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51 lines
1.7 KiB
C
51 lines
1.7 KiB
C
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#ifndef __CURVE_SIGS_H__
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#define __CURVE_SIGS_H__
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#define MAX_MSG_LEN 256
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void curve25519_keygen(unsigned char* curve25519_pubkey_out, /* 32 bytes */
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const unsigned char* curve25519_privkey_in); /* 32 bytes */
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/* returns 0 on success */
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int curve25519_sign(unsigned char* signature_out, /* 64 bytes */
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const unsigned char* curve25519_privkey, /* 32 bytes */
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const unsigned char* msg, const unsigned long msg_len,
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const unsigned char* random); /* 64 bytes */
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/* returns 0 on success */
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int curve25519_verify(const unsigned char* signature, /* 64 bytes */
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const unsigned char* curve25519_pubkey, /* 32 bytes */
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const unsigned char* msg, const unsigned long msg_len);
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/* helper function - modified version of crypto_sign() to use
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explicit private key. In particular:
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sk : private key
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pk : public key
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msg : message
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prefix : 0xFE || [0xFF]*31
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random : 64 bytes random
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q : main subgroup order
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The prefix is chosen to distinguish the two SHA512 uses below, since
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prefix is an invalid encoding for R (it would encode a "field element"
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of 2^255 - 2). 0xFF*32 is set aside for use in ECDH protocols, which
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is why the first byte here ix 0xFE.
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sig_nonce = SHA512(prefix || sk || msg || random) % q
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R = g^sig_nonce
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M = SHA512(R || pk || m)
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S = sig_nonce + (m * sk)
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signature = (R || S)
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*/
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int crypto_sign_modified(
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unsigned char *sm,
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const unsigned char *m,unsigned long long mlen,
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const unsigned char *sk, /* Curve/Ed25519 private key */
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const unsigned char *pk, /* Ed25519 public key */
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const unsigned char *random /* 64 bytes random to hash into nonce */
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);
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#endif
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