solidity signature r s v

#include <openssl/ec.h>
#include <openssl/ecdsa.h>
#include <openssl/objects.h>

void signature_parse(uint8_t signature, ECDSA_SIG parsed_signature) {
    BIGNUM r, s;
    r = BN_new();
    s = BN_new();

    BN_bin2bn(signature, 32, r);
    BN_bin2bn(signature + 32, 32, s);

    ECDSA_SIG_set0(parsed_signature, r, s);
}

int main() {
    uint8_t signature[64]; // The signature bytes
    ECDSA_SIG *parsed_signature = ECDSA_SIG_new();

    // Call signature_parse with the signature bytes and parsed_signature pointer
    signature_parse(signature, parsed_signature);

    // Further operations with parsed_signature

    ECDSA_SIG_free(parsed_signature);
    return 0;
}

Explanation:

  1. #include <openssl/ec.h> and other similar lines are preprocessor directives that include necessary header files for OpenSSL library functions related to elliptic curve operations (EC), ECDSA (Elliptic Curve Digital Signature Algorithm), and related data structures.

  2. void signature_parse(uint8_t signature, ECDSA_SIG parsed_signature) defines a function signature_parse that takes a pointer to a uint8_t array (signature) representing the signature and a pointer to an ECDSA_SIG struct (parsed_signature). This function will parse the signature into its components r and s.

  3. BIGNUM r, s; r = BN_new(); s = BN_new(); declares pointers to BIGNUM structures r and s and initializes them using BN_new(). BIGNUM is a structure in OpenSSL representing big integers.

  4. BN_bin2bn(signature, 32, r); BN_bin2bn(signature + 32, 32, s); converts the first 32 bytes of the signature array into a big integer r and the next 32 bytes into another big integer s. These represent the components of the ECDSA signature.

  5. ECDSA_SIG_set0(parsed_signature, r, s); sets the parsed_signature structure using the r and s values obtained from the signature. ECDSA_SIG_set0() initializes the r and s values of an ECDSA_SIG structure with given BIGNUM values.

  6. In the main() function, an array uint8_t signature[64]; is declared to store the signature bytes.

  7. ECDSA_SIG *parsed_signature = ECDSA_SIG_new(); declares a pointer parsed_signature to an ECDSA_SIG structure and initializes it using ECDSA_SIG_new(), allocating memory for the ECDSA_SIG structure.

  8. signature_parse(signature, parsed_signature); calls the signature_parse function with the signature array and parsed_signature pointer to parse the signature bytes and store them in the parsed_signature structure.

  9. Further operations can be performed with the parsed ECDSA signature as needed.

  10. ECDSA_SIG_free(parsed_signature); frees the memory allocated for the parsed_signature structure once it's no longer needed.

  11. return 0; ends the main() function.