masterthesis-ecdaa-network-wrapper/verifier.c

#include "verifier.h"

typedef enum verifierstate {
    ON,
    ASKISSUER,
    GOTISSUER,
} verifierstate_e;

typedef struct verifier {
    struct ecdaa_issuer_public_key_FP256BN ipk;
//    struct ecdaa_member_public_key_FP256BN mpk;
    struct ecdaa_revocations_FP256BN revocations;
    verifierstate_e state;
} verifier_t;

verifier_t verifier;
uint8_t msg[MAX_MSGSIZE];
size_t msg_len;
uint8_t chksum[MAX_CHKSUMSIZE];
size_t chksum_len;

int verifier_getissuer(char *buffer);

int verifier_attestmember(char *buffer);

int verifier_checklink(char *buffer);

int verifier_verifymsg(char *buffer);

int main(int argc, char **argv) {
    verifier.revocations.sk_list = NULL;
    verifier.revocations.bsn_list = NULL;
    char *remote_ip;
    int ret = 0;

    switch(argc) {
        case 1:
            if (0 != ecdaa_issuer_public_key_FP256BN_deserialize_file(&verifier.ipk, VERIFIER_GROUP_PK_FILE)) {
                printf("Could not import key file. Importing from %s was not successful.\n",VERIFIER_GROUP_PK_FILE);
                return 1;
            }
	    printf("verifier_setup: loaded keys from disk.\n");
            verifier.state = GOTISSUER;
            break;
        case 3:
            if( 0 == strncasecmp("--public", argv[1], 6) || 0 == strncasecmp("-p", argv[1], 2)) {
                verifier.state = ON;
                remote_ip = argv[2];
                ret = client_connect(&verifier_getissuer, remote_ip, ISSUERPORT);
                if (0 >= ret || GOTISSUER != verifier.state) {
                    printf("Error: connection to issuer failed.\n");
                }
                if(0 != ecdaa_issuer_public_key_FP256BN_serialize_file(VERIFIER_GROUP_PK_FILE, &verifier.ipk)) {
                    printf("Error saving key-pair to disk.\n");
                    return -1;
                }
		printf("verifier_setup: wrote new issuer's public key to %s.\n", VERIFIER_GROUP_PK_FILE);
            } else {
	    	printf("Error: Arguments invalid.\n");
	    }
            break;
        default:
            printf("Usage: \n Get issuer's public key: %s --public <issuer's IPv4>\n", argv[0]);
            printf("If the public key is already saved, no arguments are needed.\n");
            break;
    }
    if (GOTISSUER == verifier.state && 2 != server_start(&process_verifier, VERIFIERPORT)) {
        printf("Error: Server failed.\n");
    }
    return 0;
}

int process_verifier(char *buffer) {
    int ret = 0;
    char remote_ip[16];

    printf("> VERIFIER: %s\n", buffer);

    if (0 == strncasecmp("VERIFYMSG", buffer, 9)) {
        ret = verifier_verifymsg(&buffer[10]);
        bzero(buffer, MAX_BUFSIZE);
        if (-1 == ret) {
            printf("process_verifier: Member public key is malformed!\n");
        } else if (-2 == ret) {
            printf("process_verifier: Signature of member public key is invalid.\n");
        } else {
	    printf("process_verifier: Received message with valid DAA signature.\n");
        }
        printf("closing client session.\n");
	ret = 1;
    } else if (0 == strncasecmp("EXIT", buffer, 4)) {
        printf("closing client session.\n");
        bzero(buffer, MAX_BUFSIZE);
        ret = 1;
    } else if (0 == strncasecmp("SHUTDOWN", buffer, 8)) {
        bzero(buffer, MAX_BUFSIZE);
        ret = 2;
    } else {
        printf("unknown command.\n");
        bzero(buffer, MAX_BUFSIZE);
        strncpy(buffer, "ERR\n", 4);
        ret = 0;
    }

    if (0 == ret) {
        printf("< VERIFIER: %s\n", buffer);
    }
    return ret;
}

int verifier_getissuer(char *buffer) {
    int ret = 0;

    switch (verifier.state) {
        case ON:
            bzero(buffer, MAX_BUFSIZE);
            strncpy(buffer, "PUBLISH\n", 8);
            verifier.state = ASKISSUER;
            break;
        case ASKISSUER:
            if (0 == strncasecmp("PUBLISH", buffer, 7)) {
#ifdef DEBUG
                printf("ISSUER > VERIFIER: %s", buffer);
#endif
                uint8_t binbuf[MAX_BUFSIZE];
                char *current = &buffer[8];
                ecdaa_decode(current, binbuf, ECDAA_ISSUER_PUBLIC_KEY_FP256BN_LENGTH);
                ret = ecdaa_issuer_public_key_FP256BN_deserialize(&verifier.ipk, binbuf);
                if (-1 == ret) {
                    printf("verifier_getpublic: issuer public key is malformed!\n");
                    ret = -1;
                } else if (-2 == ret) {
                    printf("verifier_getpublic: signature of issuer public key is invalid.\n");
                    ret = -1;
                } else {
                    verifier.state = GOTISSUER;
                    ret = 1;
                }
            } else {
                printf("verifier_getpublic: did not get public key from issuer.\n");
                verifier.state = ON;
                ret = -1;
            }
            break;
        default:
            ret = -1;
    }
    if (0 == ret) {
#ifdef DEBUG
        printf("ISSUER < VERIFIER: %s", buffer);
#endif
    }
    return ret;
}

//"ATTEST <msg>0<signature w/o bsn>" or
//"ATTEST <msg>1<signature with bsn>"
int verifier_verifymsg(char *buffer) {
    char *current = buffer; 
    int has_nym = 0;
    char bsn[MAX_BSNSIZE];
    size_t bsn_len = 0;
    uint8_t binbuf[MAX_BUFSIZE];
    size_t sig_len = 0;
    struct ecdaa_signature_FP256BN sig;
    int ret = 0;

    bzero(msg, MAX_MSGSIZE);
    ret = ecdaa_decode(current, msg, MAX_MSGSIZE);
    msg_len = strlen(msg);
    current = &current[ret];
    bzero(chksum, MAX_CHKSUMSIZE);
    ret = ecdaa_decode(current, chksum, MAX_CHKSUMSIZE);
    chksum_len = strlen(chksum);
    current = &current[ret];
    has_nym = current[0] - '0';
    current = &current[1];
    bzero(bsn, MAX_BSNSIZE);

    if (has_nym) {
	sig_len = ecdaa_signature_FP256BN_with_nym_length(); 
#ifdef DEBUG
	printf("verifier_verifymsg: nym detected, signature length = %ld.\n",sig_len);
#endif
	ecdaa_decode(current, bsn, MAX_BSNSIZE);
	bsn_len = strlen(bsn);
    } else {
	sig_len = ecdaa_signature_FP256BN_length(); 
    }

    bzero(binbuf, MAX_BUFSIZE);
    ecdaa_decode(current, binbuf, sig_len);
#ifdef DEBUG
    printf("verifier_verifymsg: Signature decoded.\n");
#endif

    ret = ecdaa_signature_FP256BN_deserialize(&sig, binbuf, has_nym);
    if (0 != ret) {
        printf("verifier_verifymsg: error reading signature.\n");
        return -1;
    }
#ifdef DEBUG
    printf("verifier_verifymsg: Signature deserialized.\n");
#endif

#ifdef DEBUG
    printf("verifier_verifymsg: has_nym: %u, sig_len: %lu\n", has_nym, sig_len);
    printf("verifier_verifymsg: msg: %s, len: %lu\n", msg, msg_len);
    printf("verifier_verifymsg: chksum: %s, len: %lu\n", chksum, chksum_len);
    printf("verifier_verifymsg: bsn: %s, len: %lu\n", bsn, bsn_len);
    printf("verifier_verifymsg: sig: %s, len: %lu\n", current, sig_len);
#endif
    ret = ecdaa_signature_FP256BN_verify(&sig, &verifier.ipk.gpk, &verifier.revocations, (uint8_t *) chksum, chksum_len,
            (uint8_t *) bsn, bsn_len);
    if (0 != ret) {
        printf("verifier_verifymsg: signature not valid, ret = %i\n", ret);
        return -1;
    }

    printf("writing message to %s\n", MESSAGE_FILE);
    ecdaa_write_buffer_to_file(MESSAGE_FILE, msg, msg_len);
    printf("writing checksum to %s\n", CHECKSUM_FILE);
    ecdaa_write_buffer_to_file(CHECKSUM_FILE, chksum, chksum_len);
    return 0;
}