一篇搞定RSA加密與SHA簽名|與Java完全同步

發表於2016-06-27

看到這篇文章的同學可幸福了，當時在做RSA加密與簽名的時候網上的資料簡直不要太老，做完後實在是忍受不下去了，這篇文章我會詳細講解iOS如何實現RSA加密與簽名，並且與Java完全同步，這是我的第二篇部落格，若有什麼不足之處還請大家指教。

基礎知識

什麼是RSA？
答：RSA是一種非對稱加密演算法，常用來對傳輸資料進行加密，配合上數字摘要演算法，也可以進行文字簽名。
RSA加密中padding？
答：padding即填充方式，由於RSA加密演算法中要加密的明文是要比模數小的，padding就是通過一些填充方式來限制明文的長度。後面會詳細介紹padding的幾種模式以及分段加密。
加密和加簽有什麼區別？
答：加密：公鑰放在客戶端，並使用公鑰對資料進行加密，服務端拿到資料後用私鑰進行解密；
加簽：私鑰放在客戶端，並使用私鑰對資料進行加簽，服務端拿到資料後用公鑰進行驗籤。
前者完全為了加密；後者主要是為了防惡意攻擊，防止別人模擬我們的客戶端對我們的伺服器進行攻擊，導致伺服器癱瘓。

基本原理

RSA使用“金鑰對”對資料進行加密解密，在加密解密前需要先生存公鑰（Public Key）和私鑰（Private Key）。
公鑰(Public key): 用於加密資料. 用於公開, 一般存放在資料提供方, 例如iOS客戶端。
私鑰(Private key): 用於解密資料. 必須保密, 私鑰洩露會造成安全問題。
iOS中的Security.framework提供了對RSA演算法的支援，這種方式需要對密匙對進行處理, 根據public key生成證照, 通過private key生成p12格式的密匙。想想jave直接用字串進行加密解密簡單多了。(⊙o⊙)…

實戰

證照生成

RSA加密這塊公鑰、私鑰必不可少的。Apple是不支援直接使用字串進行加密解密的，推薦使用p12檔案。這邊教大家去生成在加密中使用到的所有檔案，並提供給Java使用，想當年這個公鑰私鑰搞了半天了。 %>_

生成模長為1024bit的私鑰
openssl genrsa -out private_key.pem 1024

生成certification require file
openssl req -new -key private_key.pem -out rsaCertReq.csr

生成certification 並指定過期時間
openssl x509 -req -days 3650 -in rsaCertReq.csr -signkey private_key.pem -out rsaCert.crt

生成公鑰供iOS使用
openssl x509 -outform der -in rsaCert.crt -out public_key.der

生成私鑰供iOS使用這邊會讓你輸入密碼，後期用到在生成secKeyRef的時候會用到這個密碼
openssl pkcs12 -export -out private_key.p12 -inkey private_key.pem -in rsaCert.crt

生成pem結尾的公鑰供Java使用
openssl rsa -in private_key.pem -out rsa_public_key.pem -pubout

生成pem結尾的私鑰供Java使用openssl pkcs8 -topk8 -in private_key.pem -out pkcs8_private_key.pem -nocrypt

以上所有的步驟都是在終端下完成的哦 (^__^)

生成公鑰和私鑰的secKeyRef

//根據你的p12檔案生成私鑰對應的SecKeyRef 這邊返回若是nil 請檢查你p12檔案的生成步驟
- (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;
}

//根據你的p12檔案生成私鑰對應的SecKeyRef 這邊返回若是nil 請檢查你p12檔案的生成步驟

- (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;

}

–

 //根據你的der檔案公鑰對應的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;
}

//根據你的der檔案公鑰對應的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;

}

加密與解密

- (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*)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

- (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

RSA加密中的Padding

RSA_PKCS1_PADDING 填充模式，最常用的模式
要求: 輸入：必須比 RSA 鑰模長(modulus) 短至少11個位元組, 也就是　RSA_size(rsa) – 11 如果輸入的明文過長，必須切割，然後填充。
輸出：和modulus一樣長
根據這個要求，對於1024bit的金鑰，block length = 1024/8 – 11 = 117 位元組
RSA_PKCS1_OAEP_PADDING
輸入：RSA_size(rsa) – 41
輸出：和modulus一樣長
RSA_NO_PADDING　　不填充
輸入：可以和RSA鑰模長一樣長，如果輸入的明文過長，必須切割，　然後填充
輸出：和modulus一樣長

簽名與驗證

//對資料進行sha256簽名
  - (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;
    }

//對資料進行sha256簽名

- (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;

}

–

      //這邊對簽名的資料進行驗證 驗籤成功，則返回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;
    }

//這邊對簽名的資料進行驗證驗籤成功，則返回YES

- (BOOL)rsaSHA256VerifyData:(NSData *)plainData withSignature:(NSData *)signature {