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| 1 | +#ifndef SECP256K1_EXTRAKEYS_H |
| 2 | +#define SECP256K1_EXTRAKEYS_H |
| 3 | + |
| 4 | +#include "secp256k1.h" |
| 5 | + |
| 6 | +#ifdef __cplusplus |
| 7 | +extern "C" { |
| 8 | +#endif |
| 9 | + |
| 10 | +/** Opaque data structure that holds a parsed and valid "x-only" public key. |
| 11 | + * An x-only pubkey encodes a point whose Y coordinate is even. It is |
| 12 | + * serialized using only its X coordinate (32 bytes). See BIP-340 for more |
| 13 | + * information about x-only pubkeys. |
| 14 | + * |
| 15 | + * The exact representation of data inside is implementation defined and not |
| 16 | + * guaranteed to be portable between different platforms or versions. It is |
| 17 | + * however guaranteed to be 64 bytes in size, and can be safely copied/moved. |
| 18 | + * If you need to convert to a format suitable for storage, transmission, or |
| 19 | + * comparison, use secp256k1_xonly_pubkey_serialize and |
| 20 | + * secp256k1_xonly_pubkey_parse. |
| 21 | + */ |
| 22 | +typedef struct { |
| 23 | + unsigned char data[64]; |
| 24 | +} secp256k1_xonly_pubkey; |
| 25 | + |
| 26 | +/** Opaque data structure that holds a keypair consisting of a secret and a |
| 27 | + * public key. |
| 28 | + * |
| 29 | + * The exact representation of data inside is implementation defined and not |
| 30 | + * guaranteed to be portable between different platforms or versions. It is |
| 31 | + * however guaranteed to be 96 bytes in size, and can be safely copied/moved. |
| 32 | + */ |
| 33 | +typedef struct { |
| 34 | + unsigned char data[96]; |
| 35 | +} secp256k1_keypair; |
| 36 | + |
| 37 | +/** Parse a 32-byte sequence into a xonly_pubkey object. |
| 38 | + * |
| 39 | + * Returns: 1 if the public key was fully valid. |
| 40 | + * 0 if the public key could not be parsed or is invalid. |
| 41 | + * |
| 42 | + * Args: ctx: a secp256k1 context object (cannot be NULL). |
| 43 | + * Out: pubkey: pointer to a pubkey object. If 1 is returned, it is set to a |
| 44 | + * parsed version of input. If not, it's set to an invalid value. |
| 45 | + * (cannot be NULL). |
| 46 | + * In: input32: pointer to a serialized xonly_pubkey (cannot be NULL) |
| 47 | + */ |
| 48 | +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_parse( |
| 49 | + const secp256k1_context* ctx, |
| 50 | + secp256k1_xonly_pubkey* pubkey, |
| 51 | + const unsigned char *input32 |
| 52 | +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); |
| 53 | + |
| 54 | +/** Serialize an xonly_pubkey object into a 32-byte sequence. |
| 55 | + * |
| 56 | + * Returns: 1 always. |
| 57 | + * |
| 58 | + * Args: ctx: a secp256k1 context object (cannot be NULL). |
| 59 | + * Out: output32: a pointer to a 32-byte array to place the serialized key in |
| 60 | + * (cannot be NULL). |
| 61 | + * In: pubkey: a pointer to a secp256k1_xonly_pubkey containing an |
| 62 | + * initialized public key (cannot be NULL). |
| 63 | + */ |
| 64 | +SECP256K1_API int secp256k1_xonly_pubkey_serialize( |
| 65 | + const secp256k1_context* ctx, |
| 66 | + unsigned char *output32, |
| 67 | + const secp256k1_xonly_pubkey* pubkey |
| 68 | +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); |
| 69 | + |
| 70 | +/** Converts a secp256k1_pubkey into a secp256k1_xonly_pubkey. |
| 71 | + * |
| 72 | + * Returns: 1 if the public key was successfully converted |
| 73 | + * 0 otherwise |
| 74 | + * |
| 75 | + * Args: ctx: pointer to a context object (cannot be NULL) |
| 76 | + * Out: xonly_pubkey: pointer to an x-only public key object for placing the |
| 77 | + * converted public key (cannot be NULL) |
| 78 | + * pk_parity: pointer to an integer that will be set to 1 if the point |
| 79 | + * encoded by xonly_pubkey is the negation of the pubkey and |
| 80 | + * set to 0 otherwise. (can be NULL) |
| 81 | + * In: pubkey: pointer to a public key that is converted (cannot be NULL) |
| 82 | + */ |
| 83 | +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_from_pubkey( |
| 84 | + const secp256k1_context* ctx, |
| 85 | + secp256k1_xonly_pubkey *xonly_pubkey, |
| 86 | + int *pk_parity, |
| 87 | + const secp256k1_pubkey *pubkey |
| 88 | +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4); |
| 89 | + |
| 90 | +/** Tweak an x-only public key by adding the generator multiplied with tweak32 |
| 91 | + * to it. |
| 92 | + * |
| 93 | + * Note that the resulting point can not in general be represented by an x-only |
| 94 | + * pubkey because it may have an odd Y coordinate. Instead, the output_pubkey |
| 95 | + * is a normal secp256k1_pubkey. |
| 96 | + * |
| 97 | + * Returns: 0 if the arguments are invalid or the resulting public key would be |
| 98 | + * invalid (only when the tweak is the negation of the corresponding |
| 99 | + * secret key). 1 otherwise. |
| 100 | + * |
| 101 | + * Args: ctx: pointer to a context object initialized for verification |
| 102 | + * (cannot be NULL) |
| 103 | + * Out: output_pubkey: pointer to a public key to store the result. Will be set |
| 104 | + * to an invalid value if this function returns 0 (cannot |
| 105 | + * be NULL) |
| 106 | + * In: internal_pubkey: pointer to an x-only pubkey to apply the tweak to. |
| 107 | + * (cannot be NULL). |
| 108 | + * tweak32: pointer to a 32-byte tweak. If the tweak is invalid |
| 109 | + * according to secp256k1_ec_seckey_verify, this function |
| 110 | + * returns 0. For uniformly random 32-byte arrays the |
| 111 | + * chance of being invalid is negligible (around 1 in |
| 112 | + * 2^128) (cannot be NULL). |
| 113 | + */ |
| 114 | +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_tweak_add( |
| 115 | + const secp256k1_context* ctx, |
| 116 | + secp256k1_pubkey *output_pubkey, |
| 117 | + const secp256k1_xonly_pubkey *internal_pubkey, |
| 118 | + const unsigned char *tweak32 |
| 119 | +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4); |
| 120 | + |
| 121 | +/** Checks that a tweaked pubkey is the result of calling |
| 122 | + * secp256k1_xonly_pubkey_tweak_add with internal_pubkey and tweak32. |
| 123 | + * |
| 124 | + * The tweaked pubkey is represented by its 32-byte x-only serialization and |
| 125 | + * its pk_parity, which can both be obtained by converting the result of |
| 126 | + * tweak_add to a secp256k1_xonly_pubkey. |
| 127 | + * |
| 128 | + * Note that this alone does _not_ verify that the tweaked pubkey is a |
| 129 | + * commitment. If the tweak is not chosen in a specific way, the tweaked pubkey |
| 130 | + * can easily be the result of a different internal_pubkey and tweak. |
| 131 | + * |
| 132 | + * Returns: 0 if the arguments are invalid or the tweaked pubkey is not the |
| 133 | + * result of tweaking the internal_pubkey with tweak32. 1 otherwise. |
| 134 | + * Args: ctx: pointer to a context object initialized for verification |
| 135 | + * (cannot be NULL) |
| 136 | + * In: tweaked_pubkey32: pointer to a serialized xonly_pubkey (cannot be NULL) |
| 137 | + * tweaked_pk_parity: the parity of the tweaked pubkey (whose serialization |
| 138 | + * is passed in as tweaked_pubkey32). This must match the |
| 139 | + * pk_parity value that is returned when calling |
| 140 | + * secp256k1_xonly_pubkey with the tweaked pubkey, or |
| 141 | + * this function will fail. |
| 142 | + * internal_pubkey: pointer to an x-only public key object to apply the |
| 143 | + * tweak to (cannot be NULL) |
| 144 | + * tweak32: pointer to a 32-byte tweak (cannot be NULL) |
| 145 | + */ |
| 146 | +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_tweak_add_check( |
| 147 | + const secp256k1_context* ctx, |
| 148 | + const unsigned char *tweaked_pubkey32, |
| 149 | + int tweaked_pk_parity, |
| 150 | + const secp256k1_xonly_pubkey *internal_pubkey, |
| 151 | + const unsigned char *tweak32 |
| 152 | +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5); |
| 153 | + |
| 154 | +/** Compute the keypair for a secret key. |
| 155 | + * |
| 156 | + * Returns: 1: secret was valid, keypair is ready to use |
| 157 | + * 0: secret was invalid, try again with a different secret |
| 158 | + * Args: ctx: pointer to a context object, initialized for signing (cannot be NULL) |
| 159 | + * Out: keypair: pointer to the created keypair (cannot be NULL) |
| 160 | + * In: seckey: pointer to a 32-byte secret key (cannot be NULL) |
| 161 | + */ |
| 162 | +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_create( |
| 163 | + const secp256k1_context* ctx, |
| 164 | + secp256k1_keypair *keypair, |
| 165 | + const unsigned char *seckey |
| 166 | +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); |
| 167 | + |
| 168 | +/** Get the public key from a keypair. |
| 169 | + * |
| 170 | + * Returns: 0 if the arguments are invalid. 1 otherwise. |
| 171 | + * Args: ctx: pointer to a context object (cannot be NULL) |
| 172 | + * Out: pubkey: pointer to a pubkey object. If 1 is returned, it is set to |
| 173 | + * the keypair public key. If not, it's set to an invalid value. |
| 174 | + * (cannot be NULL) |
| 175 | + * In: keypair: pointer to a keypair (cannot be NULL) |
| 176 | + */ |
| 177 | +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_pub( |
| 178 | + const secp256k1_context* ctx, |
| 179 | + secp256k1_pubkey *pubkey, |
| 180 | + const secp256k1_keypair *keypair |
| 181 | +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); |
| 182 | + |
| 183 | +/** Get the x-only public key from a keypair. |
| 184 | + * |
| 185 | + * This is the same as calling secp256k1_keypair_pub and then |
| 186 | + * secp256k1_xonly_pubkey_from_pubkey. |
| 187 | + * |
| 188 | + * Returns: 0 if the arguments are invalid. 1 otherwise. |
| 189 | + * Args: ctx: pointer to a context object (cannot be NULL) |
| 190 | + * Out: pubkey: pointer to an xonly_pubkey object. If 1 is returned, it is set |
| 191 | + * to the keypair public key after converting it to an |
| 192 | + * xonly_pubkey. If not, it's set to an invalid value (cannot be |
| 193 | + * NULL). |
| 194 | + * pk_parity: pointer to an integer that will be set to the pk_parity |
| 195 | + * argument of secp256k1_xonly_pubkey_from_pubkey (can be NULL). |
| 196 | + * In: keypair: pointer to a keypair (cannot be NULL) |
| 197 | + */ |
| 198 | +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_xonly_pub( |
| 199 | + const secp256k1_context* ctx, |
| 200 | + secp256k1_xonly_pubkey *pubkey, |
| 201 | + int *pk_parity, |
| 202 | + const secp256k1_keypair *keypair |
| 203 | +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4); |
| 204 | + |
| 205 | +/** Tweak a keypair by adding tweak32 to the secret key and updating the public |
| 206 | + * key accordingly. |
| 207 | + * |
| 208 | + * Calling this function and then secp256k1_keypair_pub results in the same |
| 209 | + * public key as calling secp256k1_keypair_xonly_pub and then |
| 210 | + * secp256k1_xonly_pubkey_tweak_add. |
| 211 | + * |
| 212 | + * Returns: 0 if the arguments are invalid or the resulting keypair would be |
| 213 | + * invalid (only when the tweak is the negation of the keypair's |
| 214 | + * secret key). 1 otherwise. |
| 215 | + * |
| 216 | + * Args: ctx: pointer to a context object initialized for verification |
| 217 | + * (cannot be NULL) |
| 218 | + * In/Out: keypair: pointer to a keypair to apply the tweak to. Will be set to |
| 219 | + * an invalid value if this function returns 0 (cannot be |
| 220 | + * NULL). |
| 221 | + * In: tweak32: pointer to a 32-byte tweak. If the tweak is invalid according |
| 222 | + * to secp256k1_ec_seckey_verify, this function returns 0. For |
| 223 | + * uniformly random 32-byte arrays the chance of being invalid |
| 224 | + * is negligible (around 1 in 2^128) (cannot be NULL). |
| 225 | + */ |
| 226 | +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_xonly_tweak_add( |
| 227 | + const secp256k1_context* ctx, |
| 228 | + secp256k1_keypair *keypair, |
| 229 | + const unsigned char *tweak32 |
| 230 | +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); |
| 231 | + |
| 232 | +#ifdef __cplusplus |
| 233 | +} |
| 234 | +#endif |
| 235 | + |
| 236 | +#endif /* SECP256K1_EXTRAKEYS_H */ |
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