iOS RSA2加簽、驗簽

私鑰加簽:

1.使用雜湊演算法擷取待簽名字元串的摘要

+ (NSData *)sha256:(NSString *)str {
    const char *s = [str cStringUsingEncoding:str];
    NSData *keyData = [NSData dataWithBytes:s length:strlen(s)];
    uint8_t digest [CC_SHA256_DIGEST_LENGTH] = {0};
    CC_SHA256(keyData.bytes, (CC_LONG)keyData.length, digest);
    NSData *outData = [NSData dataWithBytes:digest length:CC_SHA256_DIGEST_LENGTH];
    return outData;
}
           

2.使用私鑰字元串擷取SecKeyRef指針，通過讀取pem檔案即可擷取，網上代碼很多。也可使用指數、模數生成，參考Objective-C-RSA。

示例代碼

// 私鑰
+ (SecKeyRef)addPrivateKey:(NSString *)key{
    NSRange spos;
    NSRange epos;
    spos = [key rangeOfString:@"-----BEGIN RSA PRIVATE KEY-----"];
    if(spos.length > 0){
        epos = [key rangeOfString:@"-----END RSA PRIVATE KEY-----"];
    }else{
        spos = [key rangeOfString:@"-----BEGIN PRIVATE KEY-----"];
        epos = [key rangeOfString:@"-----END PRIVATE KEY-----"];
    }
    if(spos.location != NSNotFound && epos.location != NSNotFound){
        NSUInteger s = spos.location + spos.length;
        NSUInteger e = epos.location;
        NSRange range = NSMakeRange(s, e-s);
        key = [key substringWithRange:range];
    }
    key = [key stringByReplacingOccurrencesOfString:@"\r" withString:@""];
    key = [key stringByReplacingOccurrencesOfString:@"\n" withString:@""];
    key = [key stringByReplacingOccurrencesOfString:@"\t" withString:@""];
    key = [key stringByReplacingOccurrencesOfString:@" "  withString:@""];
    
    // This will be base64 encoded, decode it.
    NSData *data = base64_decode(key);
    data = [AOPRSA stripPrivateKeyHeader:data];
    if(!data){
        return nil;
    }
    
    //a tag to read/write keychain storage
    NSString *tag = @"RSAUtil_PrivKey";
    NSData *d_tag = [NSData dataWithBytes:[tag UTF8String] length:[tag length]];
    
    // Delete any old lingering key with the same tag
    NSMutableDictionary *privateKey = [[NSMutableDictionary alloc] init];
    [privateKey setObject:(__bridge id) kSecClassKey forKey:(__bridge id)kSecClass];
    [privateKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
    [privateKey setObject:d_tag forKey:(__bridge id)kSecAttrApplicationTag];
    SecItemDelete((__bridge CFDictionaryRef)privateKey);
    
    // Add persistent version of the key to system keychain
    [privateKey setObject:data forKey:(__bridge id)kSecValueData];
    [privateKey setObject:(__bridge id) kSecAttrKeyClassPrivate forKey:(__bridge id)
     kSecAttrKeyClass];
    [privateKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)
     kSecReturnPersistentRef];
    
    CFTypeRef persistKey = nil;
    OSStatus status = SecItemAdd((__bridge CFDictionaryRef)privateKey, &persistKey);
    if (persistKey != nil){
        CFRelease(persistKey);
    }
    if ((status != noErr) && (status != errSecDuplicateItem)) {
        return nil;
    }
    
    [privateKey removeObjectForKey:(__bridge id)kSecValueData];
    [privateKey removeObjectForKey:(__bridge id)kSecReturnPersistentRef];
    [privateKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecReturnRef];
    [privateKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
    
    // Now fetch the SecKeyRef version of the key
    SecKeyRef keyRef = nil;
    status = SecItemCopyMatching((__bridge CFDictionaryRef)privateKey, (CFTypeRef *)&keyRef);
    if(status != noErr){
        return nil;
    }
    return keyRef;
}

// 公鑰
+ (SecKeyRef)addPublicKey:(NSString *)key{
    NSRange spos = [key rangeOfString:@"-----BEGIN PUBLIC KEY-----"];
    NSRange epos = [key rangeOfString:@"-----END PUBLIC KEY-----"];
    if(spos.location != NSNotFound && epos.location != NSNotFound){
        NSUInteger s = spos.location + spos.length;
        NSUInteger e = epos.location;
        NSRange range = NSMakeRange(s, e-s);
        key = [key substringWithRange:range];
    }
    key = [key stringByReplacingOccurrencesOfString:@"\r" withString:@""];
    key = [key stringByReplacingOccurrencesOfString:@"\n" withString:@""];
    key = [key stringByReplacingOccurrencesOfString:@"\t" withString:@""];
    key = [key stringByReplacingOccurrencesOfString:@" "  withString:@""];
    
    // This will be base64 encoded, decode it.
    NSData *data = base64_decode(key);
    data = [AOPRSA stripPublicKeyHeader:data];
    if(!data){
        return nil;
    }
    
    //a tag to read/write keychain storage
    NSString *tag = @"RSAUtil_PubKey";
    NSData *d_tag = [NSData dataWithBytes:[tag UTF8String] length:[tag length]];
    
    // Delete any old lingering key with the same tag
    NSMutableDictionary *publicKey = [[NSMutableDictionary alloc] init];
    [publicKey setObject:(__bridge id) kSecClassKey forKey:(__bridge id)kSecClass];
    [publicKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
    [publicKey setObject:d_tag forKey:(__bridge id)kSecAttrApplicationTag];
    SecItemDelete((__bridge CFDictionaryRef)publicKey);
    
    // Add persistent version of the key to system keychain
    [publicKey setObject:data forKey:(__bridge id)kSecValueData];
    [publicKey setObject:(__bridge id) kSecAttrKeyClassPublic forKey:(__bridge id)
     kSecAttrKeyClass];
    [publicKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)
     kSecReturnPersistentRef];
    
    CFTypeRef persistKey = nil;
    OSStatus status = SecItemAdd((__bridge CFDictionaryRef)publicKey, &persistKey);
    if (persistKey != nil){
        CFRelease(persistKey);
    }
    if ((status != noErr) && (status != errSecDuplicateItem)) {
        return nil;
    }
    
    [publicKey removeObjectForKey:(__bridge id)kSecValueData];
    [publicKey removeObjectForKey:(__bridge id)kSecReturnPersistentRef];
    [publicKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecReturnRef];
    [publicKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
    
    // Now fetch the SecKeyRef version of the key
    SecKeyRef keyRef = nil;
    status = SecItemCopyMatching((__bridge CFDictionaryRef)publicKey, (CFTypeRef *)&keyRef);
    if(status != noErr){
        return nil;
    }
    return keyRef;
}

           

3.使用sha256WithRSA加密資料

storString為待加迷字元串

// 加簽
+ (NSString *)encryptSHA256Data:(NSString *)storString {
    // 使用雜湊演算法擷取字元串摘要
    NSData *outData = [self sha256:storString];
    // 私鑰key
    SecKeyRef privateKey = [AOPRSA addPrivateKey:@"privateKey"];
    
    // sha256WithRSA加密
    size_t signedHashBytesSize = SecKeyGetBlockSize(privateKey);
    uint8_t* signedHashBytes = malloc(signedHashBytesSize);
    memset(signedHashBytes, 0x0, signedHashBytesSize);
    
    size_t hashBytesSize = CC_SHA256_DIGEST_LENGTH;
    uint8_t* hashBytes = malloc(hashBytesSize);
    if (!CC_SHA256([outData bytes], (CC_LONG)[outData length], hashBytes)) {
        return nil;
    }
    SecKeyRawSign(privateKey,
                  kSecPaddingPKCS1SHA256,
                  hashBytes,
                  hashBytesSize,
                  signedHashBytes,
                  &signedHashBytesSize);
    
    NSData* signedHash = [NSData dataWithBytes:signedHashBytes length:(NSUInteger)signedHashBytesSize];
    
    if (hashBytes)
        free(hashBytes);
    if (signedHashBytes)
        free(signedHashBytes);
    
    NSString *signString = [signedHash base64EncodedStringWithOptions:NSUTF8StringEncoding];
    NSString *encodedString = [AOPUtility encoding:signString];
    return encodedString;
}
           

公鑰驗簽:

response為驗證字元串，signString為簽名字元串

+ (BOOL)decryptSHA256Data:(NSString *)signString response:(NSString *)response {
    // 使用雜湊演算法擷取字元串摘要
    NSData *outData = [self sha256:response];
    // 将公鑰字元串轉為SecKeyRef
    SecKeyRef publicKey = [AOPRSA addPublicKey:@"publicKey"];
    // 簽名base64解碼
    NSData *signData = [[NSData alloc] initWithBase64EncodedString:signString options:NSDataBase64DecodingIgnoreUnknownCharacters];
    // 簽名驗證
    size_t signedHashBytesSize = SecKeyGetBlockSize(publicKey);
    const void* signedHashBytes = [signData bytes];
    size_t hashBytesSize = CC_SHA256_DIGEST_LENGTH;
    uint8_t* hashBytes = malloc(hashBytesSize);
    if (!CC_SHA256([outData bytes], (CC_LONG)[outData length], hashBytes)) {
        return NO;
    }
    
    OSStatus status = SecKeyRawVerify(publicKey,
                                      kSecPaddingPKCS1SHA256,
                                      hashBytes,
                                      hashBytesSize,
                                      signedHashBytes,
                                      signedHashBytesSize);
    
    if (hashBytes)
        free(hashBytes);
    
    return status == errSecSuccess;
}