ios/Runner/RsaAndBase64/RSAEncryptor.m
#import "RSAEncryptor.h"
#import <Security/Security.h>

@implementation RSAEncryptor

static NSString *base64_encode_data(NSData *data){
  data = [data base64EncodedDataWithOptions:0];
  NSString *ret = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
  return ret;
}

static NSData *base64_decode(NSString *str){
  NSData *data = [[NSData alloc] initWithBase64EncodedString:str options:NSDataBase64DecodingIgnoreUnknownCharacters];
  return data;
}

#pragma mark - 使用'.der'公钥文件加密

//加密
+ (NSString *)encryptString:(NSString *)str publicKeyWithContentsOfFile:(NSString *)path{
  if (!str || !path)  return nil;
  return [self encryptString:str publicKeyRef:[self getPublicKeyRefWithContentsOfFile:path]];
}

//获取公钥
+ (SecKeyRef)getPublicKeyRefWithContentsOfFile:(NSString *)filePath{
  NSData *certData = [NSData dataWithContentsOfFile:filePath];
  if (!certData) {
    return nil;
  }
  SecCertificateRef cert = SecCertificateCreateWithData(NULL, (CFDataRef)certData);
  SecKeyRef key = NULL;
  SecTrustRef trust = NULL;
  SecPolicyRef policy = NULL;
  if (cert != NULL) {
    policy = SecPolicyCreateBasicX509();
    if (policy) {
      if (SecTrustCreateWithCertificates((CFTypeRef)cert, policy, &trust) == noErr) {
        SecTrustResultType result;
        if (SecTrustEvaluate(trust, &result) == noErr) {
          key = SecTrustCopyPublicKey(trust);
        }
      }
    }
  }
  if (policy) CFRelease(policy);
  if (trust) CFRelease(trust);
  if (cert) CFRelease(cert);
  return key;
}

+ (NSString *)encryptString:(NSString *)str publicKeyRef:(SecKeyRef)publicKeyRef{
  if(![str dataUsingEncoding:NSUTF8StringEncoding]){
    return nil;
  }
  if(!publicKeyRef){
    return nil;
  }
  NSData *data = [self encryptData:[str dataUsingEncoding:NSUTF8StringEncoding] withKeyRef:publicKeyRef];
  NSString *ret = base64_encode_data(data);
  return ret;
}

#pragma mark - 使用'.12'私钥文件解密

//解密
+ (NSString *)decryptString:(NSString *)str privateKeyWithContentsOfFile:(NSString *)path password:(NSString *)password{
  if (!str || !path) return nil;
  if (!password) password = @"";
  return [self decryptString:str privateKeyRef:[self getPrivateKeyRefWithContentsOfFile:path password:password]];
}

//获取私钥
+ (SecKeyRef)getPrivateKeyRefWithContentsOfFile:(NSString *)filePath password:(NSString*)password{
  
  NSData *p12Data = [NSData dataWithContentsOfFile:filePath];
  if (!p12Data) {
    return nil;
  }
  SecKeyRef privateKeyRef = NULL;
  NSMutableDictionary * options = [[NSMutableDictionary alloc] init];
  [options setObject: password forKey:(__bridge id)kSecImportExportPassphrase];
  CFArrayRef items = CFArrayCreate(NULL, 0, 0, NULL);
  OSStatus securityError = SecPKCS12Import((__bridge CFDataRef) p12Data, (__bridge CFDictionaryRef)options, &items);
  if (securityError == noErr && CFArrayGetCount(items) > 0) {
    CFDictionaryRef identityDict = CFArrayGetValueAtIndex(items, 0);
    SecIdentityRef identityApp = (SecIdentityRef)CFDictionaryGetValue(identityDict, kSecImportItemIdentity);
    securityError = SecIdentityCopyPrivateKey(identityApp, &privateKeyRef);
    if (securityError != noErr) {
      privateKeyRef = NULL;
    }
  }
  CFRelease(items);
  
  return privateKeyRef;
}

+ (NSString *)decryptString:(NSString *)str privateKeyRef:(SecKeyRef)privKeyRef{
  NSData *data = [[NSData alloc] initWithBase64EncodedString:str options:NSDataBase64DecodingIgnoreUnknownCharacters];
  if (!privKeyRef) {
    return nil;
  }
  data = [self decryptData:data withKeyRef:privKeyRef];
  NSString *ret = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
  return ret;
}

#pragma mark - 使用公钥字符串加密

/* START: Encryption with RSA public key */

//使用公钥字符串加密
+ (NSString *)encryptString:(NSString *)str publicKey:(NSString *)pubKey{
  NSData *data = [self encryptData:[str dataUsingEncoding:NSUTF8StringEncoding] publicKey:pubKey];
  NSString *ret = base64_encode_data(data);
  return ret;
}

+ (NSData *)encryptData:(NSData *)data publicKey:(NSString *)pubKey{
  if(!data || !pubKey){
    return nil;
  }
  SecKeyRef keyRef = [self addPublicKey:pubKey];
  if(!keyRef){
    return nil;
  }
  return [self encryptData:data withKeyRef:keyRef];
}

+ (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 = [self 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;
}

+ (NSData *)stripPublicKeyHeader:(NSData *)d_key{
  // Skip ASN.1 public key header
  if (d_key == nil) return(nil);
  
  unsigned long len = [d_key length];
  if (!len) return(nil);
  
  unsigned char *c_key = (unsigned char *)[d_key bytes];
  unsigned int  idx     = 0;
  
  if (c_key[idx++] != 0x30) return(nil);
  
  if (c_key[idx] > 0x80) idx += c_key[idx] - 0x80 + 1;
  else idx++;
  
  // PKCS #1 rsaEncryption szOID_RSA_RSA
  static unsigned char seqiod[] =
  { 0x30,   0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01,
    0x01, 0x05, 0x00 };
  if (memcmp(&c_key[idx], seqiod, 15)) return(nil);
  
  idx += 15;
  
  if (c_key[idx++] != 0x03) return(nil);
  
  if (c_key[idx] > 0x80) idx += c_key[idx] - 0x80 + 1;
  else idx++;
  
  if (c_key[idx++] != '\0') return(nil);
  
  // Now make a new NSData from this buffer
  return ([NSData dataWithBytes:&c_key[idx] length:len - idx]);
}

+ (NSData *)encryptData:(NSData *)data withKeyRef:(SecKeyRef) keyRef{
  const uint8_t *srcbuf = (const uint8_t *)[data bytes];
  size_t srclen = (size_t)data.length;
  
  size_t block_size = SecKeyGetBlockSize(keyRef) * sizeof(uint8_t);
  void *outbuf = malloc(block_size);
  size_t src_block_size = block_size - 11;
  
  NSMutableData *ret = [[NSMutableData alloc] init];
  for(int idx=0; idx<srclen; idx+=src_block_size){
    //NSLog(@"%d/%d block_size: %d", idx, (int)srclen, (int)block_size);
    size_t data_len = srclen - idx;
    if(data_len > src_block_size){
      data_len = src_block_size;
    }
    
    size_t outlen = block_size;
    OSStatus status = noErr;
    status = SecKeyEncrypt(keyRef,
                           kSecPaddingPKCS1,
                           srcbuf + idx,
                           data_len,
                           outbuf,
                           &outlen
                           );
    if (status != 0) {
      NSLog(@"SecKeyEncrypt fail. Error Code: %d", status);
      ret = nil;
      break;
    }else{
      [ret appendBytes:outbuf length:outlen];
    }
  }
  
  free(outbuf);
  CFRelease(keyRef);
  return ret;
}

/* END: Encryption with RSA public key */

#pragma mark - 使用私钥字符串解密

/* START: Decryption with RSA private key */

//使用私钥字符串解密
+ (NSString *)decryptString:(NSString *)str privateKey:(NSString *)privKey{
  if (!str) return nil;
  NSData *data = [[NSData alloc] initWithBase64EncodedString:str options:NSDataBase64DecodingIgnoreUnknownCharacters];
  data = [self decryptData:data privateKey:privKey];
  NSString *ret = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
  return ret;
}

+ (NSData *)decryptData:(NSData *)data privateKey:(NSString *)privKey{
  if(!data || !privKey){
    return nil;
  }
  SecKeyRef keyRef = [self addPrivateKey:privKey];
  if(!keyRef){
    return nil;
  }
  return [self decryptData:data withKeyRef:keyRef];
}

+ (SecKeyRef)addPrivateKey:(NSString *)key{
  NSRange spos = [key rangeOfString:@"-----BEGIN RSA PRIVATE KEY-----"];
  NSRange epos = [key rangeOfString:@"-----END RSA 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 = [self 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;
}

+ (NSData *)stripPrivateKeyHeader:(NSData *)d_key{
  // Skip ASN.1 private key header
  if (d_key == nil) return(nil);
  
  unsigned long len = [d_key length];
  if (!len) return(nil);
  
  unsigned char *c_key = (unsigned char *)[d_key bytes];
  unsigned int  idx     = 22; //magic byte at offset 22
  
  if (0x04 != c_key[idx++]) return nil;
  
  //calculate length of the key
  unsigned int c_len = c_key[idx++];
  int det = c_len & 0x80;
  if (!det) {
    c_len = c_len & 0x7f;
  } else {
    int byteCount = c_len & 0x7f;
    if (byteCount + idx > len) {
      //rsa length field longer than buffer
      return nil;
    }
    unsigned int accum = 0;
    unsigned char *ptr = &c_key[idx];
    idx += byteCount;
    while (byteCount) {
      accum = (accum << 8) + *ptr;
      ptr++;
      byteCount--;
    }
    c_len = accum;
  }
  
  // Now make a new NSData from this buffer
  return [d_key subdataWithRange:NSMakeRange(idx, c_len)];
}

+ (NSData *)decryptData:(NSData *)data withKeyRef:(SecKeyRef) keyRef{
  const uint8_t *srcbuf = (const uint8_t *)[data bytes];
  size_t srclen = (size_t)data.length;
  
  size_t block_size = SecKeyGetBlockSize(keyRef) * sizeof(uint8_t);
  UInt8 *outbuf = malloc(block_size);
  size_t src_block_size = block_size;
  
  NSMutableData *ret = [[NSMutableData alloc] init];
  for(int idx=0; idx<srclen; idx+=src_block_size){
    //NSLog(@"%d/%d block_size: %d", idx, (int)srclen, (int)block_size);
    size_t data_len = srclen - idx;
    if(data_len > src_block_size){
      data_len = src_block_size;
    }
    
    size_t outlen = block_size;
    OSStatus status = noErr;
    status = SecKeyDecrypt(keyRef,
                           kSecPaddingNone,
                           srcbuf + idx,
                           data_len,
                           outbuf,
                           &outlen
                           );
    if (status != 0) {
      NSLog(@"SecKeyEncrypt fail. Error Code: %d", status);
      ret = nil;
      break;
    }else{
      //the actual decrypted data is in the middle, locate it!
      int idxFirstZero = -1;
      int idxNextZero = (int)outlen;
      for ( int i = 0; i < outlen; i++ ) {
        if ( outbuf[i] == 0 ) {
          if ( idxFirstZero < 0 ) {
            idxFirstZero = i;
          } else {
            idxNextZero = i;
            break;
          }
        }
      }
      
      [ret appendBytes:&outbuf[idxFirstZero+1] length:idxNextZero-idxFirstZero-1];
    }
  }
  
  free(outbuf);
  CFRelease(keyRef);
  return ret;
}

/* END: Decryption with RSA private key */

@end
