of bytes in an EdDSA private key. */
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# define EDDSA_448_SIGNATURE_BYTES (EDDSA_448_PUBLIC_BYTES + \
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EDDSA_448_PRIVATE_BYTES)
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/* EdDSA encoding ratio. */
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# define C448_EDDSA_ENCODE_RATIO 4
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/* EdDSA decoding ratio. */
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# define C448_EDDSA_DECODE_RATIO (4 / 4)
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/*
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* EdDSA key generation. This function uses a different (non-Decaf) encoding.
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*
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* pubkey (out): The public key.
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* privkey (in): The private key.
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*/
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c448_error_t c448_ed448_derive_public_key(
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uint8_t pubkey [EDDSA_448_PUBLIC_BYTES],
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const uint8_t privkey [EDDSA_448_PRIVATE_BYTES]);
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/*
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* EdDSA signing.
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*
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* signature (out): The signature.
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* privkey (in): The private key.
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* pubkey (in): The public key.
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* message (in): The message to sign.
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* message_len (in): The length of the message.
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* prehashed (in): Nonzero if the message is actually the hash of something
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* you want to sign.
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* context (in): A "context" for this signature of up to 255 bytes.
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* context_len (in): Length of the context.
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*
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* For Ed25519, it is unsafe to use the same key for both prehashed and
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* non-prehashed messages, at least without some very careful protocol-level
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* disambiguation. For Ed448 it is safe. The C++ wrapper is designed to make
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* it harder to screw this up, but this C code gives you no seat belt.
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*/
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c448_error_t c448_ed448_sign(
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uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
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const uint8_t privkey[EDDSA_448_PRIVATE_BYTES],
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const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
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const uint8_t *message, size_t message_len,
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uint8_t prehashed, const uint8_t *context,
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size_t context_len);
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/*
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* EdDSA signing with prehash.
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*
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* signature (out): The signature.
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* privkey (in): The private key.
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* pubkey (in): The public key.
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* hash (in): The hash of the message. This object will not be modified by the
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* call.
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* context (in): A "context" for this signature of up to 255 bytes. Must be the
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* same as what was used for the prehash.
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* context_len (in): Length of the context.
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*
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* For Ed25519, it is unsafe to use the same key for both prehashed and
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* non-prehashed messages, at least without some very careful protocol-level
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* disambiguation. For Ed448 it is safe. The C++ wrapper is designed to make
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* it harder to screw this up, but this C code gives you no seat belt.
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*/
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c448_error_t c448_ed448_sign_prehash(
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uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
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const uint8_t privkey[EDDSA_448_PRIVATE_BYTES],
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const uint8_t pubkey[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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/*
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* 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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* signature (in): The signature.
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* pubkey (in): The public key.
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* message (in): The message to verify.
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* message_len (in): The length of the message.
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* prehashed (in): Nonzero if the message is actually the hash of something you
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* want to verify.
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* context (in): A "context" for this signature of up to 255 bytes.
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* context_len (in): Length of the context.
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*
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* For Ed25519, it is unsafe to use the same key for both prehashed and
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* non-prehashed messages, at least without some very careful protocol-level
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* disambiguation. For Ed448 it is safe. The C++ wrapper is designed to make
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* it harder to screw this up, but this C code gives you no seat belt.
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*/
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c448_error_t c448_ed448_verify(const uint8_t
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signature[EDDSA_448_SIGNATURE_BYTES],
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const uint8_t
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pubkey[EDDSA_448_PUBLIC_BYTES],
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const uint8_t *message, size_t message_len,
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uint8_t prehashed, const uint8_t *context,
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uint8_t context_len);
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/*
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* 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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* signature (in): The signature.
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* pubkey (in): The public key.
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* hash (in): The hash of the message. This object will not be modified by the
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* call.
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* context (in): A "context" for this signature of up to 255 bytes. Must be the
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* same as what was used for the prehash.
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* context_len (in): Length of the context.
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*
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* For Ed25519, it is unsafe to use the same key for both prehashed and
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* non-prehashed messages, at least without some very careful protocol-level
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* disambiguation. For Ed448 it is safe. The C++ wrapper is designed to make
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* it harder to screw this up, but this C code gives you no seat belt.
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*/
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c448_error_t c448_ed448_verify_prehash(
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const uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
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const uint8_t pubkey[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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/*
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* EdDSA point encoding. Used internally, exposed externally.
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* Multiplies by C448_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 we handle this is to multiply by C448_EDDSA_DECODE_RATIO when
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* decoding, and by C448_EDDSA_ENCODE_RATIO when encoding. The product of
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* these ratios is always exactly the cofactor 4, so the cofactor ends up
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* cleared one way or another. But exactly how that shakes out depends on the
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* 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 C448_EDDSA_ENCODE_RATIO times the
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* EdDSA base point.
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*
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* enc (out): The encoded point.
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* p (in): 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 [EDDSA_448_PUBLIC_BYTES],
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const curve448_point_t p);
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/*
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* EdDSA point decoding. Multiplies by C448_EDDSA_DECODE_RATIO, and
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* 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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* enc (out): The encoded point.
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* p (in): The point.
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*/
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c448_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[EDDSA_448_PUBLIC_BYTES]);
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/*
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* 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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* x (out): The ECDH private key as in RFC7748
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* ed (in): The EdDSA private key
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*/
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c448_error_t c448_ed448_convert_private_key_to_x448(
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uint8_t x[X448_PRIVATE_BYTES],
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const uint8_t ed[EDDSA_448_PRIVATE_BYTES]);
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#ifdef __cplusplus
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} /* extern "C" */
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#endif
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#endif /* __C448_ED448_H__ */
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