一篇搞定RSA加密与SHA签名|与Java完全同步

本文是投稿文章，作者： Panda_iOS

看到这篇文章的同学可幸福了，当时在做RSA加密与签名的时候网上的资料简直不要太老，做完后实在是忍受不下去了，这篇文章我会详细讲解iOS如何实现RSA加密与签名， 并且与Java完全同步，这是我的第二篇博客，若有什么不足之处还请大家指教。

基础知识

基本原理

实战

证书生成

• RSA加密这块公钥、私钥必不可少的。Apple是不支持直接使用字符串进行加密解密的，推荐使用p12文件。这边教大家去生成在加密中使用到的所有文件，并提供给Java使用，想当年这个公钥私钥搞了半天了。 %>_<%

• 生成模长为1024bit的私钥openssl genrsa -out private_key.pem 1024

• 生成certification require fileopenssl req -new -key private_key.pem -out rsaCertReq.csr

• 生成certification 并指定过期时间openssl x509 -req -days3650-in rsaCertReq.csr -signkey private_key.pem -out rsaCert.crt

• 生成公钥供iOS使用openssl x509 -outform der -in rsaCert.crt -out public_key.der

• 生成私钥供iOS使用 这边会让你输入密码，后期用到在生成secKeyRef的时候会用到这个密码openssl pkcs12 -export -out private_key.p12 -inkey private_key.pem -in rsaCert.crt

• 生成pem结尾的公钥供Java使用openssl rsa -in private_key.pem -out rsa_public_key.pem -pubout

• 生成pem结尾的私钥供Java使用openssl pkcs8 -topk8 -in private_key.pem -out pkcs8_private_key.pem -nocrypt

以上所有的步骤都是在终端下完成的哦 (^__^)

生成公钥和私钥的secKeyRef

//根据你的p12文件生成私钥对应的SecKeyRef 这边返回若是nil 请检查你p12文件的生成步骤 - (SecKeyRef)getPrivateKeyRefrenceFromData:(NSData*)p12Data password:(NSString*)password {  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; }

-

 //根据你的der文件公钥对应的SecKeyRef  - (SecKeyRef)getPublicKeyRefrenceFromeData:    (NSData*)derData {   SecCertificateRef myCertificate = SecCertificateCreateWithData(kCFAllocatorDefault, (__bridge CFDataRef)derData); SecPolicyRef myPolicy = SecPolicyCreateBasicX509(); SecTrustRef myTrust; OSStatus status = SecTrustCreateWithCertificates(myCertificate,myPolicy,&myTrust); SecTrustResultType trustResult; if (status == noErr) {     status = SecTrustEvaluate(myTrust, &trustResult); } SecKeyRef securityKey = SecTrustCopyPublicKey(myTrust); CFRelease(myCertificate); CFRelease(myPolicy); CFRelease(myTrust);  return securityKey; }

加密与解密

- (NSData*)rsaEncryptData:(NSData*)data {     SecKeyRef key = [self getPublicKey];     size_t cipherBufferSize = SecKeyGetBlockSize(key);     uint8_t *cipherBuffer = malloc(cipherBufferSize * sizeof(uint8_t));     size_t blockSize = cipherBufferSize - 11;       size_t blockCount = (size_t)ceil([data length] / (double)blockSize);       NSMutableData *encryptedData = [[NSMutableData alloc] init];     for (int i=0; i    

-

- (NSData*)rsaDecryptData:(NSData*)data { SecKeyRef key = [self getPrivatKey];  size_t cipherBufferSize = SecKeyGetBlockSize(key); size_t blockSize = cipherBufferSize; size_t blockCount = (size_t)ceil([data length] / (double)blockSize);  NSMutableData *decryptedData = [[NSMutableData alloc] init];  for (int i = 0; i < blockCount; i++) {     unsigned long bufferSize = MIN(blockSize , [data length] - i * blockSize);     NSData *buffer = [data subdataWithRange:NSMakeRange(i * blockSize, bufferSize)];          size_t cipherLen = [buffer length];     void *cipher = malloc(cipherLen);     [buffer getBytes:cipher length:cipherLen];     size_t plainLen = SecKeyGetBlockSize(key);     void *plain = malloc(plainLen);          OSStatus status = SecKeyDecrypt(key, kSecPaddingPKCS1, cipher, cipherLen, plain, &plainLen);          if (status != noErr) {         return nil;     }          NSData *decryptedBytes = [[NSData alloc] initWithBytes:(const void *)plain length:plainLen];     [decryptedData appendData:decryptedBytes]; }  return decryptedData; }

RSA加密中的Padding

• RSA_PKCS1_PADDING 填充模式，最常用的模式

  要求: 输入：必须 比 RSA 钥模长(modulus) 短至少11个字节, 也就是 RSA_size(rsa) – 11 如果输入的明文过长，必须切割，然后填充。

  输出：和modulus一样长

  根据这个要求，对于1024bit的密钥，block length = 1024/8 – 11 = 117 字节

• RSA_PKCS1_OAEP_PADDING

  输入：RSA_size(rsa) – 41

  输出：和modulus一样长

• RSA_NO_PADDING 不填充

  输入：可以和RSA钥模长一样长，如果输入的明文过长，必须切割， 然后填充

  输出：和modulus一样长

签名与验证

//对数据进行sha256签名   - (NSData *)rsaSHA256SignData:(NSData *)plainData {   SecKeyRef key = [self getPrivatKey];   size_t signedHashBytesSize = SecKeyGetBlockSize(key);   uint8_t* signedHashBytes = malloc(signedHashBytesSize);   memset(signedHashBytes, 0x0, signedHashBytesSize);   size_t hashBytesSize = CC_SHA256_DIGEST_LENGTH;   uint8_t* hashBytes = malloc(hashBytesSize);   if (!CC_SHA256([plainData bytes], (CC_LONG)[plainData length], hashBytes)) {     return nil; }        SecKeyRawSign(key,               kSecPaddingPKCS1SHA256,               hashBytes,               hashBytesSize,               signedHashBytes,               &signedHashBytesSize);     NSData* signedHash = [NSData dataWithBytes:signedHashBytes                                     length:(NSUInteger)signedHashBytesSize];     if (hashBytes)     free(hashBytes);     if (signedHashBytes)     free(signedHashBytes);     return signedHash;     }

-

      //这边对签名的数据进行验证 验签成功，则返回YES     - (BOOL)rsaSHA256VerifyData:(NSData *)plainData     withSignature:(NSData *)signature {     SecKeyRef key = [self getPublicKey];     size_t signedHashBytesSize = SecKeyGetBlockSize(key);     const void* signedHashBytes = [signature bytes];     size_t hashBytesSize = CC_SHA256_DIGEST_LENGTH;     uint8_t* hashBytes = malloc(hashBytesSize);     if (!CC_SHA256([plainData bytes], (CC_LONG)[plainData length], hashBytes)) {        return NO;     }       OSStatus status = SecKeyRawVerify(key,                                   kSecPaddingPKCS1SHA256,                                   hashBytes,                                   hashBytesSize,                                   signedHashBytes,                                   signedHashBytesSize);     return status == errSecSuccess;     }

文章到此就结束了，希望这篇文章对大家有所帮助。想看demo的请点击： XYRSACryptor