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192 lines
8.2 KiB
192 lines
8.2 KiB
package secp256k1
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/*
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<HaltingState> sipa, int secp256k1_ecdsa_pubkey_create(unsigned char *pubkey, int *pubkeylen, const unsigned char *seckey, int compressed);
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<HaltingState> is that how i generate private/public keys?
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<sipa> HaltingState: you pass in a random 32-byte string as seckey
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<sipa> HaltingState: if it is valid, the corresponding pubkey is put in pubkey
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<sipa> and true is returned
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<sipa> otherwise, false is returned
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<sipa> around 1 in 2^128 32-byte strings are invalid, so the odds of even ever seeing one is extremely rare
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<sipa> private keys are mathematically numbers
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<sipa> each has a corresponding point on the curve as public key
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<sipa> a private key is just a number
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<sipa> a public key is a point with x/y coordinates
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<sipa> almost every 256-bit number is a valid private key (one with a point on the curve corresponding to it)
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<sipa> HaltingState: ok?
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<sipa> more than half of random points are not on the curve
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<sipa> and actually, it is less than the square root, not less than half, sorry :)
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!!!
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<sipa> a private key is a NUMBER
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<sipa> a public key is a POINT
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<gmaxwell> half the x,y values in the field are not on the curve, a private key is an integer.
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<sipa> HaltingState: yes, n,q = private keys; N,Q = corresponding public keys (N=n*G, Q=q*G); then it follows that n*Q = n*q*G = q*n*G = q*N
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<sipa> that's the reason ECDH works
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<sipa> multiplication is associative and commutativ
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*/
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/*
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<HaltingState> sipa, ok; i am doing compact signatures and I want to know; can someone change the signature to get another valid signature for same message without the private key
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<HaltingState> because i know they can do that for the normal 72 byte signatures that openssl was putting out
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<sipa> HaltingState: if you don't enforce non-malleability, yes
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<sipa> HaltingState: if you force the highest bit of t
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<sipa> it _creates_ signatures that already satisfy that condition
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<sipa> but it will accept ones that don't
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<sipa> maybe i should change that, and be strict
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<HaltingState> yes; i want some way to know signature is valid but fails malleability
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<sipa> well if the highest bit of S is 1, you can take its complement
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<sipa> and end up with a valid signature
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<sipa> that is canonical
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*/
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/*
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<HaltingState> sipa, I am signing messages and highest bit of the compact signature is 1!!!
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<HaltingState> if (b & 0x80) == 0x80 {
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<HaltingState> log.Panic("b= %v b2= %v \n", b, b&0x80)
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<HaltingState> }
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<sipa> what bit?
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* Pengoo has quit (Ping timeout: 272 seconds)
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<HaltingState> the highest bit of the first byte of signature
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<sipa> it's the highest bit of S
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<sipa> so the 32nd byte
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<HaltingState> wtf
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*/
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/*
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For instance, nonces are used in HTTP digest access authentication to calculate an MD5 digest
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of the password. The nonces are different each time the 401 authentication challenge
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response code is presented, thus making replay attacks virtually impossible.
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can verify client/server match without sending password over network
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*/
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/*
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<hanihani> one thing I dont get about armory for instance,
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is how the hot-wallet can generate new addresses without
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knowing the master key
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*/
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/*
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<HaltingState> i am yelling at the telehash people for using secp256r1
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instead of secp256k1; they thing r1 is "more secure" despite fact that
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there is no implementation that works and wrapping it is now taking
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up massive time, lol
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<gmaxwell> ...
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<gmaxwell> You know that the *r curves are selected via an undisclosed
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secret process, right?
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<gmaxwell> HaltingState: telehash is offtopic for this channel.
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*/
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/*
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For instance, nonces are used in HTTP digest access authentication to calculate an MD5 digest
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of the password. The nonces are different each time the 401 authentication challenge
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response code is presented, thus making replay attacks virtually impossible.
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can verify client/server match without sending password over network
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*/
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/*
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void secp256k1_start(void);
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void secp256k1_stop(void);
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* Verify an ECDSA signature.
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* Returns: 1: correct signature
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* 0: incorrect signature
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* -1: invalid public key
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* -2: invalid signature
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*
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int secp256k1_ecdsa_verify(const unsigned char *msg, int msglen,
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const unsigned char *sig, int siglen,
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const unsigned char *pubkey, int pubkeylen);
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http://www.nilsschneider.net/2013/01/28/recovering-bitcoin-private-keys.html
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Why did this work? ECDSA requires a random number for each signature. If this random
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number is ever used twice with the same private key it can be recovered.
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This transaction was generated by a hardware bitcoin wallet using a pseudo-random number
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generator that was returning the same “random” number every time.
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Nonce is 32 bytes?
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* Create an ECDSA signature.
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* Returns: 1: signature created
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* 0: nonce invalid, try another one
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* In: msg: the message being signed
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* msglen: the length of the message being signed
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* seckey: pointer to a 32-byte secret key (assumed to be valid)
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* nonce: pointer to a 32-byte nonce (generated with a cryptographic PRNG)
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* Out: sig: pointer to a 72-byte array where the signature will be placed.
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* siglen: pointer to an int, which will be updated to the signature length (<=72).
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*
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int secp256k1_ecdsa_sign(const unsigned char *msg, int msglen,
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unsigned char *sig, int *siglen,
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const unsigned char *seckey,
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const unsigned char *nonce);
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* Create a compact ECDSA signature (64 byte + recovery id).
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* Returns: 1: signature created
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* 0: nonce invalid, try another one
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* In: msg: the message being signed
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* msglen: the length of the message being signed
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* seckey: pointer to a 32-byte secret key (assumed to be valid)
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* nonce: pointer to a 32-byte nonce (generated with a cryptographic PRNG)
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* Out: sig: pointer to a 64-byte array where the signature will be placed.
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* recid: pointer to an int, which will be updated to contain the recovery id.
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*
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int secp256k1_ecdsa_sign_compact(const unsigned char *msg, int msglen,
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unsigned char *sig64,
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const unsigned char *seckey,
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const unsigned char *nonce,
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int *recid);
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* Recover an ECDSA public key from a compact signature.
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* Returns: 1: public key succesfully recovered (which guarantees a correct signature).
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* 0: otherwise.
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* In: msg: the message assumed to be signed
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* msglen: the length of the message
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* compressed: whether to recover a compressed or uncompressed pubkey
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* recid: the recovery id (as returned by ecdsa_sign_compact)
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* Out: pubkey: pointer to a 33 or 65 byte array to put the pubkey.
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* pubkeylen: pointer to an int that will contain the pubkey length.
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*
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recovery id is between 0 and 3
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int secp256k1_ecdsa_recover_compact(const unsigned char *msg, int msglen,
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const unsigned char *sig64,
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unsigned char *pubkey, int *pubkeylen,
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int compressed, int recid);
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* Verify an ECDSA secret key.
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* Returns: 1: secret key is valid
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* 0: secret key is invalid
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* In: seckey: pointer to a 32-byte secret key
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*
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int secp256k1_ecdsa_seckey_verify(const unsigned char *seckey);
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** Just validate a public key.
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* Returns: 1: valid public key
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* 0: invalid public key
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*
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int secp256k1_ecdsa_pubkey_verify(const unsigned char *pubkey, int pubkeylen);
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** Compute the public key for a secret key.
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* In: compressed: whether the computed public key should be compressed
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* seckey: pointer to a 32-byte private key.
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* Out: pubkey: pointer to a 33-byte (if compressed) or 65-byte (if uncompressed)
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* area to store the public key.
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* pubkeylen: pointer to int that will be updated to contains the pubkey's
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* length.
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* Returns: 1: secret was valid, public key stores
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* 0: secret was invalid, try again.
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*
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int secp256k1_ecdsa_pubkey_create(unsigned char *pubkey, int *pubkeylen, const unsigned char *seckey, int compressed);
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*/
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