vapid_import_private_key - add the atual functionality

[nissimeinat]

current vapid_import_private_key function just return NULL.
adding import form PEM format to EC_KEY*

[codecov-io]

Codecov Report

Merging #40 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #40   +/-   ##
=======================================
  Coverage   86.56%   86.56%           
=======================================
  Files          14       14           
  Lines        1407     1407           
=======================================
  Hits         1218     1218           
  Misses        189      189

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[Lakr233]

here is my approach

static EC_KEY*
vapid_import_private_key(const char* privateKey) {
    if (!privateKey) { return NULL; }
    size_t rawPrivKeyLen = ece_base64url_decode(privateKey,
                                                strlen(privateKey),
                                                ECE_BASE64URL_REJECT_PADDING,
                                                NULL,
                                                0);
    if (!rawPrivKeyLen) { return NULL; }
    
    uint8_t* rawPrivKey = malloc(rawPrivKeyLen);
    if (!rawPrivKey) { return NULL; }
    
    if (ece_base64url_decode(privateKey, strlen(privateKey), ECE_BASE64URL_REJECT_PADDING,
                             rawPrivKey, rawPrivKeyLen) != rawPrivKeyLen) {
        free(rawPrivKey);
        return NULL;
    }
    
    EC_KEY* key = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
    if (!key || !EC_KEY_oct2priv(key, rawPrivKey, rawPrivKeyLen)) {
        EC_KEY_free(key);
        free(rawPrivKey);
        return NULL;
    }
    
    free(rawPrivKey);
    return key;
}

[aolo2]

If you have the same usecase as me (generating VAPID tokens for different push services using the same key), then you probably want a function that sets both the private and public keys, not just the private.

static EC_KEY*
vapid_import_public_and_private_from_private_key(const char* privateKeyB64Url) {
    if (!privateKeyB64Url) { return NULL; }
    size_t rawPrivKeyLen = ece_base64url_decode(privateKeyB64Url,
                                                strlen(privateKeyB64Url),
                                                ECE_BASE64URL_REJECT_PADDING,
                                                NULL,
                                                0);
    if (!rawPrivKeyLen) { return NULL; }
    
    uint8_t* rawPrivKey = malloc(rawPrivKeyLen);
    if (!rawPrivKey) { return NULL; }
    
    if (ece_base64url_decode(privateKeyB64Url, strlen(privateKeyB64Url), ECE_BASE64URL_REJECT_PADDING,
                             rawPrivKey, rawPrivKeyLen) != rawPrivKeyLen) {
        free(rawPrivKey);
        return NULL;
    }
    
    EC_KEY* key = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);

    // Set private key
    if (!key || !EC_KEY_oct2priv(key, rawPrivKey, rawPrivKeyLen)) {
        EC_KEY_free(key);
        free(rawPrivKey);
        return NULL;
    }

    // Set public key
    BN_CTX* ctx = BN_CTX_new();

    const BIGNUM *private_key_bn = EC_KEY_get0_private_key(key);
    const EC_GROUP *group = EC_KEY_get0_group(key);
    EC_POINT *pubkey_point = EC_POINT_new(group);

    EC_POINT_mul(group, pubkey_point, private_key_bn, NULL, NULL, ctx);
    BN_CTX_free(ctx);

    EC_KEY_set_public_key(key, pubkey_point);
    
    free(rawPrivKey);
    return key;
}